肺干细胞参与低氧性肺动脉高压肺血管重构作用及机制

Lung vascular remodeling characterized by the aberrant proliferation of pulmonary artery smooth muscle cells ( PASMCs ) is the key of hypoxic pulmonary artery hypertension ( HPAH ). However, it is still difficult to identify the origin of the increased PASMCs in vivo and the origin of PASMCs is an enigma for the research of HPAH. Adult stem cell is the base of cell homeostasis and regeneration in their resident organ. Recently, adult lung stem cells ( LSCs ) is found to exist in adult lung and be involved in the regeneration and homeostasis of lung cells. The aberrant proliferation of PASMCs is the result of imbalance of PASMCs homeostasis in pulmonary vascular remodeling in HPHA, so we hypothesize that LSCs take part in the pulmonary vascular remodeling via migration and differentiation into PASMCs and / or paracine factors and may be one of the origins of increased PASMCs in HPAH. According to the homing character of adult stem cell, we established an experiment method by which we can permanently mark a part of LSCs in rats and in vivo identify whether some of the increased PASMCc in pulmonary vascular wall in HPAH origin from LSCs. This project will use the established method to further explore whether LSCs are involved in pulmonary vascular remodeling in HPAH via differentiating into PASMC and / or paracrine factor and its possible mechanism. The aim is to test our hypothesis. The results of the project will provide novel information for the cellular mechanism of pulmonary vascular remodeling in HPAH and new clue for development of drugs for the treatment of HPAH.

肺血管重构是低氧性肺动脉高压（HPAH）持续进展的关键，其主要特征是肺动脉平滑肌细胞(PASMC)异常增生，如何在体确认这些异常增生PASMC的来源以及这些PASMC究竟源于何种细胞是困扰HPAH研究的基本问题。成体干细胞是维持所居器官细胞稳态和更新的基础，最新发现肺脏存在成体肺干细胞（LSC），从稳态角度分析，肺血管重构时PASMC异常增生是PASMC稳态失衡的结果，我们推测：LSC可能参与HPAH肺血管重构且是异常增生PASMC的重要来源。课题组根据干细胞归巢特性建立了"自体部分LSC永久标记大鼠"的制备方法，能够在体确认异常增生PASMC是否源于LSC分化。本项目拟在此基础上，研究LSC是否通过迁移分化为PASMC和/或旁分泌作用参与肺血管重构，以验证上述推测并探讨其可能机制。研究结果可能为HPAH肺血管重构的细胞机制提供新知识、为以LSC为靶点开发治疗HPAH的药物提供新线索。

肺动脉平滑肌细胞(PASMCs)异常增多是低氧性肺动脉高压肺血管重构的重要原因，这些异常增多PASMCs的来源是困扰低氧性肺动脉高压肺血管重构研究的基本问题。从细胞稳态角度看,肺血管重构时PASMCs异常增多是肺血管平滑肌细胞稳态失衡的表现。成体干细胞是维持所居器官细胞稳态和更新的基础，而肺脏也存在成体肺干细胞（LSCs），因此，肺成体干细胞可能是低氧性肺动脉高压肺血管重构时PASMCs的来源之一。课题组前期参考文献报道及干细胞归巢特性建立了“自体部分LSCs标记大鼠”的初步制备方法，为在体研究异常增生PASMC是否部分源于LSCs提供了条件。在此基础上本项目进一步研究了成体肺干细胞LSCs参与低氧性肺动脉高压肺血管重构的可能作用及机制。主要进行了以下实验：（1）建立了大鼠c-kit阳性LSCs的分离培养方法,体外分化实验表明大鼠LSCs能够分化为血管平滑肌细胞、肺气道上皮细胞；（2）完善了“自体部分LSCs永久ZsGreen绿色荧光标签标记大鼠”的制备方法；（3）初步在大鼠动物模型中证明LSCs参与了低氧性肺动脉高压的肺血管重构；（4）初步证明大鼠LSCs低氧培养上清中的分泌因子对低氧性肺动脉高压肺血管重构有一定改善作用;（5）完成了LSCs低氧培养上清液对肺动脉平滑肌细胞增值、迁移等生物学行为影响的研究,LSCs培养上清中3kD和10kD之间的分子对肺动脉平滑肌细胞增殖、迁移有一定促进作用。上述实验结果表明：LSCs参与了大鼠低氧性肺动脉高压肺血管重构，可能是肺血管重构时异常增生PASMCs的部分来源，慢性低氧能够刺激LSCs迁移、增值，LSCs也可以通过旁分泌作用对原位的PASMCs生物学行为进行调控，LSCs可能成为未来治疗低氧性肺动脉高压血管重构的靶点。