Aims. The involvement of long non-coding RNA (lncRNA) in bone marrow mesenchymal stem cell (MSC) osteogenic differentiation during osteoporosis (OP) development has attracted much attention. In this study, we aimed to disclose how LINC01089 functions in human mesenchymal stem cell (hMSC) osteogenic differentiation, and to study the mechanism by which LINC01089 regulates MSC osteogenesis. Methods. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting were performed to analyze LINC01089, miR-1287-5p, and heat shock protein family A (HSP70) member 4 (HSPA4) expression. The osteogenic differentiation of MSCs was assessed through alkaline phosphatase (ALP) activity, alizarin red S (ARS) staining, and by measuring the levels of osteogenic gene marker expressions using commercial kits and RT-qPCR analysis. Cell proliferative capacity was evaluated via the Cell Counting Kit-8 (CCK-8) assay. The binding of miR-1287-5p with LINC01089 and HSPA4 was verified by performing dual-luciferase reporter and RNA immunoprecipitation (RIP) experiments. Results. LINC01089 expression was reinforced in serum samples of OP patients, but it gradually diminished while hMSCs underwent osteogenic differentiation. LINC01089 knockdown facilitated hMSC osteogenic differentiation. This was substantiated by: the increase in ALP activity; ALP, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN) messenger RNA (mRNA) levels; and level of ARS staining. Meanwhile, LINC01089 upregulation resulted in the opposite effects. LINC01089 targeted miR-1287-5p, and the LINC01089 knockdown-induced hMSC osteogenic differentiation was repressed by miR-1287-5p depletion. HSPA4 is a downstream function molecule of the LINC01089/miR-1287-5p pathway; miR-1287-5p negatively modulated HSPA4 levels and attenuated its functional effects. Conclusion. LINC01089 negatively regulated hMSC osteogenic differentiation, at least in part, via governing miR-1287-5p/HSPA4 signalling. These findings provide new insights into hMSC osteogenesis and bone metabolism. Cite this article: Bone Joint Res 2024;13(12):779–789

The multifunctional adhesion molecule CD44 is a major cell-surface receptor for hyaluronic acid (HUA). Recent data suggest that it may also bind the ubiquitous bone-matrix protein, osteopontin (OPN). Because OPN has been shown to be a potentially important protein in bone remodelling, we investigated the hypothesis that OPN interactions with the CD44 receptor on bone cells participate in the regulation of the healing of fractures. We examined the spatial and temporal patterns of expression of OPN and CD44 in healing fractures of rat femora by in situ hybridisation and immunohistochemistry. We also localised HUA in the fracture callus using biotinylated HUA-binding protein. OPN was expressed in remodelling areas of the hard callus and was found in osteocytes, osteoclasts and osteoprogenitor cells, but not in cuboidal osteoblasts which were otherwise shown to express osteocalcin. The OPN signal in osteocytes was not uniformly distributed, but was restricted to specific regions near sites where OPN mRNA-positive osteoclasts were attached to bone surfaces. In the remodelling callus, intense immunostaining for CD44 was detected in osteocyte lacunae, along canaliculi, and on the basolateral plasma membrane of osteoclasts, but not in the cuboidal osteoblasts. HUA staining was detected in fibrous tissues but little was observed in areas of hard callus where bone remodelling was progressing. Our findings suggest that OPN, rather than HUA, is the major ligand for CD44 on bone cells in the remodelling phase of healing of fractures. They also raise the possibility that such interactions may be involved in the communication of osteocytes with each other and with osteoclasts on bone surfaces. The interactions between CD44 and OPN may have important clinical implications in the repair of skeletal tissues

Aims. Long non-coding RNAs (lncRNAs) act as crucial regulators in osteoporosis (OP). Nonetheless, the effects and potential molecular mechanism of lncRNA PCBP1 Antisense RNA 1 (PCBP1-AS1) on OP remain largely unclear. The aim of this study was to explore the role of lncRNA PCBP1-AS1 in the pathogenesis of OP. Methods. Using quantitative real-time polymerase chain reaction (qRT-PCR), osteogenesis-related genes (alkaline phosphatase (ALP), osteocalcin (OCN), osteopontin (OPN), and Runt-related transcription factor 2 (RUNX2)), PCBP1-AS1, microRNA (miR)-126-5p, group I Pak family member p21-activated kinase 2 (PAK2), and their relative expression levels were determined. Western blotting was used to examine the expression of PAK2 protein. Cell Counting Kit-8 (CCK-8) assay was used to measure cell proliferation. To examine the osteogenic differentiation, Alizarin red along with ALP staining was used. RNA immunoprecipitation assay and bioinformatics analysis, as well as a dual-luciferase reporter, were used to study the association between PCBP1-AS1, PAK2, and miR-126-5p. Results. The expression of PCBP1-AS1 was pre-eminent in OP tissues and decreased throughout the development of human bone marrow-derived mesenchymal stem cells (hBMSCs) into osteoblasts. PCBP1-AS1 knockdown and overexpression respectively promoted and suppressed hBMSC proliferation and osteogenic differentiation capacity. Mechanistically, PCBP1-AS1 sponged miR-126-5p and consequently targeted PAK2. Inhibiting miR-126-5p significantly counteracted the beneficial effects of PCBP1-AS1 or PAK2 knockdown on hBMSCs’ ability to differentiate into osteoblasts. Conclusion. PCBP1-AS1 is responsible for the development of OP and promotes its progression by inducing PAK2 expression via competitively binding to miR-126-5p. PCBP1-AS1 may therefore be a new therapeutic target for OP patients. Cite this article: Bone Joint Res 2023;12(6):375–386

Aims. To investigate whether idiopathic osteonecrosis of the femoral head (ONFH) is related to impaired osteoblast activities. Methods. We cultured osteoblasts isolated from trabecular bone explants taken from the femoral head and the intertrochanteric region of patients with idiopathic ONFH, or from the intertrochanteric region of patients with osteoarthritis (OA), and compared their viability, mineralization capacity, and secretion of paracrine factors. Results. Osteoblasts from the intertrochanteric region of patients with ONFH showed lower alkaline phosphatase (ALP) activity and mineralization capacity than osteoblasts from the same skeletal site in age-matched patients with OA, as well as lower messenger RNA (mRNA) levels of genes encoding osteocalcin and bone sialoprotein and higher osteopontin expression. In addition, osteoblasts from patients with ONFH secreted lower osteoprotegerin (OPG) levels than those from patients with OA, resulting in a higher receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) ligand (RANKL)-to-OPG ratio. In patients with ONFH, osteoblasts from the femoral head showed reduced viability and mineralized nodule formation compared with osteoblasts from the intertrochanteric region. Notably, the secretion of the pro-resorptive factors interleukin-6 and prostaglandin E. 2. as well as the RANKL-to-OPG ratio were markedly higher in osteoblast cultures from the femoral head than in those from the intertrochanteric region. Conclusion. Idiopathic ONFH is associated with a reduced mineralization capacity of osteoblasts and increased secretion of pro-resorptive factors. Cite this article: Bone Joint Res 2021;10(9):619–628

Aims. The aim of this study was to develop a single-layer hybrid organic-inorganic sol-gel coating that is capable of a controlled antibiotic release for cementless hydroxyapatite (HA)-coated titanium orthopaedic prostheses. Methods. Coatings containing gentamicin at a concentration of 1.25% weight/volume (wt/vol), similar to that found in commercially available antibiotic-loaded bone cement, were prepared and tested in the laboratory for: kinetics of antibiotic release; activity against planktonic and biofilm bacterial cultures; biocompatibility with cultured mammalian cells; and physical bonding to the material (n = 3 in all tests). The sol-gel coatings and controls were then tested in vivo in a small animal healing model (four materials tested; n = 6 per material), and applied to the surface of commercially pure HA-coated titanium rods. Results. The coating released gentamicin at > 10 × minimum inhibitory concentration (MIC) for sensitive staphylococcal strains within one hour thereby potentially giving effective prophylaxis for arthroplasty surgery, and showed > 99% elution of the antibiotic within the coating after 48 hours. There was total eradication of both planktonic bacteria and established bacterial biofilms of a panel of clinically relevant staphylococci. Mesenchymal stem cells adhered to the coated surfaces and differentiated towards osteoblasts, depositing calcium and expressing the bone marker protein, osteopontin. In the in vivo small animal bone healing model, the antibiotic sol-gel coated titanium (Ti)/HA rod led to osseointegration equivalent to that of the conventional HA-coated surface. Conclusion. In this study we report a new sol-gel technology that can release gentamicin from a bioceramic-coated cementless arthroplasty material. In vitro, local gentamicin levels are in excess of what can be achieved by antibiotic-loaded bone cement. In vivo, bone healing in an animal model is not impaired. This, thus, represents a biomaterial modification that may have the potential to protect at-risk patients from implant-related deep infection. Cite this article: Bone Joint J 2021;103-B(3):522–529

Aims. It is increasingly appreciated that coordinated regulation of angiogenesis and osteogenesis is needed for bone formation. How this regulation is achieved during peri-implant bone healing, such as osseointegration, is largely unclear. This study examined the relationship between angiogenesis and osteogenesis in a unique model of osseointegration of a mouse tibial implant by pharmacologically blocking the vascular endothelial growth factor (VEGF) pathway. Materials and Methods. An implant was inserted into the right tibia of 16-week-old female C57BL/6 mice (n = 38). Mice received anti-VEGF receptor-1 (VEGFR-1) antibody (25 mg/kg) and VEGF receptor-2 (VEGFR-2) antibody (25 mg/kg; n = 19) or an isotype control antibody (n = 19). Flow cytometric (n = 4/group) and immunofluorescent (n = 3/group) analyses were performed at two weeks post-implantation to detect the distribution and density of CD31. hi. EMCN. hi. endothelium. RNA sequencing analysis was performed using sorted CD31. hi. EMCN. hi. endothelial cells (n = 2/group). Osteoblast lineage cells expressing osterix (OSX) and osteopontin (OPN) were also detected with immunofluorescence. Mechanical pull-out testing (n = 12/group) was used at four weeks post-implantation to determine the strength of the bone-implant interface. After pull-out testing, the tissue attached to the implant surface was harvested. Whole mount immunofluorescent staining of OSX and OPN was performed to determine the amount of osteoblast lineage cells. Results. Flow cytometry revealed that anti-VEGFR treatment decreased CD31. hi. EMCN. hi. vascular endothelium in the peri-implant bone versus controls at two weeks post-implantation. This was confirmed by the decrease of CD31 and endomucin (EMCN) double-positive cells detected with immunofluorescence. In addition, treated mice had more OPN-positive cells in both peri-implant bone and tissue on the implant surface at two weeks and four weeks, respectively. More OSX-positive cells were present in peri-implant bone at two weeks. More importantly, anti-VEGFR treatment decreased the maximum load of pull-out testing compared with the control. Conclusion. VEGF pathway controls the coupling of angiogenesis and osteogenesis in orthopaedic implant osseointegration by affecting the formation of CD31. hi. EMCN. hi. endothelium. Cite this article: Bone Joint J 2019;101-B(7 Supple C):108–114

Aims

Transcription factor nuclear factor kappa B (NF-κB) plays a major role in the pathogenesis of chronic inflammatory diseases in all organ systems. Despite its importance, NF-κB targeted drug therapy to mitigate chronic inflammation has had limited success in preclinical studies. We hypothesized that sex differences affect the response to NF-κB treatment during chronic inflammation in bone. This study investigated the therapeutic effects of NF-κB decoy oligodeoxynucleotides (ODN) during chronic inflammation in male and female mice.

Aims

To verify whether secretory leucocyte protease inhibitor (SLPI) can promote early tendon-to-bone healing after anterior cruciate ligament (ACL) reconstruction.

Aims

Exosomes derived from bone marrow mesenchymal stem cells (BMSCs) have been reported to be a promising cellular therapeutic approach for various human diseases. The current study aimed to investigate the mechanism of BMSC-derived exosomes carrying microRNA (miR)-136-5p in fracture healing.

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To develop an early implant instability murine model and explore the use of intermittent parathyroid hormone (iPTH) treatment for initially unstable implants.

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Circular RNAs (circRNAs) are a novel type of non-coding RNA that plays major roles in the development of diverse diseases including osteonecrosis of the femoral head (ONFH). Here, we explored the impact of hsa_circ_0066523 derived from forkhead box P1 (FOXP1) (also called circFOXP1) on bone mesenchymal stem cells (BMSCs), which is important for ONFH development.

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The aim of the HIPGEN consortium is to develop the first cell therapy product for hip fracture patients using PLacental-eXpanded (PLX-PAD) stromal cells.

Aims

Platelet concentrates, like platelet-rich plasma (PRP) and platelet lysate (PL), are widely used in regenerative medicine, especially in bone regeneration. However, the lack of standard procedures and controls leads to high variability in the obtained results, limiting their regular clinical use. Here, we propose the use of platelet-derived extracellular vesicles (EVs) as an off-the-shelf alternative for PRP and PL for bone regeneration. In this article, we evaluate the effect of PL-derived EVs on the biocompatibility and differentiation of mesenchymal stromal cells (MSCs).

Osteoarthritis (OA), one of the most common motor system disorders, is a degenerative disease involving progressive joint destruction caused by a variety of factors. At present, OA has become the fourth most common cause of disability in the world. However, the pathogenesis of OA is complex and has not yet been clarified. Long non-coding RNA (lncRNA) refers to a group of RNAs more than 200 nucleotides in length with limited protein-coding potential, which have a wide range of biological functions including regulating transcriptional patterns and protein activity, as well as binding to form endogenous small interference RNAs (siRNAs) and natural microRNA (miRNA) molecular sponges. In recent years, a large number of lncRNAs have been found to be differentially expressed in a variety of pathological processes of OA, including extracellular matrix (ECM) degradation, synovial inflammation, chondrocyte apoptosis, and angiogenesis. Obviously, lncRNAs play important roles in regulating gene expression, maintaining the phenotype of cartilage and synovial cells, and the stability of the intra-articular environment. This article reviews the results of the latest research into the role of lncRNAs in a variety of pathological processes of OA, in order to provide a new direction for the study of OA pathogenesis and a new target for prevention and treatment.

Cite this article: Bone Joint Res 2021;10(2):122–133.

Bone is one of the most highly adaptive tissues in the body, possessing the capability to alter its morphology and function in response to stimuli in its surrounding environment. The ability of bone to sense and convert external mechanical stimuli into a biochemical response, which ultimately alters the phenotype and function of the cell, is described as mechanotransduction. This review aims to describe the fundamental physiology and biomechanisms that occur to induce osteogenic adaptation of a cell following application of a physical stimulus. Considerable developments have been made in recent years in our understanding of how cells orchestrate this complex interplay of processes, and have become the focus of research in osteogenesis. We will discuss current areas of preclinical and clinical research exploring the harnessing of mechanotransductive properties of cells and applying them therapeutically, both in the context of fracture healing and de novo bone formation in situations such as nonunion.

Cite this article: Bone Joint Res 2019;9(1):1–14.

Aims

Bone metastasis ultimately occurs due to a complex multistep process, during which the interactions between cancer cells and bone microenvironment play important roles. Prior to colonization of the bone, cancer cells must succeed through a series of steps that will allow them to gain migratory and invasive properties; epithelial-to-mesenchymal transition (EMT) is known to be integral here. The aim of this study was to determine the effects of G protein subunit alpha Q (GNAQ) on the mechanisms underlying bone metastasis through EMT pathway.

Objectives

As one of the heat-stable enterotoxins, Staphylococcal enterotoxin C2 (SEC2) is synthesized by Staphylococcus aureus, which has been proved to inhibit the growth of tumour cells, and is used as an antitumour agent in cancer immunotherapy. Although SEC2 has been reported to promote osteogenic differentiation of human mesenchymal stem cells (MSCs), the in vivo function of SCE2 in animal model remains elusive. The aim of this study was to further elucidate the in vivo effect of SCE2 on fracture healing.

Objectives

Many in vitro studies have investigated the mechanism by which mechanical signals are transduced into biological signals that regulate bone homeostasis via periodontal ligament fibroblasts during orthodontic treatment, but the results have not been systematically reviewed. This review aims to do this, considering the parameters of various in vitro mechanical loading approaches and their effects on osteogenic and osteoclastogenic properties of periodontal ligament fibroblasts.

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.