Adult mammalian hearts have a very limited regeneration capacity, due largely to a lack of cardiomyocyte (CM) proliferation. It was recently reported that epicardial, but not myocardial, follistatin-like 1 (Fstl1) activates CM proliferation and cardiac regeneration after myocardial infarction (MI). Furthermore, bacterially synthesized human FSTL 1 (hFSTL1) was found to induce CM proliferation, whereas hFSTL1 synthesized in mammals did not, suggesting that post-translational modifications (e.g., glycosylation) of the hFSTL1 protein affect its regenerative activity. We used modified mRNA (modRNA) technology to investigate the possible role of specific hFSTL1 N-glycosylation sites in the induction, by hFSTL1, of CM proliferation and cardiac regeneration. We found that the mutation of a single site (N180Q) was sufficient and necessary to increase the proliferation of rat neonatal and mouse adult CMs in vitro and after MI in vivo, respectively. A single administration of the modRNA construct encoding the N180Q mutant significantly increased cardiac function, decreased scar size, and increased capillary density 28 days post-MI. Overall, our data suggest that the delivery of N180Q hFSTL1 modRNA to the myocardium can mimic the beneficial effect of epicardial hFSTL1, triggering marked CM proliferation and cardiac regeneration in a mouse MI model.

成年哺乳动物心脏的再生能力非常有限，这主要是由于缺乏心肌细胞（CM）增殖。最近有报道称，心肌梗塞 (MI) 后，心外膜卵泡抑素样 1 (Fstl1) 可激活 CM 增殖和心脏再生，但心肌却不然。此外，细菌合成的人类FSTL 1 (hFSTL1)被发现可以诱导CM增殖，而哺乳动物中合成的hFSTL1则不然，这表明hFSTL1蛋白的翻译后修饰（例如糖基化）会影响其再生活性。我们使用修饰的 mRNA (modRNA) 技术来研究特定 hFSTL1 N-糖基化位点在 hFSTL1 诱导 CM 增殖和心脏再生中的可能作用。我们发现，单个位点（N180Q）的突变对于分别增加大鼠新生儿和小鼠成年 CM 的体外增殖和 MI 后的体内增殖是充分且必要的。 MI 后 28 天，单次施用编码 N180Q 突变体的 modRNA 构建体可显着增强心脏功能、缩小疤痕大小并增加毛细血管密度。总体而言，我们的数据表明，将 N180Q hFSTL1 modRNA 递送至心肌可以模拟心外膜 hFSTL1 的有益作用，在小鼠 MI 模型中触发显着的 CM 增殖和心脏再生。