Epidermal stem cells to construct tissue-engineered skin to promote vascularization of dermal substitutes and a single-stage transplantation in vivo study. Rattus norvegicus

Composite transplantation of STSG(split-thickness skin graft) combined with acellular dermal matrix (ADM) is a promising repair method for full-thickness skin defects.Till date, there is no available engineered skin tissue able to permanently cover full thickness in a one-stage procedure.Due to delayed vascularization of ADM, a two-step procedure is often used to implant ADM in the first step and then implant STSG after full vascularization of ADM, resulting in increased treatment time and cost. Adipose stem cells (ASCs) and dermal stem cells (DSCs) promote vascularization of wound and dermal substitutes, while epidermal stem cells (EpSCs) originating from the basement layer of the skin are relatively rarely studied in tissue-engineered skin.Here, we investigated the effect of tissue engineered skin constructed with EpSCs on wound repair and its mechanism of promoting vascularization. By means of transcriptome sequencing showed that active substances secreted by ADM-cultured EpSCs promoted angiogenesis.It was found that EpSCs promoted epithelialization of the ADM surface and the generation of appendages such as hair follicles in vivo experiment. It was also found that EpSCs promoted vascularization of the full thickness of the ADM sheet for about 1 week. Next, we innovatively construct a novel tissue-engineered skin used ADM, STSG, and EpSCs combined (ASE) for one-step transplantation to repair the full-thickness skin wound in rats.The results showed that the ASE group significantly increased the survival and healing quality of the skin graft, reduced skin contraction, and improved the cosmetic appearance compared with the AS group and the STSG control group.In summary, our findings suggest that EpSCs can promote the formation of new blood vessels in dermal substitutes and can achieve one-step transplantation of composite skin, providing new ideas for the clinical treatment of one-step composite skin grafting.

脱细胞真皮基质（acellular dermal matrix, ADM）联合刃厚皮片（split-thickness skin graft, STSG）的复合移植，是治疗全层皮肤缺损的极具前景的修复方案。迄今为止，尚无成熟的组织工程皮肤（engineered skin tissue）可通过一期手术实现全层皮肤的永久性覆盖。由于脱细胞真皮基质的血管化进程较为缓慢，临床通常采用两步法手术：先植入ADM，待其完全血管化后再行刃厚皮片移植，这一流程延长了治疗时长并增加了医疗成本。脂肪干细胞（adipose stem cells, ASCs）与真皮干细胞（dermal stem cells, DSCs）可促进创面及真皮替代物的血管生成，而源自皮肤基底层的表皮干细胞（epidermal stem cells, EpSCs）在组织工程皮肤领域的相关研究相对匮乏。本研究旨在探讨表皮干细胞构建的组织工程皮肤对创面修复的作用及其促进血管生成的机制。经转录组测序（transcriptome sequencing）分析发现，经ADM培养的EpSCs所分泌的活性物质可促进血管生成。体内实验结果显示，EpSCs可促进ADM表面的上皮修复，并诱导毛囊等皮肤附属器的生成；同时可在约1周内促进脱细胞真皮基质片全层的血管化。基于上述发现，本研究创新性地构建了以ADM、STSG与EpSCs联合的新型组织工程皮肤（以下简称ASE），用于大鼠全层皮肤创面的一期移植修复。结果表明，与AS组及STSG对照组相比，ASE组可显著提升皮片存活率与修复质量，减轻皮肤挛缩，并改善修复后的外观效果。综上，本研究证实表皮干细胞可促进真皮替代物的新生血管形成，且可实现复合皮肤的一期移植，为临床一期复合皮移植治疗提供了全新的思路。