Local administration of nuclear factor of activated T cells (NFAT) c1 inhibitor to suppress early resorption and inflammation induced by bone morphogenetic protein-2

MicroRNA-151a-3p Functions in the Regulation of Osteoclast Differentiation: Significance to Postmenopausal Osteoporosis

BACKGROUND

Studies have found the pivotal role of miRNAs in the progression of postmenopausal osteoporosis (OP). However, the function of miRNAs in OP is unclear. This study aimed to explore the biological functions of microRNA-151a-3p in OP.

METHODS

RT-qPCR was employed to assess the expression of microRNA-151a-3p in serum isolated from OP patients and healthy controls. Dual-energy X-ray absorptiometry (DXA) was used to measure the bone mineral density (BMD) of the lumbar spine. The expression levels of c-Fos, NFATc1, and TRAP were tested by Western blot. Ovariectomized (OVX) rats were treated with antago microRNA-151a-3p or antago NC, and then serum and lumbar vertebrae were collected for ELISA and bone histomorphology analysis.

RESULTS

The expression of microRNA-151a-3p in postmenopausal women with osteoporosis was significantly up-regulated, and microRNA-151a-3p level was negatively correlated with BMD. During osteoclastogenesis, microRNA-151a-3p level was obviously increased. Overexpression of microRNA-151a-3p promoted the differentiation of RANKL-induced THP-1 and RAW264.7 cells into osteoclasts, whereas silencing of microRNA-151a-3p resulted in the opposite results. Silencing of microRNA-151a-3p in OVX rats altered osteoclastogenesis-related factors and raised BMD.

CONCLUSION

MicroRNA-151a-3p could partly regulate osteoporosis by promoting osteoclast differentiation, and miRNA-151a-3p could be a potential therapeutic target for postmenopausal osteoporosis.

Concentration-dependent effects of latex F1-protein fraction incorporated into deproteinized bovine bone and biphasic calcium phosphate on the repair of critical-size bone defects

F1-protein fraction (F1) is a natural bioactive compound extracted from the rubber tree, Hevea brasiliensis, and has been recently studied for its therapeutic potential in wound healing. In this study, we investigated the concentration-dependent effects of F1 (0.01%, 0.025%, 0.05%, and 0.1%) incorporated into deproteinized bovine bone (DBB) and porous biphasic calcium phosphate (pBCP), on the repair of rat calvarial critical-size bone defects (CSBD). The defects were analyzed by 3D-microtomography and 2D-histomorphometry at 12 weeks postsurgery. The binding efficiency of F1 to pBCP (96.3 ± 1.4%) was higher than that to DBB (67.7 ± 3.3%). In vivo analysis showed a higher bone volume (BV) gain in all defects treated with DBB (except in 0.1% of F1) and pBCP (except in 0.05% and 0.1% of F1) compared to the CSBD without treatment/control group (9.96 ± 2.8 mm³ ). DBB plus 0.025% F1 promoted the highest BV gain (29.7 ± 2.2 mm³ , p < .0001) compared to DBB without F1 and DBB plus 0.01% and 0.1% of F1. In the pBCP group, incorporation of F1 did not promote bone gain when compared to pBCP without F1 (15.9 ± 4.2 mm³ , p > .05). Additionally, a small BV occurred in defects treated with pBCP plus 0.1% F1 (10.4 ± 1.4 mm^3, p < .05). In conclusion, F1 showed a higher bone formation potential in combination with DBB than with pBCP, in a concentration-dependent manner. Incorporation of 0.25% F1 into DBB showed the best results with respect to bone formation/repair in CSBD. These results suggest that DBB plus 0.25% F1 can be used as a promising bioactive material for application in bone tissue engineering.

RNA-seq reveals downregulated osteochondral genes potentially related to tibia bacterial chondronecrosis with osteomyelitis in broilers

Background

Bacterial chondronecrosis with osteomyelitis (BCO) develops in the growth plate (GP) of the proximal femur and tibia and is initiated by damage to the less mineralized chondrocytes followed by colonization of opportunistic bacteria. This condition affects approximately 1% of all birds housed, being considered one of the major causes of lameness in fast growing broilers. Although several studies have been previously performed aiming to understand its pathogenesis, the molecular mechanisms involved with BCO remains to be elucidated. Therefore, this study aimed to generate a profile of global differential gene expression involved with BCO in the tibia of commercial broilers, through RNA sequencing analysis to identity genes and molecular pathways involved with BCO in chickens.

Results

Our data showed 192 differentially expressed (DE) genes: 63 upregulated and 129 downregulated in the GP of the tibia proximal epiphysis of BCO-affected broilers. Using all DE genes, six Biological Processes (BP) were associated with bone development (connective tissue development, cartilage development, skeletal system development, organ morphogenesis, system development and skeletal system morphogenesis). The analyses of the upregulated genes did not indicate any significant BP (FDR < 0.05). However, with the downregulated genes, the same BP were identified when using all DE genes in the analysis, with a total of 26 coding genes explaining BCO in the tibia: ACAN, ALDH1A2, CDH7, CHAD, CHADL, COL11A1, COMP, CSGALNACT1, CYR61, FRZB, GAL3ST1, HAPLN1, IHH, KIF26B, LECT1, LPPR1, PDE6B, RBP4A, SERINC5, SFRP1, SOX8, SOX9, TENM2, THBS1, UCHL1 and WFIKKN2. In addition, seven transcription factors were also associated to BCO: NFATC2, MAFB, HIF1A-ARNT, EWSR1-FLI1, NFIC, TCF3 and NF-KAPPAB.

Conclusions

Our data show that osteochondral downregulated genes are potential molecular causes of BCO in broilers, and the bacterial process seems to be, in fact, a secondary condition. Sixteen genes responsible for bone and cartilage formation were downregulated in BCO-affected broilers being strong candidate genes to trigger this disorder.

Implantable electrical stimulation bioreactor with liquid crystal polymer-based electrodes for enhanced bone regeneration at mandibular large defects in rabbit

The osseous regeneration of large bone defects is still a major clinical challenge in maxillofacial and orthopedic surgery. Previous studies demonstrated that biphasic electrical stimulation (ES) stimulates bone formation; however, polyimide electrode should be removed after regeneration. This study presents an implantable electrical stimulation bioreactor with electrodes based on liquid crystal polymer (LCP), which can be permanently implanted due to excellent biocompatibility to bone tissue. The bioreactor was implanted into a critical-sized bone defect and subjected to ES for one week, where bone regeneration was evaluated four weeks after surgery using micro-CT. The effect of ES via the bioreactor was compared with a sham control group and a positive control group that received recombinant human bone morphogenetic protein (rhBMP)-2 (20 μg). New bone volume per tissue volume (BV/TV) in the ES and rhBMP-2 groups increased to 132% (p < 0.05) and 174% (p < 0.01), respectively, compared to that in the sham control group. In the histological evaluation, there was no inflammation within the bone defects and adjacent to LCP in all the groups. This study showed that the ES bioreactor with LCP electrodes could enhance bone regeneration at large bone defects, where LCP can act as a mechanically resistant outer box without inflammation. Graphical abstract To enhance bone regeneration, a bioreactor comprising collagen sponge and liquid crystal polymer-based electrode was implanted in the bone defect. Within the defect, electrical current pulses having biphasic waveform were applied from the implanted bioreactor.

BMP-2 gene transfection of bone marrow stromal cells to induce osteoblastic differentiation in a rat calvarial defect model

Gene therapy for bone tissue engineering has been widely developed. Recently, non-viral DNA-based gene therapy has been reported to be a safer and more efficient method of delivering DNA into target cells. We used a non-viral gene transfection reagent to delivery bone morphogenetic protein-2 (BMP-2) gene into bone marrow stromal cells (BMSCs). Primary BMSCs were isolated from rat femurs and transfected with BMP-2 plasmids. The transfection rate was analyzed using flow cytometry. The concentration of BMP-2 protein was quantified using an enzyme-linked immunosorbent assay. Levels of osteopontin and osteocalcin were measured to evaluate osteogenic differentiation. In vivo, we designed a critical-size calvarial defect rat model to study new bone regeneration, using Matrigel as a scaffold to carry BMP-2-transfected bone marrow stromal cells into the defect site. New bone formation was assessed by micro-computed tomography, X-ray, immunohistochemical staining and histomophometry. The transfection rate after 72 h was 31.5%. The BMP-2 protein level as well as osteopontin and osteocalcin expressions were higher in the experimental group (transfected with BMP-2) than the control group (transfected with green fluorescent protein, GFP). The in vivo study suggested that bone healing occurred 12 weeks after scaffold implantation. In addition, BMP-2-transfected bone marrow stromal cells provided better osteogenic differentiation than primary bone marrow stromal cells. Our findings suggest that non-viral gene therapy may be useful in bone tissue engineering.

SIGNIFICANCE

The study has clinical implications for the wider use of BMP-2-transfected BMSCs for cell-based transplantation therapy in bone regeneration.