An analysis of the induction mechanism of transdifferentiation of connective tissue-resident fibroblasts into endothelial cells of blood vessels

【导言】近年来，骨髓源性内皮祖细胞和胚胎干细胞作为血管内皮细胞的来源，受到了广泛的关注。然而，这些细胞的使用已被指出有免疫学和伦理问题。在这项研究中，我们研究了结缔组织驻留的成纤维细胞是否能够转分化为血管内皮细胞。【材料与方法】我们进行了两个实验。在一项实验中，从血管内皮细胞表达lacZ基因的Tg小鼠角膜基质中切除一小块组织移植物，与肉瘤细胞一起移植到WT小鼠角膜袋中。在另一项实验中，我们将Tg小鼠的角膜基质细胞（成纤维细胞）培养、扩增并输注到预先植入角膜肉瘤的WT小鼠尾静脉中，诱导血管生成。新血管进入角膜后，对角膜进行X-Gal染色。这里我们使用角膜基质作为材料，因为角膜不含血管，角膜基质仅由基质细胞组成，成纤维细胞作为细胞成分。[结果]两组实验均在角膜新生血管内皮中发现少量lacZ阳性细胞。[讨论]这一结果表明，结缔组织内的成纤维细胞是内皮细胞的一个有希望的来源，可用于再生治疗、血管基因治疗或在血管假体的内表面播种和内衬。

[Introduction]Recently, bone marrow-derived endothelial progenitor cells and ES cells have been paid attention on as a source of vascular endothelial cells for regenerative therapy. However, the use of these cells has been pointed out to have immunological and ethical problems. In this study we examined whether connective tissue-resident fibroblasts are able to transdifferentiate into endothelial cells of blood vessels.[Materials and Methods]We carried out two experiments. In one experiment, a small piece of tissue graft was excised from corneal stroma of Tg mice of which endothelial cells of blood vessels expressed a lacZ gene, and was transplanted together with sarcoma cells into a cornea pocket of WT mice. In another experiment, corneal stroma cells (fibroblasts) from Tg mice were cultured, expanded and transfused into tail veins of WT mice whose cornea was engrafted with sarcoma beforehand to induce angiogenesis. After new blood vessels grew into the cornea, the cornea was processed for X-Gal staining. Here we used corneal stroma as a material, because a cornea contains no blood vessels and a corneal stroma consists of only stroma cells, fiblobrasts as cell components.[Result]In both experiments, a few lacZ positive cells were found in the endothelium of the newly formed blood vessel in the cornea.[Discussion]This result suggests that connective tissue-resident fibroblasts are a hopeful source of endothelial cells for regenerative therapy, gene therapy of blood vessel or for seeding on and lining the inner surface of vascular prosthetic grafts.