Research reported in this publication was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under award number R15AR064481, the National Science Foundation (CMMI-1404716), as well as the Arkansas Biosciences Institute.

1. Production of Extracellular Matrix Using Sacrificial Hollow Fiber Membranes
CAUTION: N-methyl-2-pyrrolidone is an irritating solvent and reproductive toxicant. Exposure to NMP may cause irritation to the skin, eyes, nose, and throat. Solvent-resistant personal protective equipment should be used when handling NMP. Use of NMP should be performed within a fume hood.
<ol>
	<li>Preparation of polysulfone polymer solution for hollow fiber membranes
	<ol>
		<li>Weigh 70 g of polysulfone pellets (molecular weight of 35 kD) in a weigh boat using an analytical balance.</li>
		<li>Transfer 314 mL (323.3 g) of N-methyl-2-pyrrolidone (NMP) to a clean borosilicate flask.</li>
		<li>Place a stir bar in the flask with NMP and place flask onto stirrer. Set the stirrer to a moderate rate of rotation.</li>
		<li>Use a dry funnel to slowly insert the prepared 70 g of polysulfone into the flask with NMP.</li>
		<li>Allow the polymer &#8220;dope&#8221; solution to stir for three days at room temperature, or until homogenized.</li>
	</ol>
	</li>
	<li>Setting concentricity and cleaning of the hollow fiber membrane spinneret 
	NOTE: Spinnerets are commercially available; correct spinneret dimensions are critical to successful membrane fabrication and are listed in the Table of Materials. Handle the spinneret very gently, as the spinneret needle is particularly fragile.
	<ol>
		<li>Use a screwdriver or drill with an appropriate screwdriver bit to carefully disassemble the spinneret.</li>
		<li>Gently flow acetone through the inlet and outlet of the spinneret, collecting any acetone and residual polymer in a glass beaker for disposal.</li>
		<li>Secure the upper body of the spinneret with the needle facing upward in a table vise.</li>
		<li>Place the outlet (bottom) body of the spinneret onto the upper body.</li>
		<li>Move the outlet body of the spinneret laterally while holding the upper body fixed on the vise until the spinneret needle is directly in the center of the outlet body.</li>
		<li>Carefully and slowly reinsert the screws connecting the two bodies of the spinneret while ensuring that the needle visible at the spinneret outlet remains centered.</li>
	</ol>
	</li>
	<li>Fabrication of polysulfone hollow fiber membranes
	<ol>
		<li>Prepare a &#8220;bore solution&#8221; containing 45 mL of N-methyl-2-pyrrolidone and 255 mL of deionized water, forming a 15% mixture of NMP with deionized water.</li>
		<li>Mount a concentric hollow fiber membrane spinneret 8 cm above the surface of a room-temperature tap water bath.</li>
		<li>Connect the polymer inlet of the spinneret and the bore inlet of the spinneret to two separate steel pressure vessels having an inner volume of at least 350 mL. Both vessels must have check valves at their outlets.</li>
		<li>Connect each of the pressure vessels to the regulators of separate N2 gas cylinders</li>
		<li>Use a funnel to insert the prepared dope solution (~315 mL) into the pressure vessel connected to the polymer inlet of the spinneret. Ensure that the top of the vessel is tightly sealed.</li>
		<li>Use a funnel to insert the prepared bore solution (300 mL) into the pressure vessel connected to the bore inlet of the spinneret. Ensure that the top of the vessel is tightly sealed.</li>
		<li>Open the check valve for the bore vessel first, then the polymer vessel second. If the spinneret is sufficiently clean, the bore solution will begin to stream out of the spinneret outlet.</li>
		<li>Pressurize both vessels to 1 PSI. Visually confirm that both polymer and bore solutions are exiting the spinneret, with a continuous white filament precipitating as the combined streams contact the water bath.</li>
		<li>Use long forceps to guide the nascent fiber under the rollers in the center of the bath, and then wind the nascent fiber around a rotating wheel connected to a motor.</li>
		<li>Set the take-up wheel and motor to rotate at a rate of approximately two meters per minute.</li>
		<li>Make minor adjustments to the regulators or take-up wheel speed as needed until a steady-state flow is achieved. The nascent fiber should form a 90&#176; angle with the surface of the water bath.</li>
		<li>Close the N2 cylinder regulators and pressure vessel check valves and disengage the take-up wheel motor after all polymer and bore solution has been extruded from the vessels.</li>
		<li>Remove the prepared hollow fiber membranes and place them into a deionized water bath for three days, exchanging deionized water once per day to remove residual solvent.</li>
		<li>Sterilize the hollow fiber membranes by autoclaving them at 121 &#176;C for 30 minutes or by immersing them for one day in 70% ethanol.</li>
	</ol>
	</li>
	<li>Cell seeding of hollow fiber membranes 
	NOTE: All cell culture procedures should be performed within a biosafety cabinet.
	<ol>
		<li>Treat the hollow fiber membranes with a 20 &#181;g/mL solution of bovine plasma fibronectin in PBS (pH = 7.4) to promote cell attachment.
		<ol>
			<li>Weigh 1 mg of powdered bovine plasma fibronectin in a weigh boat and dissolve it in 1 mL of sterile PBS (pH = 7.4) in a sterile 1.5 mL microcentrifuge tube.</li>
			<li>Incubate the 1 mg/mL bovine plasma fibronectin solution in the incubator for 30 minutes. Add the solution to 49 mL of sterile PBS in a sterile 50 mL conical centrifuge tube.</li>
			<li>Incubate the fibers in the prepared 50 mL of bovine plasma fibronectin in an incubator at 37 &#176;C with 5% CO2 for 1 hour. Recollect the fibronectin solution for later use and store in a sterile 50 mL conical centrifuge tube at 4 &#176;C.</li>
		</ol>
		</li>
		<li>Use sterile microscissors to cut the fibers to desired length (&#60;6 cm).</li>
		<li>Seed fibroblast cells directly into the lumina of the hollow fiber membranes at a seeding density of 100,000 cells per fiber using a 21-gauge needle with 1 mL syringe. 
		NOTE: A practicable target for preparing the cell-suspension for loading in the syringe is a suspension density of 100,000 cells for every 30 microliters of medium.</li>
		<li>Place six seeded fibers into a 6 cm diameter Petri dish. Allow the seeded fibers to incubate at 37 &#176;C with 5% CO2 for five minutes.</li>
		<li>Remove the seeded fibers from incubation and culture them for up to 3 weeks in DMEM/F-12 containing final concentrations of 50 &#181;g/mL L-ascorbic acid and 150 &#181;g/mL L-ascorbic acid 2-phosphate (freshly prepared and sterile filtered), 5 ng/mL TGF-&#946;1 (from sterile filtered aliquots stored at -20 &#176;C), and 1% penicillin-streptomycin in a 6 cm Petri dish within a 5% CO2 incubator at 37 &#176;C. Exchange cell medium every two days.</li>
	</ol>
	</li>
	<li>Extraction of extracellular matrix from cultured hollow fiber membranes
	<ol>
		<li>Place cultured fibers into individual scintillation vial using forceps.</li>
		<li>Place up to 5 mL of NMP into each vial using a glass pipette.</li>
		<li>Immerse the hollow fibers in NMP, performing a total of three exchanges of NMP. Slowly aspirate the old NMP using a 1 mL pipette to prevent tearing of extracted ECM. 
		NOTE: When adding fresh NMP, it is helpful to tilt the vial and allow the NMP run down the sides, otherwise the remaining ECM scaffold is subjected to shear which may cause tearing.</li>
		<li>Remove NMP and rinsed the resulting ECM thread 3 times in deionized water.</li>
		<li>Cut a 1/32-inch thick sheet of silicone rubber to a length of 3 inches, width of 1 inch and cut an 8 mm by 4 mm rectangular mold in the center of the length of rubber.</li>
		<li>Place the prepared piece of rubber onto a standard 3-inch by 1-inch microscopy slide and autoclave at 121 &#176;C for 30 minutes.</li>
		<li>Lay each ECM fiber side by side in the 8 mm by 4 mm silicone mold until there is no visible open space.</li>
		<li>Place the mold into a 50 mL conical centrifuge tube and freeze at -80&#176;C until completely frozen.</li>
		<li>Lyophilize frozen ECM mesh overnight or until completely dry. Store the mesh at 4&#176;C until ready for decellularization.</li>
	</ol>
	</li>
</ol>
2. Decellularization of Extracellular Matrix
<ol>
	<li>Prepare a solution of 1% (w/w%) sodium dodecyl sulfate (SDS) in deionized water.</li>
	<li>Incubate extracted extracellular matrix in the mold in 1% SDS for 24 hours at room temperature on a rocker with gentle agitation.</li>
	<li>Rinse extracted extracellular matrix three times in sterile phosphate-buffered saline (PBS) with gentle agitation, using 3 mL of PBS per rinse. 
	NOTE: Rinses should be performed gently to minimize tearing of prepared scaffolds.</li>
	<li>Prepare 1 L of DNAse/RNAse digestion buffer. 
	NOTE: DNAse/RNAse digestion buffer may be stored for several months at 4&#176;C.
	<ol>
		<li>Weigh 1.54 g of Tris HCl, 308 mg of MgCl2, and 56 mg of CaCl2 in separate weigh boats.</li>
		<li>Combine Tris HCl, MgCl2, and CaCl2 with 1 L of deionized water in a large flask with a stir bar and stir until all components are dissolved.</li>
		<li>Sterile filter the digestion buffer with a 0.22 &#181;m filter into a sterile 1 L borosilicate bottle and store at 4&#176;C.</li>
	</ol>
	</li>
	<li>Prepare 5 mL of DNAse/RNAse digestion solution. 
	NOTE: Digestion solution should be used within 24 hours of preparation.
	<ol>
		<li>Weigh 0.125 mg (50 kU) of DNAse I in a weigh boat and add to 5 mL of digestion buffer.</li>
		<li>Add 75 &#181;L of RNAse A stock solution to the digestion buffer.</li>
	</ol>
	</li>
	<li>Fill each mold with digestion solution and incubate at 4 &#176;C for 6 hours.</li>
	<li>Aspirate the digestion solution and rinse three times in sterile PBS.</li>
	<li>Aspirate the PBS and incubate scaffolds overnight in 10% penicillin-streptomycin in PBS at 4&#176;C.</li>
	<li>Aspirate the penicillin-streptomycin and rinse scaffolds three times in sterile PBS.</li>
	<li>Place the mold into a 50 mL conical centrifuge tube and freeze at -80&#176;C.</li>
	<li>Lyophilize the decellularized ECM mesh overnight or until completely dry.</li>
	<li>Transfer the lyophilized scaffolds within a biosafety hood to a sterile container at 4&#176;C pending use.</li>
</ol>

<ol>
	<li>Cobb, W. S., Kercher, K. W., Heniford, B. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+argument+for+lightweight+polypropylene+mesh+in+hernia+repair.">The argument for lightweight polypropylene mesh in hernia repair.</a> Surgical Innovation. 12 (1), 63-69 (2005).</li><li>Morais, J. M., Papadimitrakopoulos, F., Burgess, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomaterials/Tissue+Interactions:+Possible+Solutions+to+Overcome+Foreign+Body+Response.">Biomaterials/Tissue Interactions: Possible Solutions to Overcome Foreign Body Response.</a> The AAPS Journal. 12 (2), 188-196 (2010).</li><li>Simon, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+failure+of+the+tissue+engineered+porcine+heart+valve+SYNERGRAFT&#174;+in+pediatric+patients.">Early failure of the tissue engineered porcine heart valve SYNERGRAFT&#174; in pediatric patients.</a> European Journal of Cardio-Thoracic Surgery. 23 (6), 1002-1006 (2003).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> FDA strengthens requirements for surgical mesh for the transvaginal repair of pelvic organ prolapse to address safety risks. , (2016).</li><li>Kartus, J., Movin, T., Karlsson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Donor-site+morbidity+and+anterior+knee+problems+after+anterior+cruciate+ligament+reconstruction+using+autografts.">Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts.</a> Arthroscopy: The Journal of Arthroscopic &amp; Related Surgery. 17 (9), 971-980 (2001).</li><li>Lu, H., Hoshiba, T., Kawazoe, N., Chen, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autologous+extracellular+matrix+scaffolds+for+tissue+engineering.">Autologous extracellular matrix scaffolds for tissue engineering.</a> Biomaterials. 32 (10), 2489-2499 (2011).</li><li>Wolchok, J. C., Tresco, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+isolation+of+cell+derived+extracellular+matrix+constructs+using+sacrificial+open-cell+foams.">The isolation of cell derived extracellular matrix constructs using sacrificial open-cell foams.</a> Biomaterials. 31 (36), 9595-9603 (2010).</li><li>Roberts, K., Schluns, J., Walker, A., Jones, J. D., Quinn, K. P., Hestekin, J., Wolchok, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+derived+extracellular+matrix+fibers+synthesized+using+sacrificial+hollow+fiber+membranes.">Cell derived extracellular matrix fibers synthesized using sacrificial hollow fiber membranes.</a> Biomedical Materials. 13 (1), (2017).</li><li>Hurd, S. A., Bhatti, N. M., Walker, A. M., Kasukonis, B. M., Wolchok, J. 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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+infusion+bioreactor+for+the+accelerated+preparation+of+decellularized+skeletal+muscle+scaffolds.">Development of an infusion bioreactor for the accelerated preparation of decellularized skeletal muscle scaffolds.</a> Biotechnology Progress. 32 (3), 745-755 (2016).</li><li>Murad, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+collagen+synthesis+by+ascorbic+acid.">Regulation of collagen synthesis by ascorbic acid.</a> Proceedings of the National Academy of Sciences of the United States of America. 78 (5), 2879-2882 (1981).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-specific+extracellular+matrix+coatings+for+the+promotion+of+cell+proliferation+and+maintenance+of+cell+phenotype.">Tissue-specific extracellular matrix coatings for the promotion of cell proliferation and maintenance of cell phenotype.</a> Biomaterials. 30 (23-24), 4021-4028 (2009).</li><li>Feng, C. Y., Khulbe, K. C., Matsuura, T., Ismail, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+progresses+in+polymeric+hollow+fiber+membrane+preparation,+characterization+and+applications.">Recent progresses in polymeric hollow fiber membrane preparation, characterization and applications.</a> Separation and Purification Technology. 111, 43-71 (2013).</li><li>Domb, A. J., Kost, J., Wiseman, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Biodegradable Polymers. , (1998).</li></ol>

The authors declare that they have no competing financial interests.

The processes described enable the production of bulk ECM biomaterials in vitro using hollow fiber membranes cast by a dry-jet wet spinning system allowing for inexpensive bulk production of membranes as well as standard cell culture equipment. While the membranes fabricated in this protocol are intended for use in cell culture, the system described can also be adapted for the production of membranes for separation purposes, with pore size distribution and hollow fiber dimensions tunable by varying spinneret dim...

Implantable surgical scaffolds are a fixture of&#160;wound repair,with over one million synthetic polymer meshes implanted worldwide each year for abdominal wall repair alone1. However, following implantation the synthetic materials polymers traditionally used in the fabrication of these scaffolds tend to provoke a foreign body response, resulting in inflammation deleterious to the function of the implant and scarring of tissue2. Further, as the predominant synthetic mesh materials (i.e., polypropylene) are not appreciably remodeled by the body, they are generally applicable to tissues where scarring can be tolerated, limiting their clinical usefulness toward the treatment of tissues with higher-order function such as muscle. While there are many surgical mesh products which have been applied with clinical success, recent manufacturer recalls of synthetic surgical meshes and complications from interspecies tissue implants highlight the importance of maximizing implant biocompatibility, prompting the FDA to tighten regulations on surgical mesh manufacturers3,4. Implantation of scaffolds derived from patients&#39; own tissues reduces this immune response, but can result in significant donor-site morbidity5. Extracellular matrix (ECM) scaffolds produced in vitro are a possible alternative, as decellularized ECM scaffolds exhibit excellent biocompatibility, particularly in the case of autologous ECM implants6.
Because of the limited availability of patient tissue to harvest for autologous implantation and the risk of impeding function at the donor site, the ability to produce ECM scaffolds in vitro from the culture of human cell lines or, if possible, a patient&#39;s own cells is an attractive alternative. The primary challenges in the manufacture of substantial amounts of ECM in vitro is the sequestration of these difficult-to-capture molecules. In previous work, we have demonstrated that ECM can be produced by culturing ECM-secreting fibroblasts in sacrificial polymeric foams that are dissolved after the culture period to yield ECM which can be decellularized for implantation7,8,9,10. As ECM produced in foams tend to adopt the internal architecture of the foams, hollow fiber membranes (HFMs) were explored as a sacrificial scaffold for production of threads of ECM. Described herein are methods tasked for lab scale manufacturing of cell culture quality hollow fiber membranes and the extraction of bulk extracellular matrix fibers from the same following a period of fibroblast culture. This static culture approach is readily adoptable by laboratories containing standard mammalian cell culture equipment. ECM produced by this approach could be applied toward a variety of clinical applications.

<table>
	<tbody>
		<tr>
			<td>1/32 inch thick silicone rubber</td>
			<td>Grainger</td>
			<td>B01LXJULOM</td>
			<td></td>
		</tr>
		<tr>
			<td>20 mL Scintillation Vials, Borosilicate glass, Disposable - VWR</td>
			<td>VWR</td>
			<td>66022-004</td>
			<td>With attached white urea cap and cork foil liner</td>
		</tr>
		<tr>
			<td>3 inch by 1 inch microscopy slides</td>
			<td>VWR</td>
			<td>75799-268</td>
			<td></td>
		</tr>
		<tr>
			<td>4C refrigerator</td>
			<td>Thermo Fisher Scientific</td>
			<td>FRGG2304D</td>
			<td>Any commercial 4C refrigerator will suffice.</td>
		</tr>
		<tr>
			<td>50 mL tubes</td>
			<td>VWR</td>
			<td>21008-178</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well cell culture plates</td>
			<td>VWR</td>
			<td>10062-892</td>
			<td>Alternative brands may be used</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>VWR</td>
			<td>E646</td>
			<td>Alternative brands may be used</td>
		</tr>
		<tr>
			<td>Bore vessel</td>
			<td>McMaster-Carr</td>
			<td>89785K867</td>
			<td>6 ft 316 steel tubing</td>
		</tr>
		<tr>
			<td>Bovine Plasma Fibronectin</td>
			<td>Thermo Fisher Scientific</td>
			<td>33010018</td>
			<td>Comes as 1 mg of lyophilized protein</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>VWR/Amresco</td>
			<td>97062-590</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Culture Incubator w/ CO2</td>
			<td></td>
			<td></td>
			<td>Any appropriate CO2-supplied mammalian cell incubator will suffice.</td>
		</tr>
		<tr>
			<td>Disposable Serological Pipets, Glass - Kimble Chase</td>
			<td>VWR</td>
			<td>14673-208</td>
			<td>Alternative brands may be used</td>
		</tr>
		<tr>
			<td>DMEM/F-12, HEPES</td>
			<td>Thermo Fisher Scientific</td>
			<td>11330032</td>
			<td>Warm in water bath at 37&#176;C for 30 minutes prior to use</td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Sigma-Aldrich</td>
			<td>DN25-10MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Dope vessel</td>
			<td>McMaster-Carr</td>
			<td>89785K867</td>
			<td>6 ft 316 steel tubing</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>VWR</td>
			<td>BDH1160</td>
			<td>Dilute to 70% for sterilization</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum, qualified, US origin - Gibco</td>
			<td>Thermo Fisher Scientific</td>
			<td>26140079</td>
			<td>Mix with growth media at 10% concentration (50mL in 500mL media)</td>
		</tr>
		<tr>
			<td>Four 1/4-inch to 1&#34; reducing unions</td>
			<td>Swagelok</td>
			<td>SS-1610-6-4</td>
			<td>One reducing union for each inlet and outlet of each vessel</td>
		</tr>
		<tr>
			<td>Freeze-dryer/lyophilizer</td>
			<td>Labconco</td>
			<td>117 (A65312906)</td>
			<td>Any lyophilizer will suffice.</td>
		</tr>
		<tr>
			<td>Hexagonal Antistatic Polystyrene Weighing Dishes - VWR</td>
			<td>VWR</td>
			<td>89106-752</td>
			<td>Any weigh boat will suffice</td>
		</tr>
		<tr>
			<td>Hollow fiber membrane immersion bath</td>
			<td></td>
			<td></td>
			<td>34L polypropylene tubs may be used or large bath containers can be fabricated from welded steel sheets</td>
		</tr>
		<tr>
			<td>Hollow Fiber Membrane Spinneret</td>
			<td>AEI</td>
			<td>http://www.aei-spinnerets.com/specifications.html</td>
			<td>Made to order. Inner diameter = 0.8 mm, outer diameter = 1.6 mm</td>
		</tr>
		<tr>
			<td>Hot plate/stirrer</td>
			<td>VWR</td>
			<td>97042-634</td>
			<td></td>
		</tr>
		<tr>
			<td>Human TGF-&#946;1</td>
			<td>PeproTech</td>
			<td>100-21</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Ascorbic acid</td>
			<td>Sigma-Aldrich</td>
			<td>A4544-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Ascorbic acid 2-phosphate</td>
			<td>Sigma-Aldrich</td>
			<td>A8960-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine (200 mM) - Gibco</td>
			<td>Thermo Fisher Scientific</td>
			<td>25030081</td>
			<td>Mix with growth media at 1% concentration (5mL in 500mL media)</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>VWR/Alfa Aesar</td>
			<td>AA12315-A1</td>
			<td></td>
		</tr>
		<tr>
			<td>Minus 80 Freezer</td>
			<td>Thermo Fisher Scientific</td>
			<td>UXF40086A</td>
			<td>Any commercial -80C freezer will suffice.</td>
		</tr>
		<tr>
			<td>N2 gas cylinders (two)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NIH/3T3 cells</td>
			<td>ATCC</td>
			<td>CRL-1658</td>
			<td>Alternative fibrogenic cell lines may be used.</td>
		</tr>
		<tr>
			<td>N-methyl-2-pyrrolidone</td>
			<td>VWR</td>
			<td>BDH1141</td>
			<td>Alternative brands may be used</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin Solution - Gibco</td>
			<td>Thermo Fisher Scientific</td>
			<td>15140122</td>
			<td>Mix with growth media at 0.1% concentration (0.5 mL in 500mL media)</td>
		</tr>
		<tr>
			<td>Polysulfone</td>
			<td>Sigma-Aldrich</td>
			<td>428302</td>
			<td>Any polysulfone with an average Mw of 35,000 daltons may be used</td>
		</tr>
		<tr>
			<td>Portable Pipet-Aid Pipetting Device - Drummond</td>
			<td>VWR</td>
			<td>53498-103</td>
			<td>Alternative brands may be used</td>
		</tr>
		<tr>
			<td>PTFE tubing (1/4-inch inner diameter)</td>
			<td>McMaster-Carr</td>
			<td>52315K24</td>
			<td>Alternative brands may be used.</td>
		</tr>
		<tr>
			<td>Rat skeletal muscle fibroblasts</td>
			<td></td>
			<td></td>
			<td>Independently isolated from rat skeletal muscle. Alternative fibrogenic cell lines may be used.</td>
		</tr>
		<tr>
			<td>RNase A</td>
			<td>Sigma-Aldrich</td>
			<td>R4642</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone sheet</td>
			<td>McMaster-Carr</td>
			<td>1460N28</td>
			<td></td>
		</tr>
		<tr>
			<td>Take-up motor</td>
			<td>Greartisan</td>
			<td>B071GTTSV3</td>
			<td>200 RPM DC Motor</td>
		</tr>
		<tr>
			<td>Tris HCl</td>
			<td>VWR/Amresco</td>
			<td>97063-756</td>
			<td></td>
		</tr>
		<tr>
			<td>Two needle valves</td>
			<td>Swagelok</td>
			<td>SS-1RS4</td>
			<td></td>
		</tr>
	</tbody>
</table>

production of extracellular matrix fibers via sacrificial hollow fiber membrane cell culture

Engineered scaffolds derived from extracellular matrix (ECM) have driven significant interest in medicine for their potential in expediting wound closure and healing. Extraction of extracellular matrix from fibrogenic cell cultures in vitro has potential for generation of ECM from human- and potentially patient-specific cell lines, minimizing the presence of xenogeneic epitopes which has hindered the clinical success of some existing ECM products. A significant challenge in in vitro production of ECM suitable for implantation is that ECM production by cell culture is typically of relatively low yield. In this work, protocols are described for the production of ECM by cells cultured within sacrificial hollow fiber membrane scaffolds. Hollow fiber membranes are cultured with fibroblast cell lines in a conventional cell medium and dissolved after cell culture to yield continuous threads of ECM. The resulting ECM fibers produced by this method can be decellularized and lyophilized, rendering it suitable for storage and implantation.

Successful production of extracellular matrix from sacrificial scaffolds is contingent on appropriate scaffold fabrication, cell culture, and solvent rinse procedures. Fabrication of the hollow fiber membranes is performed using a dry-jet wet-spinning system assembled from commercially available components (Figure 1) which uses extrusion of polymer solution through the annulus of a commercially available steel spinneret (inner diameter = 0.8 mm, outer diamete...

Watch this Scientific Journal Video about Production of Extracellular Matrix Fibers via Sacrificial Hollow Fiber Membrane Cell Culture at JoVE.com

Production of Extracellular Matrix Fibers via Sacrificial Hollow Fiber Membrane Cell Culture

The goal of this protocol is production of whole extracellular matrix fibers targeted for wound repair which are suitable for preclinical evaluation as part of a regenerative scaffold implant. These fibers are produced by the culture of fibroblasts on hollow fiber membranes and extracted by dissolution of the membranes.

Engineered scaffolds derived from extracellular matrix (ECM) have driven significant interest in medicine for their potential in expediting wound closure ...

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JoVE Journal

Bioengineering

7.3K Views.  University of Arkansas. The goal of this protocol is production of whole extracellular matrix fibers targeted for wound repair which are suitable for preclinical evaluation as part of a regenerative scaffold implant. These fibers are produced by the culture of fibroblasts on hollow fiber membranes and extracted by dissolution of the membranes. 

Video: Production of Extracellular Matrix Fibers via Sacrificial Hollow Fiber Membrane Cell Culture

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Epithelial Cell Repopulation and Preparation of Rodent Extracellular Matrix Scaffolds for Renal Tissue Development

This protocol details the generation of acellular, yet biofunctional, renal extracellular matrix (ECM) scaffolds that are useful as small-scale model substrates for organ-scale tissue development. Sprague Dawley rat kidneys are cannulated by inserting a catheter into the renal artery and perfused with a series of low-concentration detergents (Triton X-100 and sodium dodecyl sulfate (SDS)) over 26 hr to derive intact, whole-kidney scaffolds with intact perfusable vasculature, glomeruli, and renal tubules. Following decellularization, the renal scaffold is placed inside a custom-designed perfusion bioreactor vessel, and the catheterized renal artery is connected to a perfusion circuit consisting of: a peristaltic pump; tubing; and optional probes for pH, dissolved oxygen, and pressure. After sterilizing the scaffold with peracetic acid and ethanol, and balancing the pH (7.4), the kidney scaffold is prepared for seeding via perfusion of culture medium within a large-capacity incubator maintained at 37 &#176;C and 5% CO2. Forty million renal cortical tubular epithelial (RCTE) cells are injected through the renal artery, and rapidly perfused through the scaffold under high flow (25 ml/min) and pressure (~230 mmHg) for 15 min before reducing the flow to a physiological rate (4 ml/min). RCTE cells primarily populate the tubular ECM niche within the renal cortex, proliferate, and form tubular epithelial structures over seven days of perfusion culture. A 44 &#181;M resazurin solution in culture medium is perfused through the kidney for 1 hr during medium exchanges to provide a fluorometric, redox-based metabolic assessment of cell viability and proliferation during tubulogenesis. The kidney perfusion bioreactor permits non-invasive sampling of medium for biochemical assessment, and multiple inlet ports allow alternative retrograde seeding through the renal vein or ureter. These protocols can be used to recellularize kidney scaffolds with a variety of cell types, including vascular endothelial, tubular epithelial, and stromal fibroblasts, for rapid evaluation within this system.

This protocol describes decellularization of Sprague Dawley rat kidneys by antegrade perfusion of detergents through the vasculature, producing acellular renal extracellular matrices that serve as templates for repopulation with human renal epithelial cells. Recellularization and use of the resazurin perfusion assay to monitor growth is performed within specially-designed perfusion bioreactors.

This protocol details the generation of acellular, yet biofunctional, renal extracellular matrix (ECM) scaffolds that are useful as small-scale model ...

Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture

Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of anchorage dependent cells on the 2-dimensional surface of tissue culture plastic. More recently, there is a growing body of data demonstrating more in vivo-like behaviors of cells grown in 3-dimensional culture systems. This manuscript describes in detail the set-up and operation of a hollow fiber bioreactor system for the in vivo-like culture of mammalian cells. The hollow fiber bioreactor system delivers media to the cells in a manner akin to the delivery of blood through the capillary networks in vivo. The system is designed to fit onto the shelf of a standard CO2 incubator and is simple enough to be set-up by any competent cell biologist with a good understanding of aseptic technique. The systems utility is demonstrated by culturing the hepatocarcinoma cell line HepG2/C3A for 7 days. Further to this and in line with other published reports on the functionality of cells grown in 3-dimensional culture systems the cells are shown to possess increased albumin production (an important hepatic function) when compared to standard 2-dimensional tissue culture.

Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture

The functional behavior of cells in culture can be improved by culturing in more in vivo-like 3-dimensional culture environments16-21. This manuscript describes the set-up and operation of a hollow fiber bioreactor system for in vivo-like mammalian tissue culture.

Tissue culture has been used for over 100 years to study cells and responses ex vivo. The convention of this technique is the growth of anchorage ...

Preparation of Extracellular Matrix Protein Fibers for Brillouin Spectroscopy

Brillouin spectroscopy is an emerging technique in the biomedical field. It probes the mechanical properties of a sample through the interaction of visible light with thermally induced acoustic waves or phonons propagating at a speed of a few km/sec. Information on the elasticity and structure of the material is obtained in a nondestructive contactless manner, hence opening the way to in vivo applications and potential diagnosis of pathology. This work describes the application of Brillouin spectroscopy to the study of biomechanics in elastin and trypsin-digested type I collagen fibers of the extracellular matrix. Fibrous proteins of the extracellular matrix are the building blocks of biological tissues and investigating their mechanical and physical behavior is key to establishing structure-function relationships in normal tissues and the changes which occur in disease. The procedures of sample preparation followed by measurement of Brillouin spectra using a reflective substrate are presented together with details of the optical system and methods of spectral data analysis.

We present a protocol for the application of Brillouin light scattering spectroscopy to elastin and trypsin-purified type I collagen fibers of the extracellular matrix to extract their full elastic properties.

Brillouin spectroscopy is an emerging technique in the biomedical field. It probes the mechanical properties of a sample through the interaction of ...

Tunable Hydrogels from Pulmonary Extracellular Matrix for 3D Cell Culture

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung tissue from porcine, rat, or mouse, the tissue is perfused and submerged in subsequent chemical detergents to remove the cellular debris. Histological comparison of the tissue before and after processing confirms removal of over 95% of double stranded DNA and alpha galactosidase staining suggests the majority of cellular debris is removed. After decellularization, the tissue is lyophilized and then cryomilled into a powder. The matrix powder is digested for 48 hr in an acidic pepsin digestion solution and then neutralized to form the pregel solution. Gelation of the pregel solution can be induced by incubation at 37 &#176;C and can be used immediately following neutralization or stored at 4 &#176;C for up to two weeks. Coatings can be formed using the pregel solution on a non-treated plate for cell attachment. Cells can be suspended in the pregel prior to self-assembly to achieve a 3D culture, plated on the surface of a formed gel from which the cells can migrate through the scaffold, or plated on the coatings. Alterations to the strategy presented can impact gelation temperature, strength, or protein fragment sizes. Beyond hydrogel formation, the hydrogel stiffness may be increased using genipin.

This is a method to create a 3-dimensional cell culture scaffold from pulmonary extracellular matrix. Intact lung is processed into hydrogels that can support the growth of cells in three-dimensions.

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung ...

Fabrication of Extracellular Matrix-derived Foams and Microcarriers as Tissue-specific Cell Culture and Delivery Platforms

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus of this article is on the methods for fabricating ECM-derived porous foams and microcarriers for use as biologically-relevant substrates in advanced 3D in vitro cell culture models or as pro-regenerative scaffolds and cell delivery systems for tissue engineering and regenerative medicine. Using decellularized tissues or purified insoluble collagen as a starting material, the techniques can be applied to synthesize a broad array of tissue-specific bioscaffolds with customizable geometries. The approach involves mechanical processing and mild enzymatic digestion to yield an ECM suspension that is used to fabricate the three-dimensional foams or microcarriers through controlled freezing and lyophilization procedures. These pure ECM-derived scaffolds are highly porous, yet stable without the need for chemical crosslinking agents or other additives that may negatively impact cell function. The scaffold properties can be tuned to some extent by varying factors such as the ECM suspension concentration, mechanical processing methods, or synthesis conditions. In general, the scaffolds are robust and easy to handle, and can be processed as tissues for most standard biological assays, providing a versatile and user-friendly 3D cell culture platform that mimics the native ECM composition. Overall, these straightforward methods for fabricating customized ECM-derived foams and microcarriers may be of interest to both biologists and biomedical engineers as tissue-specific cell-instructive platforms for in vitro and in vivo applications.

The tissue-specific extracellular matrix (ECM) is a key mediator of cell function. This article describes methods for synthesizing pure ECM-derived foams and microcarriers that are stable in culture without the need for chemical crosslinking for applications in advanced 3D in vitro cell culture models or as pro-regenerative bioscaffolds.

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus ...

Fabricating a Kidney Cortex Extracellular Matrix-Derived Hydrogel

Extracellular matrix (ECM) provides important biophysical and biochemical cues to maintain tissue homeostasis. Current synthetic hydrogels offer robust mechanical support for in vitro cell culture but lack the necessary protein and ligand composition to elicit physiological behavior from cells. This manuscript describes a fabrication method for a kidney cortex ECM-derived hydrogel with proper mechanical robustness and supportive biochemical composition. The hydrogel is fabricated by mechanically homogenizing and solubilizing decellularized human kidney cortex ECM. The matrix preserves native kidney cortex ECM protein ratios while also enabling gelation to physiological mechanical stiffnesses. The hydrogel serves as a substrate upon which kidney cortex-derived cells can be maintained under physiological conditions. Furthermore, the hydrogel composition can be manipulated to model a diseased environment which enables the future study of kidney diseases.

Here we present a protocol to fabricate a kidney cortex extracellular matrix-derived hydrogel to retain the native kidney extracellular matrix (ECM) structural and biochemical composition. The fabrication process and its applications are described. Finally, a perspective on using this hydrogel to support kidney-specific cellular and tissue regeneration and bioengineering is discussed.

Extracellular matrix (ECM) provides important biophysical and biochemical cues to maintain tissue homeostasis. Current synthetic hydrogels offer robust ...

Pancreatic Tissue-Derived Extracellular Matrix Bioink for Printing 3D Cell-Laden Pancreatic Tissue Constructs

The transplantation of pancreatic islets is a promising treatment for patients who suffer from type 1 diabetes accompanied by hypoglycemia and secondary complications. However, islet transplantation still has several limitations such as the low viability of transplanted islets due to poor islet engraftment and hostile environments. In addition, the insulin-producing cells differentiated from human pluripotent stem cells have limited ability to secrete sufficient hormones that can regulate the blood glucose level; therefore, improving the maturation by culturing cells with proper microenvironmental cues is strongly required. In this article, we elucidate protocols for preparing a pancreatic tissue-derived decellularized extracellular matrix (pdECM) bioink to provide a beneficial microenvironment that can increase glucose sensitivity of pancreatic islets, followed by describing the processes for generating 3D pancreatic tissue constructs using a microextrusion-based bioprinting technique.

Decellularized extracellular matrix (dECM) can provide suitable microenvironmental cues to recapitulate the inherent functions of target tissues in an engineered construct. This article elucidates the protocols for the decellularization of pancreatic tissue, evaluation of pancreatic tissue-derived dECM bioink, and generation of 3D pancreatic tissue constructs using a bioprinting technique.

The transplantation of pancreatic islets is a promising treatment for patients who suffer from type 1 diabetes accompanied by hypoglycemia and secondary ...

A Human 3D Extracellular Matrix-Adipocyte Culture Model for Studying Matrix-Cell Metabolic Crosstalk

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of cellular function. The ECM plays a particularly important role in adipose tissue function in obesity, and alterations in adipose tissue ECM deposition and composition are associated with metabolic disease in mice and humans. Tractable in vitro models that permit dissection of the roles of the ECM and cells in contributing to global tissue phenotype are sparse. We describe a novel 3D in vitro model of human ECM-adipocyte culture that permits study of the specific roles of the ECM and adipocytes in regulating adipose tissue metabolic phenotype. Human adipose tissue is decellularized to isolate ECM, which is subsequently repopulated with preadipocytes that are then differentiated within the ECM into mature adipocytes. This method creates ECM-adipocyte constructs that are metabolically active and retain characteristics of the tissues and patients from which they are derived. We have used this system to demonstrate disease-specific ECM-adipocyte crosstalk in human adipose tissue. This culture model provides a tool for dissecting the roles of the ECM and adipocytes in contributing to global adipose tissue metabolic phenotype and permits study of the role of the ECM in regulating adipose tissue homeostasis.

We describe a 3D human extracellular matrix-adipocyte in vitro culture system that permits dissection of the roles of the matrix and adipocytes in contributing to adipose tissue metabolic phenotype.

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of ...

Preparation of Tunable Extracellular Matrix Microenvironments to Evaluate Schwann Cell Phenotype Specification

Traumatic peripheral nervous system (PNS) injuries currently lack suitable treatments to regain full functional recovery. Schwann cells (SCs), as the major glial cells of the PNS, play a vital role in promoting PNS regeneration by dedifferentiating into a regenerative cell phenotype following injury. However, the dedifferentiated state of SCs is challenging to maintain through the time-period needed for regeneration and is impacted by changes in the surrounding extracellular matrix (ECM). Therefore, determining the complex interplay between SCs and differing ECM to provide cues of regenerative potential of SCs is essential. To address this, a strategy was created where different ECM proteins were adsorbed onto a tunable polydimethylsiloxane (PDMS) substrate which provided a platform where stiffness and protein composition can be modulated. SCs were seeded onto the tunable substrates and critical cellular functions representing the dynamics of SC phenotype were measured. To illustrate the interplay between SC protein expression and cellular morphology, differing seeding densities of SCs in addition to individual microcontact printed cellular patterns were utilized and characterized by immunofluorescence staining and western blot. Results showed that cells with a smaller spreading area and higher extent of cellular elongation promoted higher levels of SC regenerative phenotypic markers. This methodology not only begins to unravel the significant relationship between the ECM and cellular function of SCs, but also provides guidelines for the future optimization of biomaterials in peripheral nerve repair.

This methodology aims to illustrate the mechanisms by which extracellular matrix cues such as substrate stiffness, protein composition and cell morphology regulate Schwann cell (SC) phenotype.

Traumatic peripheral nervous system (PNS) injuries currently lack suitable treatments to regain full functional recovery. Schwann cells (SCs), as the ...