Exposure to supernatants of macrophages that phagocytized dead mesenchymal stem cells improves hypoxic cardiomyocytes survival.

OBJECTIVE: To observe the impact of supernatants from macrophages that phagocytized dead MSCs (pMΦ) on the survival of hypoxic cardiomyocytes.
METHODS: MSCs were isolated from bone marrow of mice and dead MSCs were harvested after 6h hypoxia. Macrophages were obtained from thioglycolate-elicited peritoneal cavity. Macrophages and dead MSCs were co-cultured for 2 days in the presence or absence of LPS (1 μg/ml). Cardiomyocytes obtained from neonatal mice were exposed to various medium including supernatants from pMΦ. MTT cell proliferation assay and mitochondria membrane potential were used to evaluate the viability of cardiomyocytes. Cytokines and chemokines (TNF-α, IFN-γ, IL-6, IL-12, PGE2, VEGF-α, Ang-1, KGF, IGF-1, PDGF-BB, and EPO) in culture medium of macrophages, MSCs and pMΦ were detected by ELISA and Real-Time-PCR.
RESULTS: phagocytic activity of macrophages to dMSC was significantly enhanced by LPS. PGE2, VEGF-α, Ang-1, KGF, IGF-1, PDGF-BB, and EPO levels were significantly increased in supernatants of pMΦ. Exposure to supernatants of pMΦ significantly improved viability and survival time of hypoxic cardiomyocytes.
CONCLUSION: Exposure to supernatants of pMΦ significantly improved viability and survival time of hypoxic cardiomyocytes, which might be linked to increased cytokines and chemokines secretion by pMΦ.