The objective of this study was to develop an injectable and biocompatible hydrogel that can deliver a cocktail of therapeutic biomolecules (secretome) secreted by human adipose-derived stem cells (hASCs) to the peri-infarct myocardium. Gelatin and Laponite® were combined to formulate a shear-thinning, nanocomposite hydrogel (nSi Gel) as an injectable carrier of secretome (nSi Gel+). The growth factor composition and the pro-angiogenic activity of the secretome were tested in vitro by evaluating the proliferation, migration and tube formation of human umbilical endothelial cells. The therapeutic efficacy of the nSi Gel+ system was then investigated in vivo in rats by intramyocardial injection into the peri-infarct region. Subsequently, the inflammatory response, angiogenesis, scar formation, and heart function were assessed. Biocompatibility of the developed nSi Gel was confirmed by quantitative PCR and immunohistochemical tests which showed no significant differences in the level of inflammatory genes, microRNAs, and cell marker expression compared to the untreated control group. In addition, the only group that showed a significant increase in capillary density, reduction in scar area and improved cardiac function was treated with the nSi Gel+. Our in vitro and in vivo findings demonstrate the potential of this new secretome-loaded hydrogel as an alternative strategy to treat myocardial infarction.

Statement of significance

Stem cell based-therapies represent a possible solution to repair damaged myocardial tissue by promoting cardioprotection, angiogenesis, and reduced fibrosis. However, recent evidence indicates that most of the positive outcomes are likely due to the release of paracrine factors (cytokines, growth factors, and exosomes) from the cells and not because of the local engraftment of stem cells. This cocktail of essential growth factors and paracrine signals is known as secretome can be isolated in vitro, and the biomolecule composition can be controlled by varying stem-cell culture conditions. Here, we propose a straightforward strategy to deliver secretome produced from hASCs by using a nanocomposite injectable hydrogel made of gelatin and Laponite®. The designed secretome-loaded hydrogel represents a promising alternative to traditional stem cell therapy for the treatment of acute myocardial infarction.

这项研究的目的是开发一种可注射且具有生物相容性的水凝胶，该水凝胶可以将人脂肪来源的干细胞（hASCs）分泌的治疗性生物分子（secretome）混合物运送至梗塞周心肌。将明胶和Laponite®合并以配制剪切稀化的纳米复合水凝胶（nSi Gel），作为分泌液组的可注射载体（nSi Gel +）。通过评估人脐带内皮细胞的增殖，迁移和管形成，在体外测试了分泌组的生长因子组成和促血管生成活性。然后在体内研究了nSi Gel +系统的治疗功效在大鼠中，通过心肌内注射到梗塞周围区域。随后，评估了炎症反应，血管生成，瘢痕形成和心脏功能。已开发的nSi凝胶的生物相容性通过定量PCR和免疫组织化学测试得到证实，与未处理的对照组相比，该基因在炎症基因，microRNA和细胞标志物表达水平上没有显着差异。此外，使用nSi Gel +治疗的唯一显示毛细血管密度显着增加，疤痕面积减少和心脏功能改善的组。我们的体外和体内研究结果表明，这种新型荷尔蒙负载水凝胶有潜力作为治疗心肌梗塞的替代策略。

重要声明

基于干细胞的疗法代表了一种可能的解决方案，可通过促进心脏保护，血管生成和减少纤维化来修复受损的心肌组织。但是，最近的证据表明，大多数积极结果可能是由于细胞中分泌了旁分泌因子（细胞因子，生长因子和外泌体），而不是由于干细胞的局部植入所致。这种必需的生长因子和旁分泌信号的混合物被称为分泌素，可以在体外分离，生物分子组成可以通过改变干细胞培养条件来控制。在这里，我们提出了一种直接的策略，即通过使用由明胶和Laponite®制成的纳米复合可注射水凝胶来递送由hASC产生的分泌蛋白组。设计的载有荷尔蒙组的水凝胶代表了用于治疗急性心肌梗塞的传统干细胞疗法的有希望的替代方法。