The field of the invention and its embodiments relate to methods for creating edible scaffolding using algae. More specifically, the field of the invention and its embodiments relate to a protocol for the sterilization and decellularization of Durvillaea antarctica, Chilean seaweed, or cochayuyo to prepare the cochayuyo to be suitable for the culture of cells.
Projections show that a growing population and the demand for meat poses a risk of insufficient land to feed the world by the year 2050 using the current methods of livestock cultivation. See, Harry Aiking, “Future Protein Supply,” Trends in Food Science & Technology, March 2011, Vol. 22, Issues 2-3, Pages 112-120, the entire contents of which are hereby incorporated by reference in its entirety. This, coupled with the health concerns associated with meat consumption, has resulted in a shift to the consumption of plant-based food products. In fact, plant-based food products provide numerous benefits as compared to the animal-based food products they replace. For example, plant-based food products provide health benefits (e.g., less cholesterol or lower levels of saturated fats) and eliminate the negative aspects of animal husbandry, including the environmental impacts of such, the animal confinement, the disruption of maternal-offspring interactions, and the slaughter of animals for their meat.
Cell-based meat (CBM) production is a promising technology that could generate meat without the need for animal agriculture. The generation of tissue requires a three-dimensional (3D) scaffold to provide support to the cells and mimic the extracellular matrix (ECM). Numerous groups have developed methods to manufacture these scaffolds that support the production of environmentally friendly cultivated products, such as cell-cultured meats. Since algae is nutrient-rich and relatively easy and inexpensive to grow, some groups have used algae-based scaffolds to grow food products.
Since mycelium contains chitin, which can be made to mimic some of the polysaccharides found in the natural ECM, and some fungi have a meaty taste and texture, other groups have used fungal mycelium as a scaffolding substrate.
However, these plant and fungi-based scaffolds are just the beginning. What is needed is an enhanced method and system in the field of animal-free scaffolding that helps cell-cultured meat producers to cut costs and reduce their environmental impact. More specifically, improved methods are needed for creating edible scaffolding using unique and sustainable materials.
KR102151203B1 describes a support for cell cultures, which has a hydrogel structure composed of cellulose and alginates extracted through the decellularization of seaweed. This application uses an ozone step in the decellularization process that is problematic. Ozone is very reactive and corrosive, thus requiring corrosion-resistant material, such as stainless steel. Ozone is extremely irritating and possibly toxic, so off-gases from the contactor must be destroyed to prevent worker exposure. This adds great cost and time to the process employed.
WO2017160862A1 describes decellularized plant tissues and the use of these plant tissues as scaffolds. Particularly, decellularized plant tissues are functionalized to allow for human cell adhesion, thereby allowing for their use as scaffolds for human cells. These scaffolds can then be used in a number of applications/markets, including as research tools for tissue engineering, regenerative medicine, and basic cellular biology.
CN111227199A describes a preparation method of ready-to-eat Durvillaea antarctica.
CN103637858A describes a manufacturing method of a three-dimensional porous scaffold in bioengineering, where a fiber structure of the scaffold includes gelatin, seaweed gel and collagen.
One group describes three animal-free scaffolds: decellularized plant tissue, chitin/chitosan and recombinant collagen scaffolds. Decellularized plant tissue provides a wide array of structures with varying biochemical, topographical and mechanical properties; chitin/chitosan-based scaffolds have shown synergistic bactericidal effects and improved cell-matrix interaction; and lastly, recombinant collagen has the potential to closely resemble native tissue, as opposed to the other two. These benefits, alongside potential scalability and tunability, open the door to applications beyond the biomedical realm, such as innovations in cellular agriculture and future food technologies. See, Santiago Campuzano, et al., “Scaffolds for 3D Cell Culture and Cellular Agriculture Applications Derived From Non-Animal Sources,” Front. Sustain. Food Syst. Mini Review, May 2019, Volume 3, Article 38, Pages 1-9, the entire contents of which is hereby incorporated by reference in its entirety.
Others have addressed different types of additives and their impact on various functional properties of seaweed based composites, their methods of incorporation, and applications with special emphasis on food and pharmaceutical usage. See, H. P. S. Abdul Khalil, et al., “Seaweed Based Sustainable Films and Composites for Food and Pharmaceutical Applications: A Review,” Renewable and Sustainable Energy Reviews, September 2017, Volume 77, Pages 353-362, the entire contents of which is hereby incorporated by reference in its entirety. Another group provides a review that summarizes and broadly classifies all of the major sustainable natural carbohydrate bio-macromolecular manifestations in nature—from botanical (cellulose, starch, and pectin), seaweed (alginate, carrageenan, and agar), microbial (bacterial cellulose, dextran, and pullulan), and animal (hyaluronan, heparin, chitin, and chitosan) sources—that have been contrived into electrospun fibers. See, K. P. Akshay Kumar, et al., “Electrospun Fibers Based on Botanical, Seaweed, Microbial, and Animal Sourced Biomacromolecules and their Multidimensional Applications,” International Journal of Biological Macromolecules, February 2021, Volume 171, Pages 130-149, the entire contents of which is hereby incorporated by reference in its entirety.
Others have developed an environmentally conscious, lean, structured meat product using decellularized plant leaf scaffold technology. See, Fatin Alkhaledi, et al., “Leef Jerky™: A Sustainable Meat Product for a Better Future,” The Worcester Polytechnic Institute, 2019, the entire contents of which is hereby incorporated by reference in its entirety. Another group has developed natural scaffolds in the form of decellularized amenity grass, which retains its natural striated topography and supports the attachment, proliferation, alignment and differentiation of murine C2C12 myoblasts, without the need for additional functionalization. See, Scott J. Allan, et al., “Decellularized Grass as a Sustainable Scaffold for Skeletal Muscle Tissue Engineering,” J. Biomed. Mater Res. A., 2021, 109(12), Pages 2471-2482, the entire contents of which is hereby incorporated by reference in its entirety.
Another group describes the utilization of green seaweed and its derived ulvan polysaccharides for the preparation of numerous chemicals (e.g., solvents, fuel, and gas) and also value-added biomaterials with various morphologies (e.g., gels, fibers, films, scaffolds, nanomaterials, and composites). See, D. Shanthana Lakshmi, et al., “A Short Review on the Valorization of Green Seaweeds and Ulvan: Feedstock for Chemicals and Biomaterials,” Biomolecules, 2020, 10(7), Page 991, the entire contents of which is hereby incorporated by reference in its entirety. One group describes the use of decellularization—recellularization approach to fabricate seaweed cellulose-based scaffolds for in vitro mammalian cell growth. See, Nurit Bar-Shai, et al., “Seaweed Cellulose Scaffolds Derived from Green Macroalgae for Tissue Engineering,” Scientific Reports, 11, Article Number 11843, the entire contents of which is hereby incorporated by reference in its entirety. Other groups describe decellularization of spinach leaves to produce an edible scaffold that has a vascular network that could potentially maintain the viability of primary bovine satellite cells as they develop into meat. See, Jordan D. Jones, et al., “Decellularized Spinach: An Edible Scaffold for Laboratory-Grown Meat,” Food Bioscience, June 2021, Volume 41, Article Number 100986, the entire contents of which is hereby incorporated by reference in its entirety.
Various similar systems exist in the art. However, their means of operation are substantially different from the present disclosure, as the other inventions fail to solve all the problems taught by the present disclosure.
The present invention and its embodiments relate to methods for creating edible scaffolding using algae. More specifically, the present invention and its embodiments relate to a protocol for the sterilization and decellularization of Durvillaea antarctica, Chilean seaweed, or cochayuyo to prepare the cochayuyo to be suitable for the culture of cells.
An embodiment of the present invention describes a method to decellularize an algae to form a scaffold for cell seeding. Decellurization is the chemical, physical or enzymatic process of treating cells to remove components from the cell that will elicit an immune response. Accordingly, decellurization affords the cells the ability to be used in ECMs (extracellular matrices) without having to be concerned about eliciting an immune response. The instant method includes numerous process steps, such as: washing an algae with distilled water. In an embodiment, the algae is a species of brown algae and in a variation, is Durvillaea antarctica, Chilean seaweed, or cochayuyo. Next, the method includes chopping and grinding the algae and transferring a selected sample of the algae to a tube, adding the distilled water, and storing the selected sample of the algae at a first temperature (e.g., about 4° C.) for a first time period (e.g., overnight or 8-18 hours). Next, the method includes extracting the distilled water and adding a first solution (e.g., an SDS solution) to the tube at a second temperature (e.g., room temperature) for a second time period (e.g., five days).
Then, the method includes centrifuging the sample for a third time period (e.g., about five minutes), removing a supernatant, and washing with the distilled water. Next, the method includes adding a second solution (e.g., a CaCl2 solution) to the tube and incubating the sample at a third temperature (e.g., about 4° C.) for a fourth time period (e.g., about twenty-four hours). Next, the method includes centrifuging the sample for a fifth time period (e.g., about 5 minutes) and removing the supernatant. Then, the method includes adding the distilled water to the tube and storing the sample at a fourth temperature (e.g., about 4° C.) for a sixth time period (e.g., overnight). Next, the method includes centrifuging the sample for a seventh time period (e.g., about five minutes), removing the supernatant, and storing the sample in a third solution (e.g., a PBS solution) at a fifth temperature until use (e.g., about −20° C.).
After freezing, the method further comprises thawing the sample in a thermal bath at a sixth temperature of about 40° C. for an eighth time period (e.g., in a range between about 5 minutes to about 10 minutes). Next, the method further includes centrifuging the sample for a ninth time period (e.g., about five minutes) and extracting the supernatant. Then, the method includes: drying the sample in an oven at a seventh temperature (e.g., about 60° C.) and for a tenth time period (e.g., about two hours). The method then includes: sterilizing the sample by autoclaving and transferring the sample, in a laminar flow hood, to tubes, adding a gelatin, and storing the sample at an eighth temperature (e.g., room temperature) for an eleventh time period (e.g., about twenty-four hours). Next, the method further includes: centrifuging the sample for a twelfth time period (e.g., about five minutes) and removing the supernatant in the laminar flow hood such that the scaffold is ready for cell seeding. The scaffold described herein is composed of sterile decellularized cochayuyo rehydrated with adhesion/carrier proteins (e.g., 1% w/v gelatin, 1% w/v albumin, and/or other molecules). Moreover, the scaffold is edible. The method may optionally further include assaying the scaffold and comparing the scaffold to collagen microcarriers in terms of cell growth.
The preferred embodiments of the present invention will now be described with reference to the drawings. Identical elements in the various figures are identified with the same reference numerals.
Reference will now be made in detail to each embodiment of the present invention. Such embodiments are provided by way of explanation of the present invention, which is not intended to be limited thereto. In fact, those of ordinary skill in the art may appreciate upon reading the present specification and viewing the present drawings that various modifications and variations can be made thereto.
In native tissues, the ECM provides structural support for cell growth and stimulates tissue regeneration. More specifically, the ECM is an intricate network composed of an array of multidomain macromolecules organized in a cell/tissue-specific manner. Components of the ECM link together to form a structurally stable composite, contributing to the mechanical properties of tissues. See, Beatrice Yue, “Biology of the Extracellular Matrix: An Overview,” J. Glaucoma, 2014, Pages S20-S23, the entire contents of which is hereby incorporated by reference in its entirety. Researchers are currently investigating unique methods to create microenvironments that mimic the biochemical and physiological structures of natural environments within the human body. Numerous fabrication strategies have been investigated for this purpose. As an illustrative example, cellulose-based matrices have been used to facilitate mammalian cell culture in vitro and in vivo. See, R. J. Hickey, et al., “Cellulose Biomaterials for Tissue Engineering,” Front. Bioeng. Biotechnol., 2019, the entire contents of which is hereby incorporated by reference in its entirety.
Cellulose is the most abundant polymer in nature and is a key structural element in the cell wall of plants. Specifically, cellulose is a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. With lignin and hemicellulose, cellulose supports plant's vertical growth. See, D. Klemm, et al., “Cellulose: Fascinating Biopolymer and Sustainable Raw Material,” Angew. Chemie Int. Ed., 2005, Vol. 44, Pages 3358-93; and L. J. Gibson, “The Hierarchical Structure and Mechanics of Plant Materials,” J. R. Soc. Interface, 2012, Vol. 9, Pages 2749-66, the entire contents of which are hereby incorporated by reference in their entireties. Due to the unique biophysical and biomechanical properties of cellulose, it may be used as a construct to guide the restructuring of cells and newly formed tissue for various applications. See, R. J. Hickey, et al., “Cellulose Biomaterials for Tissue Engineering,” Front. Bioeng. Biotechnol.,” 2019, Vol. 7, doi: 10.3389/fbioe.2019.00045, the entire contents of which is hereby incorporated by reference in its entirety.
Cellulose sources in tissue engineering include natural polymers derived from plants and synthetically-modified polymers. See, D. J. Modulevsky, et al., “Apple Derived Cellulose Scaffolds for 3D Mammalian Cell Culture,” PLoS ONE, 2014, Vol. 9, 97835; D. J. Modulevsky, et al., “Biocompatibility of Subcutaneously Implanted Plant-Derived Cellulose Biomaterials,” PLoS ONE, 2016, Vol. 11, e0157894; L. Fu, et al., “Present Status and Applications of Bacterial Cellulose-Based Materials for Skin Tissue Repair,” Carbohydr. Polym., 2013, Vol. 92, Pages 1432-42; and M. N. Nosar, et al., “Characterization of Wet-Electrospun Cellulose Acetate Based 3-Dimensional Scaffolds for Skin Tissue Engineering Applications: Influence of Cellulose Acetate Concentration,” Cellulose, 2016, Vol. 23, Pages 3239-48, the entire contents of which are hereby incorporated by reference in their entireties.
Seaweed, or macroalgae, refers to species of macroscopic, multicellular, marine algae. This term includes some types of Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) macroalgae. Macroalgae has unique properties, including a high degree of cellulose crystallinity. See, D. Klemm, et al., “Cellulose: Fascinating Biopolymer and Sustainable Raw Material,” Angew. Chemie Int. Ed., 2005, Vol. 44, Pages 3358-93; and A. Mihranyan, “Cellulose from Cladophorales Green Algae: from Environmental Problem to High-Tech Composite Materials,” Polym. Polym. Compos., 2011, Vol. 119, Pages 2449-60, the entire contents of which are hereby incorporated by reference in their entirety. Specifically, green macroalgae's matrix consist of a highly robust skeleton structure that can be utilized for cell growth. See, M. Lahaye, et al., “Structure and Functional Properties of Ulvan, a Polysaccharide from Green Seaweeds,” Biomacromolecule, 2007, Vol. 8, Pages 1765-74, the entire contents of which are hereby incorporated by reference in their entirety.
Moreover, macroalgae have high growth rates and are abundant, making its mass production affordable. See, A. Chemodanov, et al., “Design of Marine Macroalgae Photobioreactor Integrated into Building to Support Seagriculture for Biorefinery and Bioeconomy,” Bioresour. Technol., 2017, Vol. 241, Pages 1084-93, the entire contents of which is hereby incorporated by reference in its entirety. Additionally, macroalgae has the added benefits of not competing with the food supply, land for agriculture and forestry, or the freshwater supply. See, F. Fernand, et al., “Offshore Macroalgae Biomass for Bioenergy Production: Environmental Aspects, Technological Achievements and Challenges,” Renew. Sustain. Energy Rev., 2017, Vol. 75, Pages 35-45, the entire contents of which is hereby incorporated by reference in its entirety. In fact, green macroalgae derived sulfated polysaccharides (SPs) have been proposed for tissue engineering purposes. See, P. Sudha, et al., “Ulvan in Tissue Engineering,” in Encyclopedia of Marine Biotechnology (ed. Kim, S.) 1335-1350 (Wiley, 2020), the entire contents of which is hereby incorporated by reference in its entirety. For at least the aforementioned reasons, cellulose-based ECM and macroalgae-based cellulose are becoming increasingly popular.
The present invention, as described herein, relates to the use of seaweed and methodology associated with scaffold generation. A method for creating an edible scaffold using an algae (e.g., Durvillaea antarctica, Chilean seaweed, or cochayuyo) is described and depicted in
The method of
A process step 4 follows the process step 3 and includes adding a first solution (e.g., adding 9 volumes of 1% w/v SDS solution) for a first time period (e.g., about three to five days) and at a first temperature (e.g., room temperature). The solution may be refreshed every twenty-four hours. It should be appreciated that the SDS solution is sodium dodecyl sulfate in distilled, deionized water.
A process step 5 follows the process step 4 and includes keeping the flask in agitation (e.g. 180 rpm) and also includes centrifuging the sample at about 1500 rpm for a second time period (e.g., about 5 minutes). Next, the process step includes removing the supernatant. A process step 6 follows the process step 5 and includes washing with distilled water five times and checking for foam reduction.
A process step 7 follows the process step 6 and includes adding a second solution (e.g., 4 ml bleaching buffer (sodium acetate, acetic acid, and sodium chlorite solution) per gram of decellularized cochayuyo) and incubating the sample for a third time period (e.g., about two hours) and at a second temperature (e.g., about 60° C.) in agitation (e.g. 180 rpm). A process step 7 includes bleaching of the sample and ends the method of
Then, a process step 9 follows the process step 8 and includes adding a fourth solution: an acid bath to neutralize the pH and sterilize the sample (e.g. 4 ml of 0.25 M hydrochloric acid per gram of decellularized seaweed) and incubating the sample for a fifth time period (e.g., 10 to 15 minutes) and at a fourth temperature (e.g., boiling temperature). The supernatant is then removed and process step 9 includes adding the distilled water to the tube and storing the sample at a fifth temperature (e.g. 4° C.) until use.
Subsequently in a laminar flow hood, a process step 10 follows the process step 9 and includes thawing the sample in sterilized water at a sixth temperature (e.g. room temperature) for a seventh time period (e.g., 5 to 10 minutes) for five times. The process step 10 also includes adding a fifth solution (e.g. PBS) and incubating the sample for a seventh temperature (e.g., room temperature) and a ninth time period (e.g. 1 hour).
Then, in a laminar flow hood, a process step 11 follows the process step 10 and includes transferring the sterile cochayuyo to flasks (e.g., 50 mL tubes), adding about 1 volume of sterile gelatin or albumin, fibronectin or peptides RGD (e.g. 0.1 to 5%) allowing it to stand for a tenth time period (e.g. 1 hour) at room temperature, preferentially.
A process step 12 follows the process step 11 and includes adding a sixth solution (e.g. a 1:2 ratio of gelatin relative to a sterilized CaCl2) 2% solution), and then storing the sample at an eighth temperature (e.g., at about 37° C.) for an eleventh time period (e.g. 24 hours). Then, the supernatant is removed in the laminar flow hood. Now, the scaffolding is ready for cell seeding. A process step 13 follows the process step 12 to conclude the method of
The final product of the method of
The methods of the present invention differ from other edible scaffolding methods or techniques known in the art field due to the scalability, cost, and the ways in which the seaweed material can be dried and rehydrated without problems before and/or after decellularization. Also, the sample described herein can be easily sterilized without losing its form and can be hydrated with proteins. Furthermore, the scaffolding described herein can be used as a microcarrier because it can float inside the cell media, and one does not need to change the cells for differentiation.
Procedure for Decellularization of Durvillaea antarctica (Cochayuyo)
This protocol was also used in the decellularization of Pelillo (gracilaria chilensis), Luche (Pyropia columbina), and Ulva (Ulva rigida), which are several Chilean algae, without modification, and the C2C12 cells growth were tested using Ulva scaffolding.
The following procedure refers to cochayuyo only, but it should be understood that it will work with the other seaweeds enumerated herein.
The following materials were procured:
The Cochayuyo's scaffoldings are superior because they function better as microcarriers in suspension cultures relative to other scaffolds.
The following protocols lay out how to perform a cell culture on Durvillaea antarctica scaffolds.
C2C12 cell culture on Durvillaea antarctica scaffolds.
The below overall protocol can also be used for primary cultures of myoblasts or every type of mammalian cell, including stem cells and cells suitable for cultivated meat.
The following materials were used:
The following equipment was used:
Magnetic stirrer with Cimarec Biosystem 40B controller (Thermo Scientific, 50087904).
The following solutions were prepared prior to initiating the procedure:
100 mL crystal violet was made using 0.10 g crystal violet, 2.10 g citric acid, and 1 mL Triton X-100.
100 mL trypan blue was made using 0.4 g trypan blue up to 100 mL using PBS
10 mL trypsin (1×) was made using 1 mL trypsin (10×) and up to 10 mL PBS
2 L DMEM/F12 10% FBS culture medium was made using the following:
1 envelope DMEM high glucose medium
1 sachet Ham's F12 nutrient mix
4.01 g sodium bicarbonate
Make up to 2 L with water milli Q
pH 7.30
Filter through 0.22 μm membrane filter
200 mL FBS
10 mL 0.01 M HCl was made using the following:
8 μL HCl
Make up to 10 mL with distilled water.
1 mL 12 mM MTT
1 vial MTT from cell viability kit with MTT
1 mL PBS
Filtrate with 0.22 μm pyrindole filters.
10 mL MTT arrest solution was made using the following:
1 tube of SDS from the cell viability kit with MTT
10 mL 0.01 M HCl
Heat in thermal bath
2 L DMEM/F12 2% HS culture medium was made using the following:
1 sachet DMEM high glucose medium
1 sachet Ham's F12 nutrient mix
4.01 g sodium bicarbonate
Make up to 2 L with water milli Q
pH 7.30
Filter through 0.22 μm membrane filter
40 mL HS
To a T-flasks 175 culture plate, add 33 mL of DMEM/F12 10% FBS culture medium.
To a cryovial containing 1 mL frozen C2C12 cells, add 1 mL of DMEM/F12 10% FBS culture medium until the contents of the vial are melted.
This process must be done quickly, since the DMSO in which the cells are frozen is toxic to them. Add the thawed 2 mL contained in the cryovial to the T-flasks 175 culture plate. Leave the culture plate in the incubator at 37° C. and 5% CO2 until 70-80% confluence is reached.
In a T-flask 175 culture plate, remove all the culture medium. Wash the plate 3 times with PBS. It is important to remove all the culture medium and all the PBS. For this, the plate can be left in a vertical position, so that all the liquids can be removed. Add 1 mL of 1× trypsin and incubate for 10 minutes at 37° C. Subsequently, stop the protease with 10 mL of fresh culture medium and extract a 200 μL aliquot in case a cell count is required. Place the cell solution in a 50 mL tube and centrifuged at 1000 RPM (160×g) for 5 minutes. Discard the culture medium by inversion. Dilute the pellet in 6 mL of DMEM/F12 10% FBS medium.
To 3 T-flasks 175 culture plates, add 33 mL of DMEM/F12 10% FBS medium. To each plate, add 2 mL of the pellet previously resuspended in culture medium. The culture plates are incubated at 37° C. and 5% CO2 until 70-80% confluence is reached.
Procedure for Making a Viability Calibration Curve with MTT
In a T-flasks 175 culture plate, remove all the culture medium. Wash the flasks 3 times with PBS. Add 1 mL of 1×trypsin and incubate 10 minutes at 37° C. Subsequently, stop the protease with 10 mL of fresh culture medium. Place the cell solution in a 50 mL tube and centrifuged at 1000 RPM (160×g) for 5 minutes. In parallel, count cells using a 200 μL aliquot Discard the culture medium by inversion. The pellet is diluted in FBS-free DMEM/F12 medium such that 3.00 ×104 cells are obtained in 100 μL. Take 100 μL in duplicate and place in wells in a 96-well plate. It is important to resuspend the cells correctly so that the cell concentration is as accurate as possible. Subsequently, dilute the solution to obtain 2.50×104 cells in 100 μL. Then, take 100 μL in duplicate and place in wells in a 96-well plate.
The process should be repeated until the following 9 points for the calibration curve are obtained in duplicate: 3,00×104, 2,50 ×104, 2,00 ×104, 1,50 ×104, 1,00 ×104, 0,50 ×104, 0,25 ×104, 0,10 ×104 and 0 cells.
Subsequently, 10 μL of 12 mM MTT is added to each well of the plate and left incubating at 37° C. for 4 hours. Once the time period has elapsed, 100 μL of the MTT stop solution is added to each well and the plate is incubated at 37° C. for 4 hours. Then, MTT stop solution is added to each well and incubated at 37° C. for 4 to 18 hours. Finally, the absorbance of each well is measured at a wavelength of 570 nm on the SPECTROstar Omega plate reader.
The results are recorded on a graph of absorbance vs. number of cells, to which a linear fit is made to obtain a lineal equation.
Procedure for Culture on Scaffolds of Durvillaea antarctica on a Plate
Remove all the media of a T-flasks 175 culture plate. Wash the plate 3 times with PBS. Add 1 mL of 1× trypsin and incubate 10 minutes at 37° C. Subsequently, stop the protease with 10 mL of fresh culture medium and take 200 μL aliquot for cell counting. Place the cell solution in a 50 mL tube and centrifuge at 1000 RPM (160×g) for 5 minutes. In parallel, count cells using the 200 μL aliquot. Discard the culture medium by inversion. The pellet is diluted in such a way that in 10 μL 5.00×104 cells are obtained.
In parallel, 0.5 cm2 pieces of Durvillaea antarctica scaffolds are deposited in wells of a 24-well plate previously siliconized with sigmacote. Specifically, for each day of culture it is recommended to perform a septuplicate. So, each day, take samples from one well per day, cell media for analysis and a scaffolding for pictures. To siliconize with sigmacote, 100 μL of sigmacote is added to a well and the liquid is spread over the entire surface, then the 100 μL are transferred to another well to perform the same process. Once all the wells to be used have been siliconized, the plate should be left under UV light until all the remaining sigmacote evaporates.
To each piece of Durvillaea antarctica add 10 μL of the concentrated cell solution, leaving it to incubate for 40 minutes at 37° C. to promote cell adhesion to the scaffold. Once the 40 minutes have elapsed, the scaffold pieces are transferred to other 24-well plates, previously siliconized, and 1 mL of DMEM/F12 10% FBS culture medium is added. The plates are maintained at 37.0 and 5% CO2 during 7 days and each day one sample is taken for scaffolding pictures and glucose/lactate measurements.
Procedure to Characterize Scaffold Culture of Durvillaea antarctica in Plates.
To the culture made in plates using scaffoldings, do the following: Daily, take wells from the culture previously made. Keep the culture media. The scaffoldings will be helpful to make several analyses. Subsequently, wash the well with PBS twice
First, the morphology was evaluated using crystal violet and pictures taken with a microscope.
The following procedure was followed: Take the scaffolding with a tweezer and put it in a glass slide. Add 20 μl of crystal violet and soak the scaffolding with it and then remove the excess of crystal violet. Take pictures with microscope. The pictures should be taken quickly because the crystal violet dries, producing a dehydration of the algae that changes its structure.
Subsequently, the nuclei were counted using crystal violet: Three samples of Durvillaea antarctica scaffolds were introduced into 3 Eppendorf tubes, 40 μL of crystal violet is added and incubated at 37° C. for 1 hour. Subsequently, the scaffolds are vortexed at maximum power for 15 seconds, then spun in the minicentrifuge, 10 μL are extracted and deposited in a Neubauer chamber and cell counting is performed. In addition, the pieces of cochayuyo were measured with a ruler. If the cells do not detach from the scaffolds after 15 seconds in the vortex, repeat the process.
Also, MTT viability was used to characterize the culture: Another 3 samples are placed in a 96-well plate, 100 μL of fresh serum-free fresh culture medium and 10 μL of 12 mM MTT are added to each scaffold and left to incubate for 4 hours at 37° C. After the time period has elapsed, 100 μL of the MTT arrest solution is added to each well and incubated for 4 to 18 hours at 37° C.
Finally, the scaffold pieces are removed from the wells and sized with a ruler; furthermore, the absorbance of each well is measured at a wavelength of 570 nm on the SPECTROstar Omega plate reader.
From the cell count with crystal violet, a growth curve of cells/mL is made.
Subsequently, from the MTT viability assay and the linear fit of the calibration curve for cell viability, the number of viable cells is obtained, which allows the percentage of viability to be obtained using the crystal violet count as the total number of cells:
The following formula was used to calculate viability.
Viability=(Cells determined by MTT·100)/(Cells determined by crystal violet)
Where:
Viability is the percentage of viability.
Cells determined by MTT=Number of cells calculated from the calibration curve with MTT.
Cells determined by crystal violet=Number of cells calculated from a count with crystal violet.
Cell viability is included in the growth curve graph as a secondary axis. If the number of cells determined by MTT is greater than that determined by crystal violet, a viability of 100% can be assumed. If the number of cells determined by MTT is less than 0, a viability of 0% can be assumed.
In addition, an exponential fit to the exponential cell growth section is made to the growth curve, allowing the value of the maximum specific growth rate (μmax) to be obtained as the exponent of the exponential component of the equation. From μmax, the doubling time (td) was calculated as:
t
d=(1n(2))/μmax
Where:
In contrast, a growth curve of cells/cm′ is made by normalizing the total number of cells counted with crystal violet.
The cells counted with crystal violet were determined by the respective surface area of Durvillaea antarctica scaffolds. The area of the scaffolds can be calculated by assuming that the pieces have a parallelepiped or cube shape, depending on the dimensions of the scaffold.
Finally, a glucose/lactate measurement was made using the following procedure:
Daily, take culture media for each well so as to characterize it. With the culture media taken each day from the cell culture measure glucose and lactate consumption/production as follows: The stored culture media are centrifuged at 1000 RPM (95×g), for 5 minutes and then, a glucose and lactate analysis is performed, using automatic analyzer equipment Y15 and glucose and lactate measurement kits. The results are then recorded in a graph of metabolite concentration vs. hours of culture. Subsequently, the specific rate of metabolite generation or consumption is calculated with equation (5) shown below. Next, the results for the specific rate of glucose consumption and lactate generation are plotted for the time ranges in which the samples were taken. Finally, the glucose/lactate yield is calculated using equation (6) shown below.
Where:
Where:
2 spinners of 100 mL, with one magnetic stirrer located 1 mm from the bottom of the vessel, are siliconized with Sigmacote and autoclaved. Repeat the procedure on culturing the scaffolds of Durvillaea antarctica in plates as described above (until the discarding the culture medium by inversion). Dilute the pellet in fresh culture medium such that a concentration of 3.2-106 cells/mL is obtained. To the two spinners add 9.19 mL of fresh culture medium and 5.81 grams of Durvillaea antarctica scaffolds, since this mass of brown algae has a surface area identical to 0.2 grams of microcarrier cytodex 3 (golden standard in microcarriers).
The equivalent concentration of microcarriers is 2.5 g/L. Specifically, in a culture volume of 80 mL, this translates into an adhesion surface area of 400 cm2.
The spinners are inoculated with 5 mL of the cell solution. Then, they are incubated at 37° C. and 5% CO2 in cycles of 5 minutes of shaking at 35 RPM and 40 minutes of rest for 16 hours, to induce cell adhesion to the Durvillaea antarctica scaffolds.
Ideally, a magnetic stirrer is used with a cycle controller for the above task. Subsequently, the culture medium is discarded and renewed with 74.19 mL of fresh culture medium, leaving it to incubate at 37° C. and 5% CO2, with a continuous agitation of 35 RPM for 7 days.
Procedure for Characterizing Durvillaea antarctica Suspension Culture on Scaffolds.
Daily, 1 mL of the spinner culture medium is stored to perform a glucose consumption and lactate production curve. From each spinner, a sample of Durvillaea antarctica scaffolds was photographed using procedure previously described above (see the procedure to characterize scaffold culture of Durvillaea antarctica on plate above). Subsequently, 8 pieces of Durvillaea antarctica scaffolds are taken and placed in Eppendorf tubes. 8 scaffolds are generally used, since this is the amount that has the surface area corresponding to 2.5-10−3 grams of cytodex 3 microcarriers contained in 1 mL of culture. The scaffolds are washed twice with PBS
Then the Procedure to characterize scaffold culture of Durvillaea antarctica on plate was made as follows: 1 mL of crystal violet is added to each Eppendorf tube and incubated at 37° C. for 1 hr. Subsequently, the samples are vortexed at maximum power for 15 seconds, then a spin is performed in the mini-centrifuge, 10 μL of sample is taken and deposited in a Neubauer chamber and a cell count is performed.
The procedure to characterize scaffold culture of Durvillaea antarctica on plate was made as follows:
From each spinner, 3 samples of Durvillaea antarctica scaffolds with cells are extracted, placed individually in a 96-well plate, 100 μL of fresh serum-free fresh culture medium and 10 μL of 12 mM MTT are added to each scaffold and left to incubate for 4 hours at 37° C. After the time period has elapsed, 100 μL of the MTT arrest solution is added to each well and incubated for 4 to 18 hours at 37° C. Finally, the scaffold pieces are removed from the wells and sized with a ruler. The absorbance of each well is also measured at a wavelength of 570 nm on the SPECTROstar Omega plate reader.
From the cell count with crystal violet, a growth curve of cells/mL is made.
Subsequently, from the viability assay with MTT and the linear adjustment of the calibration curve for cell viability, the amount of viable cells is obtained, which allows one to obtain the viability percentage using the count with crystal violet, as the total cells according to viability equation above.
Additionally, the growth curve is exponentially adjusted to the exponential cell growth section, allowing one to obtain the value of the maximum specific growth rate (μmax), as the exponent of the exponential component of the equation. From μmax, the doubling time (td) was calculated according to the doubling time equation above.
A growth curve of cells/cm2 is made by normalizing the total number of cells counted with crystal violet by the respective surface area of Durvillaea antarctica scaffolds. When extracting 8 pieces of scaffolds, which are equivalent to a surface area of 2.5-10−3 grams of cytodex 3 microcarriers, the surface area should be 5 cm2.
Finally, the glucose-lactato were analyzed using the above procedure to characterize scaffold culture of Durvillaea antarctica on plate as follows: The stored culture media are centrifuged at 1000 RPM (95×g), for 5 minutes and then, glucose and lactate analysis are performed, using the automatic analyzer equipment in Random Access Y15 and the glucose and lactate measurement kits. The results are then recorded on a graph of metabolite concentration vs. hours of culture. Subsequently, the specific rate of metabolite generation or consumption is calculated with equation (5) above. Next, the results for the specific rate of glucose consumption and lactate generation are plotted for the time ranges in which the samples were taken. Finally, the glucose/lactate yield is calculated with above equation (6).
Procedure for Performing Differentiation of C2C12 Cells on Durvillaea antarctica Scaffolds in Suspension
From a suspension culture of C2C12 cells on Durvillaea antarctica scaffolds at their highest cell concentration, all the culture medium is removed. If the culture is grown in 80 mL, scaffold surface area of 400 cm2 and an initial seeding of 1-105 cells/mL or a ratio of these values, then the maximum concentration will be reached at 80 hours. 80 mL of DMEM/F12 2% HS differentiation medium is added. The spinners are incubated at 37° C., 5% CO2 with continuous 35 RPM agitation. Every 48 hours, the differentiation medium is discarded and renewed with 80 mL of fresh differentiation medium. The culture should be extended for at least 4 days and a maximum of 6 days.
Decellularization of Durvillaea antarctica (Cochayuyo)
The above procedures and the following examples are described now with reference to the figures.
Cochayuyo was decellularized using the protocol described herein and experiments were made in triplicate using as starting material a volume of 15 ml of dried cochayuyo cortex. The decellularization process was measured quantifying the DNA content of the supernatant using nanodrop equipment. Also, the decellularization was photographed at each stage of the process. After neutralization, the DNA content within decellularized vs. cellularized algae was compared by DNA extraction with liquid nitrogen and CTAB buffer, and then measured in nanodrop. The significant difference was analyzed with t-student in Graphpad Prism 8.
Subsequently, the remaining DNA in the supernatant was measured during decellularization. The DNA should be reduced during decellularization, indicating successful decellularization due to the cell content being removed from the cortex.
The culture was made according to the protocol disclosed herein. For these assays, C2C12 cells were used with mouse cell line myoblast progenitor. The protocols disclosed herein can be used in other cell types, and are relevant for cultivated meat.
Plate cultures were used in triplicate. Suspension culture was in duplicate, and the culture was grown for 7 days with sampling every 24 hours, in a culture volume of 80 ml.
A C2C12 differentiation protocol was used comprising 4 days of growth and 6 days of differentiation, with sampling every 48 hours during differentiation, in a culture volume of 120 mL. The protocol used was as discussed herein.
Table 1 shows a comparison of the culture parameters in plates at 37° C. and 5% CO2 (VALAVANIS, C, 2021) (MONTESANO, A, 2015) with the experimental data obtained herein. Those results will be helpful for the analysis of the scaffolding's performance of the present invention.
The cell density of the culture was measured and is shown in
Subsequently, C2C12 cells were grown on cochayuyo scaffoldings, and the results are shown in
Table 2 shows the comparison of parameters of C2C12 culture on Durvillaea antarctica scaffolds on plates at 37° C. and 5% CO2. These results provide useful data for the analysis of the performance of the scaffolding of the present invention.
The cellular density measures how many cells are using the surface of the scaffolding of the present invention.
C2C12 cells are not able to grow without attachment. Therefore, they need a surface to grow. To overcome this lack of attachment, the use of microcarriers, spherical beads with adhesion capabilities can be used. Moreover, collagen-covered microcarriers have excellent performance and are commonly used (such as a Cytodex 3 (Sigma-Aldrich)). The cell culture was made as described, and the same surface as described was used for the microcarriers and seaweed scaffoldings. At 16 h of culture, there is a media change and specific metabolites rates can change. This media change is for all the cultures.
Table 3 shows the experimental results of C2C12 culture parameters compared with a reference example.
Subsequently, C2C12 cultures were made on cochayuyo scaffoldings in suspension cultures. In that type of culture, the scaffoldings of the present invention behave as microcarriers and confer a good scalability quality. The experiment was made using the same protocol as described above with the microcarriers.
Table 4 shows the experimental parameters of cell culture on the scaffoldings of the present invention in suspension culture.
In plate cultures, the cochayuyo scaffolds grew at a similar rate but it presents a lower cell concentration. The cochayuyo scaffolds have a higher glucose/lactate yield, but in both conditions, it is between 0 and 1.5, so they are considered efficient. In suspension cultures, the cochayuyo scaffold is faster for cell growth. Although it has a lower cell concentration, its density does not significantly differ. In addition, the cochayuyo scaffolds have a higher glucose/lactate yield, but in both conditions, it is between 0 and 1.5, so they are considered efficient. This means that in suspension cultures cochayuyo scaffolds can produce equivalent cell yield in less time.
Table 5 shows a summary of experimental parameters for the different growing conditions.
Durvillaea antactica
Durvillaea antactica
indicates data missing or illegible when filed
Ulva was decellularized due to its use as a scaffold using a similar protocol from a reference. Subsequently, tests were performed with this alga to compare it with the scaffolds of the present invention. Afterward, Ulva was decellularized using the protocol “Scaffolding-microcarrier generation.” Due to the mass required to perform the suspension culture and store stock, 70 g of Ulva in a 2-liter flask was used. During decellularization with 1% SDS, the DNA content of the supernatant was measured using nanodrop equipment. The decellularization was photographed at each stage of the process. After neutralization, the DNA content of decellularized vs. cellularized algae was compared by DNA extraction with liquid nitrogen and CTAB buffer, and then the samples were measured in nanodrop. Significant differences were seen using t-student in Graphpad Prism 8.
Suspension cultures work better with algae scaffoldings. Accordingly, a suspension culture of C2C12 cells was made using Ulva scaffoldings with the same parameters used for cochayuyo. After 7 hours, cell adhesion was observed, as evidenced by the shape of the cells. No growth is evident with the naked eye between 7 and 71 hours. At 120 hours, cell death is observed.
Table 6 shows the experimental parameters of C2C12 culture on Ulva rigida scaffolding.
Comparing suspension cultures using Cochayuyo and Ulva, it is clear that there are significant differences in cell concentration and cell density, where cochayuyo has significantly better performance with comparable surface areas under cultivation (see
Finally, suspension cultures were compared between Ulva, Durvillaea, and microcarriers (cytodex 3).
It should be appreciated that the following methodologies disclosed in the following references have been incorporated by reference in their entireties: J. D. Jones, et al., “Decellularized Spinach: an Edible
Scaffold for Laboratory-Grown Meat,” Food Bioscience, 2021, Vol. 41, 100986; J. R. Gershlak, et al., “Crossing Kingdoms: Using Decellularized Plants as Perfusable Tissue Engineering Scaffolds,” Biomaterials, 2017, Vol. 125, Pages 13-22; and R. J. Hickey, et al., “Cellulose Biomaterials for Tissue Engineering,” Frontiers in Bioengineering and Biotechnology, 2019, Vol. 7, 45.
The present invention also contemplates assaying the scaffolding and comparing such to collagen microcarriers in terms of cell growth. It is hypothesized that the scaffolding described herein will perform better for myotube differentiation than unorganized differentiation in plates because it allows a 3D structure.
Assays that may be used to assess the amount and effectiveness of the decellurization process include assaying DNA levels when measuring by PicoGreen and visually assessing the absence or presence of cell nuclei. Collagen and other ECM components can be assayed and quantified by hydroxyproline content, by sGAG, by histological analysis, and by SDS-PAGE. An additional assay that may be performed includes gelation kinetics assessed by turbidimetric analysis. Other assays include the use of antibodies to look for immunogenic antigens that may or may not be present on the decellurized seaweed.
The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others or ordinary skill in the art to understand the embodiments disclosed herein.
When introducing elements of the present disclosure or the embodiments thereof, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. Similarly, the adjective “another,” when used to introduce an element, is intended to mean one or more elements. The terms “including” and “having” are intended to be inclusive such that there may be additional elements other than the listed elements.
Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made only by way of illustration and that numerous changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.
The present invention claims priority under 35 USC 119(e) to US Provisional Application No. 63/284,659 filed Dec. 1, 2021, the entire contents of which are incorporated by reference in its entirety.
Number | Date | Country | |
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63284659 | Dec 2021 | US |