以CXCR7为靶点改善EPCs功能治疗糖尿病缺血性血管疾病的效应和机制

Utilization of endothelial progenitor cells (EPCs) is a promising novel therapeutic option for regeneration of diabetic ischemic tissues. But diabetes reduces EPCs number in circulation and impairs its angiogenic function. Stromal cell derived factor 1 (SDF-1) and its receptors CXCR4 and CXCR7 are extensively found to involve in migration, chemotaxsis, proliferation and differentiation of bone marrow EPCs. Our previous study demonstrated that SDF-1 receptor CXCR7 expresses on EPCs, solely mediates the survival and coordinately mediates the proliferation, adhesion, trans-endothelial migration and tube formation of EPCs induced by SDF-1. Our preliminary study further demonstrated that the expression of CXCR7 is significantly decreased on EPCs from db/db mice, which was accompanied by significant apoptosis and tube formation impairment; incubation EPCs with ox-LDL also reduced the expression of CXCR7, induced apoptosis and tube formation impairment; but no significant changes were observed in CXCR4 expression. Based on these novel findings, we HYPOTHESIZE that the dysregulation of CXCR7 expression plays a critical role in diabetes induced EPCs apoptosis and dysfunction, and upregulation of CXCR7 can reverse apoptosis and rescue angiogenic function of EPCs. The objective of this study is to systemically evaluate the effects of CXCR7 upregulation on angiogenic function of EPCs and dissect the underlying mechanism. This study is expected to provide experimental evidence for treatment of diabetic vascular diseases targeting CXCR7.

内皮祖细胞（EPC）在血管再生过程中起关键作用，但糖尿病导致外周EPC数量减少、成血管功能受损，其机制至今未明。前期研究发现，基质细胞衍生因子（SDF-1）受体CXCR7在EPC细胞膜上表达，单独介导SDF-1诱导的EPCs存活，并与另一受体CXCR4共同介导SDF-1诱导的增殖、粘附、跨内皮迁移和血管形成。预实验发现：db/db糖尿病小鼠EPC细胞CXCR7表达显著降低，伴随着凋亡和成血管功能受损；体外高脂处理EPCs同样导致CXCR7表达下降、凋亡和成血管功能受损；而上述条件下CXCR4表达均无显著变化。据此提出科学假设：CXCR7表达失调是糖尿病EPC数量减少和功能受损的关键机制，提高CXCR7的表达能有效增强糖尿病EPC的存活和成血管功能。本课题主要目标是系统评价CXCR7对EPC功能和糖尿病血管再生的影响，并解析其分子机制，为以CXCR7为靶点治疗糖尿病心血管并发症提供依据。

本课题的总体目标是系统考察以CXCR7为靶点防治糖尿病缺血性血管疾病的可行性，构建CXCR7高表达的工程化EPC，探讨以CXCR7为靶点、采用CXCR7转基因工程细胞治疗糖尿病缺血性血管疾病的有效性和分子机制，为将来开发以CXCR7为靶点、治疗糖尿病血管并发症的药物提供科学依据。课题组紧紧围绕既定研究目标，密切关注国际、国内研究热点，积极跟踪国际前沿，创造性的完成了如下研究工作：1）采用体外基质胶管样结构形成和体内糖尿病小鼠后肢缺血（Hind limb ischemia, HLI）模型，系统评价了CXCR7 表达水平对EPC 功能和糖尿病缺血性血管生成的影响：2）通过shRNA 干扰正常EPC 细胞CXCR7 考察其是否削弱EPCs 成血管能力；3）通过慢病毒转染介导CXCR7 高表达，考察了CXCR7 上调能否改善EPCs 促进2 型糖尿病小鼠缺血后肢的血管生成和血流恢复；4）同时系统解析CXCR7 调控糖尿病EPCs 存活和成血管功能的分子机制；5）考察了以CXCR7 为靶点，采用CXCR7特异性激动剂TC14012激活CXCR7改善EPCs 功能治疗糖尿病缺血性血管疾病的可行性，从而防治糖尿病缺血性血管疾病找到了一个潜在的治疗靶点。.通过本课题的实施，正式发表SCI研究论文5篇，其中IF>10两篇，累计SCI影响因子39.503，另外还有多篇论文正在投递中；课题组主要成员多次参加国际会议，发表国际会议论文摘要27篇、并做大会发言13次；获得授权发明专利1项；以本课题为载体，培养青年教师2名、博士研究生1名，博士后2名，硕士研究生6名。