The long-term survival after vascularized composite allotransplantation (VCA) is often limited by systemic rejection as well as the adverse effects of immunosuppressants. The stromal vascular fraction (SVF) can be expanded to produce adipose-derived stem cells (ADSC) which represents a combination of endothelial cells, preadipocytes, immune cells, and ADSC. It has been demonstrated that ADSC possess consistently reliable clinical results. However, literature is scarce regarding SVF in VCA. This study seeks to determine the impact of ex vivo allograft pretreatment in combination with SVF cells in the ability to promote composite tissue allotransplantation immunotolerance. A rat hind limb allotransplant model was used to investigate the influence of ex vivo pretreatment of SVF and ADSC on VCA survival. Intravascular cell-free saline, ADSC, or SVF was infused into the models with immunosuppressants. The histopathological examination and duration that the allografts went without displaying symptoms of rejection was documented. Peripheral T lymphocytes and Tregs were quantified with flow cytometry while allotissue expressions of CD31 were quantified with immunohistochemical staining (IHC). ELISA was used to detect vascular endothelial growth factor (VEGF)-A as well as anti- and pro-inflammatory cytokines. We demonstrated that ex vivo treatment of allografts with SVF or ADSC prolonged allograft survival in contrast to medium control cohorts. There were also enhanced levels of immunomodulatory cytokines and increased VEGF-A and CD31 expression as well as reduced infiltration and proliferation of T lymphocytes along with raised Treg expressions. These studies demonstrated that adipose-derived cellular therapies prolong graft survival in an allogenic hind limb transplantation model and have the potential to establish immunotolerance.

中文翻译：

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在同种异体后肢移植模型中，脂肪细胞疗法可延长移植物存活

血管化复合同种异体移植（VCA）后的长期存活通常受到全身排斥以及免疫抑制剂的不良影响。基质血管部分（SVF）可以扩增产生脂肪来源的干细胞（ADSC），它代表内皮细胞，前脂肪细胞，免疫细胞和ADSC的组合。已经证明ADSC具有一致可靠的临床结果。但是，关于VCA中SVF的文献很少。本研究旨在确定离体同种异体移植物预处理与SVF细胞组合在促进复合组织同种异体移植免疫耐受性方面的影响。大鼠后肢同种异体移植模型用于研究离体预处理SVF和ADSC对VCA存活的影响。血管内无细胞盐水，ADSC，用免疫抑制剂将SVF或SVF注入模型。记录了同种异体移植未表现出排斥症状的组织病理学检查和持续时间。用流式细胞术定量外周T淋巴细胞和Treg，而用免疫组化染色（IHC）定量CD31的同种异体组织表达。ELISA用于检测血管内皮生长因子（VEGF）-A以及抗炎和促炎细胞因子。我们证明，与中等对照组相比，SVF或ADSC的同种异体移植物的离体治疗延长了同种异体移植物的存活。免疫调节细胞因子水平升高，VEGF-A和CD31表达增加，T淋巴细胞的浸润和增殖减少，Treg表达升高。