Abstract 414: Postnatal Cardiac Tissue Harbors Progenitor Cells With Unique Metabolic Profile

Abstract

Rationale: The developmental cardiac tissue is a proliferative organ capable of regeneration that extends briefly into the postnatal period. Studies show that the heart undergoes alterations in metabolism that coincide with cessation of regenerative processes during postnatal development. Whether cardiac cells in the early postnatal heart exhibit metabolic properties that favor regeneration remains unknown. Objective: To determine whether postnatal cardiac tissue harbors CPCs with unique metabolic profile. Methods and Results: CPCs were isolated from C57BL/6 mice aged 2-day (NCPC), 2-month (adult CPC) and 2-year old (ACPC). Morphological assessment showed NCPCs were smaller and rounded compared to CPCs and ACPCs and expressed putative stem cell markers and were negative for hematopoietic marker CD45. Interestingly, NCPCs expressed elevated levels of pluripotency markers such as LIN28 compared to ACPCs and CPCs. Increased viability, proliferation rate, metabolic activity and reduced doubling times were observed in NCPCs compared to CPCs and ACPCs measured by CyQuant, MTT, and Resazurin assays. NCPCs demonstrated a youthful phenotype and were resistant to H2O2 induced stress compared to ACPCs and CPCs as measured by β-Galactosidase and TUNEL labeling respectively together with a unique expression of paracrine factors as assessed by proteome profiler array. Interestingly, NCPCs demonstrated increased ATP generation, glycolytic activity and reduced oxidative phosphorylation compared to CPCs and ACPCs measured by seahorse assay parallel with enhanced expression of glycolytic enzymes measured by qRT-PCR and western blot. NCPCs showed increased lactate production and pyruvate kinase activity and low mitochondrial membrane potential. Interestingly, mitochondrial fuel dependency assay showed increased glutamine dependency as the fuel for mitochondrial oxidative phosphorylation. RNA-sequencing analysis demonstrated increased expression of metabolic signaling in NCPCs compared to CPCs and ACPCs. Conclusions: Postnatal cardiac tissue possesses progenitor cell population with unique metabolic profile that coincides with enhanced functional properties of NCPCs suggesting their potential therapeutic value for cardiac repair.