Patent Application
20250161539
The present invention relates to particles formed from protein biocoacervates and biomaterials as well as methods of making and using said particles and the methods of making and using particle protein biocoacervates and biomaterials. More specifically the present invention relates to collagen-based particles, such as collagen elastin hydrogel microparticles (“CEHM”), and the injection of collagen-based particles, such as CEHM formed from protein biocoacervates and biomaterials, as a liquid dispersion through a needle into tom or otherwise damaged tissue (e.g. tendons and ligaments) for purposes of accelerating and facilitating healing of said tissue.
Protein materials are generally present in the tissues of many biological species. Therefore, the development of medical devices that utilize protein materials, which mimic and/or are biocompatible with the host tissue, have been pursued as desirable devices due to their acceptance and incorporation into such tissue. For example, the utilization of protein materials to prepare drug delivery devices, tissue grafts, wound healing and other types of medical devices have been perceived as being valuable products due to their biocompatibility potential.
The use of dried protein, gelatins and/or hydrogels have previously been used as components for the preparation of devices for drug delivery, wound healing, tissue repair, medical device coating and the like. However, many of these previously developed devices do not offer sufficient strength, stability and support when administered to tissue environments that contain high solvent content, such as the tissue environment of the human body. Furthermore, the features of such medical devices that additionally incorporated pharmacologically active agents often provided an ineffective and uncontrollable release of such agents, thereby not providing an optimal device for controlled drug delivery.
A concern and disadvantage of such devices is the rapid dissolving or degradation of the device upon entry into an aqueous or high solvent environment. For example, gelatins and compressed dry proteins tend to rapidly disintegrate and/or lose their form when placed in an aqueous environment. Therefore, many dried or gelatin type devices do not provide optimal drug delivery and/or structural and durability characteristics. Also, gelatins often contain large amounts of water or other liquid that makes the structure fragile, non-rigid and unstable. It is also noted that the proteins of gelatins usually denature during preparation caused by heating, the gelation process and/or crosslinking procedures, thereby reducing or eliminating the beneficial characteristics of the protein. Alternatively, dried protein devices are often very rigid, tend to be brittle and are extremely susceptible to disintegration upon contact with solvents. The deficiencies gelatins and dried matrices have with regards to rapid degradation and structural limitations make such devices less than optimal for the controlled release of pharmacologically active agents, or for operating as the structural scaffolding for devices such as vessels, stents or wound healing implants.
Hydrogel-forming polymeric materials, in particular, have been found to be useful in the formulation of medical devices, such as drug delivery devices. See, e.g., Lee, J. Controlled Release, 2, 277 (1985). Hydrogel-forming polymers are polymers that are capable of absorbing a substantial amount of water to form elastic or inelastic gels. Many non-toxic hydrogel-forming polymers are known and are easy to formulate. Furthermore, medical devices incorporating hydrogel-forming polymers offer the flexibility of being capable to be implantable in liquid or gelled form. Once implanted, the hydrogel forming polymer absorbs water and swells. The release of a pharmacologically active agent incorporated into the device takes place through this gelled matrix via a diffusion mechanism.
However, many hydrogels, although biocompatible, are not biodegradable or are not capable of being remodeled and incorporated into the host tissue. Furthermore, most medical devices comprising of hydrogels require the use of undesirable organic solvents for their manufacture. Residual amounts of such solvents could potentially remain in the medical device, where they could cause solvent-induced toxicity in surrounding tissues or cause structural or pharmacological degradation to the pharmacologically active agents incorporated within the medical device. Finally, implanted medical devices that incorporate pharmacologically active agents in general, and such implanted medical devices comprising hydrogel-forming polymers in particular, oftentimes provide suboptimal release characteristics of the drug(s) incorporated therein. That is, typically, the release of pharmacologically active agents from an implanted medical device that includes pharmacologically active agent(s) is irregular, e.g., there is an initial burst period when the drug is released primarily from the surface of the device, followed by a second period during which little or no drug is released, and a third period during which most of the remainder of the drug is released or alternatively, the drug is released in one large burst.
Also, particles made from decellularized tissue, such as human, bovine or porcine tissue, have also been utilized in various medical applications. These decellularized tissue particles have been utilized in various applications as subcutaneous tissue fill materials. Furthermore, these substances have been shown to have some biocompatible properties, but generally are difficult to work with due to the already established matrix present in such materials. Furthermore, such tissue related materials are not conducive to the homogenous distribution of pharmacologically active agents within their matrix structure.
Additionally, other polymeric materials, such as polyvinyl pyrrolidone, polyvinyl alcohols, polyurethanes, polytetrafluoroethylene (PTFE), polyvinyl ethers, polyvinylidene halides, polyacrylonitrile, polyvinyl ketones; polyvinyl aromatics, ethylene-methyl methacrylate copolymers, polyamides, polycarbonates, polyoxymethylenes, polyimides, polyethers and other polymeric materials have been utilized as coatings for medical devices, drug delivery devices, tissue fillers or grafts, sutures and for other medical applications. These materials possess some biocompatible attributes, but are limited by their capacity to be non-thrombogenic, to be non-inflammatory, to allow direct cell integration, to deliver therapeutic agents, to allow regeneration of host tissue into the graft and/or to allow other graft materials to adhere to their surface.
The present invention relates to particles formed from protein biocoacervates and biomaterials as well as methods of making and using said particles and the methods of making and using particle protein biocoacervates and biomaterials. More specifically the present invention relates to collagen-based particles, such as collagen elastin hydrogel microparticles (“CEHM”), and the injection of collagen-based particles, such as CEHM formed from protein biocoacervates and biomaterials, as a liquid dispersion through a needle into torn or otherwise damaged tissue (e.g. tendons and ligaments) for purposes of accelerating and facilitating healing of said tissue.
The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments.
Subject matter hereof may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying figures, in which:
While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims.
The embodiments of the invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention.
An illustration of an embodiment of the particles of the present invention is depicted in
One example of an alternative method to make particles is by homogenizing a crosslinked protein-based biocoacervate thereby producing particles. In such a method a block or other shape of the protein-based biocoacervate may be crosslinked with a crosslinking agent, such as 0.01M to 10M gluteraldehyde or 1,4-butandiol diglycidylether. Once crosslinked, the protein-based biocoacervate is next placed in a homogenizer and cut into particles. One or more additional crosslinking steps may be performed after homogenization of the protein-based biocoacervate by exposing the particles to a second solution including one or more crosslinking agents, such as gluteraldehye, formaldehyde, glyoxal or 1,4-butandiol diglycidylether. It is noted that alternative crosslinking solutions and conditions (e.g. pH, temperature, solvents . . . ) may be utilized for the extra crosslinking steps.
Generally, particles of the present invention can vary in size but are normally approximately 10 nm-5 mm, preferably 500 nm-2.5 mm and more preferably 1-1000 μm. A characteristic of the particles produced from the protein-based biocoacervate material is that they no longer aggregate when in the particulate state. Furthermore, prior studies have demonstrated that the particles do not aggregate in a carrier solution, e.g., saline, and are easily delivered through small gauge needles, e.g., 16-30 gauge needles, and, preferably, 27-30 gauge needles. The particles can be made to disassociate at very slow or fast rates in aqueous solutions.
In various embodiments of the present invention, the particles can be characterized as collagen elastin hydrogel microparticles (“CEHM”) capable of injection into tom or damaged tissue utilizing a small gauge needle. The CEHM can be tailored using fabrication methods of the present invention to have desirable mechanical properties that can match or be substantially similar to properties of the torn or damaged tissue. In some instance, the fabrication methods can be controlled to provide a desired density for the CEHM for example, by controlling water content within the CEHM. A representative injection procedure of the present invention comprises a syringe injection of such CEHM as a liquid dispersion into a desired site. Saline is a solution that may be employed to prepare such a liquid dispersion, e.g., slurry, but any biocompatible solution may be utilized. Also, lubricants, such as polyvinylalcohol, polyethylene glycol, dextran, proteins (human, bovine, porcine, or equine) such as collagen, elastin, albumin, proteoglycans or glycans, hyaluronic acid, lipids, oils or any other lubricious agent, may be added to the CEHM or liquid dispersion to facilitate injection of the CEHM through a needle syringe assembly. These lubricants assist in facilitating injection of the CEHM through a syringe and also may be made to act as an immunogenic mask, thereby reducing potential inflammatory and/or immune responses. In various embodiments of the present invention the lubricants may comprise approximately less than 5% and preferably less than 1% of the particle or slurry contents. Saline has been selected for the initial material for several reasons including its common use in medical procedures and its availability in a sterile form.
The particles or particle slurry may be delivered as a liquid dispersion through small gauge needles, e.g., 16-30 gauge needles, and preferably, 27-30 gauge needles. For example,
The protein-based biocoacervates, biomaterials and devices of the present invention comprise an amorphous material that generally includes one or more primary proteins, one or more glycosaminoglycans and one or more biocompatible solvents. The amorphous material of the present invention tends to have no real or apparent crystalline or fibrous form that can be seen by the naked eye or by light microscope at 400 times or less. Such materials are different from other protein and glycosaminoglycan materials, which tend to be crystalline, fibrous or appears similar to balls of yarn. Also, the biocoacervate and a number of the biomaterial embodiments of the present invention tend to have thermoplastic and viscoelastic properties. In various embodiments of the present invention the biocoacervates, biomaterials and devices may also include one or more secondary proteins.
Additionally, embodiments of the biocoacervates, biomaterials and devices of the present invention may also include one or more therapeutic pharmacologically active agents and/or one or more additive materials, such as structural or polymeric materials. It is noted that additional additive materials, such as humectants, biocompatible polymers (e.g. proteins, polyanhydride, polylactic acid, polyurethane and the like) and/or therapeutic entities, such as stents and other medical devices may be included in the material to provide various beneficial features such as mucoadhesion, strength, elasticity, structure, enhanced biocompatibility, enhanced drug delivery and drug absorption, therapeutic functions or any other desirable characteristics. In various embodiments of the present invention, the biocoacervates or biomaterials possess a relatively homogeneous distribution of the components, including a homogenous distribution of any pharmacologically active agents and additive materials.
The biocoacervates, biomaterials and the related devices of the present invention are designed to retain the protein's natural activity and possess the capability of being formed into various sizes and configurations with structural integrity. Embodiments of the biocoacervates, biomaterials and the related devices are further designed to mimic the architectural framework of the body to support natural tissue growth. In various embodiments of the present invention the biocoacervates, biomaterials and the related devices of the present invention are biointegratable thereby allowing the integration and remodeling of the material by the host tissue.
As previously mentioned, the biocoacervates, biomaterials and the related devices normally comprise one or more biocompatible primary proteins and, in various embodiments, one or more secondary proteins. The primary and secondary proteins are generally soluble or are solubilized. Primary proteins normally have an affinity to bind with glycosaminoglycans and in some instances other proteins thereby indicating that functional groups are present on the primary proteins that attract and retain the glycosaminoglycans and possibly other proteins. Additionally, primary proteins when mixed with glycosaminoglycans in solution under proper conditions will generally form a precipitate that falls out of solution, whereas the secondary proteins will not form such a precipitate when placed in solution with glycosaminoglycans. Additionally, secondary proteins generally have a more limited binding affinity with glycosaminoglycans than their primary protein counterparts but are attracted and retained by the primary proteins in the presence of glycosaminoglycans. However, secondary proteins have been found to add very beneficial characteristics to the biocoacervates of the present invention, such as elasticity, strength, biodurability, biocompatibility and the like.
Generally, the amount of primary protein found in embodiments of the biocoacervate or biomaterials of the present invention may vary between from about 10% to about 90%, preferably from about 20% to 80% by weight, and most preferably from about 50% to 70% by weight based upon the weight of the final biocoacervate or biomaterial. Alternatively, the amount of secondary protein may vary between from about 0% to about 40%, preferably from about 10% to 30% by weight, and most preferably from about 15% to 25% by weight based upon the weight of the final biocoacervate or biomaterial.
The primary and secondary proteins utilized in the present invention may be synthetic proteins, genetically-engineered proteins, natural proteins or any combination thereof. In many embodiments of the present invention, the biocoacervates, biomaterials and the related devices include water-absorbing, biocompatible primary and secondary proteins. The utilization of a water-absorbing biocompatible protein included in the biocoacervate or biomaterial provides the advantage that, not only will the biocoacervates or biomaterials be bioresorbable, but may remodel to mimic and support the tissue it contacts. That is, the metabolites of any degradation and/or resorption of the water-absorbing biocompatible protein may be reused by the patient's body rather than excreted.
Additionally, the primary and secondary proteins of the present invention are generally purified and in a free-form state. Normally, free-form proteins are comprised of protein molecules that are not substantially crosslinked to other protein molecules, unlike tissues (e.g. decellularized tissue) or gelatins. Normally, tissue or gelatin is already in a crosslinked matrix form and is thereby limited in forming new intermolecular or intramolecular bonds. Therefore, the free-form protein molecules when added to solvent have the capacity to freely associate or intermingle with each other and other molecules or particles, such as solvents, pharmacologically active agents, additives and other proteins to form a homogeneous structure. Additionally, the binding sites of the free-form primary proteins for the attraction and retention of glycosaminoglycans or secondary proteins are generally available for binding whereas proteins derived from tissues and gelatins have generally lost some or most of its binding or interaction capability.
As previously suggested, the primary and secondary proteins utilized may either be naturally occurring, synthetic or genetically engineered. Naturally occurring primary proteins that may be utilized in biocoacervates, biomaterials and related devices of the present invention include, but are not limited to the following and their derivatives: collagen, bone morphogenic protein and its isoforms that contain glucosaminoglycan binding sites, albumin, interleukins, epidermal growth factors, fibronectin, laminin, thrombin, aprotinin, antithrombin III and any other biocompatible natural protein that includes glucosaminoglycan binding sites. Naturally occurring secondary proteins that may be utilized in biocoacervates, biomaterials and related devices of the present invention include, but are not limited to the following and their derivatives: fibrin, fibrinogen, elastin, albumin, ovalbumin, keratin, silk, silk fibroin, actin, myosin, thrombin, aprotinin, antithrombin III and any other biocompatible natural protein that have an affinity to primary proteins in the presence of glucosaminoglycans.
Examples of primary and secondary proteins that are commercially available and may be utilized in some embodiments of the present invention include Type I soluble or insoluble collagen, insoluble or soluble elastin, and soluble albumen manufactured by Kenscy Nash Corporation, 55 East Uwchlan Avenue, Exton, Pa. 19341, Sigma-Aldrich Corporation, St. Louis, Mo., USA or Elastin Products Company, Inc., P.O. Box 568, Owensville, Mo., USA 65066. It is noted that in various embodiments of the present invention, the insoluble proteins listed above would be processed to a soluble form prior to or during synthesis of a biocoacervate or biomaterial. It is further noted that combinations of natural proteins may be utilized to optimize desirable characteristics of the resulting biocoacervates and biomaterials, such as strength, degradability, resorption, etc. Inasmuch as heterogeneity in molecular weight, sequence and stereochemistry can influence the function of a protein in a biocoacervate or biomaterial, in some embodiments of the present invention synthetic or genetically engineered proteins are preferred in that a higher degree of control can be exercised over these parameters.
As previously suggested the primary and secondary proteins of the present invention are generally purified proteins. The purity of each natural protein component mixed in the solution phase (the process of making the coacervates and biomaterials will be described further below) during production of the coacervate include 20% or less other proteins or impurities, preferably 10% or less other proteins or impurities, more preferably 3% or less other proteins or impurities and if available ideally 1% or less other proteins or impurities.
Synthetic primary and secondary proteins are generally prepared by chemical synthesis utilizing techniques known in the art and generally mimic the equivalent natural protein's or natural protein derivative's chemical and/or structural makeup. Furthermore, individual proteins may be chemically combined with one or more other proteins of the same or different type to produce a dimer, trimer or other multimer. A simple advantage of having a larger protein molecule is that it will make interconnections with other protein molecules to create a stronger coacervate or biomaterial that is less susceptible to dissolving in aqueous solutions and provides additional protein structural and biochemical characteristics.
Additionally, protein molecules can also be chemically combined to any other chemical so that the chemical does not release from the biocoacervate or biomaterial. In this way, the chemical entity can provide surface modifications to the biocoacervate or biomaterial or structural contributions to the biocoacervate or biomaterial to produce specific characteristics. The surface modifications can enhance and/or facilitate cell attachment depending on the chemical substance or the cell type. The structural modifications can be used to facilitate or impede dissolution or enzymatic degradation of the biocoacervate or biomaterial, as well as increase the affinity of the biocoacervate to interact (e.g. bind or coat) with other materials.
Synthetic biocompatible proteins may be cross-linked, linked, bonded, chemically and/or physically linked to pharmacological active agents, enzymatically, chemically or thermally cleaved and utilized alone or in combination with other biocompatible proteins or partial proteins e.g. peptides, to form the biocoacervates or biomaterials. Examples of such synthetic biocompatible proteins include, but are not limited to heparin-protein, heparin-polymer, chondroitin-protein, chondroitin-polymer, heparin-cellulose, heparin-alginate, heparin-polylactide, GAGs-collagen, heparin-collagen, collagen-elastin-heparin, collagen-albumin, collagen-albumin-heparin, collagen-albumin-elastin-heparin, collagen-hyaluronic acid, collagen-chondroitin-heparin, collagen-chondroitin and the like.
A specific example of a particularly preferred genetically engineered primary protein for use in the biocoacervates or biomaterials of the present invention is human collagen produced by FibroGen, Inc., 225 Gateway Blvd., South San Francisco, Calif. 94080. Other examples of particularly preferred genetically engineered proteins for use in the biocoacervates or biomaterials of the present invention are commercially available under the nomenclature “ELP”, “SLP”, “CLP”, “SLPL”, “SLPF” and “SELP” from Protein Polymer Technologies, Inc. San Diego, Calif. ELP's, SLP's, CLP's, SLPL's, SLPF's and SELP's are families of genetically engineered protein polymers consisting of silklike blocks, elastinlike blocks, collagenlike blocks, lamininlike blocks, fibronectinlike blocks and the combination of silklike and elastinlike blocks, respectively. The ELP's, SLP's, CLP's, SLPL's, SLPF's and SELP's are produced in various block lengths and compositional ratios.
Generally, blocks include groups of repeating amino acids making up a peptide sequence that occurs in a protein. Genetically engineered proteins are qualitatively distinguished from sequential polypeptides found in nature in that the length of their block repeats can be greater (up to several hundred amino acids versus less than ten for sequential polypeptides) and the sequence of their block repeats can be almost infinitely complex. Table A, below, depicts examples of genetically engineered blocks. Table A and a further description of genetically engineered blocks may be found in Franco A. Ferrari and Joseph Cappello, Biosynthesis of Protein Polymers, in: Protein-Based Materials, (eds., Kevin McGrath and David Kaplan), Chapter 2, pp. 37-60, Birkhauser, Boston (1997).
Generally, Table A recites repetitive amino acid sequences of selected protein polymers. Listed abbreviations include: SLP=silk like protein; SLPF=SLP containing the RGD sequence from fibronectin, SLPL 3/0 and SLIT 3/1=SLP containing two difference sequences from laminin protein; ELP=elastin like protein; SELP=silk elastin like protein; CLP=collagen like protein; CLP-CB=CLP containing a cell binding domain from human collagen; and KLP=keratin like protein.
The nature of the elastin like blocks, and their length and position within the monomers influences the water solubility of the SELP polymers. For example, decreasing the length and/or content of the silklike block domains, while maintaining the length of the elastin like block domains, increases the water solubility of the polymers. For a more detailed discussion of the production of SLP's, ELP's, CLP's, SLPF's and SELP's as well as their properties and characteristics see, for example, in J. Cappello et al., Biotechnol. Prog., 6, 198 (1990), the full disclosure of which is incorporated by reference herein. One preferred SELP, SELP7, has an elastin:silk ratio of 1.33, and has 45% silklike protein material and is believed to have weight average molecular weight of 80,338.
The biocoacervates and biomaterials utilized in various embodiments of the present invention also include one or more glycosaminoglycans, proteoglycans or mucopolysaccharides. Glycosaminoglycans can be derived or synthesized from any source, including artificial, animal or plant sources. Examples of glycosaminoglycans that are utilized in the coacervates and biomaterials of the present invention include but are not limited to the heparin, heparin sulfate, keratan sulfate, dermatin, dermatin sulfate, heparin-hyaluronic acid, chondroitin, chondroitin sulfate (e.g. chondroitin 6-sulfate and chondroitin 4-sulfate), chitin, chitosan, acetyl-glucosamine, hyaluronic acid, aggrecan, decorin, biglycan, fibromodulin, lumican, combinations, glycosaminoglycan complexes or compounds and the like.
The biocoacervates and biomaterials utilized in various embodiments of the present invention also include one or more biocompatible solvents. Any biocompatible solvent may be utilized in the method and corresponding coacervate or biomaterial of the present invention. By using a biocompatible solvent, the risk of adverse tissue reactions to residual solvent remaining in the device after manufacture is minimized. Additionally, the use of a biocompatible solvent reduces the potential structural and/or pharmacological degradation of the pharmacologically active agent that some such pharmacologically active agents undergo when exposed to organic solvents. Suitable biocompatible solvents for use in the method of the present invention include, but are not limited to, water; dimethyl sulfoxide (DMSO); biocompatible alcohols, such as polyols, glycerol, methanol and ethanol; various acids, such as acetic acid, citric acid, ascorbic acid and formic acid; oils, such as olive oil, peanut oil and the like; glycols, such as ethylene glycol; and combinations of these and the like. Preferably, the biocompatible solvent comprises water. The amount of biocompatible solvent utilized in the formation of the present invention will preferably be that amount sufficient to result in the primary and secondary proteins being fluid and flowable enough to allow the protein to enter into solution. Generally, the amount of biocompatible solvent suitable for use in the method of the present invention will range from about 100% to about 50,000% by weight, in some embodiments from about 200% to about 10,000% by weight, and in other embodiments from about 300% to about 2000% by weight, based upon the weight and/or amount of the protein utilized.
In addition to the biocompatible protein(s) and the biocompatible solvent(s), the coacervates or biomaterial that may be utilized in various embodiments of the present invention may include one or more pharmacologically active agents. Generally, the distribution of the pharmacologically active agent is rendered substantially homogenous throughout the resulting coacervate or biomaterial. As used herein, “pharmacologically active agent” generally refers to a pharmacologically active agent having a direct or indirect beneficial therapeutic effect upon introduction into a host. Pharmacologically active agents further includes neutraceuticals.
The phrase “pharmacologically active agent” is also meant to indicate prodrug forms thereof. A “prodrug form” of a pharmacologically active agent means a structurally related compound or derivative of the pharmacologically active agent which, when injected to a host is converted into the desired pharmacologically active agent. A prodrug form may have little or none of the desired pharmacological activity exhibited by the pharmacologically active agent to which it is converted. Representative examples of pharmacologically active agents that may be suitable for use in the coacervates, biomaterials and related devices of the present invention include, but are not limited to, (grouped by therapeutic class):
Additionally, the biocoacervates and biomaterials of the present invention are particularly advantageous for the encapsulation, incorporation and/or scaffolding of macromolecular pharmacologically active agents such as pharmacologically active proteins, enzymes, peptides, polysaccharides, nucleic acids, cells, tissues, and the like. It is noted that the encapsulation of certain pharmacologically active agents with the biocoacervate or biomaterial of the present invention reduces, if not prevents, the potential for undesirable reaction with bodily fluids or tissues that may otherwise occur upon injection of a reactive drug delivery device without protective encapsulation. Immobilization of macromolecular pharmacologically active agents into or onto biomaterials can be difficult due to the ease with which some of these macromolecular agents denature when exposed to organic solvents, some constituents present in bodily fluids or to temperatures appreciably higher than room temperature. However, since the method of the present invention utilizes biocompatible solvents such as water, DMSO or ethanol the risk of the denaturation of these types of materials is reduced.
Furthermore, due to the size of these macromolecular pharmacologically active agents, these agents may be encapsulated within the coacervates/biocoacervates or biomaterials of the present invention and thereby are protected from constituents of bodily fluids that would otherwise denature them. Thus, the coacervates and biomaterials of the present invention allow these macromolecular agents to exert their therapeutic effects, while yet protecting them from denaturation or other structural degradation. Also, embodiments of the present invention include coacervates or biomaterials that provide presentation of therapeutic moieties of attached compounds to the biological surroundings.
Examples of cells which can be utilized as the pharmacologically active agent in the coacervates, biomaterials and related devices of the present invention include primary cultures as well as established cell lines, including transformed cells. Examples of these include, but are not limited to pancreatic islet cells, human foreskin fibroblasts, Chinese hamster ovary cells, beta cell insulomas, lymphoblastic leukemia cells, mouse 3T3 fibroblasts, dopamine secreting ventral mesencephalon cells, neuroblastoid cells, adrenal medulla cells, endothelial cells, epithelial cells, hepatocytes, T-cells, combinations of these, and the like. As can be seen from this partial list, cells of all types, including dermal, neural, blood, organ, stem, muscle, glandular, reproductive and immune system cells, as well as cells of all species of origin, can be encapsulated and/or attached successfully by this method.
Examples of pharmacologically active proteins which can be incorporated into the coacervates or biomaterials of the present invention include, but are not limited to, hemoglobin, bone morphogenic protein, desmopressin, vasporessin, oxytocin, adrenocorticocotrophic hormone, epidermal growth factor, prolactin, luliberin or luteinising hormone releasing factor, human growth factor, and the like; enzymes such as adenosine deaminase, superoxide dismutase, xanthine oxidase, and the like: enzyme systems; blood clotting factors; clot inhibitors or clot dissolving agents such as streptokinase and tissue plasminogen activator, antigens for immunization; hormones; polysaccharides such as heparin; oligonucleotides; bacteria and other microbial microorganisms including viruses; monoclonal antibodies, such as herceptin and rituximab; vitamins; cofactors; growth factors; retroviruses for gene therapy, combinations of these and the like.
An efficacious amount of the aforementioned pharmacologically active agent(s) can easily be determined by those of ordinary skill in the art taking into consideration such parameters as the particular pharmacologically active agent chosen, the size and weight of the patient, the desired therapeutic effect, the pharmacokinetics of the chosen pharmacologically active agent, and the like, as well as by reference to well-known resources such as Physicians' Desk Reference®: PDR—52 ed (1998)—Medical Economics 1974. In consideration of these parameters, it has been found that a wide range exists in the amount of the pharmacologically active agent(s) capable of being incorporated into and subsequently released from or alternatively allowed to exert the agent's therapeutic effects from within the coacervates or biomaterials.
More specifically, the amount of pharmacologically active agent that may be incorporated into and then either released from or active from within the coacervates or biomaterials may range from about 0.001% to about 60%, more preferably, from about 0.05% to about 40%, most preferably from about 0.1% to 20%, based on the weight of the coacervate material or biomaterial. It is important to note that the pharmacologically active agents are generally homogenously distributed throughout the coacervate material or biomaterial thereby allowing for a controlled release of these agents.
Finally, one or more additive materials may be added to the coacervate or biomaterial to manipulate the material properties and thereby add additional structure, enhance absorbance of the pharmacologically active agents, enhance membrane permeation by pharmacologically active agents (cell and tissue), enhance mucoadhesion or modify the release of pharmacologically active agents. That is, while a coacervate material or biomaterial that includes a relatively fast-degrading protein material without a particular additive material may readily degrade thereby releasing drug relatively quickly upon injection, a coacervate material or biomaterial that includes a particular polymeric material, such as polyanhydride, will degrade slowly, as well as release the pharmacologically active agent(s) over a longer period of time.
Examples of biodegradable and/or biocompatible additive materials suitable for use in the coacervate or biomaterial of the present invention include, but are not limited to polyurethanes, vinyl homopolymers and copolymers, acrylate homopolymers and copolymers, polyethers, cellulosics, epoxies, polyesters, acrylics, nylons, silicones, polyanhydride, polyethylene terephthalate), polyacetal, poly(lactic acid), poly(ethylene oxide)/poly(butylene terephthalate) copolymer, polycarbonate, poly(tetrafluoroethylene) (PTFE), polycaprolactone, polyethylene oxide, polyethylene glycol, poly(vinyl chloride), polylactic acid, polyglycolic acid, polypropylene oxide, poly(alkylene)glycol, polyoxyethylene, sebacic acid, polyvinyl alcohol (PVA), 2-hydroxyethyl methacrylate (HEMA), polymethyl methacrylate, 1,3-bis(carboxyphenoxy)propane, lipids, phosphatidylcholine, triglycerides, polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), poly(ethylene oxide) (PEO), poly ortho esters, poly(amino acids), polycynoacrylates, polyphophazenes, polysulfone, polyamine, poly(amido amines), fibrin, glycosaminoglycans such as hyaluronic acid or chondroitin sulfate, bioceramic materials such as hydroxyapetite, graphite, flexible fluoropolymer, isobutyl-based, isopropyl styrene, vinyl pyrrolidone, cellulose acetate dibutyrate, silicone rubber, copolymers of these, and the like.
Additionally, hydrophobic additives such as lipids can be incorporated into the coacervates or biomaterials to extend the duration of drug release or facilitate the incorporation of hydrophobic drugs. Exemplary hydrophobic substances include lipids, e.g., tristearin, ethyl stearate, phosphotidycholine, polyethylene glycol (PEG); fatty acids, e.g., sebacic acid erucic acid; combinations of these and the like. A particularly preferred hydrophobic additive useful to extend the release of the pharmacologically active agents comprises a combination of a dimer of erucic acid and sebacic acid, wherein the ratio of the dimer of erucic acid to sebacic acid is 1:4.
Alternatively, hydrophilic additives may be added to the coacervates or biomaterials of the present invention to provide desirable characteristics, such as expedite delivery of the drugs or facilitate the addition of other hydrophilic substances. Exemplary hydrophilic additives useful to shorten the release duration of the pharmacologically active agent include but are not limited to, salts, such as sodium chloride, and amino acids, such as glutamine and glycine.
Other additive materials that may be incorporated into the biocoacervates or biomaterials of the present invention to provide enhanced features include, but are not limited to, insoluble proteins (e.g. collagen, elastin . . . ), ceramics, bioceramics, glasses, bioglasses, glass-ceramics, resin cement, resin fill; more specifically, glass ionomer, calcium sulfate, Al2O3, tricalcium phosphate, calcium phosphate salts, sugars, lipoproteins, starches, ferrous salts and compounds, carbohydrates, salts, polysaccharides, carbon, magnetic particles, fibers or other magnetic substances, humectants or mucoadhesive enhancers such as glycerol and alginate, absorption or membrane permeation enhancers such as ascorbic acid, citric acid and Lauroylcarnitine.
Additional other materials that may be incorporated into the coatable composition include alloys such as, cobalt-based, galvanic-based, stainless steel-based, titanium-based, zirconium oxide, zirconia, aluminum-based, vanadium-based, molybdenum-based, nickel-based, iron-based, or zinc-based (zinc phosphate, zinc polycarboxylate).
The additives may be added at any time during the preparation of the coacervate or biomaterial. For example, additives, such as particles or fibers (drugs, insoluble proteins, hydroxy apetite . . . ), macromolecules (DNA, proteins, peptides, glycosaminoglycans (e.g. hyaluronic acid, chondroiten sulfate) . . . ), small molecules (NSAIDS, Sufentanil, Sirolimis, Paclitaxel, Estradiol, Capsaicin . . . ), combinations thereof and the like may be added to the protein solution or may be added to the molten coacervate. Such addition has the benefit of distributing the additive homogeneously throughout the coacervate or biomaterial.
If additives are to be incorporated into the coacervates or biomaterials of the present invention, they will preferably be included in an amount so that the desired result of the additive is exhibited. Generally, if included in embodiments of the biocoacervate of the present invention, the amount of additives may vary between from about 0.001% to about 60%, preferably from about 0.05% to 30% by weight, and most preferably from about 0.1% to 10% by weight based upon the weight of the biocoacervate or biomaterial.
One method of producing the coacervate of the present invention is by providing one or more selected soluble or solubilized primary proteins, such as collagen, laminin or fibronectin and, in various embodiments, one or more soluble or solubilized secondary proteins such as elastin or albumen. The primary and secondary proteins are added to a sufficient amount of biocompatible solvent, preferably water, under heat until the proteins are substantially dissolved in the solvent. The proteins are added to the solvent that is generally heated to approximately 30-150° C., preferably 40-90° C., and most preferably 40-70° C. thereby producing a protein solution.
Once the protein solution is formed, one or more glycosaminoglycans, such as heparin or chondroitin sulfate are added to the protein solution thereby forming an amorphous coacervate, which drops out of the solution. It is noted that before adding the one or more glycosaminoglycans to the protein solution one or more other materials (pharmacologically active agents, additives, etc.) may be added to the one or more heated solvents (water) while stirring. It is also noted that the secondary proteins may dissolve in a solution separate from the primary protein (e.g. the same solution as the glycosaminoglycan) and added to the primary protein solution prior to or with the solution including the glycasaminoglycan. Once the coacervate has dropped out of solution, the solution and coacervate are normally allowed to cool to between 0-35° C., preferably 10-25° C., most preferably 17-22° C. In turn, the solution is poured off the coacervate, or the coacervate is extracted from the solution.
Many embodiments of the biocoacervate and biomaterials of the present invention are thermoplastics, thereby possessing thermoplastic chemical and mechanical characteristics. Therefore, the biocoacervates and some embodiments of the biomaterials have the property of softening when heated and of hardening again when cooled; these thermoplastic materials can be remelted and cooled time after time without undergoing any substantial chemical change. In view of these thermoplastic characteristics, various embodiments of the formed biocoacervate may be reformed into any shape and size by simply heating the biocoacervate until it melts and forms a liquid.
It is noted that in forming the protein solution, the primary and secondary proteins, the biocompatible solvent(s), and optionally the pharmacologically active agent(s) and additive(s) may be combined in any manner. For example, these components may simply be combined in one step, or alternatively, the primary and secondary protein materials may be dissolved in one or multiple biocompatible solvents and an additional protein material, pharmacologically active agent and/or additive may be dissolved and/or suspended in the same or another biocompatible solvent. Once the components are placed into one or more solutions, the resulting solutions may be mixed to precipitate the amorphous biocoacervate.
Once the coacervate is formed, it may be optionally pressed or vacuumed to further form, modify, set the configuration and/or remove any excess solvent or air trapped within the biocoacervate. It is noted that the resulting coacervate may be melted and placed in vacuum to remove any excess air trapped within the coacervate. The pressing may also be performed when a melted coacervate is resetting to a solid state by pouring the melted coacervate in a mold and applying pressure while cooling. The biocoacervate may optionally be dried to reduce water content to transform the coacervate structure into more of a cohesive body material to allow it to accept compression.
Any manually or automatically operable mechanical, pneumatic, hydraulic, or electrical molding device capable of subjecting the coacervate to pressure is suitable for use in the method of the present invention. In the production of various embodiments of the present invention, a molding device may be utilized that is capable of applying a pressure of from about 100 pounds per square inch (psi) to about 100,000 psi for a time period of about one (1) seconds to about forty-eight (48) hours. Preferably, the molding device used in the method of the present invention will be capable of applying a pressure of from about 1000 psi to about 30,000 psi for a time period of from about two (2) seconds to about sixty (60) minutes. More preferably, the molding device used in the method of the present invention will be capable of applying a pressure of from about 3,000 psi to about 25.000 psi for a time period of from about three (3) seconds to about ten (10) minutes.
Compression molding devices suitable for use in the practice of the method of the present invention are generally known. Suitable devices may be manufactured by a number of vendors according to provided specifications, such as desirable pressure, desired materials for formulation, desired pressure source, desired size of the moldable and resulting molded device, and the like. For example, Gami Engineering, located in Mississauga, Ontario manufactures compression molding devices to specifications provided by the customer. Additionally, many compression molding devices are commercially available. See U.S. Pat. Nos. 6,342,250 and 7,662,409, which are incorporated by reference herein, for a description of one type of compression molding device that may be utilized in the process of the present invention.
As previously indicated, the biocoacervate of the present invention is not soluble in water at room temperature. However, the coacervate does dissolve in saline solution or other physiological solutions. A biocoacervate or biomaterial that does not dissolve in saline solution or other physiological solutions may be produced by setting the biocoacervate in the desired configuration and size by utilizing a crosslinking technique. It is also noted that various crosslinking reagents, techniques and degrees of crosslinking manipulate the melting point of the crosslinked material and its physical and biological characteristics. It has been found that the application of crosslinking to the biocoacervate will generally tend to raise the melting point of the biocoacervate.
Many crosslinking techniques known in the art may be utilized to set the biocoacervate into the desired configuration, thereby forming a biomaterial that does not dissolve in saline solution. For example, embodiments of the biocoacervate may be crosslinked by reacting the components of the biocoacervate with a suitable and biocompatible crosslinking agent. Crosslinking agents include, but are not limited to glutaraldehyde, p-Azidobenzolyl Hydazide, N-5-Azido-2-nitrobenzoyloxysuccinimide, 4-[p-Azidosalicylamido]butylamine, glycidyl ethers such as 1,4-butandiol diglycidylether, any other suitable crosslinking agent and any combination thereof. A description and list of various crosslinking agents and a disclosure of methods of performing crosslinking steps with such agents may be found in the Pierce Endogen 2001-2002 or 2003-2004 Catalog which is hereby incorporated by reference. It is also noted that multiple applications of crosslinking agents at different stages may produce desired products. For example, crosslinking the biocoacervate after initial formation and then again following particle formation of the biocoacervate has proven effective.
Furthermore, it is noted that embodiments of the coacervates of the present invention may include crosslinking reagents that may be initiated and thereby perform the crosslinking process by UV light activation or other radiation source, such as ultrasound or gamma ray or any other activation means.
The protein biocoacervate may also be crosslinked by utilizing other methods generally known in the art. For example, the coacervates of the present invention may be partially or entirely crosslinked by exposing, contacting and/or incubating a coacervate with a gaseous crosslinking reagent, liquid crosslinking reagent, light, heat or combination thereof. In various embodiments of the present invention the coacervate may be crosslinked by contacting the coacervate with a liquid crosslinking reagent, such as glutaraldehyde or 1,4-butandiol diglycidylether. In one preferred embodiment of the present invention the coacervate is crosslinked in a solution of between 0.01%-50% gluteraldehyde. Additionally, it is noted that in processes including a crosslinking agent the coacervate is generally exposed to the crosslinking agent for a period of 1 min to 24 hours, preferably between 5 min and 6 hours and more preferably between 15 min and 3 hours.
Embodiments of the present invention may also include the addition of reagents to properly pH the resulting coacervate, biomaterial and related devices of the present invention. These pH reagents may be added to the coacervate during formation of the coacervate, exposing the formed coacervate to a solution of the desired pH or adjusting the pH when the coacervate is in a melted state. The appropriate adjustment of pH thereby enhances the biocompatible characteristics of the biomaterials with the host tissue of which it is to be injected and may also act to stabilize the material in physiologic conditions. When preparing the coacervate, the pH reagents are generally added to the protein solution prior to addition of the glycosaminoglycans. However, the pH reagent may alternatively be added after the amorphous coacervate is formed.
For example, the pH reagent may be added to the melted form of the coacervate in the attempt to obtain the proper pH levels. In various embodiments of the present invention, the adjustment of pH can be performed by the addition of drops of 0.05N to 4.0N acid or base to the protein solution or melted coacervate until the desired pH is reached as indicated by a pH meter, pH paper or any pH indicator. More preferably, the addition of drops of 0.1N-0.5N acid or base are used. Although any acid or base may be used, the preferable acids and bases are HCl and KOH, NaOH or combinations thereof, respectively. It has been found that adjusting the pH at or between 4 and 9, and in many embodiments at or between 6 and 8, have provided beneficial materials.
The resulting biocoacervate preferably has the maximum solvent amount absorbable with as little excess solvent as possible while still being structured into a shape-holding amorphous solid and possessing the desired features relevant to the material's and/or device's function, e.g., preferably a solvent content of from about 20% to about 90%, more preferably a solvent content of from about 30% to about 80% and most preferably 40% to 75%. Additionally, the amount of proteins and glycosaminoglycan found in the resulting coacervate or biomaterial may vary between from about 10% to about 80%, in some embodiments from about 20% to 70% by weight, and in other embodiments from about 25% to 60% by weight based upon the weight of the resulting biocoacervate or biomaterial. The amount of glycosaminoglycan present in various embodiments of the present invention generally is about 3% to about 25%, in some embodiments about 5% to 20% by weight, and in other embodiments about 8% to 15% by weight based upon the weight of the protein included in the biocoacervate.
Since biocompatible proteins and solvents are used in the manufacture of the biocoacervates, biomaterials and related devices of the present invention, the potential for adverse tissue reactions to foreign substances, such as chemical solvents are reduced, if not substantially precluded. For all these reasons, the coacervates and biomaterials in accordance with the present invention may advantageously be used to effect a local therapeutic result in a patient in need of such treatment. More specifically, the biocoacervates and biomaterials of the present invention may be injected as a liquid dispersion to effect a local therapeutic result.
Moreover, the coacervates or biomaterials may be injected through a needle to a site within a patient to elicit a therapeutic effect either locally or systemically. For example, depending on the desired therapeutic effect, the coacervates or biomaterials may be used to regenerate tissue, repair tissue, replace tissue, and deliver local and systemic therapeutic effects such as analgesia or anesthesia, or alternatively, may be used to treat specific conditions, such as coronary artery disease, heart valve failure, cornea trauma, neural tissue defects or trauma, skin wounds, burned skin, bone defects and trauma, ligament defects and trauma, cartilage defects and trauma wrinkles and other tissue specific conditions. The coacervates or biomaterials that include pharmacologically active agents may be utilized in instances where long term, sustained, controlled release of pharmacologically active agents is desirable, such as in the treatment of surgical and post-operative pain, cancer pain, or other conditions requiring chronic pain management.
The patient to which the coacervates or biomaterials are injected may be any patient in need of a therapeutic treatment. Preferably, the patient is a mammal, reptile or bird. More preferably, the patient is a human. Furthermore, the coacervates or biomaterials can be injected in any tissue to which it is desired to effect a local therapeutic response. For example, the coacervates, biomaterials or related devices may be injected as a liquid dispersion through a small needle to accelerate and facilitate healing of a torn or otherwise damaged tendon, ligament, or fibrous capsular tissue. Furthermore, injected coacervates, biomaterials or related devices may absorb water and swell, thereby assisting the coacervates, biomaterials or related devices to stay substantially in the location where it was injected.
As previously suggested, various embodiments of the biocoacervates and biomaterials of the present invention may be utilized as drug delivery devices or tissue fillers. A drug delivery device or tissue filler produced and injected as previously disclosed or suggested includes the biocompatible features of the components of the biocoacervate or biomaterial and thereby reduces or prevents the undesirable effects of toxicity and adverse tissue reactions that may be found in many other types of drug delivery devices.
Furthermore, the controlled release characteristics of this type material provides for a higher amount of pharmacologically active agent(s) that may be incorporated into the biocoacervate or biomaterial. The controlled release of pharmacologically active agent, if present, is partially attributed to the homogenous distribution of the pharmacologically active agent(s) throughout the biocoacervate or biomaterial. This homogenous distribution provides for a more systematic, sustainable and consistent release of the pharmacologically active agent(s) by gradual degradation of the coacervate or material or by diffusion of the pharmacologically active agent(s) out of the coacervate or material. As a result, the release characteristics of the pharmacologically active agent from the biocoacervate, biomaterial and/or device are enhanced.
Additionally, as previously mentioned, other optional biocompatible additives, if included in the coacervate or biomaterial, will be compelled and influenced to interact with the various components, including the pharmacologically active agents if present, to augment their biodurability, biocompatibility and/or drug release characteristics if drugs are present in the materials. Augmentation may include inhibiting or enhancing the release characteristics of the pharmacologically active agent(s), if present. For example, a multi-layered drug delivery device may comprise alternating layers of biocoacervates or biomaterials that have sequential inhibiting and enhancing biocompatible additives included, thereby providing a pulsing release of pharmacologically active agents. A specific example may be utilizing glutamine in a layer as an enhancer and polyanhydride as an inhibitor. The inhibiting layer may include drugs or no drugs.
The drug delivery devices or tissue fillers of present invention may be formed into any shape and size, such as a cylinder, a tube, a wafer, particles or any other shape that may optimize the delivery of the devices or fillers and optionally the incorporated pharmacologically active agents included therein. For example, the composite coacervate or biomaterial may be processed into particles for subsequent injection as a therapeutic device such as a tissue filler or drug delivery device.
An illustration of an embodiment of the particles of the present invention is depicted in
One example of an alternative method to make particles is by homogenizing a crosslinked coacervate thereby producing particles. In such a method a block or other shape of the coacervate may be crosslinked with a crosslinking agent, such as 0.01M to 10M gluteraldehyde or 1,4-butandiol diglycidylether. Once crosslinked the biocoacervate is next placed in a homgenizer and cut into particles. One or more additional crosslinking steps may be performed after homogenization of the coacervate by exposing the particles to a second solution including one or more crosslinking agents, such as gluteraldehyde, formaldehyde, glyoxal or 1,4-butandiol diglycidylether. It is noted that alternative crosslinking solutions and conditions (e.g. pH, temperature, solvents . . . ) may be utilized for the extra crosslinking steps.
Generally, the particles may vary in size but are normally approximately 10 nm-5 mm, preferably 500 om-2.5 mm and more preferably 1-1000 μm. A characteristic of the particles produced from the biocoacervate material is that they no longer aggregate when in the particulate state. Furthermore, prior studies have demonstrated that the particles do not aggregate in saline and are easily delivered through small gauge needles, e.g., 16-30 gauge needles, and, preferably, 27-30 gauge needles. The particles can be made to disassociate at very slow or fast rates in aqueous solutions.
After the particles are formed using the various methods described above, they are characterized for their basic structure. First the particles may be segregated using a series of pharmaceutical drug sieves.
In various embodiments of the present invention, the particles may be utilized as a drug delivery device or a tissue filler by injecting such particles subcutaneously or intradermally into a tissue of the patient. For example, a liquid dispersion of CEHM may be injected into the tissue through a syringe with a 16-30 gauge needle. Saline is a solution that may be employed to prepare such a liquid dispersion, but any biocompatible solution may be utilized. Also, lubricants, such as polyvinylalcohol, polyethylene glycol, dextran, proteins (human, bovine, porcine, or equine) such as collagen, elastin, albumin, proteoglycans or glycans, hyaluronic acid, lipids, oils or any other lubricious agent, may be added to the particles or liquid dispersion to facilitate injection of the particles through a needle syringe assembly. These lubricants assist in facilitating the injection of the particles through the applicator, such as a syringe and also may be made to act as an immunogenic mask, thereby reducing potential inflammatory and/or immune responses. In various embodiments of the present invention the lubricants may comprise approximately less than 5% and preferably less than 1% of the particle or slurry contents. Saline has been selected for the initial material for several reasons including its common use in medical procedures and its availability in a sterile form.
A liquid dispersion of the particles or a particle slurry may be delivered through small gauge needles, e.g., 16-30 gauge needles, and preferably, 27-30 gauge needles. For example,
Also, the particles of the present invention may be injected as a liquid dispersion into a tear and/or lesion found in a ligament, tendon, or fibrous capsular tissue to accelerate and facilitate healing of the tom or otherwise damaged tissue. Medical conditions that may be treated by the injection of the disclosed CEHM include a partially or wholly tom anterior cruciate ligament (ACL), medial collateral ligament (MCL), posterior cruciate ligament (PCL), an ulnar cruciate ligament (UCL), a cranial cruciate ligament (CCL), and any number of different tendons. Alternatively, such tendon or ligament may include a flexor tendon, extensor tendon, collateral ligaments, suspensory ligaments, cranial or caudal cruciate ligament or compatible human correlates.
The present invention will now be further described with reference to the following non-limiting examples and the following materials and methods were employed. It is noted that any additional features presented in other embodiments described herein may be incorporated into the various embodiments being described.
Soluble bovine collagen (Kensey-Nash Corporation) (1.5 gs) was dissolved in distilled water (100 mls) at 42° C. To this solution was added elastin (bovine neck ligament, 0.40 g) and sodium heparinate (0.20 g) dissolved in distilled water (40 mls) at room temperature. The elastin/heparin solution was added quickly to the collagen solution with minimal stirring thereby immediately producing an amorphous coacervate precipitate. The resulting cloudy mixture was let standing at room temperature for 1-2 hrs and then refrigerated. The rubbery precipitate on the bottom of the reaction flask was rinsed three times with fresh distilled water and removed and patted dry with filter paper to yield 6.48 gs of crude coacervate (Melgel™ which was then melted at 55° C. and gently mixed to yield a uniform, rubbery, water-insoluble final product after cooling to room temperature. The supernatant of the reaction mixture was later dried down to a solid which weighed 0.417 g and was water soluble. The uniform Melgel™ material was used to fabricate both injectable compositions for tissue augmentation and biocompatible structures for vascular grafts.
MelGel™ material was prepared as described in Example 1. Nine 1 g samples of MelGel™ were cut and placed in a glass scintillation vial. The vial was then placed in a water bath at 60° C. and melted. Once melted either an additive or pH solution was added to each sample of MelGel™. The following additives were administered: polyethylene glycol, chondroitin sulfate, hydroxyapatite, glycerol, hyaluronic acid and a solution of NaOH. Each of the above mentioned additives were administered at an amount of 3.3 mg separately to four melted samples of MelGel™ with a few drops of water to maintain MelGel™ viscosity during mixing. Each of the above mentioned additives were also administered at an amount of 10 mg to another four melted samples of MelGel™ with a few drops of water to maintain MelGel™ viscosity. Finally, NaOH was added to the final melted MelGel™ sample until the MelGel™ tested neutral with pH indicator paper. The uniform Melgel™ material including additives or pH solution were crosslinked with 0.1% gluteraldehyde for 2 hours and used to fabricate injectable compositions for tissue augmentation.
A sample of Melgel™ was cut into small pieces and treated with a glutaraldehyde (0.1-1.0%) aqueous solution for up to 2 hours. The resulting coacervate (Melgel™) material was then dried at 45° C. for 24 hours and ground to a fine powder and sieved through a 150μ screen. This powder was then suspended in phosphate-buffered saline to form a liquid dispersion capable of injection through a fine needle, e.g., 16-30 gauge needled, and more preferably, a 27-30 gauge needle.
A crosslinked coacervate may be homogenized to produce particles. In such a method a block or other shape of the coacervate may be crosslinked with a crosslinking agent, such as 0.01M to 10M gluteraldehyde or 1,4-butandiol diglycidylether. Once crosslinked the biocoacervate is next placed in a homgenizer and cut into particles. One or more additional crosslinking steps may be performed after homogenization of the coacervate by exposing the particles to a second solution including one or more crosslinking agents, such as gluteraldehyde, formaldehyde, glyoxal or 1,4-butandiol diglycidylether. It is noted that alternative crosslinking solutions and conditions (e.g. pH, temperature, solvents . . . ) may be utilized for the extra crosslinking steps.
Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions.
Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted.
Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended.
Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. § 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.
This application claims priority from U.S. Provisional Application Ser. No. 63/601,163 filed Nov. 20, 2023 and entitled “INJECTION OF COLLAGEN ELASTIN HYDROGEL MICROPARTICLES INTO TORN TENDONS AND LIGAMENTS”, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63601163 | Nov 2023 | US |
