Mesenchymal stromal/stem cells (MSCs) are multipotent cells that offer a promising outcome in the field of regenerative medicine. MSCs are present in various tissues including bone marrow, fat, skin, and placenta. The interest in clinical application of these mesoderm-derived MSCs is primarily fueled by their high self-renewal capacity and multipotency. Although, early studies indicated limited differentiation capacity of MSCs into same cell lineages from which they were isolated, subsequent investigations showed differentiation potential into other cell types of mesoderm origin including osteoblasts, adipocytes, fibroblasts, cardiomyocytes, and chondrocytes. Furthermore, MSCs exhibit a remarkable feature of transdifferentiation into ectodermal, neuroectodermal, and endodermal cells, phenomena referred to as ‘stem cell plasticity’. This opened the possibility of clinical applications of MSCs in the regeneration of other tissues like corneal reconstruction, treatment of acute lung injury, oral mucosal regeneration, homing of MSCs for regeneration at sites of injury etc. Though several evidence have accrued demonstrating this phenomenon, there is still a gap in understanding the molecular mechanism of such transitions which will be important to efficiently control the process. Interestingly, the process can be drawn a parallel with the Mesenchymal to Epithelial Transitions (MET) that takes place inside the body during embryonic development or certain pathophysiological conditions. In this review, a brief attempt is first made to understand the evidence of MSC transdifferentiation based on the current knowledge about MET. We then specifically focus on systematic presentation and analysis of the microenvironment factors involved in MSC transdifferentiation to epithelial lineages which would have applications in regenerative medicine.

间充质基质/干细胞（MSC）是多能细胞，在再生医学领域提供了有希望的结果。MSC存在于各种组织中，包括骨髓，脂肪，皮肤和胎盘。这些中胚层来源的MSC在临床应用中的兴趣主要是由于它们的高自我更新能力和多能性而引起的。尽管早期研究表明，MSCs分化为相同细胞谱系的能力有限，但随后的研究表明，MSCs可以分化为中胚层来源的其他细胞类型，包括成骨细胞，脂肪细胞，成纤维细胞，心肌细胞和软骨细胞。此外，MSC表现出转分化为外胚层，神经外胚层和内胚层细胞的显着特征，这种现象称为“干细胞可塑性”。这开创了MSCs在其他组织再生中的临床应用的可能性，例如角膜重建，急性肺损伤的治疗，口腔粘膜再生，在损伤部位再生的MSCs归巢等。在理解此类转变的分子机制方面仍然存在差距，这对于有效控制过程至关重要。有趣的是，该过程可以与胚胎发育或某些病理生理条件下体内发生的间充质上皮转化（MET）平行。在这篇综述中，首先基于当前关于MET的知识，进行了简短的尝试来理解MSC转分化的证据。