Abstract 12453: Over-expression of NDNF Rejuvenates Aged Human Mesenchymal Stem Cells and Improves Mouse Heart Function After Myocardial Infarction

Abstract

Introduction: The benefits of cell transplantation for cardiac repair are diminished in aged individuals and effective methods to rejuvenate aged stem cells are required to treat the increasing number of elderly patients with heart failure. Neuron-derived neurotrophic factor (NDNF) has biological effects which could restore stem cell activity. This study determined whether NDNF could regenerate aged human bone marrow mesenchymal stem cells (hMSCs) and improve their regenerative capacity after a myocardial infarction (MI). Methods and Results: hMSCs were harvested from young (24±7 years, n=9) and aged (72±8 years, n=13) patients after informed consent, evaluated and then transfected with a lentiviral expression vector carrying the NDNF gene. NDNF overexpression was confirmed by RT-PCR and Western blot. Aged hMSCs had 54% lower NDNF mRNA levels and 66% lower NDNF protein levels (relative NDNF protein expression: 0.26±0.06 in young and 0.09±0.05 in old patients, p<0.001). Proliferation (assayed by BrdU staining) was 54% lower and migration (by a scratch-wound assay) was 58% lower in aged compared with young hMSCs. Overexpression of NDNF in aged hMSCs increased cell proliferation and decreased apoptosis. The rejuvenation of the aged hMSCs was associated with a 45% decreased in p16 (a cyclin-dependent kinase inhibitor, relative protein expression: 0.55±0.34 in NDNF-transduced hMSCs and 1.00±0.30 in non-transduced hMSCs, p=0.04). Regucalcin (a senescence marker protein) was increased 2-fold in the NDNF-transduced aged hMSCs compared with empty vector-transduced aged hMSCs. In vivo implantation of NDNF-overexpressing aged hMSCs into a mouse cardiac infarct decreased scar size and preserved function at 28 days after MI compared with mice that received aged empty vector-transduced hMSCs (fractional shortening was 26±3% in the NDNF group and 20±3% in the empty vector group, p=0.04). Exploration of potential mechanisms revealed that phospho-Akt (Ser473), a key cell survival factor, was increased in mouse heart tissue after NDNF hMSC transplantation compared to the empty vector group. Conclusions: NDNF could be an important new target to rejuvenate aged stem cells that could then become potent vehicles for cardiac repair of the aged heart after injury.