Patent Application
20170224869
The present disclosure relates to tissue products, and more particularly, to extracellular tissue matrices made from adipose tissue.
Various tissue-derived products are used to regenerate, repair, or otherwise treat diseased or damaged tissues and organs. Such products can include tissue grafts and/or processed tissues (e.g., acellular tissue matrices from skin, intestine, or other tissues, with or without cell seeding). Such products generally have properties determined by the tissue source (i.e., tissue type and animal from which it originated) and the processing parameters used to produce the tissue products. Since tissue products are often used for surgical applications and/or tissue replacement or augmentation, the products should support tissue growth and regeneration, as desired for the selected implantation site. The present disclosure provides adipose tissue products that can allow improved tissue growth and regeneration for various applications, such as breast implants.
According to certain embodiments, methods for producing tissue products are provided. The methods can include selecting an adipose tissue; mechanically processing the adipose tissue to reduce the tissue size; and treating the mechanically processed tissue to remove substantially all cellular material from the tissue; suspending the tissue in a liquid to form a suspension; layering the suspension in a mold, wherein the layering is repeated until a desired thickness is achieved in the mold; and freezing and drying the suspension in the mold to form a porous sponge. The processed tissue can be cross-linked to produce a stable three-dimensional structure.
In some embodiments, the methods include performing the freezing and drying steps after each layering cycle. Alternatively, the methods can include performing the freezing and drying steps after multiple layering cycles, or performing multiple freezing and drying cycles after each layering step.
Also provided herein are tissue products made by the disclosed processes. For example, the tissue products can be made by a process comprising selecting an adipose tissue; treating the tissue to remove substantially all cellular material from the tissue; suspending the tissue in a liquid to form a suspension; layering the suspension in a mold, wherein the layering is repeated in multiple cycles until a desired thickness is achieved in the mold; and freezing and drying the suspension in the mold to form a porous sponge.
In some embodiments, the tissue products can be made by a process that further includes performing the freezing and drying step after each layering cycle. Alternatively, the process further includes performing the freezing and drying step after multiple layering cycles; or performing multiple freezing and drying cycles after each layering step.
In some embodiments, the tissue products include a decellularized adipose extracellular tissue matrix, wherein the tissue matrix has been formed into a predetermined three-dimensional shape, and wherein the tissue matrix is partially cross-linked to maintain the three-dimensional shape.
Also provided herein is a tissue product comprising a breast implant. The implant can comprise a layered construct of acellular adipose tissue matrix including two or more layers of particulate acellular adipose tissue matrix that has been homogenized to form a suspension, dried, and stabilized. In one embodiment, the implant measures at least 5 cm in at least one dimension.
Further provided herein are methods of treatment comprising the steps of selecting a tissue site and implanting the tissue products disclosed herein into the tissue site. The methods can include implanting the treatment device in or proximate a wound or surgical site and securing at least a portion of the treatment device to tissue in or near the treatment site. The tissue product may be implanted behind the tissue site to bolster, reposition, or project the native tissue outward.
Also provided herein are methods of treatment comprising selecting a tissue site within a breast; implanting a device within the tissue site. In one embodiment, the device comprises a synthetic breast implant or tissue expander and an acellular adipose tissue matrix surrounding the breast implant or tissue expander. The method can further include removing the breast implant or tissue expander and implanting an acellular adipose tissue matrix within a void formed by removal of the breast implant or tissue expander.
Additionally, provided herein are breast treatment devices comprising a synthetic breast implant or tissue expander and a layered construct of acellular adipose tissue matrix surrounding the synthetic breast implant or tissue expander. In one embodiment, the construct includes two or more layers of particulate acellular adipose tissue matrix that has been homogenized to form a suspension, dried, and stabilized.
Reference will now be made in detail to certain exemplary embodiments according to the present disclosure, certain examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
In this application, the use of the singular includes the plural unless specifically stated otherwise. In this application, the use of “or” means “and/or” unless stated otherwise. Furthermore, the use of the term “including”, as well as other forms, such as “includes” and “included”, is not limiting. Any range described herein will be understood to include the endpoints and all values between the endpoints.
The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. All documents, or portions of documents cited in this application, including but not limited to patents, patent applications, articles, books, and treatises, are hereby expressly incorporated by reference in their entirety for any purpose.
Various human and animal tissues can be used to produce products for treating patients. For example, various tissue products for regeneration, repair, augmentation, reinforcement, and/or treatment of human tissues that have been damaged or lost due to various diseases and/or structural damage (e.g., from trauma, surgery, atrophy, and/or long-term wear and degeneration) have been produced. Such products can include, for example, acellular tissue matrices, tissue allografts or xenografts, and/or reconstituted tissues (i.e., at least partially decellularized tissues that have been seeded with cells to produce viable materials).
The present disclosure provides tissue products that are useful for treatment of adipose-containing tissues as wells as other tissue sites, including breasts. The present disclosure also provides methods for producing such tissue products.
The tissue products of the present disclosure can include adipose tissues that have been processed to remove at least some of the cellular components. In some cases, all, or substantially all cellular material is removed, thereby leaving adipose extracellular matrix proteins. In addition, the products can be processed to remove some (e.g., 10-20%, 20-30%, 30-40%, 40-50%, 60-70%, 70-80%, 80-90%, 70-90%, 70-95% (all by weight)) or all of the extracellular and/or intracellular lipids. As described further below, the extracellular matrix proteins can be further treated to produce a three-dimensional porous, or sponge-like material. In addition, to allow treatment of a selected tissue site the material can be further processed (e.g., by cross-linking) to form a stable structure.
The tissue products of the present disclosure can be used as breast implants, e.g., for breast augmentation, reconstruction (e.g., after mastectomy or other breast surgery), or any other breast procedure. The breast implants can comprise a layered construct of acellular adipose tissue matrix. In one embodiment, a layered construct of acellular adipose tissue matrix comprises two or more layers. In some embodiments, the implant measures at least 5 cm in at least one dimension.
The layered construct of such breast implants is achieved through a layering process in which each layer comprises particulate acellular adipose tissue that has been mechanically processed to form a suspension, dried, and stabilized. This layering process allows for the production of an implant that is big enough to act as a breast implant (i.e., an implant that is dimensionally sufficient to replace all or part of a breast).
As noted, the tissue products of the present disclosure are formed from adipose tissues. The adipose tissues can be derived from human or animal sources. For example, human adipose tissue can be obtained from cadavers. In addition, human adipose tissue could be obtained from live donors (e.g., with an autologous tissue). Adipose tissue may also be obtained from animals such as pigs, monkeys, or other sources. If animal sources are used, the tissues may be further treated to remove antigenic components such as 1,3-alpha-galactose moieties, which are present in pigs, but not humans or primates. In addition, the adipose tissue can be obtained from animals that have been genetically modified to remove antigenic moieties. See Xu, Hui, et al., “A Porcine-Derived Acellular Dermal Scaffold that Supports Soft Tissue Regeneration: Removal of Terminal Galactose-α-(1,3)-Galactose and Retention of Matrix Structure,” Tissue Engineering, Vol. 15, 1-13 (2009), which is incorporated by reference in its entirety.
An exemplary process for producing the tissue products of the present disclosure is illustrated in
To assist in removal of the cellular components and produce a flowable mass, the tissue can be first processed to produce small pieces (Step 12). In various embodiments, the material is cut, grinded, blended, or otherwise mechanically treated to reduce the size of the tissue and/or to form a putty or flowable material. The adipose tissue can be treated using any suitable cutting, grinding, or blending process. For example, in one embodiment, the tissue is first cut into relatively small pieces (e.g., about 2 cm×2 cm). The pieces can then be placed in a liquid that is then treated with a blade grinder or similar instrument to produce a homogenous or semi-homogenous material.
Next, the tissue is treated to remove cellular components and/or lipids. The cellular components and lipids can be removed by washing the material (Step 14). For example, in some embodiments, the material is combined with a desired amount of water or another solvent. The material and solvent are then centrifuged, and free lipids and cell debris will flow to the top, while the extracellular matrix proteins are deposited as a pellet. The protein pellet can then be resuspended, and the washing and centrifugation can be repeated until a sufficient amount of the lipids and cellular materials are removed. In some cases, the process is repeated until substantially all cellular material are removed and until a desired amount of lipid is removed.
During, before, and/or after the washing steps, additional solutions or reagents can be used to process the material (Step 16). For example, enzymes, detergents, and/or other agents may be used in one or more steps to remove cellular materials or lipids, remove antigenic materials, and/or reduce the bacteria or other bioburden of the material. For example, one or more washing steps can be included using detergents to assist in cell and lipid removal. In addition, enzymes such as lipases, DNAses, RNAses, alpha-galactosidase, or other enzymes can be used to ensure destruction of nuclear materials, antigens from xenogenic sources, and/or viruses.
After removal of cellular components, the material can then be formed into a porous or sponge-like material. Generally, the extracellular matrix is first suspended in an aqueous solvent (Step 18). A sufficient amount of solvent is used to allow the material to form a liquid mass that can be poured into a mold having the size and shape of the desired tissue product. The amount of water added can be varied based on the desired porosity of the final material. In some cases, the suspended extracellular matrix may be mechanically treated by grinding, cutting, blending or other processes one or more additional times, and the treated material can be centrifuged and resuspended one or more times to further remove cellular material or lipids (if needed) and/or to control the viscosity of the extracellular matrix.
Once any washing and grinding steps are complete, the suspended material is placed in a container or mold to form the porous, sponge-like product by a layering process (Step 20). In one embodiment, the layering process is repeated until a desired thickness is achieved in the mold. In some embodiments, the desired thickness is at least or exceeds 1.0 cm, 3.0 cm, 5.0 cm, 7.0 cm, 9.0 cm, 11.0 cm, 13.0 cm, or 15.0 cm.
Generally, the porous or sponge-like material is formed by freeze-drying the material to leave a three-dimensional matrix with a porous structure (Step 22). Freeze-drying can allow production of a three-dimensional structure that generally conforms to the shape of the mold.
The specific freeze drying protocol can be varied based on the solvent used, sample size, and/or to optimize processing time. One suitable freeze-drying process can include freezing the material to a temperature of −10° C. to −20° C. over a 30 to 45 minute period; further cooling the material down to a temperature of −40° C. to −60° C. to ensure complete freezing of all bound and unbound water in the sample; applying a vacuum of 100 to 250 mTorr; raising the temperature to −10° C. to −5° C. and holding at this condition until primary drying is completed; further raising the temperature to 20° C. for secondary drying and holding for 3 to 12 hours. The freeze-dried samples can then be removed from the freeze-dryer and packaged under a nitrogen blanket in moisture barrier pouches, such as foil pouches. An alternative freeze drying cycle for thicker cross-sections (8 cm or larger) includes a longer duration for primary drying (−10° C. hold for 72-192 hours), followed by secondary drying at 20° C. for 24-48 hours. A third freeze drying strategy is the application of several (2-10) nitrogen purge or deep vacuum cycles to facilitate heat transfer into the tissue during primary drying. A fourth strategy is the use of microwave-assisted freeze drying to impart thermal energy to the water or ice during primary drying. This accelerates heat transfer and sublimation of water from the matrix.
In some embodiments, the methods include performing the freezing and drying step after each layering cycle. Alternatively, the methods include performing the freezing and drying step after multiple layering cycles; or performing multiple freezing and drying cycles after each layering step.
After forming the porous, sponge-like material, the material can be treated so that it forms a stable three-dimensional shape (
In some embodiments, the material is cross-linked to perform the stabilization (Step 24). In some embodiments, the material is cross-linked after freeze drying. However, the material could also be cross-linked before or during the freeze-drying process. Cross-linking can be performed in a variety of ways. In one embodiment, cross-linking is accomplished by contacting the material with a cross-linking agent such as glutaraldehyde, genepin, carbodiimides, and diisocyantes. In addition, cross-linking can be performed by heating the material. For example, in some embodiments, the material can be heated to between 70° C. to 120° C., or between 80° C. and 110° C., or to about 100° C., or any values between the specified ranges in a reduced pressure or vacuum or dry gas. Further, the cross-linking can be performed by dehydrothermal treatment, including heating in a reduced pressure environment to remove moisture.
In addition, other cross-linking processes may be used to produce any of the disclosed products, including ultraviolet irradiation, gamma irradiation, and/or electron beam irradiation. In addition, a vacuum is not needed but may reduce cross-linking time. Further, lower or higher temperatures could be used as long as melting of the matrix proteins does not occur and/or sufficient time is provided for cross-linking.
In various embodiments, the cross-linking process can be controlled to produce a tissue product with desired mechanical, biological, and/or structural features. For example, cross-linking may influence the overall strength of the material, and the process can be controlled to produce a desired strength. In addition, the amount of cross-linking can affect the ability of the product to maintain a desired shape and structure (e.g., porosity) when implanted. Accordingly, the amount of cross-linking can be selected to produce a stable three-dimensional shape when implanted in a body, when contacted with an aqueous environment, and/or when compressed (e.g., by surrounding tissues or materials).
Excessive cross-linking may change the extracellular matrix materials. For example, excessive cross-linking may damage collagen or other extracellular matrix proteins. The damaged proteins may not support tissue regeneration when the tissue products are placed in an adipose tissue site or other anatomic location. In addition, excessive cross-linking can cause the material to be brittle or weak. Accordingly, the amount of cross-linking may be controlled to produce a desired level of stability, while maintaining desired biological, mechanical, and/or structural features.
Exemplary cross-linking processes can include contacting a freeze-dried material, produced as discussed above, with glutaraldehyde. For example, a 0.1% glutaraldehyde solution can be used, and the tissue can be submerged in the solution for about for 18 hours followed by extensive rinsing in water to remove the solution. Alternatively, or in combination, a dehydrothermal process can be used. For example, one exemplary dehydrothermal process includes treating the material at about 100° C. and about 20 inches of Hg for 18 hours, followed by submersion in water. The final cross-linked tissue products can be stored in a film pouch.
The adipose tissue can be produced as generally described US Patent Publication Number 2012/0310367A1 (Application number U.S. Ser. No. 13/483,674, filed May 30, 2012, to Connor). Such adipose materials can be formed generally by mechanical homogenization, washing, resuspension, and stabilization of the material. The material may be dried (e.g. by freeze drying before or after stabilization), and stabilization can be by dehydrothermal treatment, cross-linking (UV, radiation, or chemical cross-linking). In addition, the sponge may be sterilized. Sterilization may be performed after the components of the devices described herein are joined. Further, the sponge may be formed while in contact with the intact acellular tissue matrix components, or may be formed separately prior to joining. As noted above, the process described is said application can be repeated in layers to produce a desired size, shape, and thickness.
As discussed above, the tissue products should have the ability to support cell ingrowth and tissue regeneration when implanted in or on a patient. In addition, the tissue products should have the ability to act as a carrier for and support the growth of cells, including stems cell, such as adipose-derived stem cells. Accordingly, the processes discussed above should not alter the extracellular matrix proteins (e.g., by damaging protein structure and/or removing important glycosaminoglycans and/or growth factors). In some embodiments, the products will have normal collagen banding as evidenced by transmission electron microscopy.
The devices produced using the above-discussed methods can have a variety of configurations. For example,
As shown, the device 30 can include a number of layers. For example, the implant 30 can include five layers, as shown, but could include a range of layers (e.g., between 1 and 100 layers) depending on the desired size, shape, and functional properties of the implant 30, and depending on the thickness of each layer 31-35.
The various layers 31-35 can have a number of properties that can be varied among the layers 31-35. For example, in one embodiment, each of the layers is substantially identical in mechanical, microscopic, and/or biological properties, but multiple layers are provided to obtain the desired size of an implant 30.
In other embodiments, one or more physical and/or biological properties is varied among or within one or more of the layers. For example, in one embodiment, the layers 31-35 have variable mechanical or physical properties such as tensile strength, compressibility, pore size, elasticity, or other suitable properties. In addition, the layers 31-35 can include variations in biologic properties, including for example, collagenase susceptibility and/or ability to support or speed of cellular ingrowth.
In one embodiment, one or more mechanical/physical and/or biologic properties can vary from one layer 31 toward an outer layer 35. For example, in one embodiment, the most inner layer when implanted 31 will have the highest tensile strength, to support load bearing, while the most outer layer will have the lowest tensile strength.
The mechanical/physical and/or biologic properties of the layers 31-35 can be controlled by controlling the processing conditions discussed above, thereby producing variation in density, pore size, collagenase susceptibility or other properties among the layers 31-35. For example,
The density of the layers 52 and 54 can be controlled in a number of ways. For example, the density may be controlled by varying the solid content of the slurry used to produce the sponge prior to drying. Suitable solid contents may include for example, between 1% and 20%, or more preferably between 1% and 5%, 1% and 10%, 1% and 15%, 2% and 5%, 2% and 3%, or values within said ranges.
The device 30 shown in
The device 30, 36-38 can have a variety of sizes. But as noted above, the methods provided herein can provide advantages by allowing production of adipose implants having large sizes that can match those of conventional breast implants or tissue expanders. For example, using the layering methods discussed herein, implants having at least one dimension of 5 cm or greater can be produced. In other cases, the devices have a dimension of at least 6 cm, at least 7 cm, at least 8 cm, at least 10 cm, or larger.
Also disclosed herein are methods for treating a breast by implanting the tissue product. Accordingly,
In some embodiments, the layered adipose materials discussed herein can be used along with a synthetic implant or tissue expander. For example,
The synthetic implant or expander 43 can be coated with the adipose tissue matrix 42 and implanted. As such, the tissue matrix can shield the implant or expander 43 from the body to some extent, thereby preventing formation of or improving the quality of fibrotic tissue that may usually form around synthetics. Additionally, or alternatively, the coating 42 can facilitate ingrowth of cells and formation of vascularized tissues, thereby speeding or otherwise improving regeneration of healthy tissue to improve surgical results (e.g., by strengthening surrounding tissue or providing better tissue vascularity).
In some cases, the device 40 of
Further provided herein are methods of treatment comprising the steps of selecting a tissue site and implanting the tissue products disclosed herein into the tissue site. The methods can include implanting the treatment device in or proximate to a wound or surgical site and securing at least a portion of the treatment device to tissue in or near the treatment site. The tissue product may implanted behind the tissue site to bolster, reposition, or project the native tissue outward.
Also provided herein are methods of treatment comprising selecting a tissue site within a breast; implanting a device within the tissue site, and allowing tissue to grow within the acellular adipose tissue matrix. In one embodiment, the device comprises a synthetic breast implant or tissue expander and an acellular adipose tissue matrix surrounding the breast implant or tissue expander. The method can further include removing the breast implant or tissue expander and implanting an additional acellular adipose tissue matrix within a void formed by removal of the breast implant or tissue expander.
Additionally, provided herein are breast treatment devices comprising a synthetic breast implant or tissue expander, and a layered construct of acellular adipose tissue matrix surrounding the synthetic breast implant or tissue expander. In one embodiment, the construct includes two or more layers of particulate acellular adipose tissue matrix that have been homogenized to form a suspension, dried, and stabilized.
After selection of the site, a treatment device is selected. Various devices including acellular tissue matrices can be used, and the devices can include a flexible sheet having a top surface, a bottom surface, and a peripheral border. The peripheral border and shape of the devices can include any configuration discussed herein.
The tissue products described herein can be used to treat a variety of different anatomic sites. For example, as discussed throughout, the tissue products of the present disclosure are produced from adipose tissue matrices and can be used for treatment of breasts. In some cases, the tissue products can be implanted in other sites, including, for example, tissue sites that are predominantly or significantly adipose tissue. In some cases, the tissue sites can include a breast (e.g., for augmentation, replacement of resected tissue, or placement around an implant). In addition, any other adipose-tissue containing site can be selected. For example, the tissue products may be used for reconstructive or cosmetic use in the breast, face, buttocks, abdomen, hips, thighs, or any other site where additional adipose tissue having structure and feel that approximates native adipose may be desired. In any of those sites, the tissue may be used to reduce or eliminate wrinkles, sagging, or undesired shapes.
This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Number 62/292,515, which was filed on Feb. 8, 2016. The entire contents of the aforementioned application are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62292515 | Feb 2016 | US |
