Intermittently administered parathyroid hormone (PTH 1-34) has been shown to promote bone formation in both human and animal studies. The hormone and its analogues stimulate both bone formation and resorption, and as such at low doses are now in clinical use for the treatment of severe osteoporosis. By varying the duration of exposure, parathyroid hormone can modulate genes leading to increased bone formation within a so-called ‘anabolic window’. The osteogenic mechanisms involved are multiple, affecting the stimulation of osteoprogenitor cells, osteoblasts, osteocytes and the stem cell niche, and ultimately leading to increased osteoblast activation, reduced osteoblast apoptosis, upregulation of Wnt/β-catenin signalling, increased stem cell mobilisation, and mediation of the RANKL/OPG pathway. Ongoing investigation into their effect on bone formation through ‘coupled’ and ‘uncoupled’ mechanisms further underlines the impact of intermittent PTH on both cortical and cancellous bone. Given the principally catabolic actions of continuous PTH, this article reviews the skeletal actions of intermittent PTH 1-34 and the mechanisms underlying its effect. Cite this article: L. Osagie-Clouard, A. Sanghani, M. Coathup, T. Briggs, M. Bostrom, G. Blunn. Parathyroid hormone 1-34 and skeletal anabolic action: The use of parathyroid hormone in bone formation. Bone Joint Res 2017;6:14–21. DOI: 10.1302/2046-3758.61.BJR-2016-0085.R1

Objectives. Adult mice lacking the transcription factor NFAT1 exhibit osteoarthritis (OA). The precise molecular mechanism for NFAT1 deficiency-induced osteoarthritic cartilage degradation remains to be clarified. This study aimed to investigate if NFAT1 protects articular cartilage (AC) against OA by directly regulating the transcription of specific catabolic and anabolic genes in articular chondrocytes. Methods. Through a combined approach of gene expression analysis and web-based searching of NFAT1 binding sequences, 25 candidate target genes that displayed aberrant expression in Nfat1. -/-. AC at the initiation stage of OA, and possessed at least four NFAT1 binding sites in the promoter of each gene, were selected and tested for NFAT1 transcriptional activities by chromatin immunoprecipitation (ChIP) and promoter luciferase reporter assays using chondrocytes isolated from the AC of three- to four-month-old wild-type mice or Nfat1. -/-. mice with early OA phenotype. Results. Chromatin immunoprecipitation assays revealed that NFAT1 bound directly to the promoter of 21 of the 25 tested genes encoding cartilage-matrix proteins, growth factors, inflammatory cytokines, matrix-degrading proteinases, and specific transcription factors. Promoter luciferase reporter assays of representative anabolic and catabolic genes demonstrated that NFAT1-DNA binding functionally regulated the luciferase activity of specific target genes in wild-type chondrocytes, but not in Nfat1. -/-. chondrocytes or in wild-type chondrocytes transfected with plasmids containing mutated NFAT1 binding sequences. Conclusion. NFAT1 protects AC against degradation by directly regulating the transcription of target genes in articular chondrocytes. NFAT1 deficiency causes defective transcription of specific anabolic and catabolic genes in articular chondrocytes, leading to increased matrix catabolism and osteoarthritic cartilage degradation. Cite this article: M. Zhang, Q. Lu, T. Budden, J. Wang. NFAT1 protects articular cartilage against osteoarthritic degradation by directly regulating transcription of specific anabolic and catabolic genes. Bone Joint Res 2019;8:90–100. DOI: 10.1302/2046-3758.82.BJR-2018-0114.R1

During the last decades, several research groups have used bisphosphonates for local application to counteract secondary bone resorption after bone grafting, to improve implant fixation or to control bone resorption caused by bone morphogenetic proteins (BMPs). We focused on zoledronate (a bisphosphonate) due to its greater antiresorptive potential over other bisphosphonates. Recently, it has become obvious that the carrier is of importance to modulate the concentration and elution profile of the zoledronic acid locally. Incorporating one fifth of the recommended systemic dose of zoledronate with different apatite matrices and types of bone defects has been shown to enhance bone regeneration significantly in vivo. We expect the local delivery of zoledronate to overcome the limitations and side effects associated with systemic usage; however, we need to know more about the bioavailability and the biological effects. The local use of BMP-2 and zoledronate as a combination has a proven additional effect on bone regeneration. This review focuses primarily on the local use of zoledronate alone, or in combination with bone anabolic factors, in various preclinical models mimicking different orthopaedic conditions. Cite this article: I. Qayoom, D. B. Raina, A. Širka, Š. Tarasevičius, M. Tägil, A. Kumar, L. Lidgren. Anabolic and antiresorptive actions of locally delivered bisphosphonates for bone repair: A review. Bone Joint Res 2018;7:548–560. DOI: 10.1302/2046-3758.710.BJR-2018-0015.R2

Objective. In order to effectively utilize mechanical signals in the clinic as a non-drug-based intervention to improve cartilage defect regeneration after surgical treatment, it is essential to identify crucial components of the cellular response that are typical to the anabolic process. The mechanisms behind the effect of mechanical stimulation are, however, not fully understood and the signaling pathways involved in the anabolic response of chondrocytes to mechano-transduction are not well described. Therefore, a genome-wide identification of mechano-regulated genes and candidate pathways in human chondrocytes subjected to a single anabolic loading episode was performed in this study and time evolution and re-inducibility of the response was characterized. Design. Osteochondral constructs consisting of a chondrocyte-seeded collagen-scaffold connected to β-tricalcium-phosphate were pre-cultured for 35 days and subjected to dynamic compression (25% strain, 1 Hz, 9×10 minutes over 3h) before microarray-profiling was performed. Proteoglycan synthesis was determined by 35S-sulfate-incorporation over 24 hours. Protein alterations were determined by Western blotting. Results. Cell viability and hardness of constructs were unaltered by dynamic compression while proteoglycan synthesis was significantly stimulated (1.45-fold, p=0.016). Among 115 significantly regulated genes, 114 were up-regulated, 48 of them ≥ two-fold. AP-1-relevant transcription factors FOSB and FOS strongly increased in line with elevated ERK1/2-phosphorylation and rising MAP3K4 expression. Expression of proteoglycan-synthesizing enzymes CHSY1 and GALNT4 was load-responsive as were factors associated with the MAPK-, TGF-β-, calcium-, retinoic-acid-, Wnt- and Notch-signaling pathway which were significantly altered. SOX9, BMP4 and BMP6 levels rose significantly also after multiple loading episodes at daily intervals even at the 14th cycle with no indication for desensitation. Canonical pSmad2/3 and pSmad1/5/9-signalling was apparently unaltered. Conclusion. This study associates raising SOX9 protein levels, pERK stimulation and increased CHSY1 expression with anabolic loading of chondrocytes and suggests that more pathways than so far anticipated apparently work together in a complex network of stimulators and feedback-regulators. Knowledge on time evolution of mechanosensitive indicators responding to anabolic loading is crucial to maximize cartilage matrix-deposition for the generation of high-level cartilage replacement tissue

The literature on fracture repair has been reviewed. The traditional concepts of delayed and nonunion have been examined in terms of the phased and balanced anabolic and catabolic responses in bone repair. The role of medical manipulation of these inter-related responses in the fracture healing have been considered

A Ruys, School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney. The effects of bone anabolics can be maximised by systemic co-treatment with an anti-catabolic. Local treatment may reduce the total drug required and produce superior outcomes, although high dose local bisphosphonate has been reported to impair bone formation. We have explored local co-delivery of anabolic/anti- catabolic bone drugs at different doses. We manufactured biodegradable poly-D,L-lactic acid (PDLLA) polymer pellets containing 25g BMP-7 as an anabolic with or without 0.002mg-2mg Pamidronate (PAM) as an anti-catabolic. Polymer pellets were surgically implanted into the hind limb muscle of female C57BL6 mice. Animals were sacrificed at three weeks post- implantation and bone formation was assessed by radiography, microcomputed tomography (microCT) and histology. Histological staining on five Âm paraffin sections included haematoxylin/eosin, alcian blue/picrosirius red, and tartrate- resistant acid phosphatase (TRAP). Radiographic and microCT data confirmed that 0.02mg and 0.2mg local PAM doses significantly augmented BMP-7 induced bone formation. In contrast, 2mg local PAM dramatically reduced the amount of bone present. This dose was comparable to that used by Choi et al who also reported impaired bone formation in a skull defect model.2 three-dimensional microCT and histological analyses of the ectopic bone and surrounding muscle showed a cortical shell covering the polymer pellet, which had not completely resorbed. Histological analysis at the pellet/bone interface showed tissue granulation and no inflammation, suggesting a high biocompatibility of the PDLLA polymer. The presence of bisphosphonate also decreased the amount of fatty marrow tissue seen within between the cortical shell and the unresorbed polymer. For the first time we can demonstrate synergy with local BMP/bisphosphonate. This study confirms that high local PAM doses can have negative effects, indicating a need to avoid overdosing. The lack of implant degradation suggests a need to optimise polymer degradation for bone tissue engineering application

Summary. Anabolic and catabolic signalling processes within IVDs display overlapping pathways, however some pathways were identified as selective to catabolic signalling and inhibition of one of these pathways inhibited some of the catabolic factors induced by IL-1 although NFkB inhibition also affected anabolic expression. Degeneration of intervertebral discs (IVDs) is implicated in 40% of low back pain cases. In the normal disc the balance between anabolic and catabolic processes are carefully balanced. During degeneration this balance is lost in favour of catabolic processes which lead to degradation of the IVD, infiltration of blood vessels and nerves and release of cytokines which sensitise nerves to pain. Interleukin 1 (IL-1) is known to be important in the pathogenesis of IVD degeneration, here we investigated the intracellular signalling pathways activated by IL-1 and those activated by an anabolic factor (CDMP-1) to investigate differential pathways. Human nucleus pulposus cells (NP) removed during discetomy for nerve root pain were stimulated with IL-1 or CDMP-1 for 30 minutes. Site-specific phosphorylation of 46 signalling molecules were identified using R&D proteome array. The activation of ERK1/2, p38, c-jun, and IkB were confirmed using cell based ELISAs, in addition pNFκB localisation in stimulated cells was determined using immunohistochemisty. Pre-treatment with inhibitors to p38, and NFkB for 30 minutes, followed by stimulation with IL-1 (10ng/mL) or CDMP-1 (10ng/mL) for 24 hours was investigated to determine effects on anabolic and catabolic factors. In addition localisation of phosphorylated c-jun, p38 and NFkB were investigated within paraffin embedded sections of human IVD to investigate the presence of active pathways in vivo. Twenty intracellular signalling pathways were activated following CDMP-1 treatment and 8 signalling pathways activated by IL-1. Of note key classical IL-1 signalling pathways p38 MAPK, ERK 1/2 and JNK were activated by IL-1, however of these ERK 1/2 particularly was also activated by CDMP-1, whilst p38 and c-jun were only activated by IL-1. IL-1 induced activation of NFkB signalling to a greater extent than CDMP-1, these results were confirmed by the ‘in cell ELISAs’. IVD tissue samples displayed immunopositive staining for phosphorylated c-jun, NFkB and p38. Inhibition of p38 signalling inhibited IL-1 induced MMP 13 expression, but had little effect on the induction of IL-8. However inhibitors of NFkB signalling pathway failed to inhibit the induction of MMP 13 but abrogated the induced IL-6 and IL-8 expression. IL-1 induced a complete aberration of aggrecan expression by NP cells in alginate culture, this effect was partly inhibited by p38 MAPK inhibitor but was completely restored by inhibiting NFkB signalling. However the aggrecan expressed in CDMP-1 treated cells was decreased by inhibiting NFkB but not p38. Here, we have shown that anabolic and catabolic signalling processes within IVDs show a number of overlapping pathways, however a number of differential pathways were identified and inhibition of p38 MAPK and NFkB pathways inhibited a number of catabolic processes investigated which were induced by IL-1. Thus inhibition of signalling pathways could be a novel mechanism of inhibiting catabolic processes which could hold promise to inhibit degeneration at early stages of disease but also create the correct tissue niche to promote regeneration of the disc

Mechanical loading is a potent stimulator of bone formation. A screen for genes associated with mechanically-induced osteogenesis implicated the glutamate transporter GLAST-1 (1), in the mechanoresponse. We are investigating whether modulation of glutamate transporters represents a potential anabolic therapy in bone. Bone cells express functional components from each stage of the glutamate signalling pathway and activation of ionotropic glutamate receptors on osteoblasts can increase bone forming activity (2). Five high affinity Na+-dependant excitatory amino acid transporters (EAATs 1-5) regulate glutamatergic signalling. EAAT1 (GLAST-1) is expressed by osteocytes and bone-forming osteoblasts in vivo. We quantified transcripts for EAATs 1-3 and two splice variants (EAAT1a and EAAT1ex9skip) in human osteoblasts (MG63, SaOS-2 and primary) using real time-PCR. EAAT1a expression was very low whilst levels of the dominant negative EAAT1ex9skip were much higher in all cell types. EAAT1 and EAAT3 proteins were detected by immunofluorescence. We also demonstrated that glutamate transporters function in human osteoblasts. Sodium-dependent 14C-labelled glutamate uptake, sensitive to pharmacological EAAT inhibitors (t-PDC, TBOA) and extracellular glutamate concentration (10-500μM) was detected in MG63 and SaOS-2 cells. To determine whether modulation of EAATs can influence bone formation, we used pharmacological inhibitors of EAATs 1-5 (t-PDC and TBOA) and also over-expressed EAAT1exon9skip using antisense oligonucleotides (AONs) targeted to splice donor sequence of exon 9. Experiments were performed in 0-500μM glutamate. Pharmacological inhibition of EAATs over 5-21 days increased alkaline phosphatase activity and mineralisation of SaOS-2 cells and human primary osteoblasts. Over-expression of EAAT1ex9skip significantly increased cell number and decreased cell death as well as significantly increasing PCNA, Osteonectin and Type I collagen mRNAs in MG63 cells. Furthermore, over-expression of EAAT1ex9skip increased mean alkaline phosphatase activity over 48hrs in SaOS-2 cells. These data show that EAATs are expressed and functional in osteoblasts and that pharmaceutical and genetic inhibition of their activity increases bone formation. These mechanically regulated glutamate transporters are important in regulating bone homeostasis and their manipulation may represent a new anabolic therapy for the treatment of disorders such as osteoporosis or non-union fractures

Introduction. Sclerostin has been implicated in mechanotransduction in bone and recent data show a lack of response to loading in the sclerostin transgenic mouse. Sclerostin, the protein product of the SOST gene, is an attractive therapeutic target for low bone mass conditions, including osteoporosis. It is expressed exclusively by mature osteocytes in bone and we have shown that sclerostin targets pre-osteocytes/osteocytes to regulate bone mineralization and osteoclast activity, as well as inducing catabolic gene expression in osteocytes themselves and promoting osteocyte-mediated bone loss (osteocytic osteolysis). The aim of this study was to examine the direct effects of sclerostin on anabolic responses to loading in bone ex vivo. Methods. 10 × 5mm bovine sternum trabecular bone cores were perfused with osteogenic media at 37°C for up to 3 weeks in individual bone culture chambers. The cores were divided into 3 groups; a) mechanically loaded (300 cycles, 4000 μstrain, 1 Hz/day), b) identical loading regime with continuous perfusion of 50 ng/ml recombinant human sclerostin and c) unloaded controls. Loading was accomplished using a second-generation Zetos™ bone loading system. Daily measurements of bone stiffness (Young's modulus), media pH and ionic calcium concentrations were made. Histomorphometric assessment, including fluorochrome labelling analysis, was made of resin-embedded, non-decalcified samples at the end of the experiment. Gene expression in the bovine bone was examined by real-time RT-PCR. Results. Bovine bone cores showed a steady increase in Young's modulus with daily application of mechanical loading. This increase in stiffness was blocked by the co-addition of sclerostin. Sclerostin also induced bone acidification and a net release of bone calcium, indicated by the decrease in media pH and the relative increase in ionic calcium concentrations in the presence of sclerostin. Sclerostin also completely abrogated loading-induced calcium/calcein uptake. Sclerostin induced an increase in the expression of the bone resorption genes, tartrate resistant acid phosphatase (TRAP), carbonic anhydrase and cathepsin K and induced the release of β-CTX. Histological examination revealed a significant increase in the size of the osteocyte lacunae in sclerostin-treated bone cores, suggesting a role for osteocytic osteolysis in this effect. Discussion/Conclusion. The observation that sclerostin abrogated the loading-induced increase in bone stiffness constitutes direct evidence for a negative effect of sclerostin on the anabolic response to mechanical loading. Our findings may be explained in part by the observation that sclerostin negatively controls mineralization by late osteoblasts and pre-osteocytes (1). It is also possible that osteocytes themselves are capable of releasing bone mineral in response to sclerostin. This study demonstrates that sclerostin directly antagonises the anabolic effects of mechanical loading in the absence of external (circulating, neural, hormonal) influences. The mechanisms, by which sclerostin exerts these effects, warrant further study

Dupuytren’s contracture is characterised by abnormal fibroblast proliferation and extracellular matrix deposition in the palmar fascia. Fibroblast proliferation and matrix deposition in connective tissues are regulated by cytokines. A number of cytokines including transforming growth factor beta (TGFβ), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF) and epidermal growth factor (EGF) are known to have potent anabolic effects on connective tissue. The aim of this study was to investigate the role played by anabolic cytokines in the pathogenesis of Dupuytren’s disease. Twelve specimens of Dupuytren’s contracture and six control specimens of palmar fascia obtained from patients undergoing carpal tunnel release were cultured using a serumless method under standard conditions for 72 h. Levels of TGFβ-1, bFGF, PDGF and EGF in the medium were estimated using an enzyme linked immunoabsorbent assay technique. Neither Dupuytren’s tissue nor control palmar fascia produced any EGF. The mean (±S.D.)levels of bFGF, PDGF and TGFβ-1 produced by cultured palmar fascia were: 1270 ± 832, 74 ± 24, < 7, and for Dupuytren’s tissue were 722 ± 237, 139 ± 76.6, 645 ± 332, respectively. The levels of PDGF and TGFβ-1 were significantly higher in Dupuytren’s tissue. PDGF is produced in increased amounts by Dupuytren’s tissue. This may contribute to the fibroblast proliferation and increased ECM deposition observed in this condition. TGFβ-1 is not produced by normal palmar fascia but is produced in large amounts by Dupuytren’s tissue. The major physiologic role of TGFβ-1 is to stimulate formation of fibrous tissue. It plays a major role in wound healing and also in pathological conditions where fibrosis is a prominent feature. Inappropriate production of TGFβ-1 in the palmar fascia in Dupuytren’s disease may play a central role in initiating and stimulating the abnormal fibroblast proliferation and collagen synthesis seen in this condition

Aim: We hypothesize that anabolic steroid administration enhances matrix remodelling and improves the biomechanical properties of bio-artificially engineered human supraspinatus tendons (BATs). Method: BATs were treated either with nandrolone decanoate (NLS group, n=18), stretching (LNS group, n=18), or both (LS group, n=18). A control group received no treatment (NLNS group, n=18). BATs’ contractility was assessed by daily scanning and two dimensional analysis. Cytoskeletal organization was evaluated microscopically with DAPI and rhodamine phalloidin staining. Matrix metalloproteinase-3 (MMP-3) levels – an indicator of matrix remodelling – were discerned by ELISA assay, and biomechanical properties by load-to-failure testing. Results: The LS group showed greatest contractility and the best-organized actin cytoskeleton when compared to the other groups. On the second and third day of treatment, MMP-3 levels in the LS group were significantly greater than those of NLNS group and greater than NLS and LNS groups. The biomechanical properties (load to failure, ultimate stress, ultimate strain, elastic modulus, and energy to failure) in the LS group were significantly improved when compared to NLNS and NLS (p< .05) groups and 26–48% greater than those in LNS group. Conclusions: Nandrolone decanoate and load act synergistically to increase matrix remodelling and biomechanical properties of bioengineered human supraspinatus tendons. Carefully prescribed and monitored, anabolic steroids may have an important adjunct role in postoperative healing and rehabilitation of repaired rotator cuff tendons. More research is necessary to fully evaluate the safety and efficacy of anabolic steroids in this application

Summary Statement. The stable inhibition of miR-214 in the aged osteoporotic rats induced by OVX could be achieved by periodic administration of AntagomiR-214 at a dosage of 4 mg/kg and at an interval of 7 days, which will provide a potential bone anabolic strategy for treatment of osteoprosis. Introduction. MiR-214 has a crucial role in suppressing bone formation and miR-214 inhibition in osteogenic cells may be a potential anabolic strategy for ameliorating osteoporosis (Wang X, et al. 2013). An aged ovariectomised rat has been regarded as a golden model to test bone anabolic agents for reversing established osteoporosis in aged postmenopausal women (Li X, et al. 2009). However, there is still lack of evidence to demonstrate bone anabolic potential of therapeutic inhibition of miR-214 within osteogenic cells in the golden model. So, it should be necessary to establish RNAi-based administration protocol toward stable inhibition of miR-214 at a low level in the golden model. A targeted delivery system specifically facilitating Antagomir-214 approaching osteogenic cells, i.e. (Asp-Ser-Ser). 6. -liposome (Zhang G, et al 2012), was employed in this study. Objectives. This study was to investigate optimal dosage and duration for therapeutic inhibition of miR-214 within osteogenic cells in the aged osteoporotic rats induced by ovariectomy. Materials and Methods. Six-month-old female Sprague-Dawley rats were ovariectomised (OVX) and left untreated for 12 months to establish aged osteoporosis. To determine the optimal dosage for therapeutic inhibition of miR-214, the OVX rats were injected intravenously with the AntagomiR-214 at a dosage of 0.5mg/kg, 1mg/kg, 2mg/kg, 4mg/kg, 6mg/kg and 8mg/kg (n=6 for each dosage group) delivered by (Asp-Ser-Ser). 6. -liposome, respectively. Thereafter, miR-214 expression level in osteogenic cells from bilateral femur was quantified at day 2 post injection by real-time PCR analysis in combination with laser captured dissection (LCM). To determine the optimal duration of miR-214, the OVX rats were intravenously injected with the AntagomiR-214 (AntagomiR-214 group) or non-sense AntagomiR-214 (NC group) delivered by (Asp-Ser-Ser). 6. -liposome at the optimal dosage or (Asp-Ser-Ser). 6. -liposome alone (Vehicle group). Then, the miR-214 level in osteogenic cells from bilateral femur was quantified at 1, 3, 5, 7, 9, 12, 14, 16, 21 day after the single dosing (n=6 for each time-point) by real-time PCR analysis in combination with LCM, respectively. To examine the long-term effect of the AntagomiR-214 after periodic pulsed dosing, the OVX rats were administrated with the AntagomiR-214 at the optimal dosage and duration for 5 repeated injections and then the miR-214 level in osteogenic cells from bilateral femur was quantified by real-time PCR analysis in combination with LCM. Results. The miR-214 level was efficiently decreased in a dose-dependent manner by the AntogomiR-214 and reached the level lower than 10% of the baseline at a dosage of 4 mg/kg at least in the aged osteoporotic rats. The effective duration for miR-214 at a level lower than 50% of the baseline lasted for 7 days in the osteoporotic rats after the single dosing. The miR-214 level was continuously lowered until 28 days and continuously maintained later at the level lower than 10% of the baseline by the 5 pulsed dosing of the AntagomiR-214 at an interval of 7 days and at a dosage of 4 mg/kg in the osteoporotic rats. Conclusions. The stable inhibition of miR-214 for bone anabolic strategy in the aged osteoporotic rats induced by OVX could be achieved by periodic administration of AntagomiR-214 at a dosage of 4 mg/kg and at an interval of 7 days

A total of 63 women who had an operation for a fracture of the hip was randomly allocated to one year of treatment either with anabolic steroids, vitamin D and calcium (anabolic group) or with calcium only (control group). The thigh muscle volume was measured by quantitative CT. The bone mineral density of the hip, femur and tibia was assessed by quantitative CT and dual-energy x-ray absorptiometry and of the heel by quantitative ultrasound. Quantitative CT showed that the anabolic group did not lose muscle volume during the first 12 months whereas the control group did (p< 0.01). There was less bone loss in the proximal tibia in the anabolic group than in the control group. The speed of gait and the Harris hip score were significantly better in the anabolic group after six and 12 months. Anabolic steroids, even in this moderate dose, given in combination with vitamin D and calcium had a beneficial effect on muscle volume, bone mineral density and clinical function in this group of elderly women

Background: Recombinant bone morphogenic proteins (BMPs) are potent bone anabolic agents suggested for the treatment of orthopaedic complications associated with neurofibromatosis type 1 (NF1), in particular, congenital pseudarthrosis of the tibia. We have explored the effect of Nf1 haploinsufficiency on ex vivo and in vivo models of BMP-induced bone formation in Nf1+/− mice. Methods: Using an Nf1+/− knockout mouse model, we expanded primary cell cultures from calvarial and long bone osteoblasts and measured osteogenic markers, such as alkaline phosphatase and mineralization using Alizarin Red staining, and the responses of these markers to BMP-2 treatment. We also developed an in vivo muscle pouch heterotopic ossification model to assess the ability of BMP-2 to form bone. Results: Primary osteoblast cultures from Nf1+/− mice showed reduced ALP staining, ALP activity and mineralization, denoting an anabolic deficiency. Nf1+/− osteoblasts responded to BMP-2 treatment, although osteogenic markers were reduced compared to BMP-2 treated Nf1+/+osteoblasts. Heterotopic bone was induced in both genotypes by surgically implanting BMP-2, however less bone was formed in Nf1+/− mice than Nf1+/+ controls. Conclusion: These data indicate that BMP therapies have potential utility in treating orthopaedic defects in children with NF1, but that dosing may need to be optimized for this patient subgroup or that catabolism may need to be also controlled

Introduction: Between the elderly affected by femoral neck or diaphyseal fractures are emerging few serious complications as delate union, instability of osteosynthesis, re-fracture or periprosthetic fracture. In addition the co-morbidity elevate ulteriorly the risks of the new operation which is often impossible or refused. Recently it has been recommended to orthopaedic surgeons the managment and treatment of osteoporosis. The aim of this study was to consider at 2 years follow-up the functional outcome of femoral fracture in osteoporotic elderly treated with a surgical procedure followed by daily assumption of teriparatide, an anabolic agent increasing bone mineral content, density and strength. Materials and Methods: 21 compliant female between 63 and 94 years-old presenting a femoral fracture were recruited. Before operation they undergone to a routinary instrumental examins completed by bone metabolism screening. This was constituted by biochemical bone turnover markers, standard radiograms of dorsal and lumbar spine. Lumbar and contralateral femoral BMD was measured by DXA during hospitalization before the assumption of anabolic agent. They received daily subcutaneous teriparatide (20 microg) per day for 18 months, 1g of calcium and 800 UI of vitamin D3 daily as oral supplementation from day 15 by operation. All the patients repeated: xrays of affected segment at 2, 4, 6 months; biochemical bone markers 1, 3, 6, 12, 18 and 24 months; DEXA at first and second year. The evaluation of the quality of life was evaluated in terms of recovery of walking, need of re.operation, occurance of new fracture and with a questionnaire. Results: eleven lateral femoral neck fracture treated with endomedullary nail, six medial femoral neck fracture treated with cemented endoprosthesis, four periprosthetic fracture of the femur treated with plaque and screws. The healing was detected with radiograms before 4th month. The vitamin D was at lower levels at admission but the supplementation was sufficient to normalize. The other biochemical variables of bone formation and resorption peaked within the consolidation process then remained normalized for two years. Lumbar and contralateral femoral BMD were increased after 12 months and maintained at 24 months. At 2 years follow-up all patients live, walk in autonomy without or with stick and none of them have needed a re-operation or was afflicted by new vertebral or non vertebral fracture. Conclusions: The clinical relevance of the present study is the significant improvement of functional outcome and quality of life after femoral fracture in osteoporotic elderly with post-operative assumption of anbolic agent as Teriparatide

Introduction. Following tear of its tendon, the muscle undergoes retraction, atrophy and fatty infiltration. These changes are inevitable and considered irreversible and limit the potential of successful repair of musculotendinous units. It was the purpose of this study to test the hypothesis that administration of anabolic steroids can prevent these muscular changes following experimental supraspinatus tendon release in the rabbit. Methods. The supraspinatus tendon was experimentally released in 20 New Zealand rabbits. Musculotendinous retraction was monitored over a period of 6 weeks. The seven animals in group I had no additional intervention, six animals in group II had local and seven animals in group III had systemic administration of nandrolone deconate during six weeks of retraction. At the time of sacrifice, in-vivo muscle performance as well as radiologic and histologic muscle changes were investigated. Results. Supraspinatus retraction was significantly higher in group I (1.8 ± 0.2cm) than in group II (1.5 ± 0.3cm, p = 0.044) or III (1.2 ± 0.3cm, p = 0.001). The reduction in radiological cross sectional area, as a measure for atrophy, was significant in groups I (p = 0.013) and II (p = 0.030) and insignificant in group III (p = 0.149). Histologically, there was no fatty infiltration in the treated groups II (p = 1.000) and III (p = 0.812), but in the untreated group I (p = 0.0312). The work of the respective muscle during one standardized contraction with supramaximal stimulation decreased markedly in groups I (p = 0.056) and II (p = 0.0528), and also but less in group III (p = 0.23). Conclusion. This is the first documentation of prevention of important muscle alterations after chronic retraction of the musculotendinous unit caused by rotator cuff tear. Nandrolone deconate administration in the post tendon release phase prevented fatty infiltration of the supraspinatus muscle and reduced functional muscle impairment caused by myo-tendinous retraction

Evidence is accumulating for the role of bone in the pathogenesis of osteoarthritis (OA). Previous studies have shown a generalised increase in bone mass and hypo-mineralisation in OA patients. However, the molecular and cellular mechanisms involved in the increased bone mass and matrix compositional profiles in OA, at distal skeletal sites to the articular cartilage, have not yet been well defined. This study examined whether gene expression of bone anabolic factors, trabecular bone architecture and matrix mineralisation are altered in human OA and non-OA hipbone. Intertrochanteric (IT) trabecular bone samples were obtained from 15 primary hip OA patients (mean age 65 [48–85] years) and 13 closely age- and gender-matched autopsy controls (mean age 63 [44–83] years). Semi-quantitative RT-PCR analysis revealed elevated mRNA expression levels of alkaline phosphatase (p < 0.002), osteocalcin (p < 0.0001), osteopontin (p < 0.05), collagen type-I α chains COL1A1 (p < 0.0001) and COL1A2 (p < 0.002), in OA bone compared to control, suggesting possible increases in osteoblastic biosynthetic activity and/or bone turnover at the IT region in OA. Interestingly, the ratio of COL1A1:COL1A2 mRNA was almost 2-fold greater in OA bone compared to control (p < 0.001), suggesting the potential presence of collagen type-I homotrimer at the distal site that may associate with hypomineralisation in OA individuals. Using a quantitative backscatter electron imaging technique, mineralisation profiles of IT trabecular bone indicated decreased mineralisation in the OA group compared to the control group (24.2 weight percent calcium [wt%Ca] versus 25.3 wt%Ca). Bone histomorphometric analysis found OA IT bone had increased surface density of bone and decreased trabecular separation compared to control bone. Taken together with a reported increase in diffuse microdamage in OA IT bone (Fazzalari et al. Bone 31:697–702, 2002), possibly due to hypomineralisation, these results are consistent with the altered bone material properties found in OA individuals. The finding of differential gene expression, altered mineralisation and architectural changes in OA bone, at a skeletal site distal to the active site of joint degeneration, supports the concept of systemic involvement of bone in the pathogenesis of OA

Regulation of articular cartilage homeostasis is a complex process in which biologic and mechanical factors are involved. Hyperactivation of Wnt signaling, associated with osteoarthritis (OA), could jeopardize the protective anabolic effect of physiological loading. Here, we investigated the role of excessive Wnt signalling in cartilage molecular responses to loading. Human cartilage explants were harvested from hips of donors without OA. The Wnt agonist CHIR99021 was used to activate Wnt signalling 24 hours before cartilage explants were subjected to a loading protocol consisting of 2 cycles of 1 hour of 10% compression at 1 Hz, followed by 1-hour free swelling. Mechano-responsiveness was evaluated using the expression of type II collagen, aggrecan and MMP-13. Expression of known target genes TCF-1 and c-JUN was evaluated as positive control for Wnt and mechanical stimulation, respectively. In the absence of loading, CHIR99021 decreased the expression of the cartilage anabolic genes type II collagen and aggrecan, and increased the levels of MMP-13, corroborating that Wnt hyperactivation disrupts cartilage homeostasis. In the absence of Wnt hyperactivation, the applied loading protocol, representative for a physiologic stimulation by mechanical loading, led to an increase in type II collagen and aggrecan levels. However, when cartilage explants were subjected to mechanical stimulation in the presence of CHIR99021, the expression of cartilage anabolic genes was decreased, indicating changes to the cells’ mechano-responsiveness. Interestingly, mechanical stimulation was able to reduce the expression levels of MMP-13 compared to the condition of CHIR stimulation without loading. Hyperactivation of Wnt signaling switches the anabolic effect of physiologic compressive loading towards a potential catabolic effect and could contribute to the development and progression of OA

Aims. We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants. Methods. An established allografted revision protocol was implemented bilaterally into the stifle joints of 24 canines. At revision surgery, each animal received one BMP-2 (5 µg) functionalized implant, and one raw implant. One group (12 animals) received bone graft impregnated with zoledronate (0.005 mg/ml) before impaction. The other group (12 animals) received untreated bone graft and systemic zoledronate (0.1 mg/kg) ten and 20 days after revision surgery. Animals were observed for an additional four weeks before euthanasia. Results. No difference was detected on mechanical implant fixation (load to failure, stiffness, energy) between local or systemic zoledronate. Addition of BMP-2 had no effect on implant fixation. In the histomorphometric evaluation, implants with local zoledronate had more area of new bone on the implant surface (53%, p = 0.025) and higher volume of allograft (65%, p = 0.007), whereas implants in animals with systemic zoledronate had the highest volume of new bone (34%, p = 0.003). Systemic zoledronate with BMP-2 decreased volume of allograft by 47% (p = 0.017). Conclusion. Local and systemic zoledronate treatment protects bone at different stages of maturity; local zoledronate protects the allograft from resorption and systemic zoledronate protects newly formed bone from resorption. BMP-2 in the dose evaluated with experimental revision implants was not beneficial, since it significantly increased allograft resorption without a significant compensating anabolic effect. Cite this article: Bone Joint Res 2021;10(8):488–497