内皮祖细胞来源的angiocrine信号诱导肺泡化与BPD防治策略研究

Endothelial progenitor cells (EPCs) have became the new target of developing therapeutic strategies for bronchopulmonary dysplasis (BPD). Our previous findings indicated the reduced biological activity of EPC represented possible major limitations for the success of EPC transplantations. Angiocrine factors by paracrine secretion of EPCs have an important role of supporting organ development. We will investigate: 1) the changes of angiocrine factors derived from EPC after hyperoxia exposure; 2) the effect of the conditioned media from EPC culture in vitro on the proliferation and differentiation of alveolar epithelial cells type II (AECII) and alveolarization of BPD models in preterm rats; 3) the effect of regulating EPC derived angiocrine signals by VEGFR2 gene transfer and siRNA conditioned deletion of VEGFR2 on the proliferation and differentiation of AECII and alveolarization of BPD models. The investigations will elucidate the damaged EPC-derived angiocrine signals after hyperoxia exposure mediate the inhibition of alveolarization, thus involving in the pathogenesis of BPD, and demonstrate the activation of VEGFR2 signals major induce the production of angiocrine factors from EPC. These findings suggest that targeting of EPC-derived angiocrine factors may represent an interesting novel opportunity to impact on endogenous lung alveolarization responses. This approach may also serve to optimize cell-based treatment approaches and contribute to the development of new therapeutic strategies of BPD.

近年来内皮祖细胞（EPC）成为支气管肺发育不良（BPD）防治策略的新靶标。但本课题组前期研究提示单纯以提高EPC数目为目标的细胞移植防治BPD效果欠佳。最新EPC旁分泌angiocrine因子支持器官发育的作用受到高度关注。本项目通过细胞和动物整体水平实验，研究高氧暴露对EPC旁分泌angiocrine因子的影响；EPC的体外培养液对AECII增殖分化及早产大鼠肺泡化的影响；采用腺病毒转染或siRNA技术高表达或敲低EPC的VEGFR2基因表达，调控ECP来源的angiocrine信号，对体外培养AECII增殖分化和早产大鼠肺泡化的影响，以阐明高氧暴露破坏EPC来源的angiocrine信号，导致肺泡化受阻参与BPD发生的作用机制，以及证实VEGFR2活化在诱导EPC产生angiocrine因子中的关键性作用，为进一步优化EPC细胞移植治疗方法，发展BPD防治新策略提供全新思路和实践依据。

近年来EPC 旁分泌功能在支气管肺发育不良（BPD）防治作用受到高度关注。本研究发现：1.细胞实验：1）EPC可 旁分泌angiocrine 因子，包括肺发育相关生长因子VEGF和FGF10；2）高氧暴露损伤EPC的旁分泌功能，抑制VEGF、FGF10表达；3）高氧暴露可抑制ACEII的增殖，降低ACEII表达SP-C mRNA，促进ACEII表达AQP5 mRNA，促进ACEII向ACEI分化；4）EPC培养上清能够促进高氧暴露下AECII增殖，维持AECII本身特性，抑制AECII向AECI分化；5）高氧暴露下EPC培养上清对AECII功能的维持作用有限，证实高氧暴露损害EPC的旁分泌功能及对AECII保护作用；2.动物实验：1）高氧暴露可影响新生鼠肺组织的正常发育，产生类似“新型”BPD的病理结构; 2）EPC旁分泌因子可改善高氧肺损伤的肺泡结构，增加微血管密度3）angiocrine 因子可显著上调肺KGF的表达但对VEGF的上调作用有限，提示KGF可能是angiocrine 因子主要调控靶点；4）angiocrine 因子可上调肺组织SP-C,SP-A表达，提示其对肺上皮有重要保护作用；5）外泌体是EPC旁分泌的重要组分，其对肺损伤的保护作用有待进一步研究；本研究证实EPC 具有旁分泌angiocrine 因子功能，可保护AECII功能，改善高氧新生鼠BPD模型肺结构，有助于BPD肺损伤修复。