Endothelin-1 reduces catabolic activity of human mesenchymal stem/stromal cells during chondro- and osteo-lineage differentiation

Biomechanical Modulation of Dental Pulp Stem Cell (DPSC) Properties for Soft Tissue Engineering

Dental pulp regeneration strategies frequently result in hard tissue formation and pulp obliteration. The aim of this study was to investigate whether dental pulp stem cells (DPSCs) can be directed toward soft tissue differentiation by extracellular elasticity. STRO-1-positive human dental pulp cells were magnetically enriched and cultured on substrates with elasticities of 1.5, 15, and 28 kPa. The morphology of DPSCs was assessed visually. Proteins relevant in mechanobiology ACTB, ITGB1, FAK, p-FAK, TALIN, VINCULIN, PAXILLIN, ERK 1/2, and p-ERK 1/2 were detected by immunofluorescence imaging. Transcription of the pulp marker genes BMP2, BMP4, MMP2, MMP3, MMP13, FN1, and IGF2 as well as the cytokines ANGPT1, VEGF, CCL2, TGFB1, IL2, ANG, and CSF1 was determined using qPCR. A low stiffness, i.e., 1.5 kPa, resulted in a soft tissue-like phenotype and gene expression, whereas DPSCs on 28 kPa substrates exhibited a differentiation signature resembling hard tissues with a low cytokine expression. Conversely, the highest cytokine expression was observed in cells cultured on intermediate elasticity, i.e., 15 kPa, substrates possibly allowing the cells to act as “trophic mediators”. Our observations highlight the impact of biophysical cues for DPSC fate and enable the design of scaffold materials for clinical pulp regeneration that prevent hard tissue formation.

Exosomal MicroRNA-23-5p Derived from Bone Marrow Mesenchymal Stem Cells Relieves Inflammatory Response in Rheumatoid Arthritis

We aimed to explore the mechanism underlying microRNA-23-5p from exosomes (exo-miR-23-5p) of BMSCs in rheumatoid arthritis (RA). The candidate related genes of miR-23-5p were screened in RA by bioinformatics analysis through gain- and loss-function method along with analysis of histopathological changes in mice and RAC2 expression as well as the level of pro-inflammatory factors. In vivo RA model was established to detect miR-23-5p’s effect on RA. miR-23-5p level was significantly reduced in RA cells and RAC2 was highly expressed. Expression of RAC2 was inhibited and targeted by miR-23-5p in RA. Exo-miR-23-5p treatment effectively alleviated joint destruction, reduced inflammatory factor secretion in tissues and serum, as well as decreased RAC2 expression in RA model. In conclusion, the miR-23-5p in the BMSC-exo delays the inflammatory response in RA, indicating that it might be a new target for treating RA.

Bone Marrow-Derived Mesenchymal Stem Cells (BMSCs)-Exosome Carrying MiRNA-312 Inhibits Sevoflurane-Induced Cardiomyocyte Apoptosis Through Activation of Phosphatidylinositol 3-Kinase/Protein Kinase B (PI3K/AKT) Pathway

This study was to explore the mechanism by how exosomes (exo) derived from BMSCs affects cardiomyocyte apoptosis. BMSCs were isolated and incubated with cardiomyocytes while the cardiomyocytes were exposed to sevoflurane or DMSO treatment. Apoptotic cells were calculated and level of apoptosis related proteins was detected by Western blot. Through transfection with microRNA-(miRNA)-312 inhibitor, we evaluated the effect of BMSC-exo on the sevoflurane-induced apoptosis. Sevoflurane significantly inhibited the viability of cardiomyocytes and induced cardiomyocyte apoptosis. Besides, sevoflurane decreased the expression of miR-312 and enhanced Bax expression in cardiomyocytes through restraining the phosphorylation of MAPK/ERK. Treatment with BMSC-exo, however, activated MAPK/ERK signaling by up-regulating miR-312, thereby inhibiting cardiomyocyte apoptosis, promoting cardiomyocyte proliferation, and elevating the level of Bcl-2. In conclusion, BMSC-exo-derived miR-312 inhibits sevoflurane-induced cardiomyocyte apoptosis by activating PI3K/AKT signaling pathway.

An in vitro chondro-osteo-vascular triphasic model of the osteochondral complex

The generation of engineered models of the osteochondral complex to study its pathologies and develop possible treatments is hindered by the distinctly different properties of articular cartilage and subchondral bone, with the latter characterized by vascularization. In vitro models of the osteochondral complex have been mainly engineered as biphasic constructs containing just cartilage and bone cells, a condition very dissimilar from the in vivo environment. The different cellular components of the osteochondral complex are governed by interacting biochemical signaling; hence, to study the crosstalk among chondrocytes, osteoblasts, and endothelial cells, we have developed a novel triphasic model of the osteochondral tissue interface. Wet-spun poly(ε-caprolactone) (PCL) and PCL/hydroxyapatite (HA) scaffolds in combination with a methacrylated gelatin (gelMA) hydrogel were used as the polymeric backbone of the constructs. The scaffold components were engineered with human bone marrow derived mesenchymal stem cells (hMSCs) and human umbilical vein endothelial cells (HUVECs), and differentiated using a dual chamber microphysiological system (MPS) bioreactor that allows the simultaneous, separate flow of media of different compositions for induced differentiation of each compartment towards a cartilaginous or osseous lineage. Within the engineered Microphysiological Vascularized Osteochondral System, hMSCs showed spatially distinct chondrogenic and osteogenic markers in terms of histology and gene expression. HUVECs formed a stable capillary-like network in the engineered bone compartment and enhanced both chondrogenic and osteogenic differentiation of hMSCs, resulting in the generation of an in vitro system that mimics a vascularized osteochondral interface tissue.