This work was funded by the Frankel Foundation and the Northwestern Memorial Hospital McCormick Grant (Operation RESTORE). Research reported in this publication was supported by the National Institute of General Medicial Sciences of the National Institutes of Health under Award&#160;Number T32GM008152. This work was supported by the Northwestern University Microsurgery Core and Behavioral Phenotyping Core.

All experiments were conducted in accordance with the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health (NIH) and were approved by the Northwestern University Animal Care and Use Committee. The specific procedures were performed under protocol IS00001663.
NOTE: Two strains of rats were used, Lewis rats and August Copenhagen x Irish (ACI) rats. Animals were divided into three treatment groups: allotransplant without immune suppression (ACI to Lewis), allotran...

<ol>
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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+for+reimplantation+and+transplantation+of+a+complex+organ:+the+rat+hind+limb.">A model for reimplantation and transplantation of a complex organ: the rat hind limb.</a> Journal of Surgical Research. 24 (6), 501-506 (1978).</li><li>Brandacher, G., Grahammer, J., Sucher, R., Lee, W. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+for+basic+and+translational+research+in+reconstructive+transplantation.">Animal models for basic and translational research in reconstructive transplantation.</a> Birth Defects Research Part C: Embryo Today. 96 (1), 39-50 (2012).</li><li>Furtmuller, G. 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=Orthotopic+Hind+Limb+Transplantation+in+the+Mouse.">Orthotopic Hind Limb Transplantation in the Mouse.</a> Journal of Visualized Experiments. (108), e53483 (2016).</li><li>Sucher, R., 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=Orthotopic+hind-limb+transplantation+in+rats.">Orthotopic hind-limb transplantation in rats.</a> Journal of Visualized Experiments. (41), e2022 (2010).</li><li>Horner, B. 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=In+vivo+observations+of+cell+trafficking+in+allotransplanted+vascularized+skin+flaps+and+conventional+skin+grafts.">In vivo observations of cell trafficking in allotransplanted vascularized skin flaps and conventional skin grafts.</a> Journal of Plastic, Reconstructive &amp; Aesthetic Surgery. 63 (4), 711-719 (2010).</li><li>Fleissig, 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=Modified+Heterotopic+Hindlimb+Osteomyocutaneous+Flap+Model+in+the+Rat+for+Translational+Vascularized+Composite+Allotransplantation+Research.">Modified Heterotopic Hindlimb Osteomyocutaneous Flap Model in the Rat for Translational Vascularized Composite Allotransplantation Research.</a> Journal of Visualized Experiments. (146), e59458 (2019).</li><li>Zhou, X., 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=A+series+of+rat+segmental+forelimb+ectopic+implantation+models.">A series of rat segmental forelimb ectopic implantation models.</a> Scientific Reports. 7 (1), (2017).</li><li>Adamson, L. A., 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=A+modified+model+of+hindlimb+osteomyocutaneous+flap+for+the+study+of+tolerance+to+composite+tissue+allografts.">A modified model of hindlimb osteomyocutaneous flap for the study of tolerance to composite tissue allografts.</a> Microsurgery. 27 (7), 630-636 (2007).</li><li>Ulusal, A. E., Ulusal, B. G., Hung, L. M., Wei, F. 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A., 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=enzyme+responsive,+tacrolimus-eluting+hydrogel+enables+long-term+survival+of+orthotopic+porcine+limb+vascularized+composite+allografts:+A+proof+of+concept+study.">enzyme responsive, tacrolimus-eluting hydrogel enables long-term survival of orthotopic porcine limb vascularized composite allografts: A proof of concept study.</a> PLoS One. 14 (1), 0210914 (2019).</li><li>Cottrell, B. L., 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=Neuroregeneration+in+composite+tissue+allografts:+effect+of+low-dose+FK506+and+mycophenolate+mofetil+immunotherapy.">Neuroregeneration in composite tissue allografts: effect of low-dose FK506 and mycophenolate mofetil immunotherapy.</a> Plastic and Reconstructive Surgery. 118 (3), 5 (2006).</li><li>Benhaim, P., Anthony, J. P., Lin, L. Y., McCalmont, T. H., Mathes, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+long-term+study+of+allogeneic+rat+hindlimb+transplants+immunosuppressed+with+RS-61443.">A long-term study of allogeneic rat hindlimb transplants immunosuppressed with RS-61443.</a> Transplantation. 56 (4), 911-917 (1993).</li><li>Greene, E. 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W., 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=A+preclinical+canine+model+for+composite+tissue+transplantation.">A preclinical canine model for composite tissue transplantation.</a> Journal of Reconstructive Microsurgery. 26 (3), 201-207 (2010).</li><li>Ibrahim, Z., 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=A+modified+heterotopic+swine+hind+limb+transplant+model+for+translational+vascularized+composite+allotransplantation+(VCA)+research.">A modified heterotopic swine hind limb transplant model for translational vascularized composite allotransplantation (VCA) research.</a> Journal of Visualized Experiments. (80), e50475 (2013).</li><li>Fries, C. A., 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=A+Porcine+Orthotopic+Forelimb+Vascularized+Composite+Allotransplantation+Model:+Technical+Considerations+and+Translational+Implications.">A Porcine Orthotopic Forelimb Vascularized Composite Allotransplantation Model: Technical Considerations and Translational Implications.</a> Plastic and Reconstructive Surgery. 138 (3), 71 (2016).</li><li>Kim, M., Fisher, D. T., Powers, C. A., Repasky, E. A., Skitzki, J. 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G., Serafin, 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> A Laboratory Manual of Microsurgery. Fourth Printing. , (1986).</li><li>Tseng, S. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+to+quantify+the+velocity+dependence+of+common+gait+measurements+from+automated+rodent+gait+analysis+devices.">Methods to quantify the velocity dependence of common gait measurements from automated rodent gait analysis devices.</a> Journal of Neuroscience Methods. 253, 244-253 (2015).</li><li>Yeh, L. S., Gregory, C. R., Theriault, B. R., Hou, S. M., Lecouter, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+functional+model+for+whole+limb+transplantation+in+the+rat.">A functional model for whole limb transplantation in the rat.</a> Plastic and Reconstructive Surgery. 105 (5), 1704-1711 (2000).</li></ol>

Limb transplant, under the broader category of vascularized component allotransplantation (VCA), has widely applicable therapeutic promise as yet unfulfilled. The main roadblocks lie in unsolved immunological issues unique to VCA and neuromotor recovery techniques used currently. Development of new techniques will depend on animal modeling that is flexible, robust, and reproducible.
Many animal models have been established in VCA, each with specific advantages4. Non-hum...

Limb transplant under the broader category of vascularized-composite allotransplant (VCA) or composite tissue allotransplant (CTA) has yet to fulfill its therapeutic promise. Since the first successful human hand transplants in Lyon, France and Louisville, Kentucky in 1998 and 1999, over 100 upper extremity transplants have been performed worldwide in carefully selected patients1. Wider applicability has been stymied by substantial immunosuppression and limited functional neuromotor recovery. Current immunosuppression strategies result in 85% incidence of acute rejection in the face of 77% incidence of opportunistic infection2. On the other hand, functional recovery after hand transplant occurs; mean Disability of Arm Shoulder and Hand (DASH) scores improve from 71 to 43, but that level of function may still qualify as a disability2. Given the nonlife saving nature of limb transplant, current techniques must be refined in animal models to take the next step in VCA.
Since the first rat model of limb transplant in 19783, many innovative animal models have been developed to advance the field of VCA4, incorporating vascular cuffed anastomoses to minimize operative time5,6, heterotopic osteomyocutaneous transplants to minimize physiologic insult to the recipient animal7,8,9,10,11, and novel immunologic approaches7,12,13,14. The rat model of orthotopic right hind limb mid-thigh transplant presented here emphasizes meticulous, time-tested microsurgical techniques such as hand sewn vascular anastomoses and neural coaptation as an upfront investment in a robust, reproducible model platform to simultaneously investigate both aspects of current VCA limitation: immunosuppression strategies and functional neuromotor recovery.

<table>
	<tbody>
		<tr>
			<td>Anesthesia machine</td>
			<td>Vet Equip</td>
			<td>911103</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5cc syringe</td>
			<td>Exel</td>
			<td>26018</td>
			<td></td>
		</tr>
		<tr>
			<td>18-gauge needle</td>
			<td>BD</td>
			<td>305196</td>
			<td></td>
		</tr>
		<tr>
			<td>1cc syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>22-gauge needle</td>
			<td>BD</td>
			<td>305156</td>
			<td></td>
		</tr>
		<tr>
			<td>24-gauge angiocatheter</td>
			<td>Sur-Vet</td>
			<td>SROX2419V</td>
			<td></td>
		</tr>
		<tr>
			<td>25-gauge needle</td>
			<td>Exel</td>
			<td>26403</td>
			<td></td>
		</tr>
		<tr>
			<td>3 cc syringe</td>
			<td>BD</td>
			<td>309657</td>
			<td></td>
		</tr>
		<tr>
			<td>5cc syringe</td>
			<td>Exel</td>
			<td>26230</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol</td>
			<td>Fisher Scientific</td>
			<td>HC-600-1GAL</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia induction chamber</td>
			<td>Vet Equip</td>
			<td>941443</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthetic gas scavenger system</td>
			<td>Vet Equip</td>
			<td>931401</td>
			<td></td>
		</tr>
		<tr>
			<td>Bipolar electrocautery</td>
			<td>Aura</td>
			<td>26-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Bitter Spray Mist</td>
			<td>Henry Schein</td>
			<td>5553</td>
			<td></td>
		</tr>
		<tr>
			<td>Bone wax</td>
			<td>CP Medical</td>
			<td>CPB31A</td>
			<td></td>
		</tr>
		<tr>
			<td>Breathing circuit</td>
			<td>Vet Equip</td>
			<td>921413</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenophine</td>
			<td>Reckitt Benckiser</td>
			<td>12496075705</td>
			<td></td>
		</tr>
		<tr>
			<td>Castro-Viejos needle drivers</td>
			<td>Roboz</td>
			<td>RS-6416</td>
			<td></td>
		</tr>
		<tr>
			<td>Cordless rotary saw</td>
			<td>Dremel</td>
			<td>8050-N/18</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton swab stick</td>
			<td>Fisher Scientific</td>
			<td>23-400-101</td>
			<td>For hemostasis</td>
		</tr>
		<tr>
			<td>DigiGait Appparatus and Software</td>
			<td>Mouse Specifics</td>
			<td>MSI-DIG, DIG-SOFT</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont forceps (#4)</td>
			<td>Roboz</td>
			<td>RS-4972</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont forceps (#5)</td>
			<td>Roboz</td>
			<td>RS-5035</td>
			<td></td>
		</tr>
		<tr>
			<td>Enrofloxacin</td>
			<td>Norbrook</td>
			<td>ANADA 200-495</td>
			<td></td>
		</tr>
		<tr>
			<td>FK-506</td>
			<td>Astellas</td>
			<td>301601</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Kendall</td>
			<td>1903</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Covidien</td>
			<td>8044</td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>Microflex</td>
			<td>DGP-350-M</td>
			<td></td>
		</tr>
		<tr>
			<td>Hair clippers</td>
			<td>Oster</td>
			<td>078005-010-003</td>
			<td></td>
		</tr>
		<tr>
			<td>Handheld monopolar electrocautery</td>
			<td>Bovie</td>
			<td>AA00</td>
			<td></td>
		</tr>
		<tr>
			<td>Hargreaves Apparatus</td>
			<td>Ugo Basile S.R.L. Gemonio, Italy</td>
			<td>37370</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating pad</td>
			<td>Walgreens</td>
			<td>126987</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Fresenius Kabi</td>
			<td>42592K</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot plate</td>
			<td>Corning</td>
			<td>PC-351</td>
			<td>For warming resusscitation fluid</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Henry Schein</td>
			<td>29405</td>
			<td></td>
		</tr>
		<tr>
			<td>Lactated ringers</td>
			<td>Baxter</td>
			<td>2B2074</td>
			<td></td>
		</tr>
		<tr>
			<td>Large petri dish</td>
			<td>Fisher Scientific</td>
			<td>FB0875713</td>
			<td>For donor graft while in chilled saline</td>
		</tr>
		<tr>
			<td>Meloxicam</td>
			<td>Henry Schein</td>
			<td>49755</td>
			<td></td>
		</tr>
		<tr>
			<td>micro Collin Hartmann retractor</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Micro dissecting scissors</td>
			<td>Roboz</td>
			<td>RS-5841</td>
			<td></td>
		</tr>
		<tr>
			<td>Microfibrillar collagen powder</td>
			<td>BD</td>
			<td>1010590</td>
			<td>For hemostasis</td>
		</tr>
		<tr>
			<td>Microvascular clips</td>
			<td>Roboz</td>
			<td>RS-5420</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal saline</td>
			<td>Baxter</td>
			<td>2F7124</td>
			<td></td>
		</tr>
		<tr>
			<td>Opthalmic lube</td>
			<td>Dechra</td>
			<td>IS4398</td>
			<td></td>
		</tr>
		<tr>
			<td>Rapmycin</td>
			<td>MedChem Express</td>
			<td>HY-10219</td>
			<td></td>
		</tr>
		<tr>
			<td>Small petri dish</td>
			<td>Fisher Scientific</td>
			<td>FB0875713A</td>
			<td>For warmed resusscitation fluid</td>
		</tr>
		<tr>
			<td>Sterile drapes</td>
			<td>ProAdvantage</td>
			<td>N207100</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical gown</td>
			<td>Cardinal Health</td>
			<td>9511</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical mask</td>
			<td>3M</td>
			<td>1805</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical microscope, optic model OPMIMD</td>
			<td>Zeiss</td>
			<td>169756</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical microscope, Universal S3</td>
			<td>Zeiss</td>
			<td>243188</td>
			<td></td>
		</tr>
		<tr>
			<td>Suture 10-0 nylon</td>
			<td>Covidien</td>
			<td>N2512</td>
			<td></td>
		</tr>
		<tr>
			<td>Suture 5-0 vicryl</td>
			<td>Ethicon</td>
			<td>J213H</td>
			<td></td>
		</tr>
		<tr>
			<td>Suture 7-0 silk tie</td>
			<td>Teleflex</td>
			<td>103-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Tape</td>
			<td>3M</td>
			<td>1530-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic instrument cleaner</td>
			<td>Roboz</td>
			<td>RS-9911</td>
			<td></td>
		</tr>
		<tr>
			<td>Vessel dilation forceps</td>
			<td>Roboz</td>
			<td>RS-5047</td>
			<td></td>
		</tr>
	</tbody>
</table>

taking the next step: a neural coaptation orthotopic hind limb transplant model to maximize functional recovery in rat

Limb transplant in particular and vascularized composite allotransplant (VCA) in general have wide therapeutic promise that have been stymied by current limitations in immunosuppression and functional neuromotor recovery. Many animal models have been developed for studying unique features of VCA, but here we present a robust reproducible model of orthotopic hind limb transplant in rats designed to simultaneously investigate both aspects of current VCA limitation: immunosuppression strategies and functional neuromotor recovery. At the core of the model rests a commitment to meticulous, time-tested microsurgical techniques such as hand sewn vascular anastomoses and hand sewn neural coaptation of the femoral nerve and the sciatic nerve. This approach yields durable limb reconstructions that allow for longer lived animals capable of rehabilitation, resumption of daily activities, and functional testing. With short-term treatment of conventional immunosuppressive agents, allotransplanted animals survived up to 70 days post-transplant, and isotransplanted animals provide long lived controls beyond 200 days post-operatively. Evidence of neurologic functional recovery is present by 30 days post operatively. This model not only provides a useful platform for interrogating immunological questions unique to VCA and nerve regeneration, but also allows for in vivo testing of new therapeutic strategies specifically tailored for VCA.

Survival and recovery depend on meticulous surgical technique. Attention to the vascular anastomoses and the neural anastomoses, as well as the bone coaptation as described above is crucial maximizing the success of this model. Operative design and representative anastomotic results are shown in Figure 1.
Overall mortality was dependent on immunosuppression strategy, with the majority of isotransplanted animals attaining the study endpoint of 100-200 post-operativ...

Watch this Scientific Journal Video about Taking the Next Step: a Neural Coaptation Orthotopic Hind Limb Transplant Model to Maximize Functional Recovery in Rat at JoVE.com

Taking the Next Step: a Neural Coaptation Orthotopic Hind Limb Transplant Model to Maximize Functional Recovery in Rat

This protocol presents a robust, reproducible model of vascularized composite allotransplant (VCA) geared toward simultaneous study of immunology and functional recovery. The time invested in meticulous technique in a right mid-thigh hind limb orthotopic transplant with hand sewn vascular anastomoses and neural coaptation yields the ability to study functional recovery.

Limb transplant in particular and vascularized composite allotransplant (VCA) in general have wide therapeutic promise that have been stymied by current ...

This video will provide detailed description, how to perform an orthotopic right hind limb, mid-thigh transplanted rat. The donor rat right hind limb is amputated at mid-thigh level, then stored on ice. The recipient rat right hind limb is also amputated at mid-thigh level.The donor rat limb is then attached to the recipient rat. We will describe how to reattach the bone, artery, vein, nerve, muscle, and skin systems. Limb transplant, more specifically, vascularized composite allotransplant, VCA, has wide therapeutic promise.But it's currently limited by techniques, immunosuppression, and poor functional neuromotor recovery. Our model emphasizes meticulous time-tested microsurgical techniques, such as hand-sewn vascular anastomosis and neural coaptation. We've performed over 200 of these surgeries in over a year.Although there's an initial learning curve to the beginning microsurgeon, by using this video to learn our method and their committing to dedicated practice, any microsurgeon will be able to master this model. All experiments were conducted in accordance with the guide for the care and use of laboratory animals of the National Institutes of Health, NIH, and were approved by the Northwestern University Animal Care and Use Committee. The specific procedures were performed on a protocol IS 00001663.Select a rat aged eight to 16 weeks old weighing between 250 and 400 grams at the time of surgery. Induce general anesthesia with 5%isoflurane through a vaporizer before trimming the rat's hind limb fur. Using a nose cone to maintain anesthesia between two to 2.5%position the rat on the operating board with a heater underneath.Disinfect the hairless skin with 70%rubbing alcohol and protect the surgical field with sterile gauze. Using an appropriate microsurgical microscope and the microsurgical instruments shown here, along with easy-to-access bipolar and monopolar electrocautery, you will be ready to begin the dissection. Use a scissors to make a circumferential and skin incision around the right hind limb.Start in the inguinal crease immediately at roughly the same level as the inguinal ligament and extend dorsal laterally to complete the circumferential incision. And then expose the muscular layer directly beneath the incision, dissect and cauterized the superficial epigastric vessels, which lead from the muscular layer to the proximal skin flap just created. Reflect the proximal flap superomedially to the inguinal ligament and the distal skin flap inferolaterally to the knee.Use a wire retractor or rolled gauze to help expose the field. Observed that the inguinal anatomy of the rat is similar to humans;from lateral to medial lie the nerve, artery, and vein. Dissect out the femoral nerve, divide it sharply at the inguinal ligament proximal to the bifurcation, if possible.Retract the divided nerve inferiorly, keeping it safely out of the way, covered beneath moist gauze. Turning attention to the femoral artery and vein use four centimeter long 7-0 silk ties to atraumatically retract the vessels instead of handling them directly. Paying close attention now will improve your final anastomotic result.Ligate all branches of the femoral vessels with 7-0 silk ties. Divide the branches between the ties. Arterial and venous branches which require division include the superficial circumflex iliac and the muscular vessels.The superficial circumflex iliac is usually largest and appears to dive deep as would the profunda femoral in humans, but the profunda is absent in the rat. More distal branches of the femoral vessels, such as highest genicular and the saphenous branch do not usually require division. Now ligate the femoral artery with 7-0 silk ties as proximal to the inguinal ligament as possible and divide between the ties.Similar to the artery, ligate and divide the femoral vein. Reflect both artery and vein inferiorly, safely out of the way, covered beneath moist gauze together with the femoral nerve covered previously. Dissect the ventral muscle groups, taking care to cauterize any visible vessel that arises.Attention to hemostasis now will minimize recipient blood loss during reprofusion later. Deep to the ventral muscle groups, identify and sharply divide the sciatic nerve proximal to its branches. All three sciatic branches are usually visible, tibial, peroneal and sural.All three should be preserved in the donor limb. A fourth cutaneous branch is not typically seen in this dissection. Finish dividing the remaining ventral and dorsal muscle groups at mid-thigh level with meticulous hemostasis.It may be necessary to retract the limb medially to complete dividing the muscles. Transect the femur bone at mid-shaft using a handheld cordless rotary saw. The limb is now free from the donor.Having removed the limb graft from the donor, cut the silk tied ends from the graft side femoral artery and vein stumps, thereby re-opening the vessels. Insert a 24-gauge angiocatheter into the graft artery stump and flush the graft with 250 international units of heparin diluted in 5 milliliters of ice-cold normal saline, being careful to watch it flow out of the open vein. Slowly, gently flush the graft for around three minutes.Excess forceful flushing may damage the endothelium. Place the graft in a chilled saline dish nested in an ice bucket until transplantation. Euthanize the donor rat with bilateral thoracotomy.The recipient surgery begins similar to the donor surgery, anesthetizing the rat, trimming the fur, making a circumferential incision in the inguinal crease, reflecting the skin flaps, dissecting out the femoral nerve, artery, and vein. And ligating the same branch vessels as described previously. However, during this operation, divide the femoral nerve more distally than for the donor, but proximally to the bifurcation if possible.Divide and free the femoral artery and vein and proximately clamp them respectively at the level of the inguinal ligament with microsurgical bulldog clamps. Continue the surgery as described previously, dividing the ventral endorsing muscles of the thigh at mid-thigh level with meticulous hemostasis, while retracting the limb medially as necessary. Identify and divide the sciatic nerve proximal to the branch point and transect the femur at mid-shaft using the rotary saw.Remove the recipient native right hind limb and dispose appropriately in accordance with local Animal Care and Use Committee guidelines. It is very important at this stage to turn down the isoflurane to one to 1.5%through the nose cone. Too much anesthesia during this less painful part of the procedure will lead to the rat's death.It is time to coapt the bones together. Using the handheld rotary saw, shave off any irregularities from both the donor and recipient femur cut ends. Cut off the hub end of an 18-gauge needle, which will become the femur intramedullary rod.Before manipulating the bone, apply a small amount of a bone wax to the recipient cut end of the femur bone to reduce marrow bleeding during the reaming process. Coapt the donor and recipient femoral bones using the 18-gauge needle as an intramedullary rod. Some force is necessary, but do not ream either bone so far as to fracture the cortex.As needed, remove the needle and trim it to inappropriate length so that both bones fit smoothly over the needle with no needle showing in between the bone. Place a small support such as a pad of gauze or a small rock or modelling clay underneath the donor limb to keep it off tension. Reapproximate the ventral muscle groups with eight to 10 simple interrupted 5-0 polyglactin sutures so that the graft does not rotate around the femur needle.This gives the limb stability for the anastomoses. Now begin the anastomoses. Periodically irrigate the graft and surgical field with ice-cold saline for better visualization and to reduce ischemic reperfusion injury.Align the donor and recipient femoral arteries and anastomose in end-to-end fashion using simple interrupted 10-0 nylon suture, avoiding both tension and looping. The artery requires an average of six sutures. Similar to the artery, anastomose the donor and recipient femoral veins in end-to-end fashion.The vein requires six to eight sutures. Generous cold saline irrigation, atraumatic vessel handling technique, and leaving long tails to serve as stay sutures for vessel retraction are important tools for effective microsurgical anastomoses. Place a moderate amount of hemostatic cellulose powder on both anastomoses, and subsequently remove the proximal microsurgical bulldog clamps on the vein and the artery.Inspect both anastomoses for good patency and flow. Use cotton swab sticks to gently prod the vein and inspect for good hemostasis on both anastomoses. When both anastomoses are confirmed satisfactory, trim any remaining long stay suture tails to match the others.Repositioning the rat to the left lateral decubitus position, use liberal electrocautery to attain meticulous hemostasis of any reperfusion muscle bleeding. Attention is turned to the nerve anastomoses once muscle hemostasis is assured. Reapproximate the dorsal muscle groups which lie directly under the sciatic nerve with simple interrupted 5-0 polyglactin sutures.Trim back any nerve cut ends that appear ragged. Reapproximate the sciatic nerve with 10-0 nylon sutures striving for epineural bites. Eight to 10 simple interrupted sutures will usually suffice.Reapproximate the remaining dorsal muscle groups with 5-0 polyglactin sutures. Then close the dorsal skin with 4-0 polyglactin continuous running suture. Repositioning the rat to supine position, reapproximate the femoral nerve with 10-0 nylon suture, again, striving for epineural bites.Two to three simple interrupted sutures will usually suffice. Close the remaining ventral skin in the same fashion as the dorsal skin. Avoid excess suture tail, which can be irritating to the rat once awake.Once the animals are out of the immediate postoperative window, they can be tested for neuromotor recovery. The Hargreaves test is used to test thermal sensation. Place the rat in the testing container and allowed it to acclimatize for 20 minutes.The apparatus glass is confirmed clean, and the heat source is confirmed to be working with the investigator's finger. Before testing, confirm the rat is awake and the tested paw is positioned over the infrared motion detector. Transmit thermal energy at intensity level 90.Time delay in the animal moving its paw away from the heat source is recorded. If no movement occurs within 20 seconds, the test is aborted to prevent injury. Obtain five trials per tested limb, excluding the highest and lowest value before calculating the mean withdrawal latency time for each animal.Here's depicted operative design in cartoon format. The right hind limb of both donor and recipient rats are amputated at mid-thigh level as sciatic cross-section. Femoral artery, vein, and nerve, as well as the sciatic nerve and femur bone must then be reconnected in the recipient surgery.The model can be used to show differential survival effects of immune suppression and transplant strategy. With this technique, long-term survival is achievable. The model can be used to investigate sensory nerve recovery, which may be evident by four weeks postoperatively.Motor function can also be interrogated using a gait analysis platform. Here, we have presented a rat model platform with favorable survival characteristics, which we use to probe sensory and motor recovery as seen in the proceeding figures. Limb transplant under the broader category of VCA, vascularized component allotransplantation has widely applicable therapeutic promise is yet unfulfilled.The main roadblocks line current immunosuppression and neuromotor recovery techniques. Development of new techniques will depend on flexible, robust, and reproducible animal modeling. Using this platform, it is our hope that investigators will be able to advance multiple facets of limb transplant.Thank you for watching and good luck in your next steps.

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Research

JoVE Journal

Medicine

7.2K vistas.  Northwestern University. Este video proporcionará una descripción detallada, cómo realizar una extremidad posterior ortotópica, rata trasplantada de muslo medio. La extremidad posterior derecha de la rata donante se amputa a nivel del muslo medio y luego se almacena en hielo. La extremidad posterior derecha de la rata receptora también se amputa a nivel medio del muslo.A continuación, la extremidad de la rata donante se une a la rata receptora. Describiremos cómo volver a conectar los sistemas óseo, ar...