Molecular impacts of photobiomodulation on bone regeneration: A systematic review.

Photobiomodulation (PBM) encompasses a light application aimed to increase healing process, tissue regeneration, and reducing inflammation and pain. PBM is specifically aimed to modify the expression of cellular molecules; however, PBM impacts on cellular and molecular pathways especially in bone regenerative medicine have been investigated in scattered different studies. The purpose of the current study is to systematically review evidence on molecular impact of PBM on bone regeneration. A comprehensive electronic search in Medline, Scopus, EMBASE, EBSCO, Cochrane library, web of science, and google scholar was conducted from January 1975 to October 2018 limited to English language publications on administrations of photobiomodulation for bone regeneration which evaluated biological factors. In addition, hand search of selected journals was done to retrieve all articles. This systematic review was performed based on PRISMA guideline. Among these studies, five articles reported in vitro results, twelve articles were in vivo, and three of them were clinical trials. The data tabulated according to the type of markers (osteogenic markers, angiogenic markers, growth factors, and inflammation mediators). PBM's effects depend on many parameters which energy density is more important than the others. PBM can significantly enhance expression of osteocalcin, collagen, RUNX-2, vascular endothelial growth factor, bone morphogenic proteins, and COX-2. Although since the heterogeneity of the studies and their limitations, an evidence-based decision for definite therapeutic application of PBM is still unattainable, the findings of our review can help other researchers to ameliorate their study design and elect more efficient approach for their investigation.

[Effect of Hydroxy Safflower Yellow A on glucocorticoid-induced bone marrow mesenchymal stem cells osteogenic differentiation].

OBJECTIVE: To observe the effect of Hydroxy Safflower Yellow A (HSYA) on the expression of osteogenic markers, such as alkaline phosphatase, Cbf(alpha)l and type I collagen, and explore the mechanism of HSYA in the prevention and treatment of glucocorticoid-induced ischemic necrosis of femoral head. METHODS: Fifteen healthy and adult New Zealand white rabbits were collected and weighted 0.9 to 1.3 kg. The rabbits were injected abdominally with anesthetic drugs, then received marrow cavity puncture of tibia and anterior superior iliac spine to get bone marrow blood. Rabbits bone marrow mesenchymal stem cells (BMSCs) were separated from the bone marrow blood, cultured in vitro and passaged. The 3rd generation of BMSCs which had good growth condition were randomly divided into blank group, model group and HSYA groups with different doses. The BMSCs in model group were treated with high dose of dexamethasone to induce adipogenic differentiation of cells cultured in vitro, and inhibit osteogenic differentiation. The BMSCs in HSYA groups received high dose of dexamethasone and different concentrations of HSYA simultaneously. The blank group received not any special handling. After a week,the expressions of alkaline phosphatase, Cbf(alpha)l and type I collagen mRNA were detected. RESULTS: The alkaline phosphatase activity was significantly decreased in BMSCs of the model group as compared with the blank group (P < 0.01), and the expression of Cbf(alpha)l and type I collagen mRNA were also decreased significantly (P<0.01). The alkaline phosphatase activity was significantly increased in BMSCs of each HSYA group as compared with the model group (P < 0.05 or P < 0.01), and the expression of Cbf(alpha)l and type I collagen mRNA were also increased significantly (P < 0.05 or P < 0.01). CONCLUSION: The mechanism of HSYA may be related to the effect of antagonism to the reduced osteogenic differentiation induced by glucocorticoid.

YY1 represses the transcriptional activity of Runx2 in C2C12 cells.

Runx2 is a major transcription factor that induces osteoblast differentiation by bone morphogenetic proteins (BMPs). Conversely, YY1 is a transcription factor that inhibits BMP2-induced cell differentiation. Until now, there has been no understanding of how osteoblast differentiation by Runx2 and YY1 is regulated. In this study we focused on the relationship between Runx2 and YY1. We confirmed that alkaline phosphatase staining is repressed by YY1. Runx2 interacted with YY1 through Runt and the C-terminus domain of Runx2. YY1 markedly repressed the Runx2-mediated enhancement of transcriptional activity on the osteocalcin and alkaline phosphatase promoters. Knockdown of YY1 enhanced BMP2- and Runx2-induced osteoblast differentiation. YY1 decreased Runx2 DNA binding affinity. The results indicate that YY1 represses osteoblast differentiation by an interaction with Runx2 and inhibits the transcriptional activity of Runx2.

Panax notoginseng saponins promotes proliferation and osteogenic differentiation of rat bone marrow stromal cells.

AIM OF THE STUDY: Panax notoginseng saponins (PNS) is the main effective component of Panax notoginseng, have various pharmacologic activities such as antioxidant, anti-inflammatory, and estrogen-like bioactivities, have been shown to be an effective agent on anti-osteoporosis. Bone marrow stromal cells (BMSCs) play a crucial homeostatic role in skeletal modeling and remodeling due to their capability to differentiate into osteooblasts. Whether PNS has effect on osteogenic differentiation of BMSCs are unknown. This study was designed to investigate the effects of PNS on the proliferation and osteogenic differentiation of BMSCs in vitro. MATERIALS AND METHODS: When BMSCs cultivated in the basal medium or the osteogenic induction medium (OS with or without PNS), cell proliferation was analyzed using an MTT assay, the mineralization was assessed using Alizarin red S staining, the alkaline phosphatase activity was measured using a commercial kit, the mRNA level of osteogenic gene and PPARγ2 gene were determined using RT-PCR, the protein level of PPARγ2 was analyzed by Western blotting. RESULTS: BMSCs cultured in the basal medium with PNS caused a significant increase in proliferation. PNS treatment increased ALP activity, Alizarin red S staining and mRNA level of ALP, Cbfa 1, OC, and BSP, whereas decreased the mRNA level and protein expression of PPARγ2 during osteogenic induction. In addition, the effects of PNS treatment were dose-dependent relationship. CONCLUSION: PNS could stimulate BMSCs proliferation and promote their osteogenic differentiation by up-regulation expression of osteogenic marker gene and down-regulation expression of adipogenic marker gene in a dose-dependent manner. Thus, PNS may play an important therapeutic role in osteoporosis patients by improving osteogenic differentiation of BMSCs.

Short bouts of mechanical loading are as effective as dexamethasone at inducing matrix production by human bone marrow mesenchymal stem cell.

Dexamethasone (Dex) is used widely to induce differentiation in human mesenchymal stem cells (hMSCs); however, using a pharmaceutical agent to stimulate hMSC differentiation is not the best choice for engineered tissue transplantation due to potential side-effects. The goal of the present study was to investigate the effects of dynamic compressive loading on differentiation and mineralized matrix production of hMSCs in 3D polyurethane scaffolds, using a loading regimen previously shown to stimulate mineralised matrix production of mature bone cells (MLO-A5). hMSCs were seeded in polyurethane scaffolds and cultured in standard culture media with or without Dex. Cell-seeded scaffolds were compressed at 5% global strain for 2 h on day 9 and then every 5 days in a media-filled sterile chamber. Samples were tested for mRNA expression of alkaline phosphatase (ALP), osteopontin (OPN), collagen type 1 (col 1) and runt-related transcription factor-2 (RUNX-212 h) after the first loading, cell viability by MTS assay and alkaline phosphatase activity at day 12 of culture and cell viability, collagen content by Sirius red and calcium content by alizarin red at day 24 of culture. Neither Dex nor loading had significant effects on cell viability. Collagen content was significantly higher (p<0.01) in the loaded group compared with the non-loaded group in all conditions. There was no difference in ALP activity or the amount of collagen and calcium produced between the non-loaded group supplemented with Dex and the loaded group without Dex. We conclude that dynamic loading has the ability to stimulate osteogenic differentiation of hMSC in the absence of glucocorticoids.

Icariin isolated from Epimedium pubescens regulates osteoblasts anabolism through BMP-2, SMAD4, and Cbfa1 expression.

Epimedii herba is one of the most frequently used herbs in formulas prescribed for the treatment of osteoporosis in China. The main active flavonoid glucoside extracted from Epimedium pubescens is Icariin, which has been reported to enhance bone healing and reduce osteoporosis occurrence. However, the detailed molecular mechanisms remain unclear. In this present study, we examine the molecular mechanisms of icariin by using primary osteoblast cell cultures obtained from adult mice. The osteoblast cells were harvested from 8-month old female Imprinting Control Region (ICR) mice. The effects of icariin stimulation on the proliferation, differentiation and maturation of osteoblasts were examined. The production of nitric oxide (NO) and caspase-3 were analyzed, along with the gene expressions of bone morphogenetic protein-2 (BMP-2), SMAD4, Cbfa1/Runx2, OPG, and RANKL. The viability of the osteoblasts reached its maximum at 10(-8)M icariin. At this concentration, icariin increased the proliferation and matrix mineralization of osteoblasts and promoted NO synthesis. With icariin treatment, the BMP-2, SMAD4, Cbfa1/Runx2, and OPG gene expressions were up-regulated; the RANKL gene expression was however down-regulated. Concurrent treatment involving the BMP antagonist (Noggin) or the NOS inhibitor (L-NAME) diminished the icariin-induced cell proliferation, ALP activity, NO production, as well as the BMP-2, SMAD4, Cbfa1/Runx2, OPG, RANKL gene expressions. In this study, we demonstrate that in vitro icariin is a bone anabolic agent that may exert its osteogenic effects through the induction of BMP-2 and NO synthesis, subsequently regulating Cbfa1/Runx2, OPG, and RANKL gene expressions. This effect may contribute to its action on the induction of osteoblasts proliferation and differentiation, resulting in bone formation.