Bone marrow mesenchymal stem cells (MSCs) are a promising cell source for regenerative medicine; however, their cellular physiology is not fully understood. The present study aimed at exploring the potential roles of the two dominant functional ion channels, intermediate-conductance Ca²⁺-activated potassium (IK_Ca) and volume-sensitive chloride ( I_Cl.vol) channels, in regulating proliferation of mouse MSCs. We found that inhibition of IK_Ca with clotrimazole and I_Cl.vol with 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB) reduced cell proliferation in a concentration-dependent manner. Knockdown of KCa3.1 or Clcn3 with specific short interference (si)RNAs significantly reduced IK_Ca or I_Cl.vol density and channel protein and produced a remarkable suppression of cell proliferation (by 24.4 ± 9.6% and 29.5 ± 7.2%, respectively, P < 0.05 vs. controls). Flow cytometry analysis showed that mouse MSCs retained at G₀/G₁ phase (control: 51.65 ± 3.43%) by inhibiting IK_Ca or I_Cl.vol using clotrimazole (2 μM: 64.45 ± 2.20%, P < 0.05) or NPPB (200 μM: 82.89 ± 2.49%, P < 0.05) or the specific siRNAs, meanwhile distribution of cells in S phase was decreased. Western blot analysis revealed a reduced expression of the cell cycle regulatory proteins cyclin D1 and cyclin E. Collectively, our results have demonstrated that IK_Ca and I_Cl.vol channels regulate cell cycle progression and proliferation of mouse MSCs by modulating cyclin D1 and cyclin E expression.

PURPOSE: Relapsed or refractory extranodal natural killer/T-cell lymphoma (R/R ENKTL) is a rare and aggressive type of non-Hodgkin lymphoma with limited treatment options. This phase II study evaluated the efficacy and safety of sugemalimab, an anti–PD-L1 monoclonal antibody, in R/R ENKTL. METHODS: Eligible patients received sugemalimab 1,200 mg intravenously once every 3 weeks for up to 24 months or until progression, death, or study withdrawal. The primary end point was objective response rate (ORR) assessed by an independent radiologic review committee. Key secondary end points included ORR assessed by the investigators, complete response rate, duration of response, and safety. RESULTS: At the data cutoff (February 23, 2022), 80 patients were enrolled and followed for a median of 18.7 months. At baseline, 54 (67.5%) had stage IV disease and 39 (48.8%) had received ≥2 lines of prior systemic therapy. Independent radiologic review committee–assessed ORR was 44.9% (95% CI, 33.6 to 56.6); 28 (35.9%) patients achieved a complete response and seven (9.0%) achieved a partial response, with a 12-month duration of response rate of 82.5% (95% CI, 62.0 to 92.6). Investigator-assessed ORR was 45.6% (95% CI, 34.3 to 57.2), and 24 (30.4%) patients achieved a complete response. Most treatment-emergent adverse events were grade 1-2 in severity, and grade ≥ 3 events were reported in 32 (40.0%) patients. CONCLUSION: Sugemalimab showed robust and durable antitumor activity in R/R ENKTL. Treatment was well tolerated with expected safety profile for this drug class.

Bone marrow mesenchymal stem cells (MSCs) are used as a cell source for cardiomyoplasty; however, the cellular electrophysiological properties are not fully understood. The present study was to investigate the functional ionic channels in undifferentiated mouse bone marrow MSCs using whole cell patch-voltage clamp technique, RT-PCR, and Western immunoblotting analysis. We found that three types of ionic currents were present in mouse MSCs, including a Ca²⁺-activated K⁺ current ( I_KCa), an inwardly rectifying K⁺ current ( I_Kir), and a chloride current ( I_Cl). I_Kir was inhibited by Ba²⁺, and I_KCa was activated by the Ca²⁺ ionophore A-23187 and inhibited by the intermediate-conductance I_KCa channel blocker clotrimazole. I_Cl was activated by hyposmotic (0.8 T) conditions and inhibited by the chloride channel blockers DIDS and NPPB. The corresponding ion channel genes and proteins, KCa3.1 for I_KCa, Kir2.1 for I_Kir, and Clcn3 for I_Cl, were confirmed by RT-PCR and Western immunoblotting analysis in mouse MSCs. These results demonstrate that three types of functional ion channel currents (i.e., I_Kir, I_KCa, and I_Cl) are present in mouse bone marrow MSCs.

Natural killer/T-cell lymphoma (NKTCL) is an aggressive Epstein-Barr virus (EBV)-associated non-Hodgkin lymphoma with a poor prognosis. Recent genomic and transcriptomic studies of tumor tissues have advanced our understanding of NKTCL pathogenesis, but the systemic immune profile at initial diagnosis remains incompletely elucidated. In this study, we characterized the immune landscape of peripheral blood mononuclear cells (PBMCs) from 20 newly diagnosed NKTCL patients and 12 healthy donors using single-cell RNA sequencing and confirmed our results through flow cytometry and PrimeFlow. We identified a distinct proliferative-NK/T (Proli-NK/T) cell subset in NKTCL, characterized by high expression of cell cycle-related genes but lacking a malignant phenotype. Additionally, we observed a reduction in total and classical memory B cells, accompanied by enrichment of apoptosis and cell differentiation signatures. NK cells showed increased expression of HLA class II and activation markers, along with enhanced predicted interactions with CD4⁺ T cells. The decrease of naive CD4⁺ T cells might imply their skewed differentiation into Th1 and Th17 cells, while expansion of granzyme K (GZMK⁺)-expressing CD8⁺ central memory T cells was associated with interferon-γ-driven responses. Patients with a high intracellular EBV load exhibited accumulation of highly cytotoxic CD56^dim_PTPRCAP NK cells and GZMK⁺ GZMB⁺ CD8⁺ effector memory T cells, along with a marked depletion of memory B cells. This implies a correlation between intracellular EBV burden and peripheral immune dysregulation in NKTCL. We have uncovered the dynamic changes in PBMCs of newly diagnosed NK/T cell lymphoma patients and identified specific characteristics in patients with high intracellular EBV levels. Our findings provide new insights into the immunopathogenesis of NKTCL, offering valuable information for immune-based stratification and the development of therapeutic strategies.