Functional Effect of Pim1 Depends upon Intracellular Localization in Human Cardiac Progenitor Cells

Area of Science:

• Cardiovascular Biology
• Stem Cell Biology
• Regenerative Medicine

Background:

• Human cardiac progenitor cells (hCPCs) show therapeutic potential for heart failure but decline with age.
• Genetic modification is needed to enhance the regenerative capacity of aged hCPCs.
• Pim1 kinase influences hCPC proliferation, survival, metabolism, and rejuvenation.

Purpose of the Study:

• To investigate the effects of subcellularly targeted Pim1 overexpression on hCPC function.
• To determine if mitochondrial or nuclear targeting of Pim1 enhances specific cardioprotective properties.
• To assess the potential of targeted Pim1 to rejuvenate aged hCPCs.

Main Methods:

• Adult hCPCs were isolated from patients with left ventricular assist devices.
• hCPCs were genetically engineered to overexpress Pim1 (PimWT), mitochondrially targeted Pim1 (Mito-Pim1), or nuclearly targeted Pim1 (Nuc-Pim1).
• Cellular senescence, proliferation, survival, telomere length, and mitochondrial integrity were assessed.

Main Results:

• Nuc-Pim1 reduced senescence markers (β-galactosidase, p16, p53), preserved telomere length, and increased nucleostemin.
• Mito-Pim1 enhanced survival by upregulating Bcl-2/Bcl-XL and decreasing cell death post-H2O2 treatment, maintaining mitochondrial integrity.
• Mito-Pim1 increased proliferation via cell cycle modulators (Cyclin D, CDK4, phospho-Rb).

Conclusions:

• Targeted subcellular localization of Pim1 kinase significantly enhances key stem cell properties in aged hCPCs.
• Mitochondrial and nuclear targeting of Pim1 offer distinct advantages for improving hCPC proliferation, survival, and youthful characteristics.
• This approach allows for tailored enhancement of hCPCs to overcome patient variability and improve therapeutic potential in heart failure treatment.