This work was supported by the Office of the Assistant Secretary of Defense for Health Affairs through the Congressionally Directed Medical Research Program under Award No. W81XWH-17-1-0680. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the Department of Defense.

All animals received humane care in accordance with the NIH Guide for the Care and Use of Laboratory Animals. The Institutional Animal Care and Use Committee (IACUC-protocol 2017N000184) and Animal Care and Use Review Office (ACURO) approved all animal protocols. Inbred male Lewis rats (250-400 g) were used for all experiments.
1. Surgery
<ol>
	<li>Anesthetize the Lewis rats using isoflurane inhalation. Induce anesthesia with 5% isoflurane in the induction chamber, and maintain anesthesia wi...

<ol>
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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=Penis+transplantation:+first+US+experience.">Penis transplantation: first US experience.</a> Annals of Surgery. 267 (5), 983-988 (2018).</li><li>Grajek, 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=First+complex+allotransplantation+of+neck+organs:+larynx,+trachea,+pharynx,+esophagus,+thyroid,+parathyroid+glands,+and+anterior+cervical+wall:+a+case+report.">First complex allotransplantation of neck organs: larynx, trachea, pharynx, esophagus, thyroid, parathyroid glands, and anterior cervical wall: a case report.</a> Annals of Surgery. 266 (2), 19-24 (2017).</li><li>Pribaz, J. J., Caterson, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+and+limitations+of+conventional+autologous+reconstruction+of+the+head+and+neck.">Evolution and limitations of conventional autologous reconstruction of the head and neck.</a> Journal of Craniofacial Surgery. 24 (1), 99-107 (2013).</li><li>Lipson, R. 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=Vascularized+limb+transplantation+in+the+rat.+I.+Results+with+syngeneic+grafts.">Vascularized limb transplantation in the rat. I. Results with syngeneic grafts.</a> Transplantation. 35 (4), 293-299 (1983).</li><li>Lipson, R. 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=Vascularized+limb+transplantation+in+the+rat.+II.+Results+with+allogeneic+grafts.">Vascularized limb transplantation in the rat. II. Results with allogeneic grafts.</a> Transplantation. 35 (4), 300-304 (1983).</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>Arav, A., Friedman, O., Natan, Y., Gur, E., Shani, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+hindlimb+cryopreservation+and+transplantation:+a+step+toward+"organ+banking".">Rat hindlimb cryopreservation and transplantation: a step toward "organ banking".</a> American Journal of Transplantation. 17 (11), 2820-2828 (2017).</li><li>Gok, 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=Development+of+an+ex-situ+limb+perfusion+system+for+a+rodent+model.">Development of an ex-situ limb perfusion system for a rodent model.</a> ASAIO Journal. 65 (2), 167-172 (2019).</li><li>Gok, E., Rojas-Pena, A., Bartlett, R. H., Ozer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+skeletal+muscle+metabolomic+changes+associated+with+static+cold+storage.">Rodent skeletal muscle metabolomic changes associated with static cold storage.</a> Transplantation Proceedings. 51 (3), 979-986 (2019).</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>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: JoVE. (146), e59458 (2019).</li><li>Ulusal, A. E., Ulusal, B. G., Hung, L. M., Wei, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterotopic+hindlimb+allotransplantation+in+rats:+an+alternative+model+for+immunological+research+in+composite-tissue+allotransplantation.">Heterotopic hindlimb allotransplantation in rats: an alternative model for immunological research in composite-tissue allotransplantation.</a> Microsurgery. 25 (5), 410-414 (2005).</li><li>Jang, Y., Park, Y. E., Yun, C. W., Kim, D. H., Chung, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+vest-collar+as+a+rodent+collar+to+prevent+licking+and+scratching+during+experiments.">The vest-collar as a rodent collar to prevent licking and scratching during experiments.</a> Lab Anim. 50 (4), 296-304 (2016).</li><li>Kern, B., 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+novel+rodent+orthotopic+forelimb+transplantation+model+that+allows+for+reliable+assessment+of+functional+recovery+resulting+from+nerve+regeneration.">A novel rodent orthotopic forelimb transplantation model that allows for reliable assessment of functional recovery resulting from nerve regeneration.</a> American Journal of Transplantation. 17 (3), 622-634 (2017).</li><li>Perez-Abadia, G., 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=Low-dose+immunosuppression+in+a+rat+hind-limb+transplantation+model.">Low-dose immunosuppression in a rat hind-limb transplantation model.</a> Transplant International. 16 (12), 835-842 (2003).</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>Fleissig, Y. Y., Beare, J. E., LeBlanc, A. J., Kaufman, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+the+rat+hind+limb+transplant+as+an+experimental+model+of+vascularized+composite+allotransplantation:+Approaches+and+advantages.">Evolution of the rat hind limb transplant as an experimental model of vascularized composite allotransplantation: Approaches and advantages.</a> SAGE Open Medicine. 8, 2050312120968721 (2020).</li><li>Lindboe, C. F., Presthus, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+denervation,+immobilization+and+cachexia+on+fibre+size+in+the+anterior+tibial+muscle+of+the+rat.">Effects of denervation, immobilization and cachexia on fibre size in the anterior tibial muscle of the rat.</a> Acta Neuropathologica. 66 (1), 42-51 (1985).</li><li>Nazzal, J. A., Johnson, T. S., Gordon, C. R., Randolph, M. A., 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=Heterotopic+limb+allotransplantation+model+to+study+skin+rejection+in+the+rat.">Heterotopic limb allotransplantation model to study skin rejection in the rat.</a> Microsurgery. 24 (6), 448-453 (2004).</li></ol>

The authors have no disclosures.

Orthotopic limb transplantation models in rodents have been described in the literature16,17,18; however, they require a nerve repair, muscle reattachment, and a perfect osteosynthesis of the femur, which can be a very difficult step. These models are also associated with a higher morbidity and mortality rate in rodents14, especially in the short-term follow-up as the recovery of a normal function of a tr...

Over the past two decades, VCA has evolved as a revolutionary treatment for patients who suffer severe disfigurement including face1, upper limb amputations2, penile3, and other complex tissue defects4,5. However, the consequences of life-long immunosuppression still hinder a broader application of these complex reconstructive surgeries. Basic research is crucial to improve anti-rejection strategies. Increasing VCA preservation time is also essential to improve transplantation logistics and increase the donor pool (as VCA donors must fulfill more criteria than solid organ donors, including skin tone, anatomic size, gender). In this context, rat limb transplantations are widely used in studies on the immune rejection of allografts6,7, novel tolerance induction protocols8, and preservation studies9,10,11. Hence, these VCA models are a key element to master for VCA translational research.
Osteomyocutaneous flaps have been described in the literature as reliable models to study VCA in rats8,12,13,14. Although orthotopic whole-limb transplantations allow for long-term evaluation of graft function, it is a time-consuming procedure associated with higher postoperative morbidity and mortality rates14. In contrast, heterotopic limb transplantation models are non-functional, but enable reproducible studies on VCA. Postoperative outcomes can be reliably anticipated before the start of a rat VCA transplantation study. This study reports a partial heterotopic osteomyocutaneous flap transplantation model in the rat that includes frequent possible outcomes and complications that can arise intra-operatively and postoperatively during a follow-up period of three weeks.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>24 GA angiocatheter</td>
			<td>BD Insyte Autoguard</td>
			<td>381412</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 suture Black monofilament non absorbable suture</td>
			<td>Ethicon</td>
			<td>1667</td>
			<td>Used to suture the E-collar to the back of the neck</td>
		</tr>
		<tr>
			<td>4-0 suture Coated Vicryl Plus Antibacterial</td>
			<td>Ethicon</td>
			<td>VCP496</td>
			<td></td>
		</tr>
		<tr>
			<td>Adson Tissue Forceps, 11 cm, 1 x 2 Teeth with Tying Platform</td>
			<td>ASSI</td>
			<td>ASSI.ATK26426</td>
			<td></td>
		</tr>
		<tr>
			<td>Bipolar cords</td>
			<td>ASSI</td>
			<td>228000C</td>
			<td></td>
		</tr>
		<tr>
			<td>Black Polyamide Monofilament USP 10-0, 4 mm 3/8c</td>
			<td>AROSurgical</td>
			<td>T04A10N07-13</td>
			<td>Used to perform the microvascular anastomoses</td>
		</tr>
		<tr>
			<td>Buprenorphine HCl</td>
			<td>Pharmaceutical, Inc</td>
			<td>42023-179-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Dilating Forceps</td>
			<td>Fine science tools (FST)</td>
			<td>18131-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting Scissors 15 cm, Round Handle 8 mm diameter, Straight Slender Tapered Blade 7 mm, Lipshultz Pattern</td>
			<td>ASSI</td>
			<td>ASSI.SAS15RVL</td>
			<td></td>
		</tr>
		<tr>
			<td>Double Micro Clamps 5.5 x 1.5 mm</td>
			<td>Fine science tools (FST)</td>
			<td>18040-22</td>
			<td></td>
		</tr>
		<tr>
			<td>Elizabethan collar</td>
			<td>Braintree Scientific</td>
			<td>EC-R1</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps 13.5 cm long, Flat Handle, 9 mm wide Straight Tips 0.1 mm diameter (x2)</td>
			<td>ASSI</td>
			<td>ASSI.JFL31</td>
			<td></td>
		</tr>
		<tr>
			<td>Halsey Micro Needle Holder</td>
			<td>Fine science tools (FST)</td>
			<td>12500-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin Lock Flush Solution, USP, 100 units/mL</td>
			<td>BD PosiFlush</td>
			<td>306424</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Patterson Veterinary</td>
			<td>14043-704-06</td>
			<td></td>
		</tr>
		<tr>
			<td>Jewelers Bipolar Forceps Non Stick 11 cm, straight pointed tip, 0.25 mm tip diameter</td>
			<td>ASSI</td>
			<td>ASSI.BPNS11223</td>
			<td></td>
		</tr>
		<tr>
			<td>Lone Star Elastic Stays</td>
			<td>CooperSurgical</td>
			<td>3314-8G</td>
			<td>Used to retract the inguinal ligament for femoral vessels dissection</td>
		</tr>
		<tr>
			<td>Lone Star Self-Retaining Retractors</td>
			<td>CooperSurgical</td>
			<td>3301G</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro-Mosquito Hemostats</td>
			<td>Fine science tools (FST)</td>
			<td>13010-12</td>
			<td>Used to retract the inguinal fat pad distally</td>
		</tr>
		<tr>
			<td>Needle Holder, 15 cm Round Handle, 8 mm diameter, Superfine Curved Jaw 0.2 mm tip diameter, without lock</td>
			<td>ASSI</td>
			<td>ASSI.B1582</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Suture Black Monolfilament 8-0, 6.5 mm 3/8c</td>
			<td>Ethilon</td>
			<td>2808G</td>
			<td>Used to ligate collateral branches on the femoral vessels</td>
		</tr>
		<tr>
			<td>Offset Bone Nippers</td>
			<td>Fine science tools (FST)</td>
			<td>16101-10</td>
			<td></td>
		</tr>
		<tr>
			<td>S&#38;T Vascular Clamps 5.5 x 1.5 mm</td>
			<td>Fine science tools (FST)</td>
			<td>00398-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Walton scissors</td>
			<td>Fine science tools (FST)</td>
			<td>14077-09</td>
			<td></td>
		</tr>
	</tbody>
</table>

partial heterotopic hindlimb transplantation model in rats

Vascularized composite allotransplantations (VCA) represent the most advanced reconstruction option for patients without autologous surgical possibilities after a complex tissue defect. Face and hand transplantations have changed disfigured patients' lives, giving them a new aesthetic and functional social organ. Despite promising outcomes, VCA is still underperformed due to life-long immunosuppression comorbidities and infectious complications. The rat is an ideal animal model for in vivo studies investigating immunological pathways and graft rejection mechanisms. Rats are also widely used in novel composite tissue graft preservation techniques, including perfusion and cryopreservation studies. Models used for VCA in rats must be reproducible, reliable, and efficient with low postoperative morbidity and mortality. Heterotopic limb transplantation procedures fulfill these criteria and are easier to perform than orthotopic limb transplants. Mastering rodent microsurgical models requires solid experience in microsurgery and animal care. Herein is reported a reliable and reproducible model of partial heterotopic osteomyocutaneous flap transplantation in rats, the postoperative outcomes, and the means of prevention of potential complications.

In this single-operator study, 30 syngeneic heterotopic partial limb transplants were performed. Success was defined at postoperative day 21 as the absence of VCA failure or complications requiring euthanasia. The normal evolution of the graft is represented in Figure 3. The mean duration for partial limb procurement and graft inset in the recipient were 35 and 105 min, respectively; the mean ischemia time was 105 min. During follow-up, two types of complications occurred (Table 1</s...

Watch this Scientific Journal Video about Partial Heterotopic Hindlimb Transplantation Model in Rats at JoVE.com

Partial Heterotopic Hindlimb Transplantation Model in Rats

This paper presents a partial heterotopic osteomyocutaneous flap transplantation protocol in rats and its potential outcomes in the mid-term follow-up.

Vascularized composite allotransplantations (VCA) represent the most advanced reconstruction option for patients without autologous surgical possibilities ...

We present a reliable and reproducible surgical model of heterotopic hindlimb transplantation in rats. This technique is ideal for short-term studies on preservation or immune rejection in VCA. The step-by-step description will allow trainees to rapidly master the surgery.To begin, make a circumferential incision on the skin above the ankle at the distal third of the leg. Skeletonize and cauterize the saphenous artery and the terminal branch of the popliteal artery using bipolar forceps. Cauterize and cut the gastrocnemius, soleus, tibialis anterior, and biceps femoris muscles until the tibial bone is exposed.Make a 2.5 centimeter incision at the right inguinal crease and dissect the inguinal fat pad. Use a fish hook retractor to grasp the inguinal ligament. Hold the inguinal fat pad distally with clamping forceps and retract the fat pad to expose the femoral vessels.Dissect the femoral vessels, individualize the Murphy branches, and ligate with 8/0 nylon ties. Heparinize the donor rat by injecting the heparin in the penile dorsal vein using a 27.5 gauge needle. Complete the skin incision around the hip.Use the bipolar forceps to cauterize the biceps femoris and gluteus superficialis muscles, then cauterize and cut the sciatic nerve at mid-femur length. Expose the femur proximally at the level of the posterior femoral crest and ligate the femoral vessels with nylon ties at the level of the inguinal ligament. Perform an arteriotomy on the femoral artery just below the ligature and dilate to insert the 24 gauge angiocatheter.Cauterize and cut the remaining muscle underneath the pedicle to expose the anterior side of the femur. Use the bone cutter to cut the tibia proximally and cut the femur as distally as possible. Flush the partial hindlimb with two milliliters of heparin saline to obtain a clear venous outflow.Place the hindlimb on ice in a sterile gauze until the microvascular transfer. Dissect the inguinal fat pad and recline the inguinal fat pad distally to expose the femoral vessels. Use a hook to retract the inguinal ligament and clamping forceps to hold the inguinal fat pad distally.Dissect the femoral vessels, individualize the Murphy branches, and ligate with nylon ties as demonstrated. Ligate both vessels above the epigastric vessels using nylon ties. Place the approximator clamps proximally, dilate the vessel lens, and rinse with heparin saline.Make an incision on the left flank above the hip and create a subcutaneous pocket with a subcutaneous tunnel to the inguinal crease. Place the proximal part of the partial limb and the inguinal fat pad through the subcutaneous tunnel for microvascular transfer. Perform the venous and arterial anastomoses using nylon sutures.Remove both approximator clamps and observe the revascularization of the limb. Perform a milking test on both vessels to assess the patency of each anastomosis. Make a longitudinal skin incision on the medial side of the transplanted limb and insert the graft.Remove the excess skin of the graft and close the wound with separate sutures and a running suture using absorbable 4/0 sutures. Suture together the inguinal fat pads of the transplanted limb and the recipient using two separate absorbable sutures and close the inguinal crease after the last checkup of the microvascular anastomosis. The evolution of the heterotopic hindlimb model was monitored until the end of the study.The hair regrowth was observed during the first postoperative week, and the cutaneous retraction appeared after two weeks. Vascularized composite allotransplantation failure can occur during the first postoperative week due to microvascular thrombosis. Venous thrombosis was the cause of early euthanasia in 20%of the cases, all of which occurred before postoperative day five.The skin appeared blue and became darker each day. Self-mutilation is a serious concern in nonsensate grafts and often occurs between postoperative day two and seven. If limited to less than a third of the graft surface and concerns only skin, surgical debridement and suture using non-absorbable sutures can be discussed with the staff veterinarian.Prevention of self-mutilation relies on using an e-collar stitched to the neck until postoperative day seven and cleaning any blood or crust on the animal's surgical wounds. Severe autophagia of multiple layers of the graft leads to euthanasia of the animal. Dermal cysts appeared after postoperative day 14, sometimes with a cutaneous necrotic center before the fistula.It is crucial to ensure that the graft placement will not prevent the animal from being ambulatory, and that the pedicle is not kinked or tight during the graft inset. Our team performed preservation studies in the procured limbs before transplantation. The effects of different durations of static cold storage have been evaluated as well as different limb perfusion protocols.

partial-heterotopic-hindlimb-transplantation-model-in-rats

Research

JoVE Journal

Immunology and Infection

2.6K Görüntüleme.  Massachusetts General Hospital, Harvard Medical School. Sıçanlarda heterotopik hindlimb transplantasyonunun güvenilir ve tekrarlanabilir cerrahi modelini sunuyoruz. Bu teknik, VCA'da koruma veya immün ret üzerine kısa süreli çalışmalar için idealdir. Adım adım açıklama, kursiyerlerin ameliyata hızlı bir şekilde hakim olmasını sağlayacaktır.Başlamak için, bacağın distal üçte biri olan ayak bileğinin üzerindeki deride çevresel bir kesi yapın. Bipolar kümeser kullanarak saphenöz arteri ve popliteal arterin ter...