Canonical pathways for validating steroid-associated osteonecrosis in mice.

The present study aimed to establish and evaluate a preclinical model of steroid-associated osteonecrosis (SAON) in mice. Sixteen 24-week-old male C57BL/6 mice were used to establish SAON by two intraperitoneal injections of lipopolysaccharide (LPS), followed by three subcutaneous injections of methylprednisolone (MPS). Each injection was conducted on working day, with an interval of 24 h. Six cycles of injections were conducted. Additional twelve mice (age- and gender-matched) were used as normal controls. At 2 and 6 weeks after completing induction, bilateral femora and bilateral tibiae were collected for histological examination, micro-CT scanning, and bulk RNA sequencing. All mice were alive until sacrificed at the indicated time points. The typical SAON lesion was identified by histological evaluation at week 2 and week 6 with increased lacunae and TUNEL+ osteocytes. Micro-CT showed significant bone degeneration at week 6 in SAON model. Histology and histomorphometry showed significantly lower Runx2+ area, mineralizing surface (MS/BS), mineral apposition rate (MAR), bone formation rate (BFR/BS), type H vessels, Ki67+ (proliferating) cells, and higher marrow fat fraction, osteoclast number and TNFα+ areas in SAON group. Bulk RNA-seq revealed changed canonical signaling pathways regulating cell cycle, angiogenesis, osteogenesis, and osteoclastogenesis in the SAON group. The present study successfully established SAON in mice with a combination treatment of LPS and MPS, which could be considered a reliable and reproducible animal model to study the pathophysiology and molecular mechanism of early-stage SAON and to develop potential therapeutic approaches for the prevention and treatment of SAON.

Engineered MgO nanoparticles for cartilage-bone synergistic therapy.

The emerging therapeutic strategies for osteoarthritis (OA) are shifting toward comprehensive approaches that target periarticular tissues, involving both cartilage and subchondral bone. This shift drives the development of single-component therapeutics capable of acting on multiple tissues and cells. Magnesium, an element essential for maintaining skeletal health, shows promise in treating OA. However, the precise effects of magnesium on cartilage and subchondral bone are not yet clear. Here, we investigated the therapeutic effect of Mg2+ on OA, unveiling its protective effects on both cartilage and bone at the cellular and animal levels. The beneficial effect on the cartilage-bone interaction is primarily mediated by the PI3K/AKT pathway. In addition, we developed poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with nano-magnesium oxide modified with stearic acid (SA), MgO&SA@PLGA, for intra-articular injection. These microspheres demonstrated remarkable efficacy in alleviating OA in rat models, highlighting their translational potential in clinical applications.

Excess glucocorticoids inhibit murine bone turnover via modulating the immunometabolism of the skeletal microenvironment.

Elevated bone resorption and diminished bone formation have been recognized as the primary features of glucocorticoid-associated skeletal disorders. However, the direct effects of excess glucocorticoids on bone turnover remains unclear. Here, we explored the outcomes of exogenous glucocorticoid treatment on bone loss and delayed fracture healing in mice and found that reduced bone turnover was a dominant feature, resulting in a net loss of bone mass. The primary effect of glucocorticoids on osteogenic differentiation was not inhibitory; instead, they cooperated with macrophages to facilitate osteogenesis. Impaired local nutrient status, notably, obstructed fatty acid transportation, was a key factor contributing to glucocorticoid-induced impairment of bone turnover in vivo. Furthermore, fatty acid oxidation in macrophages fueled the ability of glucocorticoid-liganded receptors to enter the nucleus and then promoted the expression of Bmp2, a key cytokine that facilitates osteogenesis. Metabolic reprogramming by localized fatty acid delivery partly rescued glucocorticoid-induced pathology by restoring a healthier immune-metabolic milieu. These data provide insights into the multifactorial metabolic mechanisms by which glucocorticoids generate skeletal disorders, thus suggesting possible therapeutic avenues.

Fumarate Hydratase-Deficient Renal Cell Carcinoma With Predominant Tubulocystic Features Mimics Tubulocystic Renal Cell Carcinoma.

CONTEXT.­: Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) rarely exhibits a predominant tubulocystic architecture with few other components. RCC with pure tubules and cysts lined by eosinophilic tumor cells with prominent nucleoli would raise the diagnosis of tubulocystic RCC. It is important to differentiate the 2 entities because they lead to different outcomes. OBJECTIVE.­: To address the concern, a multicenter study was implemented to explore useful clinicopathologic features in differentiation between tubulocystic FH-deficient RCC and tubulocystic RCC. DESIGN.­: Clinical factors included age, sex, tumor size, and outcome. Morphologic factors included cell morphology, presence or absence of a nontubulocystic component, and stromal findings. Immunohistochemistry, fluorescence in situ hybridization, and next-generation sequencing were performed to explore the protein expression and molecular profiles of the 2 entities. RESULTS.­: We evaluated 6 patients with tubulocystic RCC and 10 patients with tubulocystic FH-deficient RCC. Tubulocystic RCC exhibited a small size (<4.0 cm, pT1a), low Ki-67 index (<5%), retained FH, and negative 2SC expression. Tubulocystic FH-deficient RCC had a relatively large size and a high Ki-67 index. Perinucleolar haloes, loss of FH, and 2SC positivity were always observed. Pure tubulocystic architecture was not observed in FH-deficient RCC, because focal nontubulocystic components can always be seen. CONCLUSIONS.­: We emphasized multiple sectioning to identify a nontubulocystic architecture to exclude tubulocystic RCC. Moreover, tumor size, FH/2SC staining, and the Ki-67 index can differentiate tubulocystic FH-deficient RCC from tubulocystic RCC. The diagnosis of tubulocystic RCC was not recommended in renal mass biopsy because of the limited tissues sampled.

Engineered biochemical cues of regenerative biomaterials to enhance endogenous stem/progenitor cells (ESPCs)-mediated articular cartilage repair.

As a highly specialized shock-absorbing connective tissue, articular cartilage (AC) has very limited self-repair capacity after traumatic injuries, posing a heavy socioeconomic burden. Common clinical therapies for small- to medium-size focal AC defects are well-developed endogenous repair and cell-based strategies, including microfracture, mosaicplasty, autologous chondrocyte implantation (ACI), and matrix-induced ACI (MACI). However, these treatments frequently result in mechanically inferior fibrocartilage, low cost-effectiveness, donor site morbidity, and short-term durability. It prompts an urgent need for innovative approaches to pattern a pro-regenerative microenvironment and yield hyaline-like cartilage with similar biomechanical and biochemical properties as healthy native AC. Acellular regenerative biomaterials can create a favorable local environment for AC repair without causing relevant regulatory and scientific concerns from cell-based treatments. A deeper understanding of the mechanism of endogenous cartilage healing is furthering the (bio)design and application of these scaffolds. Currently, the utilization of regenerative biomaterials to magnify the repairing effect of joint-resident endogenous stem/progenitor cells (ESPCs) presents an evolving improvement for cartilage repair. This review starts by briefly summarizing the current understanding of endogenous AC repair and the vital roles of ESPCs and chemoattractants for cartilage regeneration. Then several intrinsic hurdles for regenerative biomaterials-based AC repair are discussed. The recent advances in novel (bio)design and application regarding regenerative biomaterials with favorable biochemical cues to provide an instructive extracellular microenvironment and to guide the ESPCs (e.g. adhesion, migration, proliferation, differentiation, matrix production, and remodeling) for cartilage repair are summarized. Finally, this review outlines the future directions of engineering the next-generation regenerative biomaterials toward ultimate clinical translation.

Blockage of Osteopontin-Integrin ß3 Signaling in Infrapatellar Fat Pad Attenuates Osteoarthritis in Mice.

The knowledge of osteoarthritis (OA) has nowadays been extended from a focalized cartilage disorder to a multifactorial disease. Although recent investigations have reported that infrapatellar fat pad (IPFP) can trigger inflammation in the knee joint, the mechanisms behind the role of IPFP on knee OA progression remain to be defined. Here, dysregulated osteopontin (OPN) and integrin ß3 signaling are found in the OA specimens of both human and mice. It is further demonstrated that IPFP-derived OPN participates in OA progression, including activated matrix metallopeptidase 9 in chondrocyte hypertrophy and integrin ß3 in IPFP fibrosis. Motivated by these findings, an injectable nanogel is fabricated to provide sustained release of siRNA Cd61 (RGD- Nanogel/siRNA Cd61) that targets integrins. The RGD- Nanogel possesses excellent biocompatibility and desired targeting abilities both in vitro and in vivo. Local injection of RGD- Nanogel/siRNA Cd61 robustly alleviates the cartilage degeneration, suppresses the advancement of tidemark, and reduces the subchondral trabecular bone mass in OA mice. Taken together, this study provides an avenue for developing RGD- Nanogel/siRNA Cd61 therapy to mitigate OA progression via blocking OPN-integrin ß3 signaling in IPFP.

Visible light antibacterial potential of cement mortar incorporating Cu-ZnO/g-C3N4 nanocomposites.

In this work, a hybrid Cu-ZnO/g-C3N4 nanocomposite was synthesized and introduced to fabricate photocatalytic cement mortars by internal mixing. The bactericidal properties of the photocatalytic mortars were explored by using E. coli, S. aureus and P. aeruginosa as a bacteria test strain. The results showed that the Cu-ZnO/g-C3N4 nanocomposite had an enhanced harvesting of visible light energy and exhibited excellent stability during the photocatalytic process, which favored a long-term usage performance. The sterilizing efficiency of the photocatalytic cement mortars improved with an increasing content of Cu-ZnO/g-C3N4 nanocomposites. A possible bactericidal mechanism was proposed based on the active species trapping experiments, verifying that the photogenerated holes (h+) and ˙O2 - radicals were the main active species.

Injectable magnesium oxychloride cement foam-derived scaffold for augmenting osteoporotic defect repair.

HYPOTHESIS: Cement augmentation has been widely applied to promote osteoporotic fracture healing, whereas the existing calcium-based products suffer from the excessively slow degradation, which may impede bone regeneration. Magnesium oxychloride cement (MOC) shows promising biodegradation tendency and bioactivity, which is expected to be a potential alternative to the classic calcium-based cement for hard-tissue-engineering applications. EXPERIMENTS: Here, a hierarchical porous MOC foam (MOCF)-derived scaffold with favorable bio-resorption kinetic and superior bioactivity is fabricated through Pickering foaming technique. Then, a systematic characterization in terms of material properties and in vitro biological performance have been conducted to evaluate the feasibility of the as-prepared MOCF scaffold to be a bone-augmenting material for treating osteoporotic defects. FINDINGS: The developed MOCF shows excellent handling performance in the paste state, while exhibiting sufficient load-bearing capacity after solidification. In comparison with the traditional bone cement, calcium deficient hydroxyapatite (CDHA), our porous MOCF scaffold demonstrates a much higher biodegradation tendency and better cell recruitment ability. Additionally, the eluted bioactive ions by MOCF commits to a biologically inductive microenvironment, where the in vitro osteogenesis is significantly enhanced. It is anticipated that this advanced MOCF scaffold will be competitive for clinical therapies to augment osteoporotic bone regeneration.

Water-Immiscible Coacervate as a Liquid Magnetic Robot for Intravascular Navigation.

Developing magnetic ultrasoft robots to navigate through extraordinarily narrow and confined spaces like capillaries in vivo requires synthesizing materials with excessive deformability, responsive actuation, and rapid adaptability, which are difficult to achieve with the current soft polymeric materials, such as elastomers and hydrogels. We report a magnetically actuatable and water-immiscible (MAWI) coacervate based on the assembled magnetic core-shell nanoparticles to function as a liquid robot. The degradable and biocompatible millimeter-sized MAWI coacervate liquid robot can remain stable under changing pH and salt concentrations, release loaded cargoes on demand, squeeze through an artificial capillary network within seconds, and realize intravascular targeting in vivo guided by an external magnetic field. We believe the proposed "coacervate-based liquid robot" can implement demanding tasks beyond the capability of conventional elastomer or hydrogel-based soft robots in the field of biomedicine and represents a distinct design strategy for high-performance ultrasoft robots.

A novel visceral adiposity index predicts bone loss in female early rheumatoid arthritis patients detected by HR-pQCT.

The purpose of this prospective study is to compare the Chinese visceral adiposity index (CVAI) between early rheumatoid arthritis (ERA) patients and healthy controls; and to assess the relationship between CVAI and the bone microstructure using high-resolution peripheral quantitative computed tomography (HR-pQCT) in ERA patients. 104 female ERA and 100 age-, gender- and BMI-matched healthy controls were recruited for the comparison of CVAI. All ERA patients were prospectively followed for 1 year. HR-pQCT scan of the distal radius, tibia and second metacarpal head were performed at baseline and after one-year. ERA patients were divided into two sub-groups according to the median CVAI value (65.73) (low CVAI and high CVAI groups). CVAI in the ERA group was significantly higher than the controls group (p = 0.01). At baseline, the high CVAI group had a higher ESR level (p = 0.004) while the cortical volumetric bone mineral density (vBMD) was lower (at both the distal radius and tibia, all p < 0.05) compared to the low CVAI group. Linear regression analysis revealed that a higher baseline CVAI was an independent predictor of a lower cortical vBMD at month 12 (distal radius: B = - 0.626, p = 0.022, 95%CI - 1.914 to - 0.153; tibia: B = - 0.394, p = 0.003, 95%CI - 1.366 to - 0.290); and a greater reduction in trabecular vBMD (tibia: B = 0.444, p = 0.001, 95%CI 0.018-0.063; distal radius: B = 0.356, p = 0.008, 95%CI 0.403-0.063). In summary, CVAI is an independent predictor of trabecular bone loss in female patients with ERA, which may be augmented by a chronic inflammatory state in patients with visceral dysfunction of fat metabolism.Trial registration: http://Clinicaltrial.gov no: NCT01768923, 16/01/2013.

The effect of drug holiday on preventing medication-related osteonecrosis of the jaw in osteoporotic rat model.

Background: Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication associated with antiresorptive medications managing osteoporosis, such as bisphosphonates (BPs). To date, there is very limited evidence from prospective, controlled studies to support or refute the controversial prevention regimen that if a discontinuation of BPs before dentoalveolar surgery, so called "drug holiday", is effective in reducing the risk of MRONJ development in patients with osteoporosis. We proposed an experimental animal study, aiming to investigate the prevention of MRONJ following tooth extractions in osteoporotic condition, with the implementation of a BP drug holiday. Methods: Twenty rats were subjected to bilateral ovariectomy. After establishing the osteoporotic condition, all rats were exposed to weekly injections of zoledronate acid (ZA) for 8 weeks. After ZA treatment, 10 rats were subjected to dental extraction and defined as control group, and the rest 10 rats assigned to the DH group had a drug holiday of 8 weeks prior to dental extraction. Eight weeks after the dentoalveolar surgery, bone turnover biomarker in serum, occurrence of MRONJ-like lesion and histomorphometric assessment of osteonecrosis in mandible, and bone microarchitecture indices in femur, were examined. Results: Eight weeks after dental extraction, the DH group showed a recovered osteoclastic activity, indicated by significantly increased number of osteoclasts in the mandibles and serum level of C-terminal telopeptides of type I collagen, as compared to the control group. No significant differences were observed in the gross-view and histological occurrences of MRONJ-like lesions between the two groups.There was no significant difference in bone microarchitecture in the femur between the control and DH groups before ZA therapy and 8 weeks after dental extraction. Conclusion: Our data provided the first experimental evidence in the osteoporotic animal model that the implementation of a BP holiday in prior to dental extractions could partially recover osteoclastic activity, but could not alleviate the development of MRONJ-like lesion or exacerbate the osteoporotic condition in the femur. Longer-term drug holiday, or combination of drug holiday and other prophylaxes to prevent MRONJ in patients with osteoporosis could be worth exploring in future studies, to pave the way for clinical managements. The translational potential of this article: This in vivo prospective study reported that a recovery of osteoclastic activity by a BP drug holiday for 8 weeks in osteoporosis rats did not alleviate the development of MRONJ-like lesion followed by dental extractions. It contributes to the understanding of regimens to prevent MRONJ.

Injectable bioactive glass/sodium alginate hydrogel with immunomodulatory and angiogenic properties for enhanced tendon healing.

Tendon healing is a complex process involving inflammation, proliferation, and remodeling, eventually achieving a state of hypocellularity and hypovascularity. Currently, few treatments can satisfactorily restore the structure and function of native tendon. Bioactive glass (BG) has been shown to possess immunomodulatory and angiogenic properties. In this study, we investigated whether an injectable hydrogel fabricated of BG and sodium alginate (SA) could be applied to enhance tenogenesis following suture repair of injured tendon. We demonstrated that BG/SA hydrogel significantly accelerated tenogenesis without inducing heterotopic ossification based on histological analysis. The therapeutic effect could attribute to increased angiogenesis and M1 to M2 phenotypic switch of macrophages within 7 days post-surgery. Morphological characterization demonstrated that BG/SA hydrogel partially reverted the pathological changes of Achilles tendon, including increased length and cross-sectional area (CSA). Finally, biomechanical test showed that BG/SA hydrogel significantly improved ultimate load, failure stress, and tensile modulus of the repaired tendon. In conclusion, administration of an injectable BG/SA hydrogel can be a novel and promising therapeutic approach to augment Achilles tendon healing in conjunction with surgical intervention.

The clinicopathological features and prognosis of multifocal high-grade gliomas in adults with H3F3A mutation.

OBJECTIVES: To explore the clinicopathological features and prognosis of multifocal high-grade gliomas (M-HGGs) with H3F3A mutation in adults. METHODS: Four adult patients with H3F3A-mutant M-HGGs who were treated at our institution from August 2020 to December 2021 were reviewed, including clinical, pathological and radiologic data. A series of 16 adult patients with M-HGGs without H3F3A mutation was used as a comparative group. Progression-free survival (PFS) and overall survival (OS) were compared between the groups using the Kaplan-Meier method. RESULTS: All patients were IDH wild-type and TERT wild-type, and P53 was overexpressed. A patient with the H3 G34R mutation and 1 of 3 patients with the H3 K27 M mutation had MGMT promoter methylation. The lesions with the H3 G34R mutation were located in the cerebral hemisphere; the lesions with H3 K27 alterations were mainly in the midline structure, and the cerebral hemisphere could also be involved. One patient underwent subtotal resection (STR), and 3 patients underwent biopsy. All patients received radiotherapy, and the median PFS and OS were 9.5 months and 14.5 months, respectively. The clinical outcomes were similar to those of non-H3F3A-mutated M-HGGs patients (median PFS and OS were 7.0 months and 18.0 months, respectively). CONCLUSION: We describe the clinicopathological features and outcomes of 4 adult M-HGGs patients with H3F3A mutation, and found this mutation doesn't appear to have a negative outcome with the administration of current therapies.

Bioactive glass-elicited stem cell-derived extracellular vesicles regulate M2 macrophage polarization and angiogenesis to improve tendon regeneration and functional recovery.

Effective countermeasures for tendon injury remains unsatisfactory. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs)-based therapy via regulation of Mφ-mediated angiogenesis has emerged as a promising strategy for tissue regeneration. Still, approaches to tailor the functions of EVs to treat tendon injuries have been limited. We reported a novel strategy by applying MSC-EVs boosted with bioactive glasses (BG). BG-elicited EVs (EVB) showed up-regulation of medicinal miRNAs, including miR-199b-3p and miR-125a-5p, which play a pivotal role in M2 Mφ-mediated angiogenesis. EVB accelerated angiogenesis via the reprogrammed anti-inflammatory M2 Mφs compared with naïve MSC-EVs (EVN). In rodent Achilles tendon rupture model, EVB local administration activated anti-inflammatory responses via M2 polarization and led to a spatial correlation between M2 Mφs and newly formed blood vessels. Our results showed that EVB outperformed EVN in promoting tenogenesis and in reducing detrimental morphological changes without causing heterotopic ossification. Biomechanical test revealed that EVB significantly improved ultimate load, stiffness, and tensile modulus of the repaired tendon, along with a positive correlation between M2/M1 ratio and biomechanical properties. On the basis of the boosted nature to reprogram regenerative microenvironment, EVB holds considerable potential to be developed as a next-generation therapeutic modality for enhancing functional regeneration to achieve satisfying tendon regeneration.

Advanced Hydrogel systems for mandibular reconstruction.

Mandibular defect becomes a prevalent maxillofacial disease resulting in mandibular dysfunctions and huge psychological burdens to the patients. Considering the routine presence of oral contaminations and aesthetic restoration of facial structures, the current clinical treatments are however limited, incapable to reconstruct the structural integrity and regeneration, spurring the need for cost-effective mandibular tissue engineering. Hydrogel systems possess great merit for mandibular reconstruction with precise involvement of cells and bioactive factors. In this review, current clinical treatments and distinct mode(s) of mandible formation and pathological resorption are summarized, followed by a review of hydrogel-related mandibular tissue engineering, and an update on the advanced fabrication of hydrogels with improved mechanical property, antibacterial ability, injectable form, and 3D bioprinted hydrogel constructs. The exploration of advanced hydrogel systems will lay down a solid foundation for a bright future with more biocompatible, effective, and personalized treatment in mandibular reconstruction.

Filum terminale arteriovenous shunt with nidus structure: a report of rare condition and treatment consideration.

BACKGROUND:  In the literature, filum terminale arteriovenous shunts (FTAVSs) always feature a single shunt point. Nidus-type FTAVSs have rarely been reported, and the best treatment strategy is unclear. This is a report of one exceptional case of a nidus-type FTAVS and surgical treatment of the lesion. CASE DESCRIPTION: The patient suffered from cauda equina syndrome for 9 months. Magnetic resonance imaging and spinal angiography revealed a nidus-type FTAVF at the L2 level. Surgical resection was performed in the hybrid operating room, and the nidus was completely resected with the assistance of intraoperative methylene blue angiography and neurophysiological monitoring. The postoperative neurological function was stable. CONCLUSIONS: A nidus-type arteriovenous shunt could originate from the FT, and in such cases, complete surgical resection with intraoperative neurophysiological monitoring in a hybrid operating room should be suggested.

Engineered Dynamic Hydrogel Niches for the Regulation of Redox Homeostasis in Osteoporosis and Degenerative Endocrine Diseases.

Osteoporosis and degenerative endocrine diseases are some of the major causes of disability in the elderly. The feedback loop in the endocrine system works to control the release of hormones and maintain the homeostasis of metabolism, thereby regulating the function of target organs. The breakdown of this feedback loop results in various endocrine and metabolic disorders, such as osteoporosis, type II diabetes, hyperlipidemia, etc. The direct regulation of redox homeostasis is one of the most attractive strategies to redress the imbalance of the feedback loop. The biophysical regulation of redox homeostasis can be achieved through engineered dynamic hydrogel niches, with which cellular mechanics and redox homeostasis are intrinsically connected. Mechanotransduction-dependent redox signaling is initiated by cell surface protein assemblies, cadherins for cell-cell junctions, and integrins for cell-ECM interactions. In this review, we focused on the biophysical regulation of redox homeostasis via the tunable cell-ECM interactions in the engineered dynamic hydrogel niches. We elucidate processes from the rational design of the hydrogel matrix to the mechano-signaling initiation and then to the redox response of the encapsulated cells. We also gave a comprehensive summary of the current biomedical applications of this strategy in several degenerative endocrine disease models.

Controlled Release of Bone Morphogenetic Protein-2 Augments the Coupling of Angiogenesis and Osteogenesis for Accelerating Mandibular Defect Repair.

Reconstruction of a mandibular defect is challenging, with high expectations for both functional and esthetic results. Bone morphogenetic protein-2 (BMP-2) is an essential growth factor in osteogenesis, but the efficacy of the BMP-2-based strategy on the bone regeneration of mandibular defects has not been well-investigated. In addition, the underlying mechanisms of BMP-2 that drives the bone formation in mandibular defects remain to be clarified. Here, we utilized BMP-2-loaded hydrogel to augment bone formation in a critical-size mandibular defect model in rats. We found that implantation of BMP-2-loaded hydrogel significantly promoted intramembranous ossification within the defect. The region with new bone triggered by BMP-2 harbored abundant CD31+ endomucin+ type H vessels and associated osterix (Osx)+ osteoprogenitor cells. Intriguingly, the new bone comprised large numbers of skeletal stem cells (SSCs) (CD51+ CD200+) and their multi-potent descendants (CD51+ CD105+), which were mainly distributed adjacent to the invaded blood vessels, after implantation of the BMP-2-loaded hydrogel. Meanwhile, BMP-2 further elevated the fraction of CD51+ CD105+ SSC descendants. Overall, the evidence indicates that BMP-2 may recapitulate a close interaction between functional vessels and SSCs. We conclude that BMP-2 augmented coupling of angiogenesis and osteogenesis in a novel and indispensable way to improve bone regeneration in mandibular defects, and warrants clinical investigation and application.