Glycyrrhizic Acid Promotes Osteogenic Differentiation of Human Bone Marrow Stromal Cells by Activating the Wnt/ß-Catenin Signaling Pathway.

Glycyrrhizic acid (GA) is a major triterpene glycoside isolated from liquorice root that has been shown to inhibit osteoclastogenesis. However, there have been no reports regarding the effect of GA on osteogenic differentiation. Therefore, this study was performed to explore the effects and mechanism of action of GA on osteogenesis. A CCK-8 array was used to assess cell viability. The osteogenic capability was investigated by real-time quantitative PCR, western blotting and immunofluorescence analyses. ALP staining and ARS were used to evaluate ALP activity and mineralization, respectively. GA-GelMA hydrogels were designed to verify the therapeutic effects of GA in vivo by radiographic analysis and histological evaluation. Our results show that GA had no significant influence on the viability or proliferation of human bone marrow stromal cells (hBMSCs). GA promoted osteogenic differentiation and enhanced calcium deposition. Furthermore, ratio of active ß-catenin and total ß-catenin protein increased after treatment with GA. Wnt/catenin signaling inhibitor partially attenuated the effects of GA on osteogenic differentiation. In a mouse femoral fracture model, GA-GelMA hydrogels accelerated bone healing. Our results show that GA promotes the osteogenic differentiation of hBMSCs by modulating the Wnt/ß-catenin signaling pathway. GA-GelMA hydrogels promoted bone fracture healing. GA has potential as a cost-effective treatment of bone defects.

Low-dose IL-34 has no effect on osteoclastogenesis but promotes osteogenesis of hBMSCs partly via activation of the PI3K/AKT and ERK signaling pathways.

BACKGROUND: Inflammatory microenvironment is significant to the differentiation and function of mesenchymal stem cells (MSCs). It evidentially influences the osteoblastogenesis of MSCs. IL-34, a newly discovered cytokine, playing a key role in metabolism. However, the research on its functional role in the osteogenesis of MSCs was rarely reported. Here, we described the regulatory effects of low-dose IL-34 on both osteoblastogenesis and osteoclastogenesis. METHODS: We performed the osteogenic effects of hBMSCs by exogenous and overexpressed IL-34 in vitro, so were the osteoclastogenesis effects of mBMMs by extracellular IL-34. CCK-8 was used to assess the effect of IL-34 on the viability of hBMSCs and mBMMs. ALP, ARS, and TRAP staining was used to evaluate ALP activity, mineral deposition, and osteoclastogenesis, respectively. qRT-PCR and Western blotting analysis were performed to detect the expression of target genes and proteins. ELISA was used to evaluate the concentrations of IL-34. In vivo, a rat tibial osteotomy model and an OVX model were established. Radiographic analysis and histological evaluation were performed to confirm the therapeutic effects of IL-34 in fracture healing and osteoporosis. Statistical differences were evaluated by two-tailed Student's t test, one-way ANOVA with Bonferroni's post hoc test, and two-way ANOVA with Bonferroni multiple comparisons post hoc test in the comparison of 2 groups, more than 2 groups, and different time points of treated groups, respectively. RESULTS: Promoted osteoblastogenesis of hBMSCs was observed after treated by exogenous or overexpressed IL-34 in vitro, confirmed by increased mineral deposits and ALP activity. Furthermore, exogenous or overexpressed IL-34 enhanced the expression of p-AKT and p-ERK. The specific AKT and ERK signaling pathway inhibitors suppressed the enhancement of osteoblastogenesis induced by IL-34. In a rat tibial osteotomy model, imaging and histological analyses testified the local injection of exogenous IL-34 improved bone healing. However, the additional IL-34 has no influence on both osteoclastogenesis of mBMMs in vitro and osteoporosis of OVX model of rat in vivo. CONCLUSIONS: Collectively, our study demonstrate that low-dose IL-34 regulates osteogenesis of hBMSCs partly via the PIK/AKT and ERK signaling pathway and enhances fracture healing, with neither promoting nor preventing osteoclastogenesis in vitro and osteoporosis in vivo.

Withanolide B promotes osteogenic differentiation of human bone marrow mesenchymal stem cells via ERK1/2 and Wnt/ß-catenin signaling pathways.

BACKGROUND: The treatment of bone defects has always been a problem for clinicians. In recent years, research on human bone mesenchymal stem cells (hBMSCs) has found that promoting their osteogenic differentiation could be a useful therapeutic strategy for bone healing. Previous studies have been reported that Withania somnifera Dunal inhibits osteoclastogenesis by inhibiting the NF-κB signaling pathway. Withanolide B is an active component of W. somnifera Dunal, but its role in osteogenic differentiation of hBMSCs remains unknown. Here, we performed a preliminary study on the role of Withanolide B in promoting osteogenic differentiation and its possible mechanism. METHODS: We investigated the effect of Withanolide B on osteogenic differentiation of hBMSCs in vitro and in vivo. The effect of Withanolide B on the activity of hBMSCs was verified by CCK-8 assay and quantitative Real-time polymerase chain reaction (qPCR) and Western blotting analysis were used to verify the effect of Withanolide B on osteogenic differentiation-specific genes and proteins. The effect of Withanolide B on ALP activity and mineral deposition was verified by ALP and ARS staining. We then used a rat tibial osteotomy model to observe the effect of Withanolide B on bone healing. RESULTS: Withanolide B is noncytotoxic to hBMSCs and can effectively promote their osteogenic differentiation. Moreover, we found that Withanolide B can regulate the osteogenic differentiation of hBMSCs through the ERK1/2 and Wnt/ß-catenin signaling pathways. When inhibitors of the ERK1/2 and Wnt/ß-catenin signaling pathways were used, the enhancement of osteogenic differentiation induced by Withanolide B was attenuated. Withanolide B also effectively promoted bone healing in the rat tibial osteotomy model. CONCLUSIONS: Our results suggest that Withanolide B can promote the osteogenic differentiation of hBMSCs through the ERK1/2 and Wnt/ß-catenin signaling pathways and can effectively promote bone defect healing.

An injectable recombinant human milk fat globule-epidermal growth factor 8-loaded copolymer system for spinal cord injury reduces inflammation through NF-κB and neuronal cell death.

Spinal cord injury (SCI) is a common disease and a major cause of paralysis, carrying much burden around the world. Despite the progress made with growth factors therapy, the response rate of acute SCI treatment still remains unsatisfactory, due largely to complex and severe inflammatory reactions. Herein, we prepare a MFG-E8-loaded copolymer system-based anti-inflammation therapy for SCI treatment. It is shown that the MFG-E8-loaded copolymer system can decrease pro-inflammatory cytokine expression and neuron death. In a rat model of crush-caused SCI, the copolymer system shows significant therapeutic efficacy by ameliorating inflammation, decreasing fibrotic scar, promoting myelin regeneration and suppressing overall SCI severity.

Bioactive Elastic Scaffolds Loaded with Neural Stem Cells Promote Rapid Spinal Cord Regeneration.

Despite decades of research, spinal cord injury (SCI) still causes irreparable damage to the human body. Key challenges that hinder the regeneration and extension of neurons following SCI must be overcome, including the overexpressed glial scar formation and strong inflammatory responses in lesion tissue. Transplantation of neural stem cells (NSCs) represents a promising therapeutic method due to its beneficial roles like growth factor secretion and anti-inflammation. However, NSCs usually differentiate into astrocytes, which is considered as one potential limitation of current NSC therapy. Herein, we fabricate an elastic poly(sebacoyl diglyceride) (PSeD) scaffold to mimic the mechanical properties of the natural spinal cord. The PSeD scaffold is coated with poly(sebacoyl diglyceride)-isoleucine-lysine-valine-alanine-valine-serine (PSeD-IKVAVS) to create a bioactive interface. The core point of this topic is divided into two parts. First, PSeD is a bioelastomer and its mechanical properties are similar to those of the natural spinal cord. This feature reduces the direct stimulation to the spinal cord tissue by the elastomer and then reduces the immune response or resistance caused by the host spinal cord tissue. Second, the IKVAVS peptide modifies PSeD to create a bioactive interface to support NSC growth and differentiation. In the in vivo study, the number of CD68-positive macrophages decreased in the PSeD-IKVAVS/NSC group compared to that in the SCI group (20% vs 60%). The low inflammation induced by the scaffold was beneficial to NSCs, resulting in increased locomotor recovery, as indicated by the increased Basso-Beattie-Bresnahan score (5, the average score in the PSeD-IKVAVS/NSC group, vs 2, the average score in the SCI group). Based on the above two characteristics, a PSeD-IKVAVS bioelastomer is fabricated, which provides a beneficial and bioactive microenvironment for NSCs after transplantation.

Dihydroartemisinin Promotes the Osteogenesis of Human Mesenchymal Stem Cells via the ERK and Wnt/ß-Catenin Signaling Pathways.

Dihydroartemisinin (DHA), which is considered to be one of the active compounds within Artemisia annua, has extensively been used in recent years as the most effective drug against malaria, having many biological functions including anticancer, antifungal, and immunomodulatory activities. However, DHA plays a role in the regulation of the proliferation and human mesenchymal stem cells (hMSCs) osteogenic differentiation that remains unknown. We explored DHA's effect on hMSCs' proliferation as well as the osteogenic differentiation, together with its underlying mechanisms of action. We showed that DHA enhanced osteogenic differentiation but had no significant effect on hMSCs' proliferation. It probably exerted its functions through the signaling pathways of ERK1/2 as well as Wnt/ß. Because DHA has low toxicity and costs, it might be regarded as an important drug for fracture treatment and tissue engineering.