Validation of a novel genomic biomarker of mesenchymal stem cell scalability and implications of genotype status on cellular senescence phenotypes

Why growing stem cells gets harder with time

Stem cells from adult bone marrow are a mainstay of many experimental therapies, from repairing damaged bones to calming inflammation. But there is a catch: to treat a patient, labs must grow these cells outside the body, and the longer they are expanded, the more they slow down and behave like "aged" cells. This study explores why some people’s stem cells age more slowly in the dish, and whether a tiny missing piece of DNA can help scientists pick the most robust cells for future treatments.

A missing gene that changes the rules

The researchers focused on a gene called GSTT1, which helps cells detoxify harmful molecules produced during normal metabolism and stress. Surprisingly, a sizable fraction of people entirely lack this gene – they are "GSTT1 null." Earlier work hinted that bone marrow stem cells from these individuals might grow faster and keep their protective chromosome caps, called telomeres, longer. In this project, the team examined stem cells from six healthy donors, grouped them into GSTT1-positive and GSTT1-null, and then tracked how the cells behaved during many rounds of growth and after exposure to X‑ray radiation, a strong trigger of cellular aging.

Fast-growing cells that resist aging signals

When the scientists followed cell numbers over several days, GSTT1-null stem cells multiplied more rapidly at early passages than cells carrying the gene. Over very long expansion, growth rates between groups became more similar, but the early advantage was clear. To probe aging directly, the team used a classic stain that turns senescent, or aged, cells blue. After many rounds of division, and again after irradiation, GSTT1-null cultures consistently contained fewer blue, senescent cells than GSTT1-positive cultures. Importantly, this difference did not come from slower shortening of telomeres or from higher activity of the enzyme that maintains telomeres (hTERT); both measures looked similar regardless of GSTT1 status, suggesting another mechanism was at work.

Quieter stress and inflammation in the dish

To understand what made GSTT1-null cells more resilient, the researchers measured activity of genes linked to cell cycle arrest, DNA damage, and the so‑called senescence-associated secretory phenotype  a cocktail of inflammatory and stress signals that aging cells release. Cells with GSTT1 present showed higher levels of key "stop" signals such as p21 and p14, especially at later passages and after irradiation. They also ramped up IL‑6, a potent inflammatory molecule, and other stress-related genes more strongly than GSTT1-null cells. In contrast, GSTT1-null stem cells maintained lower levels of these aging and inflammatory markers, while keeping higher levels of ACTA2 and TWIST1, genes associated with structural integrity and stem-like behavior. Notably, both genotypes retained similar ability to specialize into bone and fat cells, meaning the protective effect was not simply due to loss of normal stem cell function.

What this could mean for future cell therapies

Together, the findings suggest that bone marrow stem cells lacking GSTT1 are partly shielded from the usual wear-and-tear of lab expansion and radiation. They grow faster early on, accumulate fewer overtly aged cells, and maintain a less inflammatory profile, even though their chromosomes shorten at similar rates. For companies and clinics that manufacture large numbers of stem cells, GSTT1-null status could serve as a practical genetic marker to identify donors whose cells tolerate expansion better, potentially yielding more consistent and potent therapies. Of course, the study used a small donor pool and non-clinical culture conditions, so larger, carefully controlled studies are needed. Still, the work highlights how a single inherited difference can tip the balance between youthful and aging behavior in stem cells grown for regenerative medicine.

Citation: Ardana, I.K.K.G., Maldonado, V.V., Barnes, C.L. et al. Validation of a novel genomic biomarker of mesenchymal stem cell scalability and implications of genotype status on cellular senescence phenotypes. Sci Rep 16, 6219 (2026). https://doi.org/10.1038/s41598-026-37517-8

Keywords: mesenchymal stem cells, cellular senescence, biomarkers, cell therapy manufacturing, GSTT1 polymorphism