Polycomb and wnt pathway modulation rejuvenates aged cardiac progenitor cells

Abstract Introduction Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide, with aging being a major risk factors. During senescence, the heart undergoes structural and functional changes that impairs its regenerative capacity. Cardiac stem cells (CSCs) have emerged as a promising source for myocardial repair; however, their function declines with age. Epigenetic regulators, particularly Polycomb group proteins, are critical in maintaining stem cell identity and function. Understanding how Polycomb proteins modulate CSC aging may open new therapeutic strategies for age-related cardiovascular diseases. Purpose This study aims to explore whether targeted modulation of BMI1—a key Polycomb group protein—and the β-catenin signaling pathway can rejuvenate aged cardiac stem cells (CSCs) and restore their regenerative potential. Methods Cardiac stem cells (CSCs) were isolated from the hearts of young (2–3 months) and aged (20–24 months) C57BL/6 mice. Following isolation, CSCs underwent immunophenotyping to characterize surface marker expression. Functional assays, including clonogenicity, spheroid formation, and cardiomyogenic differentiation, were performed to assess their regenerative potential. The expression of senescence markers, apoptosis-related proteins, and DNA damage indicators was also evaluated through molecular and immunocytochemical analyses. To investigate the role of BMI1, aged CSCs were transduced to either overexpress or downregulate BMI1 using lentiviral vectors. Additionally, aged CSCs were treated with conditioned medium containing Wnt3a to modulate β-catenin signaling. Results Aged cardiac stem cells (CSCs) showed reduced proliferation and cardiomyogenic differentiation compared to young CSCs, alongside increased expression of senescence markers (p16, p21), apoptosis, and DNA damage (γH2AX). BMI1 overexpression in aged CSCs improved clonogenicity, spheroid formation, and proliferation, while its downregulation worsened these features and increased senescence marker expression. Wnt3a treatment activated β-catenin signaling, enhancing proliferation and stemness in aged CSCs. A transient Wnt3a exposure followed by cardiogenic morphogens restored the cardiomyogenic potential of aged CSCs to levels similar to young cells. Conclusion Our findings demonstrates that cardiac stem cells aging is not an irreversible. Aged CSCs, when cultured under optimal conditions and subjected to clonal selection, can recover morphological, functional, and molecular characteristics comparable to those of young CSCs. Both BMI1 and the canonical Wnt/β-catenin pathway play crucial roles in regulating CSC aging. The ability to reactivate functional CSCs in elderly patients could represent an innovative and personalized approach for the treatment of chronic post-infarction heart failure.