Sca-1+ stem cell survival and engraftment in the infarcted heart: dual role for preconditioning-induced connexin-43

Area of Science:

• Stem cell biology
• Regenerative medicine
• Cardiovascular research

Background:

• Elevated connexin-43 (Cx-43) in stem cells preconditioned with insulin-like growth factor-1 (IGF-1) demonstrates cytoprotective properties.
• This preconditioning also reprograms stem cells towards cardiomyogenic differentiation.

Purpose of the Study:

• To investigate the cytoprotective effects of IGF-1 preconditioning on Sca-1+ cells.
• To assess the role of Cx-43 in IGF-1-mediated stem cell reprogramming and survival.
• To evaluate the therapeutic potential of preconditioned Sca-1+ cells in a rat model of myocardial infarction.

Main Methods:

• Sca-1+ cells were preconditioned with IGF-1 and subjected to oxygen-glucose deprivation to evaluate survival.
• Cell viability assays (LDH release, cytochrome c, mitochondrial membrane potential) and analysis of cardiac-specific markers (MEF-2c, GATA4, Cx-43) were performed.
• In vivo studies involved transplantation of preconditioned or non-preconditioned Sca-1+ cells into rats with induced myocardial infarction.

Main Results:

• IGF-1 preconditioning significantly improved Sca-1+ cell survival under oxygen-glucose deprivation, mediated by PI3K/Akt-dependent caspase-3 downregulation.
• Preconditioned cells showed upregulated cardiac-specific markers, including a 3.5-fold increase in Cx-43.
• In vivo, transplantation of preconditioned cells led to 5.5-fold higher survival, enhanced blood vessel density, reduced infarct size, and improved cardiac function compared to non-preconditioned cells.

Conclusions:

• IGF-1 preconditioning effectively reprograms Sca-1+ cells for enhanced survival and cardiomyogenic differentiation.
• Connexin-43 (Cx-43) is crucial for the prosurvival signaling and therapeutic efficacy of IGF-1-preconditioned stem cells.
• These findings highlight a promising strategy for stem cell-based cardiac repair.