Potential Applications of Induced Pluripotent Stem Cells for Cardiovascular Diseases

Therapeutic effect of adipose-derived stem cells injected into pericardial cavity in rat heart failure

AIMS

There are few studies on the treatment of heart failure by injecting stem cells into the pericardial cavity. Can the cells injected into the pericardial cavity migrate through the epicardium to the myocardial tissue? Whether there is therapeutic effect and the mechanism of therapeutic effect are still unclear. This study investigated the therapeutic efficacy and evidence of cell migration of adipose-derived stem cells (ADSCs) injected into the pericardial cavity in rat heart failure. The aim of this study is to demonstrate the effectiveness and mechanism of treating heart failure by injecting stem cells into the pericardial cavity, laying an experimental foundation for a new approach to stem cell therapy for heart disease in clinical practice.

METHODS AND RESULTS

The inguinal adipose tissue of male SD rats aged 4-6 weeks was taken, ADSCs were isolated and cultured, and their stem cell surface markers were identified. Forty rats aged 6-8 weeks were divided into sham operation group, heart failure group, and treatment group; there were 15 rats in the heart failure group and 15 rats in the treatment group. The heart failure model was established by intraperitoneal injection of adriamycin hydrochloride. The heart function of the three groups was detected by small animal ultrasound. The model was successful if the left ventricular ejection fraction < 50%. The identified ADSCs were injected into the pericardial cavity of rats in the treatment group. The retention of transplanted cells in pericardial cavity was detected by small animal in vivo imaging instrument, and the migration of transplanted cells into myocardial tissue was observed by tissue section and immunofluorescence. Western blotting and immunohistochemical staining were used to detect brain natriuretic peptide (BNP), α-smooth muscle actin (α-SMA), and C-reactive protein (CRP). ADSCs express CD29, CD44, and CD73. On the fourth day after injection of ADSCs into pericardial cavity, they migrated to myocardial tissue through epicardium and gradually diffused to deep myocardium. The cell density in the pericardial cavity remains at a high level for 10 days after injection and gradually decreases after 10 days. Compared with the heart failure group, the expression of BNP and α-SMA decreased (P < 0.05 and P < 0.001, respectively), and the expression of CRP in the treatment group was higher than that in the heart failure group (P < 0.0001). A small amount of BNP, α-SMA, and CRP was expressed in the myocardium of the sham operation group. After injection of ADSCs, interleukin-6 in myocardial tissue was significantly lower than that in heart failure myocardium (P < 0.01). After treatment, vascular endothelial growth factor A was significantly higher than that of heart failure (P < 0.01).

CONCLUSIONS

Pericardial cavity injected ADSCs can penetrate the epicardium, migrate into the myocardium, and have a therapeutic effect on heart failure. Their mechanism of action is to exert therapeutic effects through anti-inflammatory, anti-fibrosis, and increased angiogenesis.

Small Extracellular Vesicles Derived from Induced Pluripotent Stem Cells in the Treatment of Myocardial Injury

Induced pluripotent stem cell (iPSC) therapy brings great hope to the treatment of myocardial injuries, while extracellular vesicles may be one of the main mechanisms of its action. iPSC-derived small extracellular vesicles (iPSCs-sEVs) can carry genetic and proteinaceous substances and mediate the interaction between iPSCs and target cells. In recent years, more and more studies have focused on the therapeutic effect of iPSCs-sEVs in myocardial injury. IPSCs-sEVs may be a new cell-free-based treatment for myocardial injury, including myocardial infarction, myocardial ischemia-reperfusion injury, coronary heart disease, and heart failure. In the current research on myocardial injury, the extraction of sEVs from mesenchymal stem cells induced by iPSCs was widely used. Isolation methods of iPSCs-sEVs for the treatment of myocardial injury include ultracentrifugation, isodensity gradient centrifugation, and size exclusion chromatography. Tail vein injection and intraductal administration are the most widely used routes of iPSCs-sEV administration. The characteristics of sEVs derived from iPSCs which were induced from different species and organs, including fibroblasts and bone marrow, were further compared. In addition, the beneficial genes of iPSC can be regulated through CRISPR/Cas9 to change the composition of sEVs and improve the abundance and expression diversity of them. This review focused on the strategies and mechanisms of iPSCs-sEVs in the treatment of myocardial injury, which provides a reference for future research and the application of iPSCs-sEVs.

Exosomes derived from induced pluripotent stem cells suppresses M2-type macrophages during pulmonary fibrosis via miR-302a-3p/TET1 axis

Idiopathic pulmonary fibrosis (PF) is a type of chronic lung disease. Here, we investigated the effect of induced pluripotent stem cell (iPSC)-derived exosomes (iPSC-exosomes) on M2-type macrophages which play a critical role in pulmonary fibrosis. Exosomes were purified from the conditioned medium of iPSCs. Mice models of pulmonary fibrosis were established by intratracheal instillation with 5 mg/kg bleomycin. Thereafter, the histopathological changes and collagen deposition were detected by HE and masson staining. Meanwhile the level of M2-type macrophages was elevated by immunofluorescence staining with F4/80 and Arg-1. Luciferase reporter assay was conducted to verify the binding of miR-302a-3p to ten-eleven translocation 1 (TET1). Our results showed that, after treatment with iPSC-exosomes, the pulmonary fibrosis induced by bleomycin was relieved, with less collagen deposition. In addition, the increased M2-type macrophages in PF mice were reduced upon treatment with iPSC-exosomes. Moreover, we found that the iPSC-exosomes showed higher level of miR-302a-3p. Interestingly, the level of miR-302a-3p in the lungs of PF mice was increased upon treatment with iPSC-exosomes. Furthermore, we verified that TET1 was a direct target of miR-302a-3p. Up-regulation of miR-302a-3p or TET1 silencing repressed M2-type macrophages. Down-regulation of miR-302a-3p abolished the beneficial effects of iPSC-exosomes on pulmonary fibrosis. Collectively, our study revealed that iPSC-exosomes delivered miR-302a-3p to suppress the M2-type macrophages via targeting TET1, thus mitigating pulmonary fibrosis. This study indicates that iPSC-exosomes may become a potential therapeutic agent for pulmonary fibrosis.