Aims

The aims of this study, using a porcine model of multiple trauma, were to investigate the expression of microRNAs at the fracture site, in the fracture haematoma (fxH) and in the fractured bone, compared with a remote unfractured long bone, to characterize the patterns of expression of circulating microRNAs in plasma, and identify and validate messenger RNA (mRNA) targets of the microRNAs.

Addressing bone defects is a complex medical challenge that involves dealing with various skeletal conditions, including fractures, osteoporosis (OP), bone tumours, and bone infection defects. Despite the availability of multiple conventional treatments for these skeletal conditions, numerous limitations and unresolved issues persist. As a solution, advancements in biomedical materials have recently resulted in novel therapeutic concepts. As an emerging biomaterial for bone defect treatment, graphene oxide (GO) in particular has gained substantial attention from researchers due to its potential applications and prospects. In other words, GO scaffolds have demonstrated remarkable potential for bone defect treatment. Furthermore, GO-loaded biomaterials can promote osteoblast adhesion, proliferation, and differentiation while stimulating bone matrix deposition and formation. Given their favourable biocompatibility and osteoinductive capabilities, these materials offer a novel therapeutic avenue for bone tissue regeneration and repair. This comprehensive review systematically outlines GO scaffolds’ diverse roles and potential applications in bone defect treatment.

Cite this article: Bone Joint Res 2024;13(12):725–740.

The December 2024 Spine Roundup³⁶⁰ looks at: Rostral facet joint violations in robotic- and navigation-assisted pedicle screw placement; The inhibitory effect of non-steroidal anti-inflammatory drugs and opioids on spinal fusion: an animal model;L5-S1 transforaminal lumbar interbody fusion is associated with increased revisions compared to L4-L5 TLIF at two years; Immediate versus gradual brace weaning protocols in adolescent idiopathic scoliosis: a randomized clinical trial; Effectiveness and cost-effectiveness of an individualized, progressive walking, and education intervention for the prevention of low back pain recurrence in Australia (WalkBack): a randomized controlled trial; Usefulness and limitations of intraoperative pathological diagnosis using frozen sections for spinal cord tumours; Effect of preoperative HbA1c and blood glucose level on the surgical site infection after lumbar instrumentation surgery; How good are surgeons at achieving their alignment goals?

Introduction. The objective of the work is construction of a multi-bioactive scaffold based on that allows a space/time control over the regeneration of damaged bones by Medication-Related Osteonecrosis of the Jaw using a minimal invasive approach based on the injection of the fast-degrading pro neuro and angiogenic ELR (Elastin-Like Recombinamers) based hydrogels. Method. Chemical crosslinking facilitated the creation of multi-bioactive scaffolds using ELRs with reactive groups. Cell-loaded multi-bioactive scaffolds, prepared and incubated, underwent evaluation for adhesion, proliferation, angiogenic, and neurogenic potential. In vitro assessments utilized immunofluorescence staining and ELISA assays, while live-recorded monitoring and live-dead analysis ensured cytocompatibility. In rat and rabbit models, preformed scaffolds were subcutaneously implanted, and the regenerative process was evaluated over time. Rabbit models with MRONJ underwent traditional or percutaneous implantation, with histological evaluation following established bone histological techniques. Result. A 3D scaffold using ELR that combines various peptides with different degradation rates to guide both angiogenesis and neurogenesis has been developed. Notably, scaffolds with different degradation rates promoted distinct patterns of vascularization and innervation, facilitating integration with host tissue. This work demonstrates the potential for tailored tissue engineering, where the scaffold's bioactivities and degradation rates can control angiogenesis and neurogenesis. In an animal model of medication-related osteonecrosis of the jaw (MRONJ), the scaffold showed promising results in promoting bone regeneration in a necrotic environment, as confirmed by histological and imaging analyses. This study opens avenues for novel tissue-engineering strategies where precise control over vascularization and nerve growth is crucial. Conclusion. A groundbreaking dual approach, simultaneously targeting angiogenesis and innervation, addresses the necrotic bone in MRONJ syndrome. Vascularization and nerve formation play pivotal roles in driving reparative elements for bone regeneration. The scaffold achieves effective time/space control over necrotic bone regeneration. The authors are grateful for funding from the Spanish Government (PID2020-118669RA-I00)

Introduction. Endochondral ossification (EO) is the process of bone development via a cartilage template. It involves multiple stages, including chondrogenesis, mineralisation and angiogenesis. Importantly, how cartilage mineralisation affects angiogenesis during EO is not fully understood. Here we aimed to develop a new in vitro co-culture model to recapitulate and study the interaction between mineralised cartilage generated from human mesenchymal stromal cells (hMSCs) and microvascular networks. Method. Chondrogenic hMSC pellets were generated by culture with transforming growth factor (TGF)-β3. For mineralised pellets, β-glycerophosphate (BGP) was added from day 7 and TGF-β3 was withdrawn on day 14. Conditioned medium (CM) from the pellets was used to evaluate the effect on human umbilical vein endothelial cells (HUVECs) in migration, proliferation and tube formation assays. To perform direct co-cultures, pellets were embedded in fibrin hydrogels containing vessel-forming cells (HUVECs, adipose stromal cells) for 10 days with BGP to induce mineralisation. The pellets and hydrogels were characterised by immunohistochemistry and confocal imaging. Result. The CM from d14 chondrogenic or mineralised pellets significantly stimulated HUVEC migration and proliferation, as well as in vitro vascular network formation. When CM from pellets subjected to prolonged mineralisation (d28) was used, these effects were strongly reduced. When chondrogenic and mineralised pellets were directly co-cultured with vessel-forming cells in fibrin hydrogels, the cartilage matrix (collagen type II/X stainings) and the mineral deposition (von Kossa staining) were well preserved. Confocal imaging analyses demonstrated the formation of microvascular networks with well-formed lumina. Importantly, more microvascular structures were formed in the proximity of chondrogenic pellets than mineralized pellets. Conclusion. The angiogenic properties of tissue engineered cartilage are significantly reduced upon prolonged mineralisation. We developed a 3D co-culture model to study the role of angiogenesis in endochondral bone formation, which can have applications in disease modelling studies

Aims

This study aimed to demonstrate the promoting effect of elastic fixation on fracture, and further explore its mechanism at the gene and protein expression levels.

Aims

To explore the efficacy of extracorporeal shockwave therapy (ESWT) in the treatment of osteochondral defect (OCD), and its effects on the levels of transforming growth factor (TGF)-β, bone morphogenetic protein (BMP)-2, -3, -4, -5, and -7 in terms of cartilage and bone regeneration.

Aims. Given the possible radiation damage and inaccuracy of radiological investigations, particularly in children, ultrasound and superb microvascular imaging (SMI) may offer alternative methods of evaluating new bone formation when limb lengthening is undertaken in paediatric patients. The aim of this study was to assess the use of ultrasound combined with SMI in monitoring new bone formation during limb lengthening in children. Methods. In this retrospective cohort study, ultrasound and radiograph examinations were performed every two weeks in 30 paediatric patients undergoing limb lengthening. Ultrasound was used to monitor new bone formation. The number of vertical vessels and the blood flow resistance index were compared with those from plain radiographs. Results. We categorized the new bone formation into three stages: stage I (early lengthening), in which there was no obvious callus formation on radiographs and ultrasound; stage II (lengthening), in which radiographs showed low-density callus formation with uneven distribution and three sub-stages could be identified on ultrasound: in Ia punctate callus was visible; in IIb there was linear callus formation which was not yet connected and in IIc there was continuous linear callus. In stage III (healing), the bone ends had united, the periosteum was intact, and the callus had disappeared, as confirmed on radiographs, indicating healed bone. A progressive increase in the number of vertical vessels was noted in the early stages, peaking during stages IIb and IIc, followed by a gradual decline (p < 0.001). Delayed healing involved patients with a prolonged stage IIa or those who regressed to stage IIa from stages IIb or IIc during lengthening. Conclusion. We found that the formation of new bone in paediatric patients undergoing limb lengthening could be reliably evaluated using ultrasound when combined with the radiological findings. This combination enabled an improved assessment of the prognosis, and adjustments to the lengthening protocol. While SMI offered additional insights into angiogenesis within the new bone, its role primarily contributed to the understanding of the microvascular environment rather than directly informing adjustments of treatment. Cite this article: Bone Joint J 2024;106-B(7):751–758

Aims

Adenosine, lidocaine, and Mg²⁺ (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery.

INTRODUCTION. Stimulation of angiogenesis via the delivery of growth factors (GFs) like vascular endothelial growth factor (VEGF) is a promising strategy for the treatment of avascular necrosis (AVN). Tyraminated poly-vinyl-alcohol hydrogels (PVA-Tyr), which have the ability to covalently incorporate GFs, were proposed as a platform for the controlled delivery of therapeutic levels VEGF to the necrotic areas[1]. Nevertheless, PVA hydrophilicity and bioinertness limits its integration with the host tissues. The aim of this study was to investigated the effectiveness of incorporating gelatin, an FDA-approved, non-immunogeneic biomaterial with biological recognition sites, as a strategy to facilitate blood vessels invasion of PVA-Tyr hydrogels and to restore the vascular supply to necrotic tissues. METHODS. Progressively higher gelatin concentrations (0.01–5wt%) were incorporated in the PVA-Tyr network. Hydrogel physico-chemical properties and endothelial cell attachment were evaluated. Afterwards, the capability of the released VEGF and gelatin to promote vascularization was evaluated via chorioallantoic membrane (CAM) assay. VEGF-loaded PVA-Tyr hydrogels with or without gelatin (n=7) were implanted in a subcutaneous mouse model for 3 weeks. Vascularization (CD31+ cells) and cell infiltration (H&E) were evaluated. Finally, AVN was induced in 6 weeks old male piglets as previously described [2]. A transphyseal hole (3mm) was drilled and PVA-Tyr hydrogels with 1% gelatin were delivered in the defects. Piglets were euthanized after 4 weeks and microCT analysis was performed. RESULTS. The incorporation of 1% gelatin significantly enhanced cell attachment without compromising hydrogels physical properties, degradation time, VEGF retention and release. Thus, this gelatin concentration was selected for further analysis. Additionally, the covalent incorporation of VEGF or gelatin to the PVA-Tyr network does not hamper their bioactivity, as both still promoted neo-angiogenesis in a CAM assay. Following subcutaneous implantation, the presence of gelatin did not increase the cellular infiltration in the PVA-Tyr hydrogels. Nevertheless, higher vascular infiltration was observed in the groups where either gelatin or VEGF were included. Additionally, preliminary microCT results indicated that the delivery of PVA-Tyr hydrogels containing 1% gelatin in an AVN model was effective in preventing the necrosis-associated resorption of the bone. DISCUSSION & CONCLUSIONS. These results indicated that the presence of either gelatin or VEGF was sufficient to promote vascular infiltration. Additionally, preliminary results suggested the suitability of the developed hydrogels to treat AVN

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.

Aims

Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells.

The April 2024 Foot & Ankle Roundup³⁶⁰ looks at: Safety of arthroscopy combined with radial extracorporeal shockwave therapy for osteochondritis of the talus; Bipolar allograft transplantation of the ankle; Identifying risk factors for osteonecrosis after talar fracture; Balancing act: immediate versus delayed weightbearing in ankle fracture recovery; Levelling the field: proximal supination osteotomy’s efficacy in severe and super-severe hallux valgus; Restoring balance: how adjusting the tibiotalar joint line influences movement after ankle surgery.

Aims

The present study investigated receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), and Runt-related transcription factor 2 (RUNX2) gene expressions in giant cell tumour of bone (GCTB) patients in relationship with tumour recurrence. We also aimed to investigate the influence of CpG methylation on the transcriptional levels of RANKL and OPG.

Aims

This study aimed to explore the biological and clinical importance of dysregulated key genes in osteoarthritis (OA) patients at the cartilage level to find potential biomarkers and targets for diagnosing and treating OA.

There is still no consensus on which concentration of mesenchymal stem cells (MSCs) to use for promoting fracture healing in a rat model of long bone fracture. To assess the optimal concentration of MSCs for promoting fracture healing in a rat model. Wistar rats were divided into four groups according to MSC concentrations: Normal saline (C), 2.5 × 106 (L), 5.0 × 106 (M), and 10.0 × 106 (H) groups. The MSCs were injected directly into the fracture site. The rats were sacrificed at 2 and 6 자 post-fracture. New bone formation [bone volume (BV) and percentage BV (PBV)] was evaluated using micro-computed tomography (CT). Histological analysis was performed to evaluate fracture healing score. The protein expression of factors related to MSC migration [stromal cell-derived factor 1 (SDF-1), transforming growth factor-beta 1 (TGF-β1)] and angiogenesis [vascular endothelial growth factor (VEGF)] was evaluated using western blot analysis. The expression of cytokines associated with osteogenesis [bone morphogenetic protein-2 (BMP-2), TGF-β1 and VEGF] was evaluated using real-time polymerase chain reaction. Micro-CT showed that BV and PBV was significantly increased in groups M and H compared to that in group C at 6 wk post-fracture (P = 0.040, P = 0.009; P = 0.004, P = 0.001, respectively). Significantly more cartilaginous tissue and immature bone were formed in groups M and H than in group C at 2 and 6 wk post-fracture (P = 0.018, P = 0.010; P = 0.032, P = 0.050, respectively). At 2 wk post fracture, SDF-1, TGF-β1 and VEGF expression were significantly higher in groups M and H than in group L (P = 0.031, P = 0.014; P < 0.001, P < 0.001; P = 0.025, P < 0.001, respectively). BMP-2 and VEGF expression were significantly higher in groups M and H than in group C at 6 wk postfracture (P = 0.037, P = 0.038; P = 0.021, P = 0.010). Compared to group L, TGF-β1 expression was significantly higher in groups H (P = 0.016). There were no significant differences in expression levels of chemokines related to MSC migration, angiogenesis and cytokines associated with osteogenesis between M and H groups at 2 and 6 wk post-fracture. The administration of at least 5.0 × 106 MSCs was optimal to promote fracture healing in a rat model of long bone fractures

Tendinopathy is the most common form of chronic tendon disorders, accounting for up 30% of all musculoskeletal clinic visits [1]. In tendon disease, the largely avascular tendon tissue often becomes hypervascularized and fibrotic [2]. As blood vessel growth and angiogenic signaling molecules are often induced by the lack of adequate nutrients and oxygen, hypoxic signaling is speculated to be a root cause of tendon neovascularization and tendinopathy [3,4,5]. However, how the vascular switch is initiated in tendons, and how vascularization contributes to tendon pathology remains unknown. In this talk, we provide evidence that HIF-1α is implicated in tendon disease and HIF-1α stabilization in human tendon cells induces vascular recruitment of endothelial cells via VEGFa secretion. More interesting, HIF-1α stabilization in tendon cells in vivo, seems to recapitulate all main features of fibrotic human tendon disease, including vascular ingrowth, matrix disorganization, changes in tissue mechanics, cell proliferation and innervation. Surprisingly, in vivo knock-out of VEGFa rescued angiogenesis in the tendon core but it did not affect tendon mechanical properties and tissue pathophysiological changes, suggesting that blood vessels ingrowth might not be a primary cause but a consequence of HIF-1α activation

Bone regeneration is an area of acute medical need, but its clinical success is hampered by the need to ensure rapid vascularization of osteogenic grafts. Vascular Endothelial Growth Factor (VEGF) is the master regulator of vascular growth and during bone development angiogenesis and osteogenesis are physiologically coupled through so-called angiocrine factors produced by blood vessels. However, how to exploit this process for therapeutic bone regeneration remains a challenge (1). Here we will describe recent work aiming at understanding the cross-talk between vascular growth and osteogenesis under conditions relevant for therapeutic bone regeneration. To this end we take advantage of a unique platform to generate controlled signalling microenvironments, by the covalent decoration of fibrin matrices with tunable doses and combinations of engineered growth factors. The combination of human osteoprogenitors and hydroxyapatite in these engineered fibrin matrices provides a controlled model to investigate how specific molecular signals regulate vascular invasion and bone formation in vivo. In particular, we found that:. 1). Controlling the distribution of VEGF protein in the microenvironment is key to recapitulate its physiologic function to couple angiogenesis and osteogenesis (2);. 2). Such coupling is exquisitely dependent on VEGF dose and on a delicate equilibrium between opposing effects. A narrow range of VEGF doses specifically activates Notch1 signaling in invading blood vessels, inducing a pro-osteogenic functional state called Type H endothelium, that promotes differentiation of surrounding mesenchymal progenitors. However, lower doses are ineffective and higher ones paradoxically inhibit both vascular invasion and bone formation (Figure 1) (3);. 3). Semaphorin3a (Sema3a) acts as a novel pro-osteogenic angiocrine factor downstream of VEGF and it mediates VEGF dose-dependent effects on both vascular invasion and osteogenic progenitor stimulation. In conclusion, vascularization of osteogenic grafts is not simply necessary in order to enable progenitor survival. Rather, blood vessels can actively stimulate bone regeneration in engineered grafts through specific molecular signals that can be harnessed for therapeutic purposes. Acknowledgements: This work was supported in part by the European Union Horizon 2020 Program (Grant agreement 874790 – cmRNAbone). For any figures and tables, please contact the authors directly

The pathophysiological basis of alterations in trabecular bone of patients with osteonecrosis of the femoral head (ONFH) remains unclear. ONFH has classically been considered a vascular disease with secondary changes in the subchondral bone. However, there is increasing evidence suggesting that ONFH could be a bone disease, since alterations in the functionality of bone tissue distant from the necrotic lesion have been observed. We comparatively studied the transcriptomic profile of trabecular bone obtained from the intertrochanteric region of patients with ONFH without an obvious aetiological factor, and patients with osteoarthritis (OA) undergoing total hip replacement in our Institution. To explore the biological processes that could be affected by ONFH, we compared the transcriptomic profile of trabecular bone from the intertrochanteric region and the femoral head of patients affected by this condition. Differential gene expression was studied using an Affymetrix microarray platform. Transcriptome analysis showed a differential signature in trabecular bone from the intertrochanteric region between patients with ONFH and those with OA. The gene ontology analyses of the genes overexpressed in bone tissue of patients with ONFH revealed a range of enriched biological processes related to cell adhesion and migration and angiogenesis. In contrast, most downregulated transcripts were involved in cell division. Trabecular bone in the intertrochanteric region and in the femoral head also exhibited a differential expression profile. Among the genes differentially expressed, we highlighted those related with cytokine production and immune response. This study identified a set of differently expressed genes in trabecular bone of patients with idiopathic ONFH, which might underlie the pathophysiology of this condition. Acknowledgements: This work was supported by grants PI18/00643 and PI22/00939 from ISCIII-FEDER, Ministerio de Ciencia, Innovación y Universidades (MICINN)-AES

Macrophages (Mφ) are immune cells that play a crucial role in both innate and adaptive immunity as they are involved in a wide range of physiological and pathological processes. Depending on the microenvironment and signals present, Mφ can polarize into either M1 or M2 phenotypes, with M1 macrophages exhibiting pro-inflammatory and cytotoxic effects, while M2 macrophages having immunosuppressive and tissue repair properties. Macrophages have been shown to play key roles in the development and progression or inhibition of various diseases, including cancer. For example, macrophages can stimulate tumor progression by promoting immunosuppression, angiogenesis, invasion, and metastasis. This work aimed to investigate the effect of extracellular vesicles (EVs)-derived from polarized macrophages on an osteosarcoma cell line. Monocytes were extracted from buffy coats and cultured in RPMI medium with platelet lysate or M-CSF. After 6 days of seeding, Mφ were differentiated into M1 and M2 with INF-γ/LPS and IL-4/IL-13, respectively. The medium with M1 or M2 derived EVs was collected and EVs were isolated by differential centrifugation and size exclusion chromatography and its morphology and size were characterized with SEM and NTA, respectively. The presence of typical EVs markers (CD9, CD63) was assessed by Western Blot. Finally, EVs from M1 or M2-polarized Mφ were added onto osteosarcoma cell cultures and their effect on cell viability and cell cycle, proliferation, and gene expression was assessed. The EVs showed the typical shape, size and surface markers of EVs. Overall, we observed that osteosarcoma cells responded differentially to EVs isolated from the M1 and M2-polarized Mφ. In summary, the use of Mφ-derived EVs for the treatment of osteosarcoma and other cancers deserves further study as it could benefit from interesting traits of EVs such as low immunogenicity, nontoxicity, and ability to pass through tissue barriers. Acknowledgements: Carlos III Health Institute and the European Social Fund for contract CP21/00136 and project PI22/01686