Direct cell to cell transfer of microRNA for tissue repair

描述（由申请人提供）：我们研究的变革性质在于通过小RNA种类（包括调节性microRNA）的直接交换来详细研究细胞与细胞之间的通信。在过去的二十年里，我们研究了人类间充质干细胞的生物学，并将它们改造成递送载体，以分泌转基因蛋白产物，用于受损组织中周围细胞或远处细胞通过系统性蛋白质生产的受体介导的摄取。然而，在过去的两年中，我们开发了新的尚未发表的数据，表明RNA种类可以通过直接的细胞间通讯从MSC直接转移到靶细胞。通过使用先进的视频显微镜和分子技术，我们已经确定，这种细胞接触依赖的细胞间转移不发生通过小间隙连接，而是通过外泌体运输和直接穿梭的小RNA物种通过隧道纳米管。已知间充质干细胞对受损的、缺氧的或发炎的微环境快速响应，并支持其他细胞类型的生长、存活和分化，包括造血干细胞、脉管系统细胞、神经元等。这种现象被认为几乎完全是由于细胞外蛋白的分泌。相反，我们假设MSC对靶细胞命运的控制也可以通过RNA种类的直接转移来介导。我们假设，从人MSC直接转移microRNA到靶细胞是调节组织修复和增加损伤部位靶细胞存活的常见机制。我们计划的研究将使用我们建立的异种移植伤口模型系统来探索这种新颖的，非传统的，潜在的范式转移假说。

DESCRIPTION (provided by applicant): The transformative nature of our research lies in the detailed study of cell-to-cell communication through direct exchange of small RNA species, including regulatory microRNA. For the past twenty years we have studied the biology of human mesenchymal stem cells and have engineered them to become delivery vehicles to secrete transgene protein products for receptor-mediated uptake by surrounding cells in a damaged tissue or by distant cells through systemic protein production. However in the past two years we have developed new as-yet unpublished data showing that direct transfer of RNA species can occur from the MSC to target cells through direct cell-to- cell communication. Through the use of advanced videomicroscopy and molecular techniques we have determined that this cell-contact-dependent intercellular transfer does not occur through small gap junctions but rather through exosomal transport and direct shuttle of small RNA species through tunneling nanotubules. Mesenchymal stem cells are known to respond rapidly to a damaged, hypoxic or inflamed microenvironment and to support the growth, survival and differentiation of other cell types, including hematopoietic stem cells, cells of the vasculature, neurons and others. This phenomenon has been thought to be almost entirely due to the secretion of extracellular proteins. In contrast, we hypothesize that the control of the fate of target cells by MSC can be also mediated through direct transfer of RNA species. We hypothesize that direct transfer of microRNA from human MSC to target cells is a common mechanism for modulating tissue repair and increasing target cell survival at sites of injury. Our planned studies will use our established xenotransplantation wound model systems to explore this novel, unconventional, and potentially paradigm-shifting hypothesis.