# Validation of a Novel Genomic Biomarker of Mesenchymal Stem Cell Scalability and Implications of Genotype Status on Cellular Senescence Phenotypes

## TL;DR

This study identifies a genetic marker, GSTT1, that helps determine which bone marrow stem cells resist aging during lab expansion, potentially improving their use in regenerative medicine.

## Contribution

The study validates GSTT1 genotype as a novel biomarker for mesenchymal stem cell scalability and senescence resistance.

## Key findings

- GSTT1 null BM-MSCs show higher proliferative potential and fewer senescent cells compared to other genotypes.
- GSTT1 null cells exhibit lower expression of senescence-related genes like p21 Waf1 and IL-6.
- These cells also show higher expression of genes like TWIST1 and ACTA2, especially at low passages.

## Abstract

Ex vivo expansion impairs the regenerative potential of bone marrow-derived mesenchymal stem cells (BM-MSCs), primarily by inducing cellular senescence. Interestingly, populations of BM-MSCs that exhibit resistance to senescence even after prolonged expansion have been reported. However, a reliable strategy to identify these populations is still underway. Previously, the GSTT1 gene has been identified as a biomarker for BM-MSC scalability but its effects on BM-MSC senescence have not yet been studied. Here, we investigate the role of GSTT1 genotype in BM-MSC senescence. First, we identified the GSTT1 genotype (either homozygous positive, heterozygous, or homozygous negative) of nine BM-MSC groups. Then, we performed long-term in vitro culture and exposed cells to irradiation as senescence models. After that, their proliferative potential, their SASP, and the expression of key genes were investigated. The results show that GSTT1 null BM-MSCs have a higher proliferative potential and exhibit fewer senescent cells in culture when compared to the other genotypes. Additionally, these cells exhibit a lower expression of p21 Waf1, p14ARF, IL-6, PDXN, and 53BP1 and a higher expression of TWIST1 and ACTA2 genes, especially at low passages. A GSTT1 null genotype can serve as a potential biomarker to identify BM-MSC populations with higher resistance to senesce.