Department of Plastic Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
Microsurgery. 2024 Feb;44(2):e31136. doi: 10.1002/micr.31136.
Above elbow transplants represent 19% of the upper extremity transplants. Previous large-animal models have been too distal or heterotopic, did not use immunosuppression and had short survival. We hypothesize that an orthotopic forelimb transplant model, under standard immunosuppression, is feasible and can be used to address questions on peri-transplant ischemia reperfusion injury, and post-transplantation vascular, immunologic, infectious, and functional outcomes.
Four forelimbs were used for anatomical studies. Four mock transplants were performed to establish technique/level of muscle/tendon repairs. Four donor and four recipient female Yucatan minipigs were utilized for in-vivo transplants (endpoint 90-days). Forelimbs were amputated at the midarm and preserved through ex vivo normothermic perfusion (EVNP) utilizing an RBC-based perfusate. Hourly perfusate fluid-dynamics, gases, electrolytes were recorded. Contractility during EVNLP was graded hourly using the Medical Research Council scale. EVNP termination criteria included systolic arterial pressure ≥115 mmHg, compartment pressure ≥30 mmHg (at EVNP endpoint), oxygen saturation reduction of 20%, and weight change ≥2%. Indocyanine green (ICG) angiography was performed after revascularization. Limb rejection was evaluated clinically (rash, edema, temperature), and histologically (BANFF classification) collecting per cause and protocol biopsies (POD 1, 7, 30, 60 and endpoint). Systemic infections were assessed by blood culture and tissue histology. CT scan was used to confirm bone bridging at endpoint.
Animals 2, 4 reached endpoint with grade 0-I rejection. Limbs 1, 3 presented grade III rejection on days 6, 61. CsA troughs averaged 461 ± 189 ng/mL. EVNLP averaged 4.3 ± 0.52 h. Perfusate lactate, PO , and pH were 5.6 ± 0.9 mmol/L, 557 ± 72 mmHg and 7.5 ± 0.1, respectively. Muscle contractions were 4 [1] during EVNLP. Transplants 2, 3, 4 showed bone bridging on CT.
We present preliminary evidence supporting the feasibility of an orthotopic, mid-humeral forelimb allotransplantation model under standard immunosuppression regimen. Further research should validate the immunological, infectious, and functional outcomes of this model.
肘部以上的移植占上肢移植的 19%。以前的大动物模型要么太偏远，要么异位，要么不使用免疫抑制剂，要么存活时间短。我们假设在标准免疫抑制下，同种异体前肢移植模型是可行的，可以用来解决移植前缺血再灌注损伤以及移植后血管、免疫、感染和功能结果的问题。
使用 4 个前肢进行解剖学研究。进行了 4 次模拟移植，以建立技术/肌肉/肌腱修复水平。使用雌性尤卡坦小型猪的 4 个供体和 4 个受体进行体内移植（终点为 90 天）。在前臂中段截断前肢，并通过使用基于红细胞的灌流液进行离体常温灌流（EVNP）进行保存。每小时记录灌流液的流体动力学、气体和电解质。每小时使用医学研究委员会（Medical Research Council）量表对 EVNLP 期间的收缩性进行分级。EVNP 终止标准包括收缩压≥115mmHg、间隔压≥30mmHg（在 EVNP 终点时）、氧饱和度降低 20%和体重变化≥2%。再灌注后进行吲哚菁绿（Indocyanine green，ICG）血管造影。根据临床（皮疹、水肿、温度）和组织学（BANFF 分类）评估肢体排斥反应（根据原因和方案采集活检）（POD 1、7、30、60 和终点）。通过血液培养和组织学评估系统感染。CT 扫描用于确认终点处的骨桥接。
动物 2、4 达到终点时排斥反应为 0-1 级。肢体 1、3 在第 6、61 天出现 3 级排斥反应。环孢素谷浓度平均为 461±189ng/mL。EVNLP 平均持续 4.3±0.52 小时。灌流液乳酸、PO 和 pH 值分别为 5.6±0.9mmol/L、557±72mmHg 和 7.5±0.1。EVNLP 期间肌肉收缩为 4[1]。移植 2、3、4 在 CT 上显示骨桥接。
我们初步证明了在标准免疫抑制方案下进行同种异体、肱骨中段前肢移植模型的可行性。进一步的研究应该验证该模型的免疫学、感染学和功能结果。
