Aloin promotes osteogenesis of bone-marrow-derived mesenchymal stem cells via the ERK1/2-dependent Runx2 signaling pathway.

Osteoporosis is characterized by low bone mass and the degeneration of bone structure, conditions which increase the risk of fracture. Aloin has been shown to affect bone metabolism, but its role in osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) remains unclear. The aim of our study was to determine whether aloin promotes the proliferation and osteogenic differentiation of BMSCs and, if so, whether it acts via activation of the ERK1/2-Runx2 signaling pathway. We found that the different concentrations of aloin tested had no obvious cytotoxic effects on the viability of BMSCs. Under osteogenic induction conditions, aloin increased cellular alkaline phosphatase activity, promoted BMSC mineralization, and increased osteogenic-related gene expression. In addition, treating the BMSCs with the signal transduction inhibitor PD98059 (ERK1/2) effectively attenuated Runx2 activation in these cells and also suppressed osteoblastic differentiation. Overall, our study demonstrates that aloin promotes osteogenic differentiation of BMSCs through activation of the ERK1/2-Runx2 signaling pathway.

Biomineralization improves mechanical and osteogenic properties of multilayer-modified PLGA porous scaffolds.

Poly-(lactide-co-glycolide acid) (PLGA) has been widely investigated as scaffold material for bone tissue engineering owing to its biosafety, biodegradability, and biocompatibility. However, the bioinert surface of PLGA may fail in regulating cellular behavior and directing osteointegration between the scaffold and the host tissue. In this article, oxidized chondroitin sulfate (oCS) and type I collagen (Col I) were assembled onto PLGA surface via layer by layer technique (LbL) as an adhesive coating for the attachment of inorganic minerals. The multilayer-modified PLGA scaffold was mineralized in vitro to ensure the deposition of nanohydroxyapatite (nHAP). It was found that nHAP crystals were more uniformly and firmly attached on the multilayer-modified PLGA as compared with the pure PLGA scaffold, which remarkably improved PLGA surface and mechanical properties. Additionally, in vitro biocompatibility of PLGA scaffold, in terms of bone mesenchymal stem cells (BMSCs) attachment, spreading and proliferation was greatly enhanced by nHAP coating and multilayer deposition. Furthermore, the fabricated composite scaffold also shows the ability to promote the osteogenic differentiation of BMSCs through the up-regulation of osteogenic marker genes. Thus, this novel biomimetic composite scaffold might achieve a desirable therapeutic result for bone tissue regeneration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2714-2725, 2018.

Toxoplasma gondii induces autophagy and apoptosis in human umbilical cord mesenchymal stem cells via downregulation of Mcl-1.

Autophagy and apoptosis are critical for controlling Toxoplasma gondii (T. gondii) infection. T. gondii infection during pregnancy can damage the fetus and cause birth defects; however, the molecular mechanisms of this process are poorly understood. This study aims to determine the activities of autophagy and apoptosis as well as their regulatory mechanisms during T. gondii infection by using human umbilical cord mesenchymal stem cells (hUC-MSCs) as a model of congenital diseases. LC3B, a hallmark protein of autophagy was incrementally upregulated with the infection duration, whereas p62 was downregulated in T. gondii-infected hUC-MSCs. Concurrent to this result, the invasion of T. gondii into hUC-MSCs increased in a time-dependent manner. The expression levels of Bcl-2 family proteins including Bcl-2, Bcl-xL, Bim, Bax, Bid and Bak were not altered; however, Mcl-1 levels in hUC-MSCs were dramatically decreased upon T. gondii infection. In addition, at 24 h post-infection, cleaved PARP and cleaved caspase-3 protein levels were elevated in hUC-MSCs. Importantly, Mcl-1 overexpression reduced the levels of autophagy- and apoptosis-related proteins in T. gondii-infected hUC-MSCs. Mcl-1 proteins were primarily expressed in the fraction containing mitochondria and strongly interacted with Beclin-1 under normal conditions; however, these interactions were remarkably attenuated by T. gondii infection. These results suggest that mitochondrial Mcl-1 is an essential signaling mediator regulating the activation of autophagy and apoptosis during T. gondii infection.

Glycogen synthase kinase 3 (GSK3)-inhibitor SB216763 promotes the conversion of human umbilical cord mesenchymal stem cells into neural precursors in adherent culture.

The ability to generate neural progenitor cells from human umbilical cord mesenchymal stem cells (hUC-MSCs) has provided an option to treat neurodegenerative diseases. To establish a method for this purpose, we characterized the early neural markers of hUC-MSCs-derived cells under different conditions. We found that neither the elimination of signals for alternative fate nor N2 supplement was sufficient to differentiate hUC-MSCs into neural precursor cells, but the GSK3 inhibitor SB216763 could promote an efficient neural commitment of hUC-MSCs. The results indicated that Wnt/ß-catenin might play an important role during the early neural differentiation of hUC-MSCs. Here, we report a method for hUC-MSCs to commit efficiently into a neural fate within a short period of time. This protocol provides an efficient method for hUC-MSCs-based neural regeneration.

Effect of Mesenchymal Stem Cells and Platelet-Rich Plasma on the Bone Healing of Ovariectomized Rats.

We evaluated the efficacy of platelet-rich plasma (PRP) in combination with allogeneic bone marrow mesenchymal stem cells (BMSCs) for the treatment of osteoporotic bone defects in an ovariectomized rat model. By day 42 after injury, in vivo microcomputed tomography (micro-CT) imaging revealed that bone defects of control rats and ovariectomized rats treated with PRP and BMSCs were completely repaired, whereas those of ovariectomized rats treated with PRP or BMSCs alone exhibited slower healing. Histological data were consistent with these results. We also assessed changes to bone trabeculae in the proximal tibial growth plate. In ovariectomized rats treated with PRP or with a combination of PRP and BMSCs, the trabecular connectivity densities (Conn.D), bone volume ratios (BV/TV), and numbers (Tb.N) in the defect areas increased significantly from day 7 to day 42. These results indicate that PRP treatment enhances bone microarchitecture in osteoporosis. Moreover, expression levels of osteogenesis-specific marker genes including RUNX2, OSX, and OPN were significantly upregulated in rats treated with PRP and BMSCs compared to those of other groups. Thus, we conclude that treatment with PRP combined with BMSCs significantly promotes healing of osteoporotic bone defects. This study provides an alternative strategy for the treatment of osteoporotic bone loss.

Poly (L-lactic acid) porous scaffold-supported alginate hydrogel with improved mechanical properties and biocompatibility.

PURPOSE: Polymer porous scaffolds and hydrogels have been separately employed and explored for a wide range of applications including cell encapsulation, drug delivery, and tissue engineering. METHODS: In this study, a three-dimensional poly (L-lactic acid) (PLLA) scaffold with interconnected and homogeneously distributed pores was fabricated to support the alginate hydrogel (Alg). The gels were filled into the porous scaffold, which acted as an analogue of native extracellular matrix (ECM) for entrapment of cells within a support of predefined shape. The mechanical strength of the composite scaffold was characterized by compression testing. The chondrocyte behavior in the scaffold was determined by inverted microscopy, scanning electron microscopy (SEM) and MTT viability assay. The repair efficiency of such a composite scaffold was further investigated in dog spinal defects by histological evaluation after implantation for 4 weeks. RESULTS: Results showed that the composite scaffold possessed superior mechanical properties and hierarchical porous structure in comparison to pure Alg. Cell culture revealed that the cells presented a specific cartilage status in the composite scaffold in line with higher adherence and proliferation ratio. The histological analyses suggested that the composite scaffold substantially promotes its integration in the host tissue accompanied with a low inflammatory reaction and new tissue formation. CONCLUSIONS: The method thus provides a useful pathway for scaffold preparation that can simultaneously achieve suitable mechanical properties and good biocompatibility.