Safety profiling of genetically engineered Pim-1 kinase overexpression for oncogenicity risk in human c-kit+ cardiac interstitial cells

Abstract

Advanced approaches to stem cell-based therapies is necessary for myocardial regenerative therapy because treatments have yielded modest results in the clinic. Our group previously demonstrated genetic modification of cardiac stem cells with Pim-1 kinase overexpression rejuvenated aged cells and potentiated myocardial repair. Despite these encouraging findings, concerns were raised regarding oncogenic risk associated with Pim-1 kinase overexpression. Testing of these c-kit+ cardiac interstitial cells (cCICs), derived from heart failure patient samples, overexpressing Pim-1 (cCICs-Pim-1) for indices of oncogenic risk was assessed by soft agar colony formation, micronucleation, gamma-Histone 2AX foci, and transcriptome profiling. Collectively, findings demonstrate comparable phenotypic and biological properties of cCICsPim-1 compared to baseline control cCICs with no evidence for oncogenic phenotype. Using a highly-selective and continuous sensor for quantitative assessment of PIM1 kinase activity, a 7-fold increase in cCICs-Pim-1 versus cCICs resulted. Kinase activity was elevated in IKKs, AKT/SGK, CDK1-3, p38, and ERK1/2 in addition to Pim-1, correlating Pim-1 overexpression to contribute to Pim-1-mediated effects. Enhancement of cellular survival, proliferation, and other beneficial properties to augment stem cell-mediated repair without oncogenic risk is a feasible, logical, and safe approach to improve efficacy and overcome current limitations inherent to cellular adoptive transfer therapeutic interventions.