Hydroxyurea Induces Bone Marrow Mesenchymal Stromal Cells Senescence and Modifies Cell Functionality In Vitro

Area of Science:

• Cell Biology
• Stem Cell Biology
• Pharmacology

Background:

• Hydroxyurea (HU) is an antineoplastic agent acting as an antimetabolite.
• HU induces DNA replication stress and can trigger premature senescence.
• The effect of HU on bone marrow-derived mesenchymal stem/stromal cells (BMMSCs) remains unclear.

Purpose of the Study:

• To investigate the impact of HU on human BMMSC growth, senescence, differentiation, and immunomodulatory functions.
• To elucidate the underlying molecular mechanisms of HU's effects on BMMSCs.

Main Methods:

• Treatment of human BMMSCs with Hydroxyurea.
• Assessment of cell morphology, proliferation, cell cycle, and senescence markers (β-galactosidase, p16INK4).
• Evaluation of osteogenic and adipogenic differentiation potential.
• Analysis of immunomodulatory capacity via T-cell proliferation assays and induction of myeloid-derived suppressor cells.
• Investigation of signaling pathways including mTOR and p38 MAPK.

Main Results:

• HU inhibited BMMSC growth and induced senescence-like changes (morphology, replicative potential, cell cycle arrest at S phase, increased β-galactosidase and p16INK4 expression) without affecting viability.
• HU-treated BMMSCs showed reduced osteogenic and adipogenic differentiation but enhanced T-cell inhibition.
• HU treatment preserved BMMSC interaction with the myeloid cell compartment and did not affect the induction of monocytic myeloid-derived suppressor cells.
• Downregulation of mTOR and p38 MAPK signaling pathways was observed in HU-treated BMMSCs.

Conclusions:

• Hydroxyurea induces a senescence-like phenotype in BMMSCs, altering their differentiation and immunomodulatory properties.
• HU enhances BMMSC immunomodulatory functions, particularly T-cell inhibition, while preserving myeloid cell interactions.
• The observed effects are mechanistically linked to the downregulation of mTOR and p38 MAPK signaling pathways.