Name: procurement and perfusion-decellularization of porcine vascularized flaps in a customized perfusion bioreactor
Uploaded: 2022-08-01T13:00:00
Description: Watch this Scientific Journal Video about Procurement and Perfusion-Decellularization of Porcine Vascularized Flaps in a Customized Perfusion Bioreactor at JoVE.com

All procedures involving animal subjects have been approved by the University Health Network Institutional Animal Care and Use Committee (IACUC) and are performed in accordance with University Health Network Animal Resource Centre protocol and procedures and Canadian Council on Animal Care Guidelines.&#160;Five Yorkshire pigs (35-50 kg; age approximately 12 weeks old) were used for all experiments.
1. Perfusion bioreactor fabrication
<ol>
	<li>See Figure 1 for all t...

<ol>
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Global Open. 6 (2), 1651 (2018).</li><li>Issa, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascularized+composite+allograft-specific+characteristics+of+immune+responses.">Vascularized composite allograft-specific characteristics of immune responses.</a> Transplant International. 29 (6), 672-681 (2016).</li><li>Kueckelhaus, M., 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=Vascularized+composite+allotransplantation:+Current+standards+and+novel+approaches+to+prevent+acute+rejection+and+chronic+allograft+deterioration.">Vascularized composite allotransplantation: Current standards and novel approaches to prevent acute rejection and chronic allograft deterioration.</a> Transplant International. 29 (6), 655-662 (2016).</li><li>Iske, J., 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=Composite+tissue+allotransplantation:+Opportunities+and+challenges.">Composite tissue allotransplantation: Opportunities and challenges.</a> Cellular and Molecular Immunology. 16 (4), 343-349 (2019).</li><li>Londono, R., Gorantla, V. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascularization+in+tissue+engineering.">Vascularization in tissue engineering.</a> Trends in Biotechnology. 26 (8), 434-441 (2008).</li><li>Zhang, Q., 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=Decellularized+skin/adipose+tissue+flap+matrix+for+engineering+vascularized+composite+soft+tissue+flaps.">Decellularized skin/adipose tissue flap matrix for engineering vascularized composite soft tissue flaps.</a> Acta Biomaterialia. 35, 166-184 (2016).</li><li>Jank, B. J., 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=Creation+of+a+bioengineered+skin+flap+scaffold+with+a+perfusable+vascular+pedicle.">Creation of a bioengineered skin flap scaffold with a perfusable vascular pedicle.</a> Tissue Engineering - Part A. 23 (13-14), 696-707 (2017).</li><li>Giatsidis, G., Guyette, J. P., Ott, H. C., Orgill, D. P. <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+a+large-volume+human-derived+adipose+acellular+allogenic+flap+by+perfusion+decellularization.">Development of a large-volume human-derived adipose acellular allogenic flap by perfusion decellularization.</a> Wound Repair and Regeneration. 26 (2), 245-250 (2018).</li><li>Zhang, J., 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=Perfusion-decellularized+skeletal+muscle+as+a+three-dimensional+scaffold+with+a+vascular+network+template.">Perfusion-decellularized skeletal muscle as a three-dimensional scaffold with a vascular network template.</a> Biomaterials. 89, 114-126 (2016).</li><li>Duisit, J., 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=Decellularization+of+the+porcine+ear+generates+a+biocompatible,+nonimmunogenic+extracellular+matrix+platform+for+face+subunit+bioengineering.">Decellularization of the porcine ear generates a biocompatible, nonimmunogenic extracellular matrix platform for face subunit bioengineering.</a> Annals of Surgery. 267 (6), 1191-1201 (2018).</li><li>Duisit, J., 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=Perfusion-decellularization+of+human+ear+grafts+enables+ECM-based+scaffolds+for+auricular+vascularized+composite+tissue+engineering.">Perfusion-decellularization of human ear grafts enables ECM-based scaffolds for auricular vascularized composite tissue engineering.</a> Acta Biomaterialia. 73, 339-354 (2018).</li><li>Duisit, J., 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=Bioengineering+a+human+face+graft:+The+matrix+of+identity.">Bioengineering a human face graft: The matrix of identity.</a> Annals of Surgery. 266 (5), 754-764 (2017).</li><li>Haughey, B. 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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+of+tissue+decellularization+used+for+preparation+of+biologic+scaffolds+and+in+vivo+relevance.">Methods of tissue decellularization used for preparation of biologic scaffolds and in vivo relevance.</a> Methods. 84, 25-34 (2015).</li><li>Mendibil, U., 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+decellularization+methods:+Rationale+and+strategies+to+achieve+regenerative+compounds.">Tissue-specific decellularization methods: Rationale and strategies to achieve regenerative compounds.</a> International Journal of Molecular Sciences. 21 (15), 5447 (2020).</li><li>Lupon, E., 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=Engineering+vascularized+composite+allografts+using+natural+scaffolds:+A+systematic+review.">Engineering vascularized composite allografts using natural scaffolds: A systematic review.</a> Tissue Engineering. Part B Reviews. 28 (3), 677-693 (2022).</li><li>Duisit, J., Maistriaux, L., Bertheuil, N., Lellouch, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+vascularized+composite+tissues+by+perfusion+decellularization/recellularization:+Review.">Engineering vascularized composite tissues by perfusion decellularization/recellularization: Review.</a> Current Transplantation Reports. 8, 44-56 (2021).</li><li>Adil, A., Xu, M., Haykal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recellularization+of+bioengineered+scaffolds+for+vascular+composite+allotransplantation.">Recellularization of bioengineered scaffolds for vascular composite allotransplantation.</a> Frontiers in Surgery. 9, 843677 (2022).</li><li>Phelps, E. A., Garc&#237;a, A. 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The proposed protocol uses the perfusion of low concentration SDS to decellularize a range of porcine-derived flaps. With this procedure, acellular omentum, tensor fascia lata, and radial forearm flaps can be successfully decellularized using a protocol that favors low concentration SDS. Preliminary optimization experiments have determined that SDS at a low concentration (0.05%) between 2 days to 5 days is capable of removing cellular material for the omentum, tensor fascia lata, and radial forearm flap when analyzed wit...

Traumatic injury and tumor removal can lead to large and complex soft tissue defects. These defects can impair patient quality of life, cause loss of function, and result in permanent disability. While techniques such as autologous tissue flap transfer have been commonly practiced, issues with flap availability and donor site morbidity are major limitations1,2,3. Vascularized composite allotransplantation (VCA) is a promising alternative that transfers composite tissues, e.g., muscle, skin, vasculature, as a single unit to recipients. However, VCA requires long-term immunosuppression, which leads to drug toxicity, opportunistic infections, and malignancies4,5,6.
Tissue-engineered acellular scaffolds are a potential solution to these limitations7. Acellular tissue scaffolds can be obtained using decellularization methods, which remove cellular material from native tissues while preserving the underlying extracellular matrix (ECM) microarchitecture. In contrast to the use of synthetic materials in tissue engineering, the use of biologically derived scaffolds offers a biomimetic ECM substrate that allows biocompatibility and the potential for clinical translation8. Following decellularization, the subsequent recellularization of scaffolds with recipient-specific cells can then generate functional, vascularized tissues with little to no immunogenicity9,10,11. By developing an effective protocol to obtain acellular tissues using perfusion decellularization techniques, a broad range of tissue types can be engineered. In turn, building on this technique allows the application to more complex tissues. To date, perfusion decellularization of vascularized soft tissues has been investigated using simple vascularized tissues such as a full thickness fasciocutaneous flap in rodent12, porcine13, and human models14, as well as porcine rectus abdominis skeletal muscle15. Additionally, complex vascularized tissues have also been perfusion decellularized as demonstrated in porcine and human ear16,17 models and human full-face graft models18.
Here, the protocol describes the decellularization of vascularized free flaps using biologically derived ECM scaffolds. We present the decellularization of three clinically relevant flaps: 1) the omentum, 2) the tensor fascia lata, and 3) the radial forearm, all of which are representative of workhorse flaps used routinely in reconstructive surgery and have not been previously examined in animal studies within the context of tissue decellularization. These bioengineered flaps offer a versatile and readily available platform that has the potential for clinical applications for use in the field of large soft tissue defect repair and reconstruction.

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		<tr >
			<td >0.2 &#181;m pore Acrodisk Filter</td>
			<td >VWR</td>
			<td >CA28143-310</td>
			<td ></td>
		</tr>
		<tr >
			<td >0.9 % Sodium Chloride Solution (Normal Saline)</td>
			<td>Baxter</td>
			<td>JF7123</td>
			<td></td>
		</tr>
		<tr >
			<td >20 L Polypropylene Carboy</td>
			<td>Cole-Parmer</td>
			<td>RK-62507-20</td>
			<td></td>
		</tr>
		<tr >
			<td >3-0 Sofsilk Nonabsorbable Surgical Tie</td>
			<td>Covidien</td>
			<td>&#160;LS639</td>
			<td></td>
		</tr>
		<tr >
			<td >3-way Stopcock</td>
			<td>Cole-Parmer</td>
			<td>UZ-30600-04</td>
			<td></td>
		</tr>
		<tr >
			<td >Adson Forceps</td>
			<td>Fine Science Tools</td>
			<td>11027-12</td>
			<td></td>
		</tr>
		<tr >
			<td >Antibiotic-Antimycotic Solution, 100X</td>
			<td>Wisent</td>
			<td>450-115-EL</td>
			<td></td>
		</tr>
		<tr >
			<td >Atropine Sulphate 15 mg/30ml</td>
			<td>Rafter 8 Products</td>
			<td>238481</td>
			<td></td>
		</tr>
		<tr >
			<td >BD Angiocath 20-Gauge</td>
			<td>VWR</td>
			<td>BD381134</td>
			<td></td>
		</tr>
		<tr >
			<td >BD Angiocath 22-Gauge</td>
			<td>VWR</td>
			<td>BD381123</td>
			<td></td>
		</tr>
		<tr >
			<td >BD Angiocath 24-Gauge</td>
			<td>VWR</td>
			<td>BD381112</td>
			<td></td>
		</tr>
		<tr >
			<td >Calcium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>C4901</td>
			<td>DNAse Co-factor</td>
		</tr>
		<tr >
			<td >DNase I from bovine pancreas</td>
			<td>Sigma-Aldrich</td>
			<td>DN25</td>
			<td></td>
		</tr>
		<tr >
			<td >DNA assay (Quant-iT PicoGreen dsDNA Assay Kit)</td>
			<td>Invitrogen</td>
			<td>P7589</td>
			<td></td>
		</tr>
		<tr >
			<td >DPBS, 10X</td>
			<td>Wisent</td>
			<td>311-415-CL</td>
			<td>&#160;without Ca++/Mg++</td>
		</tr>
		<tr >
			<td >Halsted-Mosquito Hemostat</td>
			<td>Fine Science Tools</td>
			<td>13008-12</td>
			<td></td>
		</tr>
		<tr >
			<td >Heparin, 1000 I.U./mL</td>
			<td>Leo Pharma A/S</td>
			<td>453811</td>
			<td></td>
		</tr>
		<tr >
			<td >Ketamine Hydrochloride&#160; 5000 mg/50 ml</td>
			<td>Bimeda-MTC Animal Health Inc.</td>
			<td>612316</td>
			<td></td>
		</tr>
		<tr >
			<td >Ismatec Pump Tygon 3-Stop Tubing</td>
			<td>Cole-Parmer</td>
			<td>RK-96450-40</td>
			<td>Internal Diameter:&#160; 1.85 mm</td>
		</tr>
		<tr >
			<td >Ismatec REGLO 4-Channel Pump</td>
			<td>Cole-Parmer</td>
			<td>78001-78</td>
			<td></td>
		</tr>
		<tr >
			<td >Ismatec Tubing Cassettes</td>
			<td>Cole-Parmer</td>
			<td>RK-78016-98</td>
			<td></td>
		</tr>
		<tr >
			<td >Isoflurane 99.9%, 250 ml</td>
			<td>Pharmaceutical Partners of Canada Inc.</td>
			<td>2231929</td>
			<td></td>
		</tr>
		<tr >
			<td >LB Agar Lennox</td>
			<td>Bioshop Canada</td>
			<td>LBL406.500</td>
			<td>Sterility testing agar plates</td>
		</tr>
		<tr >
			<td >Magnesium Sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>M7506</td>
			<td>DNAse Co-factor</td>
		</tr>
		<tr >
			<td >Masterflex L/S 16 Tubing</td>
			<td>Cole-Parmer</td>
			<td>RK-96410-16</td>
			<td></td>
		</tr>
		<tr >
			<td >Midazolam 50 mg/10 ml</td>
			<td>Pharmaceutical Partners of Canada Inc.</td>
			<td>2242905</td>
			<td></td>
		</tr>
		<tr >
			<td >Monopolar Cautery Pencil</td>
			<td>Valleylab</td>
			<td>E2100</td>
			<td></td>
		</tr>
		<tr >
			<td >Normal Buffered Formalin, 10%</td>
			<td>Sigma-Aldrich</td>
			<td>HT501128</td>
			<td></td>
		</tr>
		<tr >
			<td >N&#176;11 scalpel blade</td>
			<td>Swann Morton</td>
			<td>303</td>
			<td></td>
		</tr>
		<tr >
			<td >Papain from papaya latex</td>
			<td>Sigma-Aldrich</td>
			<td>P3125</td>
			<td></td>
		</tr>
		<tr >
			<td >Peracetic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>269336</td>
			<td></td>
		</tr>
		<tr >
			<td >Plastic Barbed Connector for 1/4&#34; to 1/8&#34; Tube ID</td>
			<td>McMaster-Carr</td>
			<td>5117K61</td>
			<td></td>
		</tr>
		<tr >
			<td >Plastic Barbed Tube 90&#176; Elbow Connectors</td>
			<td>McMaster-Carr</td>
			<td>5117K76</td>
			<td></td>
		</tr>
		<tr >
			<td >Plastic Quick-Turn Tube Plugs</td>
			<td>McMaster-Carr</td>
			<td>51525K143</td>
			<td>Male Luer</td>
		</tr>
		<tr >
			<td >Plastic Quick-Turn Tube Sockets</td>
			<td>McMaster-Carr</td>
			<td>51525K293</td>
			<td>Female Luer</td>
		</tr>
		<tr >
			<td >Punch Biopsy Tool</td>
			<td>Integra Miltex</td>
			<td>3332</td>
			<td></td>
		</tr>
		<tr >
			<td >Potassium Chloride 40 mEq/20 ml</td>
			<td>Hospira Healthcare Corporation</td>
			<td>37869</td>
			<td></td>
		</tr>
		<tr >
			<td >Povidone-Iodine, 10%</td>
			<td>Rougier</td>
			<td>833133</td>
			<td></td>
		</tr>
		<tr >
			<td >Serological Pipet, 2mL</td>
			<td>Fisher Science</td>
			<td>13-678-27D</td>
			<td></td>
		</tr>
		<tr >
			<td >Snap Lid Airtight Containers</td>
			<td>SnapLock</td>
			<td>142-3941-4</td>
			<td></td>
		</tr>
		<tr >
			<td >Sodium Dodecyl Sulfate Powder</td>
			<td>Sigma-Aldrich</td>
			<td>L4509</td>
			<td></td>
		</tr>
		<tr >
			<td >Surgical Metal Ligation Clips, Small</td>
			<td >Teleflex</td>
			<td >001200</td>
			<td></td>
		</tr>
		<tr >
			<td >Stevens Tenotomy Scissors, 115 mm, straight</td>
			<td >B. Braun</td>
			<td >BC004R</td>
			<td></td>
		</tr>
		<tr >
			<td >TruWave Pressure Monitoring Set</td>
			<td >Edwards Lifesciences</td>
			<td >PX260</td>
			<td></td>
		</tr>
	</tbody>
</table>

procurement and perfusion-decellularization of porcine vascularized flaps in a customized perfusion bioreactor

Large volume soft tissue defects lead to functional deficits and can greatly impact the patient&#39;s quality of life. Although surgical reconstruction can be performed using autologous free flap transfer or vascularized composite allotransplantation (VCA), such methods also have disadvantages. Issues such as donor site morbidity and tissue availability limit autologous free flap transfer, while immunosuppression is a significant limitation of VCA. Engineered tissues in reconstructive surgery using decellularization/recellularization methods represent a possible solution. Decellularized tissues are generated using methods that remove native cellular material while preserving the underlying extracellular matrix (ECM) microarchitecture. These acellular scaffolds can then be subsequently recellularized with recipient-specific cells.
This protocol details the procurement and decellularization methods used to achieve acellular scaffolds in a pig model. In addition, it also provides a description of the perfusion bioreactor design and setup. The flaps include the porcine omentum, tensor fascia lata, and the radial forearm. Decellularization is performed via ex vivo perfusion of low concentration sodium dodecyl sulfate (SDS) detergent followed by DNase enzyme treatment and peracetic acid sterilization in a customized perfusion bioreactor.
Successful tissue decellularization is characterized by a white-opaque appearance of flaps macroscopically. Acellular flaps show the absence of nuclei on histological staining and a significant reduction in DNA content. This protocol can be used efficiently to generate decellularized soft tissue scaffolds with preserved ECM and vascular microarchitecture. Such scaffolds can be used in subsequent recellularization studies and have the potential for clinical translation in reconstructive surgery.

This protocol to decellularize vascularized porcine flaps relies on the perfusion of an ionic-based detergent, SDS, through the flap vasculature in a customized perfusion bioreactor. Prior to decellularization, three vascularized flaps in a porcine model were procured and cannulated according to their main supplying vessels. The flaps were immediately flushed after procurement in order to maintain a patent, perfusable vasculature to allow for successful decellularization. Using airtight snap-lid containers, a customized ...

Watch this Scientific Journal Video about Procurement and Perfusion-Decellularization of Porcine Vascularized Flaps in a Customized Perfusion Bioreactor at JoVE.com

Procurement and Perfusion-Decellularization of Porcine Vascularized Flaps in a Customized Perfusion Bioreactor

The protocol describes the surgical procurement and subsequent decellularization of vascularized porcine flaps by the perfusion of sodium dodecyl sulfate detergent through the flap vasculature in a customized perfusion bioreactor.

Large volume soft tissue defects lead to functional deficits and can greatly impact the patient&#39;s quality of life. Although surgical reconstruction ...

This method describes the surgical procurement of three vascularized porcine flaps and their subsequent perfusion decellularization. This method can aid efforts to regenerate porcine flaps using a tissue decellularization and recellularization approach. The main advantage of this technique is its versatility to achieve profusion decellularization across a variety of vascularized porcine flaps in a simple to assemble bioreactor setup.The technique described here can be broadly applied to other vascularized flaps as a potential tissue engineering solution using porcine flaps in reconstructive surgery. To begin, make an inflow and outflow tubing by measuring approximately 50 centimeters of LS16 platinum-coated silicone tubing. Connect one end to a yellow 3-stop pump tubing and the other to a sterile 2 milliliter serological pipette to carry perfusate from the detergent reservoirs into the bioreactor chamber.Autoclave the chamber and tubings in individually wrapped sterile packaging. For omental flap procurement, place a 12-week old anesthetized Yorkshire pig in the supine position, and then prepare the abdomen in the usual sterile fashion. Perform a xipho-umbilical laparotomy to enter the abdomen and mobilize the stomach cephalad, and place the omentum into the operative field.Starting at the left aspect of the greater curvature, where the left gastroepiploic artery joins the splenic artery, skeletonize the left gastroepiploic artery and vein using straight Stevens tenotomy scissors. Then ligate and divide both separately using surgical ties or clips. Proceed along the greater curvature of the stomach from left to right to ligate and divide the short vascular branches arising from the omentum, supplying the greater curvature of the stomach.Continue the mobilization of the greater omentum until the junction of the right gastroepiploic vessels and gastroduodenal artery is encountered. Then ligate and divide the right gastroepiploic artery and vein to free the omental flap and allow for flap cannulation later. For tensor fascia lata flap procurement, place the pig in the lateral decubitus position.Mark the interior flap boundary from the anterior superior iliac spine, or ASIS, towards the lateral patella, and a posterior boundary approximately 8 to 10 centimeters caudally. Use a scalpel to make a sharp incision at the distal margin at the patella. Deepen the incision through the subcutaneous tissues to reach the fascia overlying the rectus femoris, and continue the incisions towards the ASIS along the marked boundaries.To isolate the fascial flap alone, remove the overlying skin component from the underlying fascia layer. Then ligate or cauterize small perforator vessels to the skin. Return to the distal border of the flap, and incise the deep fascia.Mobilize the fascia off the underlying vastus lateralis muscle towards the ASIS. After tracing the pedicle toward the deep femoral vessels, skeletonize the lateral circumflex femoral artery and vein supplying the fascial flap. Then ligate and divide flap vessels proximally, where they join the deep femoral vessels and allow for later cannulation.For radial forearm flap procurement, mark a 3 by 3 centimeter square on the radial aspect of an extended pig forearm. Draw a line between the midpoint of the proximal flap margin and the antecubital fossa to denote the approximate course of the radial artery pedicle. Confirm the arterial course with palpation.Next, incise the skin using a scalpel at the distal aspect with a depth up to the antebrachial fascia. Blunt dissect with tenotomy scissors until the distal radial artery and its vena comitantes are encountered. Then ligate and divide the artery and veins with surgical ties or clips.Continue the skin incisions on the radial and ulnar margins of the marked skin square. Then mobilize the flap off the underlying radial bone with a surgical blade or cautery, proceeding from an ulnar to radial direction while raising the skin flap proximally toward the antecubital fossa. Using tenotomy scissors, skeletonize the radial artery and vena comitantes proximally at the antecubital fossa, where they join the brachial artery and veins, respectively.Dissect the vessels from the surrounding fibro-fatty tissues to isolate the vascular pedicle. Then ligate and divide the artery and vein separately to free the radial forearm flap. Next, cannulate the pedicle vessels with 20 to 24-gauge angiocatheter secured with 3-0 silk ties.Flush heparinized saline into the flap arterial cannula until a clear venous outflow is observed. While working in a laminar flow Biosafety cabinet, place flaps in the bioreactor tissue chamber. Prime inflow tubing with sterile heparinized saline to remove residual air and arrange flaps to allow connection between the flap arterial cannula and the male luer connector.Then use sterile hemostats to screw the arterial cannula onto the connector. Then flush the heparinized saline through the stopcock to check that the luer connection is without leaks, and that the flops can be perfused with evidence of venous outflow. After closing the tissue chamber lid, connect the inflow tubing with a yellow 3-stop pump tubing to the inflow stopcock of the tissue chamber.Also, attach an inline pressure sensor transducer to the inflow 3-way stopcock for perfusion pressure monitoring. Next, turn on the inflow peristaltic pump and on the initial screen, move to the third tab using the arrow to set the tubing ID to 1.85 millimeters. Then set the perfusion rate from the second tab.The input rate as the mode of delivery is set to 2 milliliters per minute. Ensure the flow direction is correct as displayed on the screen. Load the 3-stop pump tubing to the peristaltic pump with a compatible cassette.Set the outflow pump setting to a rate at 4 milliliters per minute. Connect the outflow tubing with a yellow 3-stop pump tubing to the outflow stopcock of the tissue chamber. Then load the 3-stop pump tubing to the peristaltic pump, and start the flow for both pumps by pressing the power button on each pump.Begin the perfusion decellularization of flaps with heparinized saline in the tissue chamber for 15 minutes to remove any retained blood clots. Upon completion, replace the residual saline with 500 milliliters of sodium dodecyl sulfate, or SDS, decellularization solution to submerge the flap. Next, transfer the inflow tubing to the SDS solution and profuse the tissue.After SDS decellularization, aspirate the remaining SDS before perfusing the flap with PBS for one day. After SDS perfusion decellularization, sequentially perfuse the flaps in DNA solution for two hours, and then in PBS for one day, followed by transferring the inflow tubing into peracetic acid and ethanol in distilled water to sterilize the flaps by perfusing for three hours. Once done, remove the flaps aseptically and immerse them into two washes of PBS containing 1%antibiotics antimycotics for 15 minutes each.Store flaps at 4 degrees Celsius until ready for recellularization. Use a 3 to 10 millimeter punch biopsy tool to obtain tissue samples for evaluation of decellularized flaps. The isolated decellularized flaps flushed under manual control demonstrated evidence of outflow from the freely draining venous cannula of omentum, tensor fascia lata, and radial forearm flap.The gross morphology of the native omentum, tensor fascia lata, and radial forearm flaps appeared pink colored immediately after the procurement. In comparison, decellularized tissues were characteristically white or opaque in appearance. Histological examination of native tissues with hematoxylin and eosin showed the presence of blue nuclei.In decellularized flaps, histological staining revealed loss of cellular material without blue nuclear staining, indicating an acellular tissue scaffold. Additional quantification of DNA content showed a significant decrease in DNA in acellular scaffolds compared to native tissues. The most important consideration is a surgical technique used during procurement, taking care to avoid damage to the flap pedicle in order to permit subsequent perfusion decellularization.Following perfusion decellularization, the resulting flaps may be recellularized with tissue specific cell populations in order to regenerate the native tissue compartments.

Research

JoVE Journal

Bioengineering

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