Aims

To investigate the effects of senescent osteocytes on bone homeostasis in the progress of age-related osteoporosis and explore the underlying mechanism.

Aims. LY3023414 is a novel oral phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dual inhibitor designed for advanced cancers, for which a phase II clinical study was completed in March 2020; however, little is known about its effect on bone modelling/remodelling. In this study, we aimed to explore the function of LY3023414 in bone modelling/remodelling. Methods. The function of LY3023414 was explored in the context of osteogenesis (bone formation by osteoblasts) and osteoclastogenesis (osteoclast formation and bone resorption). Murine preosteoblast MC3T3-E1 cell line and murine bone marrow-derived macrophage cells (BMMs) were subjected to different treatments. An MTS cell proliferation assay was used to examine the cytotoxicity. Thereafter, different induction conditions were applied, such as MCSF and RANKL for osteoclastogenesis and osteogenic media for osteogenesis. Specific staining, a bone resorption assay, and quantitative real-time polymerase chain reaction (qRT-PCR) were subsequently used to evaluate the effect of LY3023414. Moreover, small interfering RNA (siRNA) was applied to knockdown Akt1 or Akt2 for further validation. Lastly, western blot was used to examine the exact mechanism of action. Results. LY3023414 attenuated PI3K/protein kinase B (Akt)/GSK3-dependent activation of β-catenin and nuclear factor-activated T cell 1 (NFATc1) during osteogenesis and osteoclastogenesis, respectively. LY3023414 mainly inhibited osteoclast formation instead of mature osteoclast function. Moreover, it suppressed osteogenesis both in the early stage of differentiation and late stage of calcification. Similarly, gene knockdown of Akt isoforms by siRNA downregulated osteogenic and osteoclastogenic processes, indicating that Akt1 and Akt2 acted synergistically. Conclusion. LY3023414 can suppress osteogenesis and osteoclastogenesis through inhibition of the PI3K/Akt/GSK3 signalling pathway, which highlights the potential benefits and side effects of LY3023414 for future clinical applications. Cite this article: Bone Joint Res 2021;10(4):237–249

Aims. Several artificial bone grafts have been developed but fail to achieve anticipated osteogenesis due to their insufficient neovascularization capacity and periosteum support. This study aimed to develop a vascularized bone-periosteum construct (VBPC) to provide better angiogenesis and osteogenesis for bone regeneration. Methods. A total of 24 male New Zealand white rabbits were divided into four groups according to the experimental materials. Allogenic adipose-derived mesenchymal stem cells (AMSCs) were cultured and seeded evenly in the collagen/chitosan sheet to form cell sheet as periosteum. Simultaneously, allogenic AMSCs were seeded onto alginate beads and were cultured to differentiate to endothelial-like cells to form vascularized bone construct (VBC). The cell sheet was wrapped onto VBC to create a vascularized bone-periosteum construct (VBPC). Four different experimental materials – acellular construct, VBC, non-vascularized bone-periosteum construct, and VBPC – were then implanted in bilateral L4-L5 intertransverse space. At 12 weeks post-surgery, the bone-forming capacities were determined by CT, biomechanical testing, histology, and immunohistochemistry staining analyses. Results. At 12 weeks, the VBPC group significantly increased new bone formation volume compared with the other groups. Biomechanical testing demonstrated higher torque strength in the VBPC group. Notably, the haematoxylin and eosin, Masson’s trichrome, and immunohistochemistry-stained histological results revealed that VBPC promoted neovascularization and new bone formation in the spine fusion areas. Conclusion. The tissue-engineered VBPC showed great capability in promoting angiogenesis and osteogenesis in vivo. It may provide a novel approach to create a superior blood supply and nutritional environment to overcome the deficits of current artificial bone graft substitutes. Cite this article: Bone Joint Res 2023;12(12):722–733

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

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

We describe two patients aged 16 and 25 years with osteogenesis imperfecta who sustained displaced fractures of the acetabulum following minor trauma. The femoral heads were deformed by impact against the acetabular margin and both cases underwent surgical reconstruction. The quality of the bone and soft tissues made the operations challenging. There were potential complications specific to osteogenesis imperfecta, including bleeding, the creation of secondary fracture lines and shredding of the soft-tissue. The cases provide useful guidelines for addressing these difficulties

Objectives. Up to 10% of fractures result in undesirable outcomes, for which female sex is a risk factor. Cellular sex differences have been implicated in these different healing processes. Better understanding of the mechanisms underlying bone healing and sex differences in this process is key to improved clinical outcomes. This study utilized a macrophage–mesenchymal stem cell (MSC) coculture system to determine: 1) the precise timing of proinflammatory (M1) to anti-inflammatory (M2) macrophage transition for optimal bone formation; and 2) how such immunomodulation was affected by male versus female cocultures. Methods. A primary murine macrophage-MSC coculture system was used to demonstrate the optimal transition time from M1 to M2 (polarized from M1 with interleukin (IL)-4) macrophages to maximize matrix mineralization in male and female MSCs. Outcome variables included Alizarin Red staining, alkaline phosphatase (ALP) activity, and osteocalcin protein secretion. Results. We found that 96 hours of M1 phenotype in male cocultures allowed for maximum matrix mineralization versus 72 hours in female cocultures. ALP activity and osteocalcin secretion were also enhanced with the addition of IL-4 later in male versus female groups. The sex of the cells had a statistically significant effect on the optimal IL-4 addition time to maximize osteogenesis. Conclusion. These results suggest that: 1) a 72- to 96-hour proinflammatory environment is critical for optimal matrix mineralization; and 2) there are immunological differences in this coculture environment due to sex. Optimizing immunomodulation during fracture healing may enhance and expedite the bone regeneration response. These findings provide insight into precise immunomodulation for enhanced bone healing that is sex-specific. Cite this article: K. Nathan, L. Y. Lu, T. Lin, J. Pajarinen, E. Jämsen, J-F. Huang, M. Romero-Lopez, M. Maruyama, Y. Kohno, Z. Yao, S. B. Goodman. Precise immunomodulation of the M1 to M2 macrophage transition enhances mesenchymal stem cell osteogenesis and differs by sex. Bone Joint Res 2019;8:481–488. DOI: 10.1302/2046-3758.810.BJR-2018-0231.R2

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. Methods. We used a murine model of chronic inflammation induced by continuous intramedullary delivery of lipopolysaccharide-contaminated polyethylene particles (cPE) using an osmotic pump. Specimens were evaluated using micro-CT and histomorphometric analyses. Sex-specific osteogenic and osteoclastic differentiation potentials were also investigated in vitro, including alkaline phosphatase, Alizarin Red, tartrate-resistant acid phosphatase staining, and gene expression using reverse transcription polymerase chain reaction (RT-PCR). Results. Local delivery of NF-κB decoy ODN in vivo increased osteogenesis in males, but not females, in the presence of chronic inflammation induced by cPE. Bone resorption activity was decreased in both sexes. In vitro osteogenic and osteoclastic differentiation assays during inflammatory conditions did not reveal differences among the groups. Receptor activator of nuclear factor kappa Β ligand (Rankl) gene expression by osteoblasts was significantly decreased only in males when treated with ODN. Conclusion. We demonstrated that NF-κB decoy ODN increased osteogenesis in male mice and decreased bone resorption activity in both sexes in preclinical models of chronic inflammation. NF-κB signalling could be a therapeutic target for chronic inflammatory diseases involving bone, especially in males. Cite this article: Bone Joint Res 2024;13(1):28–39

Aims. Bone regeneration during treatment of staphylococcal bone infection is challenging due to the ability of Staphylococcus aureus to invade and persist within osteoblasts. Here, we sought to determine whether the metabolic and extracellular organic matrix formation and mineralization ability of S. aureus-infected human osteoblasts can be restored after rifampicin (RMP) therapy. Methods. The human osteoblast-like Saos-2 cells infected with S. aureus EDCC 5055 strain and treated with 8 µg/ml RMP underwent osteogenic stimulation for up to 21 days. Test groups were Saos-2 cells + S. aureus and Saos-2 cells + S. aureus + 8 µg/ml RMP, and control groups were uninfected untreated Saos-2 cells and uninfected Saos-2 cells + 8 µg/ml RMP. Results. The S. aureus-infected osteoblasts showed a significant number of intracellular bacteria colonies and an unusual higher metabolic activity (p < 0.005) compared to uninfected osteoblasts. Treatment with 8 µg/ml RMP significantly eradicated intracellular bacteria and the metabolic activity was comparable to uninfected groups. The RMP-treated infected osteoblasts revealed a significantly reduced amount of mineralized extracellular matrix (ECM) at seven days osteogenesis relative to uninfected untreated osteoblasts (p = 0.007). Prolonged osteogenesis and RMP treatment at 21 days significantly improved the ECM mineralization level. Ultrastructural images of the mineralized RMP-treated infected osteoblasts revealed viable osteoblasts and densely distributed calcium crystal deposits within the extracellular organic matrix. The expression levels of prominent bone formation genes were comparable to the RMP-treated uninfected osteoblasts. Conclusion. Intracellular S. aureus infection impaired osteoblast metabolism and function. However, treatment with low dosage of RMP eradicated the intracellular S. aureus, enabling extracellular organic matrix formation and mineralization of osteoblasts at later stage. Cite this article: Bone Joint Res 2022;11(5):327–341

Study of 16 patients with Type III osteogenesis imperfecta showed marked elongation of the pedicles of the vertebrae in all cases, a deformity which was not seen in other types of the disease. Posterior rib angulation was also noted in Type III disease. These features have proved useful in suggesting the diagnosis of osteogenesis imperfecta even before long bones have fractured and in categorizing patients with osteogenesis imperfecta into the correct type for prognostic purposes

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. Methods. Specific keywords were used to search electronic databases (EMBASE, PubMed, and Web of Science) for English-language literature published between 1995 and 2017. Results. A total of 26 studies from the 555 articles obtained via the database search were ultimately included, and four main types of biomechanical approach were identified. Compressive force is characterized by static and continuous application, whereas tensile force is mainly cyclic. Only nine studies investigated the mechanisms by which periodontal ligament fibroblasts transduce mechanical stimulus. The studies provided evidence from in vitro mechanical loading regimens that periodontal ligament fibroblasts play a unique and dominant role in the regulation of bone remodelling during orthodontic tooth movement. Conclusion. Evidence from the reviewed studies described the characteristics of periodontal ligament fibroblasts exposed to mechanical force. This is expected to benefit subsequent research into periodontal ligament fibroblasts and to provide indirectly evidence-based insights regarding orthodontic treatment. Further studies should be performed to explore the effects of static tension on cytomechanical properties, better techniques for static compressive force loading, and deeper analysis of underlying regulatory systems. Cite this article: M. Li, C. Zhang, Y. Yang. Effects of mechanical forces on osteogenesis and osteoclastogenesis in human periodontal ligament fibroblasts: A systematic review of in vitro studies. Bone Joint Res 2019;8:19–31. DOI: 10.1302/2046-3758.81.BJR-2018-0060.R1

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. Materials and Methods. Rat MSCs were used to test the effects of SEC2 on their proliferation and osteogenic differentiation potentials. A rat femoral fracture model was used to examine the effect of local administration of SEC2 on fracture healing using radiographic analyses, micro-CT analyses, biomechanical testing, and histological analyses. Results. While SEC2 was found to have no effect on rat MSCs proliferation, it promoted the osteoblast differentiation of rat MSCs. In the rat femoral fracture model, the local administration of SEC2 accelerated fracture healing by increasing fracture callus volumes, bone volume over total volume (BV/TV), and biomechanical recovery. The SEC2 treatment group has superior histological appearance compared with the control group. Conclusion. These data suggest that local administration of SEC2 may be a novel therapeutic approach to enhancing bone repair such as fracture healing. Cite this article: T. Wu, J. Zhang, B. Wang, Y. Sun, Y. Liu, G. Li. Staphylococcal enterotoxin C2 promotes osteogenesis of mesenchymal stem cells and accelerates fracture healing. Bone Joint Res 2018;7:179–186. DOI: 10.1302/2046-3758.72.BJR-2017-0229.R1

Basilar impression is a well-recognised though rare complication of osteogenesis imperfecta. Three patients, all members of the same family, with advanced basilar impression complicating osteogenesis imperfecta tarda, are described. The clinical features in these cases illustrate the natural history of this condition: from asymptomatic ventricular dilatation, through the foramen magnum compression syndrome, to death from brain-stem compression. The radiological criteria on which the diagnosis is based, are defined. Review of the literature reveals only seven previously documented cases, all in patients with mild forms of osteogenesis imperfecta. The unusually low incidence of basilar impression in osteogenesis imperfecta and its apparent restriction to patients with mild forms of the disease is discussed. The examination of close relatives of patients with basilar impression and osteogenesis imperfecta is emphasised in order to anticipate the onset of severe neurological complications

Osteogenesis imperfecta is a rare inherited disorder of connective tissue which may present with recurrent fractures which are prone to nonunion and malunion resulting in deformity. Some patients develop osteoarthritis of the hip. Formation of hyperplastic callus after recurrent fractures may deform the shape of the femur and preclude the use of standard implants at joint replacement. Replacement can thus be technically demanding. We present a case of bilateral hip replacement in a patient with osteogenesis imperfecta and hyperplastic callus which was treated by the use of long femoral allografts and cemented femoral stems

Bone regeneration and repair are crucial to ambulation and quality of life. Factors such as poor general health, serious medical comorbidities, chronic inflammation, and ageing can lead to delayed healing and nonunion of fractures, and persistent bone defects. Bioengineering strategies to heal bone often involve grafting of autologous bone marrow aspirate concentrate (BMAC) or mesenchymal stem cells (MSCs) with biocompatible scaffolds. While BMAC shows promise, variability in its efficacy exists due to discrepancies in MSC concentration and robustness, and immune cell composition. Understanding the mechanisms by which macrophages and lymphocytes – the main cellular components in BMAC – interact with MSCs could suggest novel strategies to enhance bone healing. Macrophages are polarized into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, and influence cell metabolism and tissue regeneration via the secretion of cytokines and other factors. T cells, especially helper T1 (Th1) and Th17, promote inflammation and osteoclastogenesis, whereas Th2 and regulatory T (Treg) cells have anti-inflammatory pro-reconstructive effects, thereby supporting osteogenesis. Crosstalk among macrophages, T cells, and MSCs affects the bone microenvironment and regulates the local immune response. Manipulating the proportion and interactions of these cells presents an opportunity to alter the local regenerative capacity of bone, which potentially could enhance clinical outcomes. Cite this article: Bone Joint Res 2024;13(9):462–473

We investigated the fracture-free survival of long bones stabilised by a telescopic intramedullary rod (TIMR) in patients with osteogenesis imperfecta with respect to the remodelling status of fracture or osteotomy sites and TIMR regions, in order to identify risk factors for fracture. A total of 44 femora and 28 tibiae in 25 patients with a mean age of 5.0 years (1.9 to 10.5) at presentation were studied. There were six patients with Sillence type I, five with type III, 13 with type IV and one with type V osteogenesis imperfecta. All received bisphosphonate treatment at the same stage during the mean follow-up of 7.3 years (0.5 to 18.1). The fracture-free survival was estimated at 6.2 years (95% confidence interval 5.1 to 7.3) by Kaplan-Meier analysis. More than half the fracture or osteotomy sites remained in a less-remodelled state at the latest follow-up or time of fracture. Of the 33 fractures, 29 (87.9%) occurred in long bones containing a less-remodelled site, and these fractures were located at this site. The relative fracture risk at the rod tip was significantly greater than in any other TIMR region (p < 0.001), and this was higher in bone segments having a less-remodelled site. This study shows a persistent fracture risk in TIMR-stabilised long bones, especially at less-remodelled fracture or osteotomy sites and at the rod tip

We report the results of using 83 expanding intramedullary rods in 24 children with osteogenesis imperfecta after a mean follow-up of five years three months. In all, 62% of the rods have expanded after one primary operation. Thirty-four additional operations were necessary; 11 for the correction of rotation or angulation deformities and 23 for revision of the rod or T-piece. All these revisions were successful. Complications were more frequent in children who required very small rods. Problems with Bailey-Dubow rods led to the development of the Sheffield rod system; 17 bones treated with these rods are included in the series. Before surgery only eight of the 24 children were able to walk but at review 20 children were walking, 15 without walking aids. Elongating intramedullary rods should be available to all children with osteogenesis imperfecta as they improve walking capability, reduce the number of fractures, prevent deformity and allow integration of the child into society

Aims. The aim of this study was to determine the fracture haematoma (fxH) proteome after multiple trauma using label-free proteomics, comparing two different fracture treatment strategies. Methods. A porcine multiple trauma model was used in which two fracture treatment strategies were compared: early total care (ETC) and damage control orthopaedics (DCO). fxH was harvested and analyzed using liquid chromatography-tandem mass spectrometry. Per group, discriminating proteins were identified and protein interaction analyses were performed to further elucidate key biomolecular pathways in the early fracture healing phase. Results. The early fxH proteome was characterized by immunomodulatory and osteogenic proteins, and proteins involved in the coagulation cascade. Treatment-specific proteome alterations were observed. The fxH proteome of the ETC group showed increased expression of pro-inflammatory proteins related to, among others, activation of the complement system, neutrophil functioning, and macrophage activation, while showing decreased expression of proteins related to osteogenesis and tissue remodelling. Conversely, the fxH proteome of the DCO group contained various upregulated or exclusively detected proteins related to tissue regeneration and remodelling, and proteins related to anti-inflammatory and osteogenic processes. Conclusion. The early fxH proteome of the ETC group was characterized by the expression of immunomodulatory, mainly pro-inflammatory, proteins, whereas the early fxH proteome of the DCO group was more regenerative and osteogenic in nature. These findings match clinical observations, in which enhanced surgical trauma after multiple trauma causes dysbalanced inflammation, potentially leading to reduced tissue regeneration, and gained insights into regulatory mechanisms of fracture healing after severe trauma. Cite this article: Bone Joint Res 2024;13(5):214–225

We used dual-energy X-ray absorptiometry (DEXA) to compare the bone mineral density (BMD) of nine children aged from 2 years 7 months to 13 years 5 months who had mild osteogenesis imperfecta with an age- and sex-matched control group. The patients had only mild clinical symptoms but DEXA detected highly significant differences in BMD between them and the controls. The mean BMD in the children with osteogenesis imperfecta was 76.7% of normal in the lumbar spine (p < 0.001) and 71.2% of normal in the femoral neck (p < 0.001). DEXA is an objective, reproducible and sensitive method of measurement of BMD in children. It may help to establish the diagnosis, to assess prognosis and possibly to monitor the response to different types of treatment

A survey was conducted to document the results of bracing and spinal fusion for scoliosis associated with osteogenesis imperfecta. Observations were made of 121 patients who underwent treatment by bracing or spinal fusion and who had been treated by 51 orthopaedic surgeons in 14 countries. The average curve before bracing measured 43 degrees. The braces were ineffective in stopping progression even in small curves. We were unable to determine whether braces slowed the rate of progression of curvature. The average age at fusion was 15 years 7 months, the average curve before operation measured 74 degrees, and the average correction was 36 per cent. The high incidence of complications was related to the size of the curve before spinal fusion, the use of Harrington instrumentation, and the presence of associated kyphosis. In the absence of pseudarthrosis or kyphosis, late bending of the fused spine did not seem to occur