Individual response to mTOR inhibition in delaying replicative senescence of mesenchymal stromal cells

Author(s)

Antonioli, Eliane ^[1] ; Torres, Natalia ^[1] ; Ferretti, Mario ^[1] ; Piccinato, Carla de Azevedo ^[1] ; Sertie, Andrea Laurato ^[1]

Affiliation

^[1] Hosp Israelita Albert Einstein, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: PLoS One; v. 14, n. 1 JAN 31 2019.
• Web of Science Citations: 2

Abstract

Background aims Delaying replicative senescence and extending lifespan of human mesenchymal stromal cells (MSCs) may enhance their potential for tissue engineering and cell based therapies. Accumulating evidence suggests that inhibitors of the mTOR signaling pathway, such as rapamycin, constitute promising pharmacological agents to retard senescence and extend stemness properties of various progenitor cell types. Here, we investigated whether the ability of rapamycin to postpone replicative senescence varies among bone marrow MSC samples (BM-MSCs) derived from different healthy donors, and explored the molecular mechanisms that drive rapamycin-mediated lifespan increment. Methods BM-MSCs at early passages were serially passaged either in absence or continuous presence of rapamycin and the number of cell population doublings until growth arrest was measured. The inhibition of mTOR signaling was assessed by the phosphorylation status of the downstream target RPS6. The expression levels of several senescence and pluripotency markers at early and late/senescent passages were analyzed by RT-qPCR, flow cytometry and western blot. Results We found that the lifespan extension in response to the continuous rapamycin treatment was highly variable among samples, but effective in most BM-MSCs. Despite all rapamycin-treated cells secreted significantly reduced levels of IL6, a major SASP cytokine, and expressed significantly higher levels of the pluripotency marker NANOG, the expression patterns of these markers were not correlated with the rapamycin-mediated increase in lifespan. Interestingly, rapamycin-mediated life-span extension was significantly associated only with repression of p16(INK4A) protein accumulation. Conclusions Taken together, our results suggest that some, but not all, BM-MSC samples would benefit from using rapamycin to postpone replicative arrest and reinforce a critical role of p16(INK4A) protein downregulation in this process. (AU)

• FAPESP's process: 14/25646-3 - Investigation of the cellular and molecular effects of RELN mutations in Autism Spectrum Disorders.
• Grantee: Andréa Laurato Sertié
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/00831-7 - Osteoarthritic chondrocytes and mesenchimal stem cells: relationship between inflammatory molecules and extracelullar matrix
• Grantee: Mario Ferretti Filho
• Support Opportunities: Regular Research Grants