Stem Cells and Development

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with the ability to differentiate into several cell types that hold great promise for therapeutic applications. However, the maintenance of proliferative and stemness capacity following in vitro expansion remains a significant challenge. Triiodothyronine (T3) plays a crucial role in embryogenesis and fetal development, yet the knowledge of its effects on MSCs’ survival and function is limited. Here, we investigate the impact of T3 treatment in bone marrow (BM)-MSCs and adipose tissue (AT)-MSCs isolated from C57BL/6J mice, to assess stemness preservation, proliferation, and gene expression during in vitro expansion. To this end, MSCs were treated with T3 at various concentrations for 24 and 48 h, and thyroid hormone-responsive and stemness-related genes expression, proliferation, clonogenic potential, and surface marker profiles were analyzed using reverse transcript quantitative PCR, Cell Counting Kit-8, colony-forming unit-fibroblast assays, and flow cytometry. Our results show that T3 exposure did not affect variability or clonogenic potential of BM-MSCs and AT-MSCs, and the expression of T3-responsive genes is activated by distinct time- and dose-dependent responses to T3 in AT-MSCs and BM-MSCs. However, in BM-MSCs, a transient increase in pluripotent markers was observed. Conversely, AT-MSCs exhibited sustained increases in Nano-g, Sca-1, and Ssea-1, particularly at 10 and 100 nM. Collectively, we observed that T3 exposure during in vitro expansion enhanced stemness features in MSCs. This finding was more prominent in AT-MSCs compared with BM-MSCs. The data suggest that T3 exposure during AT-MSCs expansion could be a valuable tool to increase the yield and stemness of these MSCs, facilitating their therapeutic use.

In pancreatic cancer, increased collagen I impairs the efficacy of gemcitabine; however, the role of gemcitabine itself in collagen I accumulation remains unclear. This study aims to explore the mechanism of gemcitabine-induced fibrosis and provide new insights to enhance its therapeutic efficacy. We analyzed COL1A1 expression in pancreatic cancer patient tumor tissues and found that gemcitabine treatment upregulated COL1A1 expression. Subsequently, cancer-associated fibroblasts (CAFs) were modeled by inducing human adipose-derived mesenchymal stem cells with tumor-derived exosomes. Using the autophagy inhibitor chloroquine (CQ) and the protein kinase B (AKT) activator SC79, we demonstrated that gemcitabine downregulated P62 expression and upregulated LC3BII, Beclin-1 expression, inducing autophagy in CAFs via decreasing AKT phosphorylation, which further led to collagen I accumulation. In addition, gemcitabine combined with CQ enhanced cell death in both CAFs and tumor cells, while inhibiting tumor cell proliferation and migration. In animal models, this combination therapy reduced gemcitabine-induced autophagy and collagen I deposition, contributing to delayed tumor growth. Collectively, gemcitabine upregulates collagen I by inducing CAF autophagy via reducing AKT phosphorylation. Targeting CAF autophagy can reduce collagen deposition, offering a promising strategy to improve the therapeutic efficacy of gemcitabine in pancreatic cancer.

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease lacking effective therapies. Mesenchymal stem cells (MSCs) show therapeutic potential; however, their efficacy is often limited. Aggregates of human umbilical cord-derived MSCs (hUC-MSCs) were generated using AggreWell™ 400 plates. The paracrine and mechanotransduction profiles of three-dimensional (3D)-MSCs were assessed by reverse transcription quantitative PCR and western blot. MASH was induced in C57BL/6J mice via a 32-week high-fat, high-fructose, and high-cholesterol (HFFC) diet, followed by tail vein injection of PBS, two-dimensional (2D)-MSCs, or 3D-MSCs. Therapeutic efficacy was evaluated via histological staining, immunohistochemistry, and serum biochemistry. RNA sequencing was performed to elucidate underlying molecular mechanisms. Under 3D culture conditions, hUC-MSCs formed relatively uniform aggregates with preserved MSC phenotypic characteristics after recovery. 3D aggregate culture enhanced the paracrine, anti-inflammatory, mechanosensitive phenotype, pro-survival, and matrix-remodeling properties of hUC-MSCs, evidenced by increased expression of hepatocyte growth factor, tumor necrosis factor-stimulated gene 6, cyclooxygenase-2, prostaglandin E synthase, B-cell lymphoma-2, and mechanotransduction-related genes, accompanied by elevated matrix metalloproteinase-2 (MMP2) and MMP9 expression in vitro. In vivo fluorescence imaging showed no significant difference in early hepatic retention between intravenously infused single-cell hUC-MSCs and 3D aggregates. In the MASH model, 3D-MSCs more effectively reduced lipid accumulation, collagen deposition, α-smooth muscle actin, hepatomegaly, and serum total cholesterol levels compared with 2D-MSCs. Moreover, 3D-MSCs enhanced the expression of anti-inflammatory interleukin-10, while suppressing inducible nitric oxide synthase. 3D-MSC therapy induced broader transcriptional remodeling than conventional MSCs, with enrichment in extracellular matrix organization, focal adhesion, and the phosphatidylinositol 3-kinase-protein kinase B signaling pathway. Consistently, western blot analysis showed that 3D-MSCs more effectively reduced hepatic p-PI3K and p-AKT levels, indicating stronger inhibition of PI3K/AKT pathway activation. 3D aggregate culture enhances the therapeutic efficacy of hUC-MSCs against MASH, supporting its translational potential for MSC-based liver therapy.