Complement factor H (CFH) is an immune regulator that inhibits the complement system. Here, we identify CFH as a secreted and regulated factor in human bone marrow skeletal stem cells (hBMSCs) culture during osteoblast (OB) differentiation. To explore its role in bone formation, we investigated the effects of CFH on OB differentiation and bone homeostasis. CFH-deficient hBMSCs exhibited impaired OB differentiation, whereas CFH overexpression or supplementation enhanced OB differentiation in hBMSCs. In vivo, CFH-deficient (CFH-/-) mice displayed reduced trabecular and cortical bone mass, decreased bone formation, and diminished bone strength. Primary CFH-/- mouse bone marrow MSCs (mBMSCs) showed reduced osteogenesis but enhanced osteoclast differentiation, consistent with lower serum levels of the bone formation marker P1NP and elevated bone resorption markers TRAPc and CTX-1. Furthermore, CFH-/- mice exhibited delayed fracture healing and accelerated bone loss following ovariectomy or high-fat diet feeding. Clinically, CFH levels in bone marrow plasma were negatively correlated with fracture risk in patients. Notably, plasma CFH levels were positively associated with bone mineral density (BMD) and were significantly reduced in patients with osteoporosis. These findings establish CFH as a key regulator of osteogenesis and bone homeostasis, with potential implications for bone-related disorders.

Hip fractures are most commonly suffered by elderly patients, but 2–11

1. Abstract Cancer-induced bone pain (CIBP) occurs in a majority of patients when primary or metastatic cancer develops within the bone. This pain has a significant impact on quality of life, yet there are limited effective treatment options available. Nerve sprouting is a complex mechanism that has been implicated in CIBP. Netrin-1 is a neuronal guidance molecule that is produced by numerous cell types, including cancer cells. In this study we aimed to determine whether netrin-1 inhibition (with NP137 – a humanized IGg1 monoclonal antibody) could ameliorate nerve sprouting, and nociception by extension, in three models of CIBP – osteosarcoma, metastatic breast cancer, and metastatic prostate cancer. Sustained administration of NP137 failed to produce an anti-nociceptive effect in these models, but a delayed onset was observed in the osteosarcoma model. NP137 did not produce a disease-modifying effect, as micro-computed tomography did not reveal reduced bone destruction in the NP137-treated groups. Additionally, there was no nerve fibre density reduction in any of the groups at the late-stage of the disease, suggesting that nerve sprouting occurs in early- to mid-stage CIBP development. Investigation of NP137 exposure indicated that serum levels of NP137 were comparable between the sham and cancer groups. Our study indicates that netrin-1 may play a role in early-stage CIBP development, but inhibition of this mechanism does not produce robust anti-nociception.

The cytokine tumor necrosis factor (TNF), a major regulator of inflammatory responses, exists in both a membrane-bound form and a soluble form. We used the nonselective TNF inhibitor etanercept and the selective inhibitor XPro1595 and compared supraspinatus muscle cytokine levels, histology, and proteomic signatures in mice after supraspinatus tendon tear. The aim was to investigate the effect of anti-TNF treatment on the early inflammatory response in the muscle after tendon tear. In addition, the effect on body composition and bone mineral content was compared in naive mice after 2 months of treatment with either etanercept or XPro1595 using dual-energy X-ray absorptiometry (DEXA) and micro-CT. Inhibition of TNF did not significantly affect DEXA indexes of body composition nor bone microarchitecture, apart from increased structure model index and decreased bone surface density at 14 days, and bone surface to volume ratio at 2 months. Supraspinatus tendon tear caused extensive inflammatory changes in the supraspinatus muscle and initiated a regenerative response. However, TNF inhibition did not significantly affect these processes recorded as density in the lesioned supraspinatus muscle of macrophages and myogenin-positive nuclei. Although both inhibitors had an effect on mitochondrial proteins, particularly etanercept tended to modulate mitochondrial function, and eternacept also influenced NF-κB signaling. Modulation of the mitochondrial proteome and the influence on NF-κB signaling seen after etanercept treatment could correspond with its known effect on apoptosis.

This scoping-review aims to highlight the current modalities of sole use of stem cells in treating fracture nonunion updating a previous systematic review from 2013. We report solitary stem cell stimulation in literature in vivo studies to obtain current knowledge in understanding the crucial role of stem cells in enhancing fracture nonunion healing. This scoping review was conducted by systematical search in PubMed, Medline and clinicaltrials.gov with a timeframe from October 2012 to September 2024. Two authors independently screened all articles, and when included, the following information was extracted: type of nonunion, localization, type of stem cells, administered dose of stem cells, surgical information, type of scaffold, control group, evaluation method, time of evaluation post intervention, and adverse events. Of 4710 articles screened, 27 articles met the criteria for inclusion. In the reviewed articles, 2 out of 5 human studies, and 8 out of 12 animal studies with a control group reported a statistically significant effect of stem cells on bone healing when used in the treatment of fracture nonunion. Comparison of the studies was difficult due to heterogeneity. The administration of mesenchymal stem cells regarding adverse events was investigated in eight human studies. Based on our reporting, the articles suggest that the perspectives of the sole use of mesenchymal stem cells in the management of fracture nonunion might be promising but remain inconclusive. Future research should be inspired by existing literature and focus on the development of well-standardized methodologies and results published.

There is an increasing demand for a suitable bone substitute to replace current clinical gold standard autografts or allografts. Majority of previous studies have focused on the early effects of substitutes on bone formation, while information on their long-term efficacies remains limited. This study investigated the efficacies of natural hydroxyapatite (nHA) derived from oyster shells and synthetic hydroxyapatite mixed with collagen (COL/HA) or chitosan (CS/HA) on bone regeneration and implant fixation in sheep. Titanium implants were inserted into critical-size defects in distal femur condyles bilaterally, and circumferential gaps around implants were filled with substitute materials or allografts (as control). 14 or 24 weeks post-operatively, the implant-bone blocks were harvested and evaluated using microarchitectural, histomorphometric, and mechanical methods. The nHA and COL/HA groups showed significant bone formation at both 14 and 24 weeks. There was a pronounced increase in bone tissue volume and ingrowth into titanium implant’s porous surfaces, significantly enhancing mechanical fixation strength at 24 weeks. CS/HA had a limited ability to induce bone formation and implant fixation. We conclude that nHA and COL/HA revealed long-term effects on enhancing bone formation and implant fixation that were at least as good as allograft after 24 weeks, and both nHA and COL/HA appear to be good alternative materials to bone allograft.

Background and purpose: Internal fixation is the preferred treatment in the non-elderly with femoral neck fractures, regardless of fracture displacement. High complication rates are reported, in particular for displaced fractures. We aimed to compare cancellous screws with angle-stable sliding compression implants for internal fixation of femoral neck fractures in the non-elderly. Methods: A systematic search was carried out in Medline, Embase, Scopus, and Cochrane. The search results were screened by 2 reviewers using Covidence and assessed for risk of bias. All comparative studies were included. The studies reported at least 1 of the following outcomes: avascular necrosis, fixation failure/cut-out, non-union, any complication, reoperation, femoral neck shortening, or Harris Hip Score (HHS). Dichotomous outcomes are reported as risk ratio (RR) and continuous outcomes as mean difference (MD). All effect measures use a random effects model. Results: The search yielded 23 studies eligible for inclusion: 4 randomized controlled trials (RCTs) and 19 retrospective cohort trials, including 1,844 fractures. Only 1 study had low risk of bias. The results demonstrated no difference in RCTs alone. Analysis of all studies showed superior outcomes in favor of angle-stable sliding compression implants for fixation failure/cut-out (RR 0.54, 95% confidence interval [CI] 0.31–0.94), any complication (RR 0.49, CI 0.28–0.87), shortening > 5 mm (RR 0.54, CI 0.37–0.80), and HHS 6–24 months (MD 3.1, CI 1.8–4.4). Conclusion: RCTs alone showed no significant differences between implant types. When including retrospective studies, angle-stable sliding compression implants demonstrated some advantages. The strength of evidence is limited by the predominance of retrospective cohort studies and high risk of bias in the included studies.

Diabetic foot ulcers are a common and severe complication of diabetes mellitus, and a risk factor for amputation. Because of the vessel insufficiency in diabetic foot ulcers (DFU), vascular endothelial growth factor (VEGF) that simulates angiogenesis is of interest to promote wound healing. This systematic review evaluates the last 16 years of in-vivo studies with VEGF stimulation as a treatment for DFU, developed based on the last published systematic article. A total of 961 articles were identified through databases in two phases. 947 articles were excluded by exclusion criteria, and four articles met our inclusion criteria and were included. The effects of VEGF on wound healing were analysed in all four studies. In three studies, the VEGF-treated wounds showed statistically faster healing than those not treated with VEGF. In one study, the VEGF-treated wounds revealed a positive trend toward faster healing. Furthermore, all four studies were in favor of using VEGF, but concluded that further research is needed. These studies showed a positive trend towards faster healing and was safe when using VEGF topically on humans. Furthermore, viral particles of VEGF seem to have a systematic effect when a dose exceeding 5.0 × 109 vp pr wound. Future research in using VEGF on DFU should focus on VEGF's relevant dosage, release rate, and specific mechanism. This review inspires further research, and a consistent study design is prerequisite such that results are more homogenic and comparable. Much effort is needed to translate the results into our clinical practice.

Healing after bone fracture is assessed by frequent radiographs, which expose patients to radiation and lacks behind biological healing. This study aimed to investigate whether the electrical impedance using electrical impedance spectroscopy correlated to quantitative scores of bone healing obtained from micro-CT and mechanical bending test.Eighteen rabbits were subjected to tibial fracture that was stabilized with external fixator. Two electrodes were positioned, one electrode placed within the medullary cavity and the other on the lateral cortex, both three millimeters from the fracture site. Impedance was measured daily across the fracture site at a frequency range of 5 Hz to 1 MHz. The animals were divided into three groups with different follow-up time: 1, 3 and 6 weeks for micro-CT (Bone volume/tissue volume (BV/TV, %)) and mechanical testing (maximum stress (MPa), failure energy (kJ/cm3), young modulus (Mpa)).There was a statistically significant correlation between last measured impedance at 5 Hz frequency immediately prior to euthanasia and BV/TV of callus (−0.68, 95%CI: (−0.87; −0.31)). Considering the mechanical testing with three-point bending, no significant correlation was found between last measured impedance at 5 Hz frequency immediately prior to euthanasia and maximum stress (−0.35, 95%CI: (−0.70; 0.14)), failure energy (−0.23, 95%CI: (−0.63; 0.26)), or young modulus (−0.28, 95%CI: (−0.66; 0.22)).The significant negative correlation between impedance and BV/TV might indicate that impedances correlate with the relative bone volume in the callus site. The lack of correlation between impedance and mechanical parameters when at the same time observing a correlation between impedance and days since operation (0-42 days), might indicate that the impedance can measure biological changes at an earlier time point than rough mechanical testing.

Abstract Purpose Healing after bone fracture is assessed by clinical examination and frequent radiographs, which expose patients to radiation and lack standardisation. This study aimed to explore electrical impedance patterns during bone healing using electrical impedance spectroscopy in 18 rabbits subjected to tibial fracture stabilised with an external fixator. Methods Impedance was measured daily across the fracture site at a frequency range of 5 Hz to 1 MHz. Biweekly radiographs were analysed using modified anterior‐posterior (AP) radiographic union score of the tibia (RUST). The animals were divided into three groups with different follow‐up times: 1, 3 and 6 weeks for micro‐computer tomography and mechanical testing. Results A decreasing trend in impedance was observed over time for all rabbits at lower frequencies. Impedance closest to 5 Hz showed a statistically significant decrease over time, with greatest decrease occurring during the first 7 postoperative days. At 5 Hz, a statistically significant correlation was found between impedance and the modified AP RUST score and between impedance and bone volume fraction. Conclusions This study showed that the electrical impedance can be measured in vivo at a distance from the fracture site with a consistent change in impedance over time and revealed significant correlation between increasing radiographic union score and decreasing impedance. Level of Evidence Not applicable.

BackgroundReliable animal models are critical for preclinical research and should closely mimic the disease. With respect to route of infection, pathogenic agent, disease progression, clinical signs, and histopathological changes. Sheep have similar bone micro- and macrostructure as well as comparable biomechanical characteristics to humans. Their use in bone research is established, however their use in bone infection research is limited. This systematic review will summarise the key features of the available bone infection models using sheep, providing a reference for further development, validation, and application.MethodThis systematic review was designed according to the PRISMA guidelines and registered with PROSPERO. Quality was assessed using SYRICLE's risk of bias tool adapted for animal studies. PubMed, MEDLINE, Web of Science and EMBASE were searched until March 2022.1921 articles were screened by two independent reviewers, and 25 were included for analysis.ResultsModels have been developed in nine different breeds. Staphylococcus aureus was used in the majority of models, typically inoculating 108 colony forming units in tibial or femoral cortical defects. Infection was established with either planktonic or biofilm adherent bacteria, with or without foreign material implanted. Most studies used both radiological and microbiological analyses to confirm osteomyelitis.ConclusionsThere is convincing evidence supporting the use of sheep in bone infection models of clinical disease. The majority of sheep studied demonstrated convincing osteomyelitis and tolerated the infection with minimal complications. Furthermore, the advantages of comparable biology and biomechanics may increase the success for translating in vivo results to successful therapies.The Translational potential of this articleIn the realm of preclinical research, the translation to viable clinical therapies is often perilous, and the quest for reliable and representative animal models remains paramount. This systematic review accentuates the largely untapped potential of sheep as large animal models, especially in bone infection research. The anatomical and biomechanical parallels between sheep and human bone structures position sheep as an invaluable asset for studying osteomyelitis and periprosthetic joint infection. This comprehensive exploration of the literature demonstrates the robustness and translational promise of these models. Furthermore, this article underscores the potential applicability for sheep in developing effective therapeutic strategies for human bone infections.

Background and purpose: The low-dose EOS Imaging System is an emerging tool for 3-dimensional measurements in orthopedics. The clinical feasibility for measuring total hip arthroplasty (THA) liner wear has not yet been investigated. We aimed to evaluate the feasibility of using EOS to measure THA liner wear by examining the experimental accuracy using a THA phantom and clinical precision of patients with THA, considering a clinically relevant precision at the 95% repeatability limit to be 0.2 mm. Methods: An experimental THA phantom with movable stem and a fixed cup with a plastic liner was constructed to simulate progressive 3D liner wear. Series of 11 pairs of radiographs with 50 μm femoral movement in between were obtained for each 3D axis in EOS. 30 patients with a THA were scanned twice using EOS to assess precision. Model-based radiostereometric analysis (RSA) was used for wear measurement. Results: The mean difference (true minus simulated wear) with standard deviation (SD) and 95% limits of agreement for experimental THA wear were 0.005 (0.037) and [–0.069 to 0.079] mm for the vertical (y) axis. The mean (SD) and 95% repeatability limit for precision for clinical measurement were –0.029 (0.105) and 0.218 mm. Conclusion: Experimental THA liner wear using EOS was within clinically relevant tolerances and without bias. The clinical precision was just outside our defined clinically relevant precision. Compared with conventional RSA, EOS is less accurate and precise but may still be of value for certain clinical applications, provided larger sample size or longer follow-up are available.

Biodegradable magnesium (Mg)-based materials show promise in managing musculoskeletal diseases, attributed to their desired proper mechanical strength, and facilitating self-regenerative processes via spatiotemporal degradation during treatments for non-weight-bearing skeletal sites. However, to achieve a long-term steady state of the local biomechanical environment, it is essential to coupling implant degeneration and neo-tissue ingrowth without sacrificing local mechanical integrity. Steroid- associated osteonecrosis (SAON) presents a formidable clinical challenge, necessitating robust mechanical support to prevent collapse of weight-bearing hip joints while reversing pathological progression. Herein, a novel tree-inspired Mg hybrid column (Mg + BC) incorporating cannulated Mg screw and injectable Mg-containing bone cement (BC) is reported. Mg + BC tuned the gradual release of mineral ions (Mg, Ca, P), OH- and H2 via electrochemical suppression and crystal re-deposition during degradation. Finite element analysis demonstrated that Mg + BC significantly reduced the proportion of relatively high load-bearing regions (CD: 26.0 %, Mg: 26.6 %, BC: 18.2 %, Mg + BC: 17.5 %) and effectively shifted the predominant loading from subchondral trabeculae to the femoral shaft cortex. The efficacy of the tree-inspired Mg hybrid column was validated in a clinically relevant bipedal emu model of SAON. Compared to standalone Mg screws, Mg + BC exhibited sustained degradation and enhanced bone-implant contact, indicating improved alignment between material degradation and tissue regeneration. After 6 months in vivo, the implant residue volume was significantly higher in the Mg + BC group (73.53 +/- 10.90 %) compared to the Mg screw group (39.10 +/- 11.31 %). The optimized degradation pattern of Mg + BC facilitated bone regeneration through modulation of macrophage recruitment and M1-to-M2 polarization shift. Notably, Mg + BC treatment significantly reduced hip joint collapse incidence (1/10) compared to CD group (7/10). The Mg + BC group maintained greater articular cartilage thickness in the intact region (1.74 +/- 0.25 mm) compared to CD group (0.71 +/- 0.15 mm). Gait analysis revealed substantial improvement in stride length for the Mg + BC group (87.14 +/- 2.29 cm) compared to CD group (60.03 +/- 1.31 cm), indicating maintenance of the hip anatomical structure and functional performance. Taken together, the tree-inspired Mg hybrid column is expected to be a unique hybrid system for bone tissue regeneration and prevention of joint collapse in weight-bearing regions affected by SAON, offering promising translational potential for clinical application.

BackgroundThe purpose of this study was to compare the biomechanical stress and stability of calcaneal fixations with and without bone defect, before and after bone grafting, through a computational approach.MethodsA finite element model of foot-ankle complex was reconstructed, impoverished with a Sanders III calcaneal fracture without bone defect and with moderate and severe bone defects. Plate fixations with and without bone grafting were introduced with walking stance simulated. The stress and fragment displacement of the calcaneus were evaluated.FindingsModerate and severe defect increased the calcaneus stress by 16.11% and 32.51%, respectively and subsequently decreased by 10.76% and 20.78% after bone grafting. The total displacement was increased by 3.99% and 24.26%, respectively by moderate and severe defect, while that of posterior joint facet displacement was 86.66% and 104.44%. The former was decreased by 25.73% and 35.96% after grafting, while that of the latter was reduced by 88.09% and 84.78% for moderate and severe defect, respectively.InterpretationOur finite element prediction supported that bone grafting for fixation could enhance the stability and reduce the risk of secondary stress fracture in cases of bone defect in calcaneal fracture.

IntroductionExperimental bone research often generates large amounts of histology and histomorphometry data, and the analysis of these data can be time-consuming and trivial. Machine learning offers a viable alternative to manual analysis for measuring e.g. bone volume versus total volume.The objective was to develop a neural network for image segmentation, and to assess the accuracy of this network when applied to ectopic bone formation samples compared to a ground truth.MethodThirteen tissue slides totaling 114 megapixels of ectopic bone formation were selected for model building. Slides were split into training, validation, and test data, with the test data reserved and only used for the final model assessment. We developed a neural network resembling U-Net that takes 512×512 pixel tiles. To improve model robustness, images were augmented online during training.The network was trained for 3 days on a NVidia Tesla K80 provided by a free online learning platform against ground truth masks annotated by an experienced researcher.ResultDuring training, the validation accuracy improved and stabilised at approx. 95%. The test accuracy was 96.1 %.ConclusionMost experiments using ectopic bone formation will yield an inter-observer or inter-method variance of far more than 5%, so the current approach may be a valid and feasible technique for automated image segmentation for large datasets. More data or a consensus-based ground truth may improve training stability and validation accuracy.The code and data of this project are available upon request and will be available online as part of our publication.

Upon transplantation, skeletal stem cells (also known as bone marrow stromal or mesenchymal stem cells) can regulate bone regeneration by producing secreted factors. Here, we identify KIAA1199 as a bone marrow stromal cell-secreted factor in vitro and in vivo. KIAA1199 plasma levels of patients positively correlate with osteoporotic fracture risk and expression levels of KIAA1199 in patient bone marrow stromal cells negatively correlates with their osteogenic differentiation potential. KIAA1199-deficient bone marrow stromal cells exhibit enhanced osteoblast differentiation in vitro and ectopic bone formation in vivo. Consistently, KIAA1199 knockout mice display increased bone mass and biomechanical strength, as well as an increased bone formation rate. They also exhibit accelerated healing of surgically generated bone defects and are protected from ovariectomy-induced bone loss. Mechanistically, KIAA1199 regulates osteogenesis by inhibiting the production of osteopontin by osteoblasts, via integrin-mediated AKT and ERK-MAPK intracellular signaling. Thus, KIAA1199 is a regulator of osteoblast differentiation and bone regeneration and could be targeted for the treatment or management of low bone mass conditions.

Neovascularization plays an essential part in the progression of several diseases as well as recovery processes such as angiogenesis-guided neurogenesis after a spinal cord injury. To visualize and quantify neovascularization in an experimental setup, it is desirable to apply a noninvasive, repeatable, and harmless technique. Here, we apply a newly developed ultrasound-based technique to construct angiographies and quantify neovascularization in the regenerating spinal cord of a regeneration competent animal model, the Mexican axolotl. We measured vessel volume fraction prior to the induction of contusion and transection spinal cord injury and repeated this measurement directly after injury and at 3, 6, 12, and 63 days after injury. Although neither of the injury types resulted in statistically significant differences in vessel volume fraction relative to sham-operated animals, there was a statistically significant increase in neovascularization over time in all groups. Additionally, vessel volume fraction at the final time point (63 days after injury) was quantified with micro-CT imaging after vascular perfusion with a contrast agent, confirming no statistically significant difference in neovascularization between injury types. Ex vivo vessel volume fraction measured by micro-CT was significantly different from the in vivo ultrasound-based measurement at the same time point. This is likely a result of incomplete vascular perfusion with the contrast agent before micro-CT imaging, which was supported by subsequent histological evaluation. In summary, the results suggest that the ultrasound-based angiographic procedure, we demonstrate here, is applicable to visualize and quantify neovascularization in a noninvasive and harmless fashion in longitudinal experiments circumventing the limitations of contrast agent-dependent techniques.

Extended Experimental Methods

Aims The primary outcome was investigating differences in wear, as measured by femoral head penetration, between cross-linked vitamin E-diffused polyethylene (vE-PE) and cross-linked polyethylene (XLPE) acetabular component liners and between 32 and 36 mm head sizes at the ten-year follow-up. Secondary outcomes included acetabular component migration and patient-reported outcome measures (PROMs) such as the EuroQol five-dimension questionnaire, 36-Item Short-Form Health Survey, Harris Hip Score, and University of California, Los Angeles Activity Scale (UCLA). Methods A single-blinded, multi-arm, 2 × 2 factorial randomized controlled trial was undertaken. Patients were recruited between May 2009 and April 2011. Radiostereometric analyses (RSAs) were performed from baseline to ten years. Of the 220 eligible patients, 116 underwent randomization, and 82 remained at the ten-year follow-up. Eligible patients were randomized into one of four interventions: vE-PE acetabular liner with either 32 or 36 mm femoral head, and XLPE acetabular liner with either 32 or 36 mm femoral head. Parameters were otherwise identical except for acetabular liner material and femoral head size. Results A total of 116 patients participated, of whom 77 were male. The median ages of the vE-PE 32 mm and 36 mm groups were 65 (interquartile range (IQR) 57 to 67) and 63 years (IQR 56 to 66), respectively, and of the XLPE 32 mm and 36 mm groups were 64 (IQR 58 to 66) and 61 years (IQR 54 to 66), respectively. Mean total head penetration was significantly lower into vE-PE acetabular liner groups than into XLPE acetabular liner groups (-0.219 mm (95% confidence interval -0.348 to -0.090); p = 0.001). There were no differences in wear according to head size, acetabular component migration, or PROMs, except for UCLA. There were no cases of aseptic loosening or failures requiring revision at long-term follow-up. Conclusion Significantly lower wear was observed in vE-PE acetabular liners than in XLPE acetabular liners. No difference in wear was observed between different head size or PROMs except for the UCLA at ten years.

Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33–36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption.