配体非依赖型ERα促小鼠骨髓c-kit+干细胞对梗死心肌的修复作用及机制

Heart failure is one of the leading causes of death worldwide. Bone marrow-derived cell transplantation emerges as a novel therapeutic strategy for heart failure. Recent studies have found that the role of estrogen and estrogen receptor α in bone marrow-derived stem cells mediated cardio-protective effects. However, there is little study on the effects of ligand-independent ERα on the behaviors of bone marrow c-kit + stem cells in myocardial repair. Our previous studies suggest that ligand-independent ERα was expressed in Bone marrow c-kit positive stem cells, and played specific roles in cell adhesion, apoptosis and cell migration. Based on these results, we hypothesize that the regulation model of growth factors- ERα-specific signal pathway-specific cell behavior is possibly existed in bone marrow c-kit+ stem cells-mediated myocardial repair. In order to clarify this hypothesis, using the methods of RT-PCR, Western Blot, we will firstly confirm the expression of ligand-independent ERα in bone marrow c-kit+ stem cells after acute myocardial infarction. Then the effects of ERα on bone marrow c-kit+ stem cell survival, growth, migration and differentiation behavior will be explored. After confirming the association between ERα and specific stem cell behaviors, we will further clarify the cross-talk among ligand-independent ERα, PI3K-Akt pathway, and P38 MAPK pathway, reveal ligand-independent ERα pathway is involved in a new mechanism of bone marrow c-kit + stem cells-mediated myocardial repair. This study will provide a new viewpoint for cell therapy and tissue engineering in treating heart failure.

心肌梗死是全球范围内致死率极高的疾病之一，雌激素通过基因组或雌激素受体ER的非转录组途径在骨髓干细胞介导的心血管损伤修复中起作用。资料表明，ERα还能通过配体非依赖途径被生长因子激活而发挥作用。我们的预实验结果提示：配体非依赖型ERα能影响骨髓c-kit+干细胞的迁移及凋亡。但其作用机制还有待进一步探讨。因此我们推测存在"细胞因子-ERα-特定信号通路-干细胞的特定行为"调控方式。为证明该思路，本项目将通过雄性小鼠心肌梗死模型和骨髓c-kit+干细胞，利用雌激素受体调节剂干预，采用RT-PCR、Western Blot等手段，明确ERα在小鼠骨髓c-kit+干细胞的表达，评估其对该细胞生长、迁移、及分泌细胞因子等的影响，体外及在体评价其修复梗死心肌的作用，在此基础上，探讨配体非依赖型ERα通过特定信号通路参与骨髓c-kit+干细胞修复梗死心肌的新机制。此研究将为心肌损伤修复提供新的思路。

心肌梗死是全球范围内致死率极高的疾病之一，干细胞修复心肌损伤的治疗模式有望成为治疗终末期心脏病的良好选择。骨髓来源细胞在心肌损伤修复过程中起着重要作用。此外，雌激素受体依赖的非转录组途径在骨髓来源干细胞介导的心血管损伤修复中发挥作用。本项目结合干细胞修复心肌损伤的理论基础，在本研究中，充分利用医院宝贵的临床样本资源，分离作用比较明确的骨髓单个核细胞c-kit+干细胞群，通过特定雌激素受体激活人骨髓来源的c-kit阳性干细胞，借鉴前期特异性雌激素受体激动剂对大鼠心脏的c-kit+干细胞的处理经验，经体外评估其是否具有促进细胞迁移及存活的功能；进一步体内证实对移植治疗梗死心肌的作用及其机制，观察和评价不同处理方式对干细胞修复心肌损伤的影响及可能的机理。本项目的研究成果，有望为心肌损伤修复提供新的治疗思路，并有望为个体化治疗心肌梗死、心肌组织的重建提供新的研究策略。