MSCs-SIS心肌补片的优化及机制探讨

Myocardial infarction (MI) remains a common and deadly disease. Cellular replacement for cardiac regeneration has emerged as a popular strategy in regenerative medicine. In our previous study, BM-MSCs-seeded SIS as a cardiac patch can be used to repair chronic myocardial infarction in rabbits, which enhances myocardial regeneration. However, only small number of BM-MSCs survived and differentiated into myocardial-like cells after transplantation was recorded. The reason may be that a lot number of transplanted BM-MSCs were dead because they were not resistant to the microenvironment characterized by hypoxia and poor nutrition supply. In addition, severe intramyocardial calcification was illustrated after myocardial transplantation which originated from BM-MSCs. This undesired spontaneous calcification of BM-MSCs was also determined in vitro after continuous culture in our previous report; and we further confirmed that hypoxia could help to inhibit this calcification. Combination with the other findings, hypoxia has been regarded as a useful tool for MSCs proliferation and stem cell preservation. Therefore, in order to create a safer and more effective MSCs-SIS cardiac patch, we will use hypoxia preprocessing to improve the survival rate of BM-MSCs and inhibit the spontaneous calcification; also what is the role of HIF-HMGB1 in this process will be investigated. Furthermore, making full use of the advantage of placental derived MSCs, we will further determine the feasible application of placental derived MSCs for myocardial regeneration as a seed cells in the form of MSCs-SIS cardiac patch.

寻找心肌梗死治疗策略，一直是再生医学的研究热点。我们研究发现，BM-MSCs和SIS构建的MSCs-SIS心肌补片，能修复兔陈旧性心梗，效果显著；但移植后只有少量的BM-MSCs存活并分化为心肌样细胞，这可能与BM-MSCs不能耐受心梗区低氧和低营养的微环境有关。有研究报道将BM-MSCs注射到心梗区后，细胞会异位钙化。我们也在体外验证了BM-MSCs具有自发钙化的特性并且低氧显著抑制这种钙化。低氧已成为促进MSCs增殖和保护MSCs干细胞特性的有效手段。因此结合已有研究成果，为了进一步构建安全有效的MSCs-SIS心肌补片，我们将利用低氧预处理来提高BM-MSCs移植后的存活率并且抑制移植后BM-MSCs的钙化，并探讨HIF-HMBG1通路在该过程的作用；同时，利用胎盘来源MSCs可短暂耐受低氧和无血清培养环境的优点，探讨胎盘来源MSCs作为MSCs-SIS心肌补片种子细胞的可行性。

心肌梗死发病率的增长，给我国带来了沉重的社会和经济负担。寻找心肌梗死治疗策略，一直是再生医学的研究热点。MSCs-SIS心肌补片已在治疗陈旧性心肌梗死上表现出良好的治疗效果，但是仍需进一步的改进，迫切需要我们研发更有效的MSCs-SIS心肌补片。本课题通过体内外实验开展了以下研究：1）细胞和SIS的相容性；2）HMGB1和低氧在骨髓间充质干细胞迁移中的调控和相关机制；3）低氧下BM-MSCs内HMGB1的表达及HMGB1对BM-MSCs凋亡、粘附影响；4）骨髓和胎盘基蜕膜来源间充质干细胞在小肠黏膜下层三维培养体系中成心肌样细胞分化能力比较；5）人骨髓和胎盘基蜕膜间充质干细胞在低氧无血清的SIS上生物学特性的对比；6）制备一种新的兔陈旧性心肌梗死模型；7）探讨低氧预处理MSCs-SIS心肌补片的治疗心肌梗死的效果。其研究结果显示：通过体内示踪实验显示，直接静脉注射MSCs后MSCs并不能直接锚定到心肌，因此通过支架材料来提高MSC的锚定率是十分必要的；SIS与骨髓、胎盘来源的MSCs有很好的相容性，可以作为良好的心肌再生补片；在低氧可以上调HMGB1的表达并协同促进MSC迁移，这种协同作用的主要机制是通过HIF-1α-SDF-1信号通路来实现；虽然HMGB1会提高MSCs的粘附能力，但是会诱导MSCs凋亡；通过动物实验发现，MSC-SIS具有良好的再生潜能，因此基于我们建立的新心肌梗死模型，我们正在探讨MSC-SIS对心肌梗死的修复效果，以进一步促进MSC-SIS心肌补片的临床转化。