Lymphatic Regeneration by Direct Cellular Reprogramming

点击翻译按钮获取中文摘要

Project Summary (Abstract) Lymphatic vessels play an important role in tissue fluid homeostasis and immune surveillance. Thus, impaired function of lymphatic vessels due to abnormal vessel development or damaged lymphatic vessels causes obstruction of draining body fluid and leads to the development of lymphedema. Despite a continuous increase in the incidence of lymphedema, therapeutic options are limited to conservative treatment or palliative surgery. Over the past decades, new biological treatments such as gene or cell therapy have emerged for treating various cardiovascular diseases. However, the effects of adult stem cells turned out to be minimal, and embryonic or induced pluripotent stem cell (ESC/iPSC)-derived cells are costly to produce and maintain and may cause side effects. To avoid these problems, a new approach, called direct reprogramming or direct conversion has been developed, in which somatic cells are converted into other lineage cells by overexpression of lineage- or cell-type specific transcription factors (TFs). This approach allows simpler and safer target cell generation and has the potential for more convenient clinical translation. With this direct reprogramming approach, we have successfully generated reprogrammed endothelial cells (rECs) via ETV2, and more recently, reprogrammed lymphatic ECs (rLECs). The overall goal of this project is to develop a direct reprogramming approach for treating lymphedema. The direct EC reprogramming approach for therapy has two options: cell therapy or direct in vivo reprogramming. In this proposal, we will follow both options. For clinical application, both require a safer delivery vector to minimize the possibility of genomic integration. Thus, we developed an adenoviral-ETV2 (Ad-ETV2) vector. As a first approach, we will develop a cell-based therapy using rLECs. As a second approach, we will develop a direct in vivo reprogramming approach without using cells. In the latter, Ad-ETV2 will be injected into animal models to see whether host cells can be reprogrammed into LECs and form new lymphatic vessels. To date, none of these two approaches have been attempted for treating lymphedema. More specifically, in Aim 1, we will generate early and late rLECs from human fibroblasts by changing various culture conditions. In Aim 2, we will determine the therapeutic effects of rLECs on experimental lymphedema and the mechanisms underlying these therapeutic effects. In Aim 3, we will explore whether ETV2 is able to directly reprogram fibroblasts into functional LECs, induce lymphatic vessel formation, and ameliorate lymphedema. We anticipate that the results of the proposed experiments will yield new insight into the role of novel cell and gene therapy for treating lymphedema.