Abstract 135: Pim-1 Modification Reverses Senescent Phenotype Of Hcpcs From Patients With Heart Disease
Rationale: Adoptive transfer of human cardiac progenitor cells (hCPCs) can repair damaged myocardium and improve function in a pathologically challenged heart. hCPC’s isolated from multiple patients exhibit differences in growth kinetics, expression of cell cycle regulators and telomere length suggesting hCPCs with slow growth kinetics may compromise effective regeneration of damaged or aged myocardium. There is a dire need to reverse the senescent phenotype of hCPCs exhibiting slow growth kinetics to improve the outcome of regenerative therapy.
Objective: Demonstrate that Pim-1 engineering reverses the senescent phenotype of human cardiac progenitor cells (hCPCs) with slow growth kinetics by increasing their telomere length and decreasing population doubling time and cell cycle inhibitors.
Methods and Results: hCPCs positive for stem cell marker c-kit were isolated from heart biopsy samples from patients undergoing Left Ventricular Assist Device (LVAD) implantation. hCPCs isolated from multiple patients were characterized for growth kinetics, telomere length, expression of cell cycling regulators. hCPCs with slow growth kinetics exhibit decreased telomere length concomitant with increased population doubling time and upregulation of senescent markers compared to hCPCs with fast growth kinetics. hCPCs were engineered to express Pim-1-GFP (hCPCeP), a fused GFP version of the kinase by using a lentivirus expression system. Cell cycling measured by population doubling time was decreased in hCPCeP. Similarly, telomere lengths in hCPCeP were significantly increased relative to control hCPCs expressing GFP (hCPCe). Similarly, the expression cell cycling inhibitors including p16 and p53 is down regulated indicative of reversal of senescent characteristics.
Conclusion: Ex vivo gene delivery of Pim-1 in hCPCS enhances telomere length and decreases population-doubling time and senescent phenotype. These changes are more significant and distinct in hCPCs with slow growth kinetics. Pim-1 modification of hCPCs with slow growth kinetics from patients with heart failure can augments their ability to regenerate damaged myocardium and address current limitations associated with senescent phenotype of aged hCPCs.
- © 2013 by American Heart Association, Inc.