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Mesenchymal stromal cells (MSCs) have been widely investigated for their regenerative capacity, anti-inflammatory properties and beneficial immunomodulatory effects across multiple clinical indications. Nevertheless, their widespread clinical utilization is limited by the variability in MSC quality, impacted by donor age, metabolism, and disease. Human induced pluripotent stem cells (hiPSCs) generated from readily accessible donor tissues, are a promising source of stable and rejuvenated MSC but differentiation methods generally require prolonged culture and result in low frequencies of stable MSCs. To overcome this limitation, we have optimized a quick and efficient method for hiPSC differentiation into footprint-free MSCs (human induced MSCs [hiMSCs]) in this study. This method capitalizes on the synergistic action of growth factors Wnt3a and Activin A with bone morphogenetic protein-4 (BMP4), leading to an enrichment of MSC after only 4 days of treatment. These hiMSCs demonstrate a significant upregulation of mesenchymal stromal markers (CD105(+), CD90(+), CD73, and cadherin 11) compared with bone marrow-derived MSCs (bmMSCs), with reduced expression of the pluripotency genes (octamer-binding transcription factor [Oct-4], cellular myelocytomatosis oncogene [c-Myc], Klf4, and Nanog homebox [Nanog]) compared with hiPSC. Moreover, they show improved proliferation capacity in culture without inducing any teratoma formation in vivo. Osteogenesis, chondrogenesis, and adipogenesis assays confirmed the ability of hiMSCs to differentiate into the three different lineages. Secretome analyses showed cytokine profiles compared with bmMSCs. Encapsulated hiMSCs in alginate beads cocultured with osteoarthritic (OA) cartilage explants showed robust immunomodulation, with stimulation of cell growth and proteoglycan production in OA cartilage. Our quick and efficient protocol for derivation of hiMSC from hiPSC, and their encapsulation in microbeads, therefore, presents a reliable and reproducible method to boost the clinical applications of MSCs. IMPACT STATEMENT: In this study, we present a novel, quick, and efficient method for the generation of mesenchymal stromal cells (MSCs) by differentiating human induced pluripotent stem cells in 4 days. The stably differentiatied and homogenous human induced MSCs (hiMSCs) are characterized for gene expression, differentiation, secretome, and immunomodulatory properties. Upon coculture with human osteoarthritic (OA) cartilage explants following encapsulation in microbeads, the hiMSC paracrine factors promote proteoglycan synthesis in the OA explants, demonstrating the potential of these hiMSCs to regenerate and repair cartilage.

Background: Metastasis is the major cause of mortality in breast cancer; however, the molecular mechanisms remain elusive. In our previous study, we demonstrated that S100A7/RAGE mediates breast cancer growth and metastasis by recruitment of tumor-associated macrophages. However, the downstream S100A7-mediated inflammatory oncogenic signaling cascade that enhances breast tumor growth and metastasis by generating the immunosuppressive tumor microenvironment (iTME) has not been studied. In this present study, we aimed to investigate the S100A7 and cPLA2 cross-talk in enhancing tumor growth and metastasis through enhancing the iTME.Methods: Human breast cancer tissue and plasma samples were used to analyze the expression of S100A7, cPLA2, and PGE2 titer. S100A7-overexpressing or downregulated human metastatic breast cancer cells were used to evaluate the S100A7-mediated downstream signaling mechanisms. Bi-transgenic mS100a7a15 overexpression, TNBC C3(1)/Tag transgenic, and humanized patient-derived xenograft mouse models and cPLA2 inhibitor (AACOCF3) were used to investigate the role of S100A7/cPLA2/PGE2 signaling in tumor growth and metastasis. Additionally, CODEX, a highly advanced multiplexed imaging was employed to delineate the effect of S100A7/cPLA2 inhibition on the recruitment of various immune cells.Results: S100A7 and cPLA2 are highly expressed and positively correlated in malignant breast cancer patients. S100A7/RAGE upregulates cPLA2/PGE2 axis in aggressive breast cancer cells. Furthermore, S100A7 is positively correlated with PGE2 in breast cancer patients. Moreover, cPLA2 pharmacological inhibition suppressed S100A7-mediated tumor growth and metastasis in multiple pre-clinical models. Mechanistically, S100A7-mediated activation of cPLA2 enhances the recruitment of immunosuppressive myeloid cells by increasing PGE2 to fuel breast cancer growth and its secondary spread. We revealed that cPLA2 inhibitor mitigates S100A7-mediated breast tumorigenicity by suppressing the iTME. Furthermore, CODEX imaging data showed that cPLA2 inhibition increased the infiltration of CD4+/CD8+ T cells in the TME. Analysis of metastatic breast cancer samples revealed a positive correlation between S100A7/cPLA2 with CD163+ tumor-associated M2-macrophages.Conclusions: Our study shows that cross-talk between S100A7 and cPLA2 plays an important role in enhancing breast tumor growth and metastasis by generating an immunosuppressive tumor microenvironment and reducing infiltration of T cells. Furthermore, S100A7 could be used as a novel non-invasive prognostic marker and cPLA2 inhibitors as promising drugs against S100A7-overexpressing metastatic breast cancer.

Background Continuous low-intensity ultrasound (cLIUS) facilitates the chondrogenic differentiation of human mesenchymal stromal cells (MSCs) in the absence of exogenously added transforming growth factor-beta (TGFβ) by upregulating the expression of transcription factor SOX9, a master regulator of chondrogenesis. The present study evaluated the molecular events associated with the signaling pathways impacting SOX9 gene and protein expression under cLIUS. Methods Human bone marrow-derived MSCs were exposed to cLIUS stimulation at 14 kPa (5 MHz, 2.5 Vpp) for 5 min. The gene and protein expression of SOX9 was evaluated. The specificity of SOX9 upregulation under cLIUS was determined by treating the MSCs with small molecule inhibitors of select signaling molecules, followed by cLIUS treatment. Signaling events regulating SOX9 expression under cLIUS were analyzed by gene expression, immunofluorescence staining, and western blotting. Results cLIUS upregulated the gene expression of SOX9 and enhanced the nuclear localization of SOX9 protein when compared to non-cLIUS-stimulated control. cLIUS was noted to enhance the phosphorylation of the signaling molecule ERK1/2. Inhibition of MEK/ERK1/2 by PD98059 resulted in the effective abrogation of cLIUS-induced SOX9 expression, indicating that cLIUS-induced SOX9 upregulation was dependent on the phosphorylation of ERK1/2. Inhibition of integrin and TRPV4, the upstream cell-surface effectors of ERK1/2, did not inhibit the phosphorylation of ERK1/2 and therefore did not abrogate cLIUS-induced SOX9 expression, thereby suggesting the involvement of other mechanoreceptors. Consequently, the effect of cLIUS on the actin cytoskeleton, a mechanosensitive receptor regulating SOX9, was evaluated. Diffused and disrupted actin fibers observed in MSCs under cLIUS closely resembled actin disruption by treatment with cytoskeletal drug Y27632, which is known to increase the gene expression of SOX9. The upregulation of SOX9 under cLIUS was, therefore, related to cLIUS-induced actin reorganization. SOX9 upregulation induced by actin reorganization was also found to be dependent on the phosphorylation of ERK1/2. Conclusions Collectively, preconditioning of MSCs by cLIUS resulted in the nuclear localization of SOX9, phosphorylation of ERK1/2 and disruption of actin filaments, and the expression of SOX9 was dependent on the phosphorylation of ERK1/2 under cLIUS.

Summary Endothelial cells (ECs) are of great value for cell therapy, tissue engineering, and drug discovery. Obtaining high-quantity and -quality ECs remains very challenging. Here, we report a method for the scalable manufacturing of ECs from human pluripotent stem cells (hPSCs). hPSCs are expanded and differentiated into ECs in a 3D thermoreversible PNIPAAm-PEG hydrogel. The hydrogel protects cells from hydrodynamic stresses in the culture vessel and prevents cells from excessive agglomeration, leading to high-culture efficiency including high-viability (>90%), high-purity (>80%), and high-volumetric yield (2.0 × 107 cells/mL). These ECs (i.e., 3D-ECs) had similar properties as ECs made using 2D culture systems (i.e., 2D-ECs). Genome-wide gene expression analysis showed that 3D-ECs had higher expression of genes related to vasculature development, extracellular matrix, and glycolysis, while 2D-ECs had higher expression of genes related to cell proliferation., Graphical Abstract, Highlights • hPSCs can be differentiated into endothelial cells in 3D thermoreversible hydrogels • The differentiation efficiency is similar to this in 2D cultures • The global gene expression and phenotypes are similar to ECs made in 2D cultures, Endothelial cells (ECs) differentiated from human pluripotent stem cells (hPSCs) are needed in large numbers for regenerative medicine. In this article, Lei and colleagues describe a simple and innovative method for the scalable production of ECs from hPSCs. The method has potential to make ECs broadly available and affordable for various applications.

The primary cilium has been implicated in mechanotransduction, however, its mechanosensory role in transducing signals under low-intensity ultrasound (LIUS) which has the potential to repair fractures and cartilage, remains uninvestigated. This study examined the impact of continuous-wave US, at the cell resonance frequency of 5.0 MHz and pressure amplitude of either 14 or 60 kPa, on the incidence, length and orientation of primary cilium in bovine articular chondrocytes. Visualization of primary cilium with acetylated α-tubulin staining demonstrated that the primary cilium was elongated, bent under US and these changes were reversible. Basal expression of phospho-ERK1/2 was lower in deciliated chondrocytes, thus implicating the role for the primary cilium in transducing signals via the MAPK/ERK pathway. This study demonstrates that the chondrocyte primary cilium is mechanosensitive and responds to US by altering its length and orientation.

Silk protein sericins, in the recent years, find application in cosmetics and pharmaceuticals and as biomaterials. We investigate the potential of sericin, extracted from both mulberryBombyx moriand different non-mulberry sources, namely, tropical tasar,Antheraea mylitta; muga,Antheraea assama; and eri,Samia ricini,as growth supplement in serum-free culture medium. Sericin supplemented media containing different concentrations of sericins from the different species are examined for attachment, growth, proliferation, and morphology of fibrosarcoma cells. The optimum sericin supplementation seems to vary with the source of sericins. The results indicate that all the sericins promote the growth of L929 cells in serum-free culture media; however,S. ricinisericin seems to promote better growth of cells amongst other non-mulberry sericins.

Human mesenchymal stem cells (hMSCs) hold great potential for cellular based therapeutics and tissue engineering applications and their expansion is an interesting prospect due to their low availability from in vivo sources. Therefore, this study investigated the effect of continuous-wave low-intensity ultrasound (LIUS) at 5.0-MHz and 14.0-kPa (