LIN28a induced metabolic and redox regulation promotes cardiac cell survival in the heart after ischemic injury

Rationale: Cell-based therapeutics have been extensively used for cardiac repair yet underperform due to inability of the donated cells to survive in near anoxia after cardiac injury. Cellular metabolism is linked to maintenance of cardiac stem cell (CSC) renewal, proliferation and survival. Ex vivo expansion alters (CSC) metabolism increasing reliance on oxygen dependent respiration. Whether promoting 'metabolic flexibility' in CSCs augments their ability to survive in near anoxia and repair the heart after injury remains untested.

Objective: Determine the effect of LIN28a induced metabolic flexibility on cardiac tissue derived stem like cell (CTSC) survival and repair after cardiac injury.

Methods and results: LIN28a expression coincides during heart development but is lost in adult CTSCs. Reintroduction of LIN28a in adult CTSC (CTSC-LIN) increased proliferation, survival, expression of pluripotency genes and reduced senescence compared to control (CTSC-GFP). Metabolomic analysis show glycolytic intermediates upregulated in CTSC-LIN together with increased lactate production, pyruvate kinase activity, glucose uptake, ECAR and expression of glycolytic enzymes compared to CTSC-GFP. Additionally, CTSC-LIN showed significantly reduced ROS generation and increase antioxidant markers. In response to H2O2 induced oxidative stress, CTSC-LIN showed increased survival and expression of glycolytic genes. LIN28a salutary effects on CTSCs were linked to PDK1/let-7 signaling pathway with loss of PDK1 or alteration of let-7 abrogating LIN28a effects. Following transplantation in the heart after myocardial infarction (MI), CTSC-LIN showed 6% survival rate at day 7 after injection compared to control cells together with increased proliferation and significant increase in cardiac structure and function 8 weeks after MI. Finally, CSTC-LIN showed enhanced ability to secrete paracrine factors under hypoxic conditions and ability to promote cardiomyocyte proliferation following ischemic cardiac injury.

Conclusions: LIN28a modification promotes metabolic flexibility in CTSCs enhancing proliferation and survival post transplantation including ability to repair the heart after myocardial injury.