Cigarette smoke impairs the hematopoietic supportive property of mesenchymal stem cells via the production of reactive oxygen species and NLRP3 activation.

BACKGROUND: Mesenchymal stem cells (MSCs) play important roles in tissue homeostasis by providing a supportive microenvironmental niche for the hematopoietic system. Cigarette smoking induces systemic abnormalities, including an impeded recovery process after hematopoietic stem cell transplantation. However, the role of cigarette smoking-mediated alterations in MSC niche function have not been investigated. METHODS: In the present study, we investigated whether exposure to cigarette smoking extract (CSE) disrupts the hematopoietic niche function of MSCs, and pathways impacted. To investigate the effects on bone marrow (BM)-derived MSCs and support of hematopoietic stem and progenitor cells (HSPCs), mice were repeatedly infused with the CSE named 3R4F, and hematopoietic stem and progenitor cells (HSPCs) supporting function was determined. The impact of 3R4F on MSCs at cellular level were screened by bulk-RNA sequencing and subsequently validated through qRT-PCR. Specific inhibitors were treated to verify the ROS or NLRP3-specific effects, and the cells were then transplanted into the animal model or subjected to coculture with HSPCs. RESULTS: Both direct ex vivo and systemic in vivo MSC exposure to 3R4F resulted in impaired engraftment in a humanized mouse model. Furthermore, transcriptomic profile analysis showed significantly upregulated signaling pathways related to reactive oxygen species (ROS), inflammation, and aging in 3R4F-treated MSCs. Notably, ingenuity pathway analysis revealed the activation of NLRP3 inflammasome signaling pathway in 3R4F-treated MSCs, and pretreatment with the NLRP3 inhibitor MCC950 rescued the HSPC-supporting ability of 3R4F-treated MSCs. CONCLUSION: In conclusion, these findings indicate that exposure to CSE reduces HSPCs supportive function of MSCs by inducing robust ROS production and subsequent NLRP3 activation.

Xeno-Free Condition Enhances Therapeutic Functions of Human Wharton's Jelly-Derived Mesenchymal Stem Cells against Experimental Colitis by Upregulated Indoleamine 2,3-Dioxygenase Activity.

The therapeutic applications of mesenchymal stem cells (MSCs) have been actively explored due to their broad anti-inflammatory and immunomodulatory properties. However, the use of xenogeneic components, including fetal bovine serum (FBS), in the expansion media might pose a risk of xenoimmunization and zoonotic transmission to post-transplanted patients. Here, we extensively compared the physiological functions of human Wharton's jelly-derived MSCs (WJ-MSCs) in a xeno-free medium (XF-MSCs) and a medium containing 10% FBS (10%-MSCs). Both groups showed similar proliferation potential; however, the 10%-MSCs showed prolonged expression of CD146, with higher colony-forming unit-fibroblast (CFU-F) ability than the XF-MSCs. The XF-MSCs showed enhanced adipogenic differentiation potential and sufficient hematopoietic stem cell (HSC) niche activity, with elevated niche-related markers including CXCL12. Furthermore, we demonstrated that the XF-MSCs had a significantly higher suppressive effect on human peripheral blood-derived T cell proliferation, Th1 and Th17 differentiation, as well as naïve macrophage polarization toward an M1 phenotype. Among the anti-inflammatory molecules, the production of indoleamine 2,3-dioxygenase (IDO) and nitric oxide synthase 2 (NOS2) was profoundly increased, whereas cyclooxygenase-2 (COX-2) was decreased in the XF-MSCs. Finally, the XF-MSCs had an enhanced therapeutic effect against mouse experimental colitis. These findings indicate that xeno-free culture conditions improved the immunomodulatory properties of WJ-MSCs and ex vivo-expanded XF-MSCs might be an effective strategy for preventing the progression of colitis.