Rationale: Mesenchymal stem cells (MSCs) possess potent immunomodulatory capability, but occasionally, clinical application of MSCs is hindered by compromised cell functionality and insufficient therapeutic efficacy. Methods: Here, well-established mouse models of dextran sulfate sodium (DSS)-induced colitis and streptozotocin (STZ)-induced type 1 diabetes (T1D) were used to evaluate therapeutic immunomodulatory effects of human umbilical cord-derived MSCs. MSCs were examined at the fifth (P5) and the fifteenth (P15) passages, and three-dimensional (3D) culture was conducted by Matrigel incorporation. A series of biochemical, histopathological and cellular assays were performed to investigate the MSC function and therapeutic performance, and immunoregulation was evaluated by in vitro co-culture with T cells and in vivo analyses of T-cell infiltration into target tissues. RNA sequencing (RNA-seq) analysis followed by immunofluorescence staining, gene expression analyses and chemical regulation were used to investigate the molecular targets. Results: MSCs lose therapeutic immunomodulatory effects after extensive expansion to P15 when cell senescence occurs. Intriguingly, 3D preconditioning of MSCs in Matrigel promotes diminished immunoregulatory capability despite extensive passages, which benefits function of P15-MSCs to modulate T-cell subsets in co-culture, suppress infiltration of pro-inflammatory T cells in the colon and pancreas tissues after infusion, ameliorate systemic inflammation, and alleviate colitis and T1D in mice. Mechanistically, 3D culture provokes transcriptomic reprogramming of MSCs toward a Yes-associated protein 1 (YAP1)-marked, Hippo signaling pathway-upregulated state with promoted release of the anti-inflammatory cytokine, transforming growth factor-beta1 (TGF-β1). Moreover, chemical regulation of YAP1 by clinically relevant drugs, verteporfin (VP) and prostaglandin E2 (PGE2), affects TGF-β1 expression and the immunomodulatory capability of MSCs during dimensional culture. Conclusions: Taken together, these findings unravel YAP1-based dimensional and chemical coordination of expanded MSC immunoregulation, which will shed light on precisely controlled translational application.
© The author(s).

Proton pump inhibitors have been explored for potentiating cancer therapies via reverting the tumor acidity and promoting the activation of anti-tumor immune responses. To regulate the intracellular pH of melanoma and immunosuppressive myeloid cells, we developed poly(L-lactide-co-glycolide) nanoparticles loaded with esomeprazole (ESO-NPs). The effect of ESO-NPs on melanoma cells was observed as alkalinization and reduction of melanin content accompanied by a decrease of microphthalmia-associated transcription factor (MITF), poliovirus receptor (PVR), and programmed death ligand 1 (PD-L1) immune checkpoint expression. ESO-NP treatment of melanoma-patient-derived and in vitro-induced myeloid-derived suppressor cells (MDSCs) reduced the expression of immunosuppression-associated molecules PD-L1, CD206, and CD163 on patient-derived myeloid cells while inducing the expression of co-stimulatory molecule CD86 and HLA-DR in the in vitro model. Our findings suggest that reprogramming the intracellular pH of melanoma and immune-suppression-associated myeloid cells with ESO-NPs can modulate the expression of proteins involved in resistance to cancer therapy and immunosuppression, thus potentially improving the response to immunotherapies.
© 2024 The Authors.

The ovary is crucial for female reproduction and health, as it generates oocytes and secretes sex hormones. Transplantation of mesenchymal stem cells (MSCs) has been shown to alleviate pathological ovarian aging. However, it is unclear whether MSCs could benefit the naturally aging ovary. In this study, we first examined the dynamics of ovarian reserve of Chinese women during perimenopause. Using a naturally aging cynomolgus monkey (Macaca fascicularis) model, we found that transplanting human embryonic stem cells-derived MSC-like cells, which we called M cells, into the aging ovaries significantly decreased ovarian fibrosis and DNA damage, enhanced secretion of sex hormones and improved fertility. Encouragingly, a healthy baby monkey was born after M-cell transplantation. Moreover, single-cell RNA sequencing analysis and in vitro functional validation suggested that apoptosis, oxidative damage, inflammation, and fibrosis were mitigated in granulosa cells and stromal cells following M-cell transplantation. Altogether, these findings demonstrate the beneficial effects of M-cell transplantation on aging ovaries and expand our understanding of the molecular mechanisms underlying ovarian aging and stem cell-based alleviation of this process.
© 2024. The Author(s).

Bone marrow plasma cells (BMPC) are the correlate of humoral immunity, consistently releasing antibodies into the bloodstream. It remains unclear if BMPC reflect different activation environments or maturation of their precursors. Here we define human BMPC heterogeneity and track the recruitment of antibody-secreting cells (ASC) from SARS-CoV-2 vaccine immune reactions to the bone marrow (BM). Trajectories based on single-cell transcriptomes and repertoires of peripheral and BM ASC reveal sequential colonisation of BMPC compartments. In activated B cells, IL-21 suppresses CD19 expression, indicating that CD19low-BMPC are derived from follicular, while CD19high-BMPC originate from extrafollicular immune reactions. In primary immune reactions, both CD19low- and CD19high-BMPC compartments are populated. In secondary immune reactions, most BMPC are recruited to CD19high-BMPC compartments, reflecting their origin from extrafollicular reactivations of memory B cells. A pattern also observable in vaccinated-convalescent individuals and upon diphtheria/tetanus/pertussis recall-vaccination. Thus, BMPC diversity reflects the evolution of a given humoral immune response.
© 2024. The Author(s).

Facial nerve (FN) injury seriously affects human social viability and causes a heavy economic and social burden. Although mesenchymal stem cell-derived exosomes (MSC-Exos) promise therapeutic benefits for injury repair, there has been no evaluation of the impact of MSC-Exos administration on FN repair. Herein, we explore the function of MSC-Exos in the immunomodulation of macrophages and their effects in repairing FN injury. An ultracentrifugation technique was used to separate exosomes from the MSC supernatant. Administrating MSC-Exos to SD rats via local injection after FN injury promoted axon regeneration and myelination and alleviated local and systemic inflammation. MSC-Exos facilitated M2 polarization and reduced the M1-M2 polarization ratio. miRNA sequencing of MSC-Exos and previous literature showed that the MAPK/NF-κb pathway was a downstream target of macrophage polarization. We confirmed this hypothesis both in vivo and in vitro. Our findings show that MSC-Exos are a potential candidate for treating FN injury because they may have superior benefits for FN injury recovery and can decrease inflammation by controlling the heterogeneity of macrophages, which is regulated by the p38 MAPK/NF-κb pathway.