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Updated: Feb 23, 2026
Assessment of the Immunomodulatory Properties of Human Mesenchymal Stem Cells MSCs
Published on: December 24, 2015
5-methoxytryptophan protects MSCs from stress induced premature senescence by upregulating FoxO3a and mTOR
Tzu-Ching Chang1,2, Min-Fen Hsu1, Chiu-Yueh Shih1
1Metabolomic Medicine Research Center China Medical University Hospital, Taichung, Taiwan.
Abstract:
5-methoxytryptophan (5-MTP) is a newly discovered tryptophan metabolite which controls stress-induced inflammatory signals. To determine whether 5-MTP protects against stress-induced mesenchymal stem cell (MSC) senescence, we incubated bone marrow-derived MSC (BM-MSC) in high-glucose medium or regular medium for 2 weeks followed by addiction of 5-MTP (10 μM) or vehicle for 48 h. 5-MTP reduced p16 and p21 expression, senescence-associated β-Gal (SA-β-Gal) and IL-6 secretion and increased BrdU incorporation. 5-MTP exerted a similar effect on BM-MSC senescence induced by a sublethal concentration of H2O2. 5-MTP enhanced FoxO3a expression and increased superoxide dismutase and catalase activities in HG BM-MSCs. Silencing of FoxO3a with siRNA abrogated 5-MTP-mediated reduction of SA-β-Gal and IL-6 secretion but not p21 or p16. Since mechanistic target of rapamycin (mTOR) is involved in cellular senescence, we determined whether 5-MTP influences mTOR expression. Our data reveal that mTOR protein level was depressed in HG-MSC which was rescued by 5-MTP. Rapamycin abrogated 5-MTP-mediated suppression of p16, p21, SA-β-Gal and IL-6 and rise of BrdU incorporation. Our findings suggest that 5-MTP protects MSCs against stress-induced senescence via FoxO3a and mTOR upregulation and has potential to improve cell expansion for cell therapy.
Insights
5-methoxytryptophan (5-MTP) protects mesenchymal stem cells (MSCs) from stress-induced aging. This tryptophan metabolite enhances cell proliferation and may improve cell therapy applications by upregulating FoxO3a and mTOR pathways.
Area of Science:
- Cell Biology
- Biochemistry
- Regenerative Medicine
Background:
- Cellular senescence, a state of irreversible growth arrest, is implicated in aging and disease.
- Mesenchymal stem cells (MSCs) are crucial for tissue repair and regenerative medicine, but their function can be compromised by stress-induced senescence.
- Tryptophan metabolites are emerging as key regulators of cellular processes, including inflammation and stress responses.
Purpose of the Study:
- To investigate the protective effects of 5-methoxytryptophan (5-MTP) against stress-induced senescence in bone marrow-derived mesenchymal stem cells (BM-MSCs).
- To elucidate the underlying molecular mechanisms, including the roles of FoxO3a and mechanistic target of rapamycin (mTOR) pathways.
Main Methods:
- BM-MSCs were subjected to stress conditions (high glucose or H2O2) and treated with 5-MTP.
- Senescence markers (p16, p21, SA-β-Gal, IL-6) and proliferation (BrdU incorporation) were assessed.
- Expression of FoxO3a and mTOR, and activities of superoxide dismutase and catalase were analyzed.
- Gene silencing (siRNA) and pharmacological inhibition (rapamycin) were employed to confirm pathway involvement.
Main Results:
- 5-MTP significantly reduced senescence markers (p16, p21, SA-β-Gal, IL-6) and increased proliferation in stressed BM-MSCs.
- 5-MTP enhanced FoxO3a expression and antioxidant enzyme activities (superoxide dismutase, catalase).
- Silencing FoxO3a partially abrogated 5-MTP's effects, while 5-MTP treatment rescued reduced mTOR levels in stressed cells.
- Rapamycin treatment counteracted the protective effects of 5-MTP.
Conclusions:
- 5-methoxytryptophan (5-MTP) effectively protects mesenchymal stem cells (MSCs) against stress-induced senescence.
- The protective mechanism involves the upregulation of FoxO3a and mechanistic target of rapamycin (mTOR) pathways.
- 5-MTP shows potential for enhancing MSC expansion and efficacy in cell therapy applications.
