The idea of regenerating lost myocardium via cell-based therapies remains as highly considerable. C-kit+ stem/progenitor cells are represented to be suitable candidates for cardiac regeneration compared to other stem cells. A multitude of cytokines from these cells are known to give such multifunctional properties; however, the associated mechanisms of these factors are yet to be totally understood. The aim of the present study was to investigate the in vitro effect of L-carnitine (LC) on cardiac differentiation of c-kit+ cells using a cytokines secretion assay. For this purpose, bone-marrow-resident-c-kit+ cells were enriched by MACS method, and were differentiated to cardiac cells using cardiomyocyte differentiation medium in the absence (control group) and presence of LC (experimental group). Also, characterization of enriched c-kit+ cells was performed using flow cytometry and immunocytochemistry. In the following, the cells were subjected to real-time PCR and Western blotting assay for gene and protein assessment, respectively. Afterward, culture medium was collected from both control (−LC) and experimental groups (+ LC) for cytokine measurement. It was found that 0.2 mM LC significantly increased the mRNA and protein expression of cardiac markers of Ang-1, Ang-2, C-TnI, VEGF, vWF, and SMA in c-kit+-cardiomyogenic-differentiated cells. Also, the significant presence of IL-6, IGF-1, TGF-β, and VEGF were obvious in the cultured media from the experimental group compared with the control group. It can be concluded that the mentioned in vitro effects of LC on cardiac differentiation of c-kit+ cells could have resulted from the secreted cytokines IL-6, IGF-1, TGF-β, and VEGF.

中文翻译：

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左旋肉碱对骨髓驻留 c-kit+ 干细胞的心脏分化通过分泌 VEGF、IL6、IGF-1 和 TGF-β 作为心脏再生的临床药物而增加

通过基于细胞的疗法再生丢失的心肌的想法仍然非常重要。与其他干细胞相比，C-kit+ 干/祖细胞被认为是心脏再生的合适候选者。已知来自这些细胞的多种细胞因子具有这种多功能特性；然而，这些因素的相关机制尚未完全了解。本研究的目的是使用细胞因子分泌试验研究左旋肉碱 (LC) 对 c-kit+ 细胞心脏分化的体外影响。为此，通过MACS方法富集骨髓驻留-c-kit+细胞，并在不存在（对照组）和存在LC（实验组）的情况下使用心肌细胞分化培养基分化为心肌细胞。还，使用流式细胞术和免疫细胞化学对富集的 c-kit+ 细胞进行表征。接下来，分别对细胞进行实时 PCR 和蛋白质印迹分析以进行基因和蛋白质评估。之后，从对照组（-LC）和实验组（+ LC）收集培养基用于细胞因子测量。发现0.2 mM LC显着增加了c-kit+-心肌分化细胞中Ang-1、Ang-2、C-TnI、VEGF、vWF和SMA的心脏标志物的mRNA和蛋白质表达。此外，与对照组相比，实验组的培养基中IL-6、IGF-1、TGF-β和VEGF的显着存在是明显的。