The miR-187 induced bone reconstruction and healing in a mouse model of osteoporosis, and accelerated osteoblastic differentiation of human multipotent stromal cells by targeting BARX2

Zhuang-Gu-Fang promotes osteoblast differentiation via myoblasts and myoblast-derived exosomal miRNAs:miR-5100, miR-126a-3p, miR-450b-5p, and miR-669a-5p

BACKGROUND

Senile osteoporosis (SOP) is an age-related systemic metabolic bone disorder. Previous studies have proved that Zhuang-Gu-Fang (ZGF) modulates myokines, stimulates osteogenic differentiation, and mitigates osteoporosis.

OBJECTIVE

To elucidate the mechanism by which ZGF promotes osteogenic differentiation via myoblast and myoblast exosomal microRNAs (miRNAs) and investigate its potential implications in senile osteoporosis.

METHODS

Characterization of ZGF and ZGF serum using UHPLC-MS/MS. An alkaline phosphatase (ALP) activity assay and staining techniques were employed to corroborate the impacts of ZGF on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) via myoblasts. Subsequently, exosomes derived from myoblasts were isolated through ultracentrifugation. The effects of ZGF on the BMSCs' osteogenic differentiation were substantiated through ALP activity, alizarin red staining, and a quantitative real-time polymerase reaction system (qRT-PCR). Selected miRNAs were identified via high-throughput sequencing and subjected to differential expression analysis, and subsequently validated through qRT-PCR. The senescence-accelerated (SAMP6) mice were selected as the SOP models. qRT-PCR analyses were further conducted to confirm the expression levels of these selected miRNAs in the muscle and bone tissues of the SAMP6 mice, and the protein expression of osteogenesis-related transcription factors OCN and Osterix in its bone tissue was evaluated by immunofluorescence staining analysis (IF).

RESULTS

ZGF may enhance the osteogenic differentiation of BMSCs through myoblasts and myoblast-derived exosomes. High-throughput sequencing, differential expression analysis, and subsequent qRT-PCR validation identified four miRNAs that stood out due to their significant differential expression: miR-5100, miR-142a-3p, miR-126a-3p, miR-450b-5p and miR-669a-5p. Moreover, the mice experiment corroborated these findings, which revealed that ZGF not only up-regulated the expression of miR-5100, miR-450b-5p and miR-126a-3p in muscle and bone tissues but also concurrently down-regulated the expression of miR-669a-5p in these tissues. IF staining analysis indicated that ZGF can significantly increase the protein expression of the osteogenic transcription factors OCN and Osterix in the bone tissue of mice with SOP.

CONCLUSIONS

ZGF can promote osteogenic differentiation of osteoblasts, regulate bone metabolism, and thereby delay the process of SOP. Perhaps, its mechanism is to upregulate myoblast-derived exosomes miR-5100, miR-126a-3p, and miR-450b-5p or downregulate miR-669a-5p. This study reports for the first time that myoblast exosomes miR-669a-5p and miR-450b-5p are novel targets for the regulation of osteoblastic differentiation and the treatment of SOP.

Zoledronic Acid Accelerates Bone Healing in Carpal Navicular Fracture via Silencing Long Non-coding RNA Growth Arrest Specificity 5 to Modulate MicroRNA-29a-3p Expression

Carpal navicular fractures are the most common carpal fractures. This study intends to explore the specific mechanism of Zoledronic Acid (ZA) in carpal navicular fracture healing via long non-coding RNA (lncRNA) growth arrest specificity 5 (GAS5) to mediate microRNA (miR)-29a-3p. A fractured rat model was constructed. Two weeks later, a subcutaneous injection of systemic ZA was implemented, and an injection of plasmid vectors interfered with GAS5 or miR-29a-3p expression was performed on the fracture site. Osteocalcin (OCN) and bone morphogenetic protein-2 (BMP-2) were determined, as well as serum levels of alkaline phosphatase (ALP), osteopontin (OPN) and osteoprotegerin (OPG) and bone mineral density. MC3T3-E1 cells were transfected with plasmid vectors interfering with GAS5 or miR-29a-3p, and cell proliferation and apoptosis were analyzed. GAS5 and miR-29a-3p expression in fractured rats was tested, together with their binding relationship. ZA promoted OCN and BMP-2 expression, increased bone mineral density and serum levels of ALP, OPN and OPG in fractured rats. GAS5 was upregulated and miR-29a-3p was down-regulated in fractured rats. Downregulation of GAS5 or upregulation of miR-29a-3p further promoted bone healing in fractured rats. GAS5 targets miR-29a-3p, and down-regulation of miR-29a-3p can reverse the effect of down-regulation of GAS5 on bone healing in fractured rats. ZA promoted the proliferation of MC3T3-E1 cells and inhibited apoptosis by regulating the GAS5/miR-29a-3p axis. ZA regulates miR-29a-3p expression by down-regulating GAS5 to promote carpal navicular fracture healing, promote MC3T3-E1 cell proliferation, and inhibit cell apoptosis.

MiR-210 improves postmenopausal osteoporosis in ovariectomized rats through activating VEGF/Notch signaling pathway

BACKGROUND

To explore the effect and mechanism of action of miR-210 on postmenopausal osteoporosis (PMPO) in ovariectomized rats in vivo.

METHODS

An ovariectomized (OVX) rat model was established by ovariectomy. Tail vein injection was performed to overexpress and knock down miR-210 in OVX rats, followed by the collection of blood and femoral tissues from each group of rats. And quantitative real-time polymerase chain reaction (qRT-PCR) was applied to assess the expression level of miR-210 in femoral tissues of each group. Micro computed tomography (Micro CT) was adopted to scan the microstructure of the femoral trabecula in each group to obtain relevant data like bone mineral density (BMD), bone mineral content (BMC), trabecular bone volume fraction (BV/TV), trabecular thickness (Tb.Th), bone surface-to-volume ratio (BS/BV), and trabecular separation (Tb.Sp). ELISA was used for determining the level of bone alkaline phosphatase (BALP), amino-terminal propeptide of type I procollagen (PINP), osteocalcin (OCN), and C-terminal telopeptide of type I collagen (CTX-1) in serum; and Western blot for the protein level of Runt-related transcription factor 2 (Runx2), osteopontin (OPN), and collagen type I alpha 1 (COL1A1) in femoral tissues.

RESULTS

MiR-210 expression was significantly decreased in femoral tissues of OVX rats. Overexpression of miR-210 could obviously increase BMD, BMC, BV/TV and Tb.Th, whereas significantly decrease BS/BV and Tb.Sp in femurs of OVX rats. Moreover, miR-210 also downregulated BALP and CTX-1 level, upregulated PINP and OCN level in the serum of OVX rats promoted the expression of osteogenesis-related markers (Runx2, OPN and COL1A1) in the femur of OVX rats. Additionally, further pathway analysis revealed that high expression of miR-210 activated the vascular endothelial growth factor (VEGF)/Notch1 signaling pathway in the femur of OVX rats.

CONCLUSION

High expression of miR-210 may improve the micromorphology of bone tissue and modulate bone formation and resorption in OVX rats by activating the VEGF/Notch1 signaling pathway, thereby alleviating osteoporosis. Consequently, miR-210 can serve as a biomarker for the diagnosis and treatment of osteoporosis in postmenopausal rats.

Prognostic and therapeutic potential of microRNAs for fracture healing processes and non-union fractures: A systematic review

BACKGROUND

Approximately 10% of all bone fractures result in delayed fracture healing or non-union; thus, the identification of biomarkers and prognostic factors is of great clinical interest. MicroRNAs (miRNAs) are known to be involved in the regulation of the bone healing process and may serve as functional markers for fracture healing.

AIMS AND METHODS

This systematic review aimed to identify common miRNAs involved in fracture healing or non-union fractures using a qualitative approach. A systematic literature search was performed with the keywords 'miRNA and fracture healing' and 'miRNA and non-union fracture'. Any original article investigating miRNAs in fracture healing or non-union fractures was screened. Eventually, 82 studies were included in the qualitative analysis for 'miRNA and fracture healing', while 19 were selected for the 'miRNA and fracture non-union' category.

RESULTS AND CONCLUSIONS

Out of 151 miRNAs, miR-21, miR-140 and miR-214 were the most investigated miRNAs in fracture healing in general. miR-31-5p, miR-221 and miR-451-5p were identified to be regulated specifically in non-union fractures. Large heterogeneity was detected between studies investigating the role of miRNAs in fracture healing or non-union in terms of patient population, sample types and models used. Nonetheless, our approach identified some miRNAs with the potential to serve as biomarkers for non-union fractures, including miR-31-5p, miR-221 and miR-451-5p. We provide a discussion of involved pathways and suggest on alignment of future research in the field.