METTL3 inhibits BMSC apoptosis and facilitates osteonecrosis repair via an m6A-IGF2BP2-dependent mechanism.

Hypoxia-induced apoptosis of bone marrow mesenchymal stem cells (BMSCs) limits the efficacy of their transplantation for steroid-induced osteonecrosis of the femoral head (SONFH). As apoptosis and RNA methylation are closely related, exploring the role and mechanism of RNA methylation in hypoxic apoptosis of BMSCs is expected to identify new targets for transplantation of BMSCs for SONFH and enhance transplantation efficacy. We performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) combined with RNA-seq on a hypoxia-induced apoptosis BMSC model and found that the RNA methyltransferase-like 3 (METTL3) is involved in hypoxia-induced BMSC apoptosis. The expression of METTL3 was downregulated in BMSCs after hypoxia and in BMSCs implanted in osteonecrosis areas. Knockdown of METLL3 under normoxic conditions promoted apoptosis of BMSCs. In contrast, overexpression of METTL3 promoted the survival of BMSCs under hypoxic conditions, and overexpression of METTL3 promoted the survival of BMSCs in the osteonecrosis area and the repair of the osteonecrosis area. Regarding the mechanism, the m6A levels of the mRNAs of anti-apoptotic genes Bcl-2, Mcl-1, and BIRC5 were significantly increased upon the overexpression of METTL3 under hypoxic conditions, which promoted the binding of Bcl-2, Mcl-1, and BIRC5 mRNAs to IGF2BP2, enhanced the mRNA stability, and increased the protein expression of the three anti-apoptotic genes. In conclusion, overexpression of METTL3 promoted m6A modification of mRNAs of Bcl-2, Mcl-1, and BIRC5, promoted the binding of IGF2BP2 to the above-mentioned mRNAs, enhanced mRNA stability, inhibited hypoxia-induced BMSC apoptosis, and promoted repair of SONFH, thereby providing novel targets for transplantation of BMSCs for SONFH.

Tensile Stress-Activated and Exosome-Transferred YAP/TAZ-Notch Circuit Specifies Type H Endothelial Cell for Segmental Bone Regeneration.

The Ilizarov technique has been continuously innovated to utilize tensile stress (TS) for inducing a bone development-like regenerative process, aiming to achieve skeletal elongation and reconstruction. However, it remains uncertain whether this distraction osteogenesis (DO) process induced by TS involves the pivotal coupling of angiogenesis and osteogenesis mediated by type H endothelial cells (THECs). In this study, it is demonstrated that the Ilizarov technique induces the formation of a metaphysis-like architecture composed of THECs, leading to segmental bone regeneration during the DO process. Mechanistically, cell-matrix interactions-mediated activation of yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) transcriptionally upregulates the expression of Notch1 and Delta-like ligand 4, which act as direct positive regulators of THECs phenotype, in bone marrow endothelial cells (BMECs) upon TS stimulation. Simultaneously, the Notch intracellular domain enhances YAP/TAZ activity by transcriptionally upregulating YAP expression and stabilizing TAZ protein, thus establishing the YAP/TAZ-Notch circuit. Additionally, TS-stimulated BMECs secrete exosomes enriched with vital molecules in this positive feedback pathway, which can be utilized to promote segmental bone defect healing, mimicking the therapeutic effects of Ilizarov technique. The findings advance the understanding of TS-induced segmental bone regeneration and establish the foundation for innovative biological therapeutic strategies aimed at activating THECs.

Enhanced Bone Regeneration through Regulation of Mechanoresponsive FAK-ERK1/2 Signaling by ZINC40099027 during Distraction Osteogenesis.

Background: Focal adhesion kinase (FAK) is activated by mechanical stimulation and plays a vital role in distraction osteogenesis (DO), a well-established but lengthy procedure for repairing large bone defects. Both angiogenesis and osteogenesis contribute to bone regeneration during DO. However, the effects of ZINC40099027 (ZN27), a potent FAK activator, on angiogenesis, osteogenesis, and bone regeneration in DO remain unknown. Methods: The angiogenic potential of human umbilical vein endothelial cells (HUVECs) was evaluated using transwell migration and tube formation assays. The osteogenic activity of bone marrow mesenchymal stem cells (BMSCs) was assessed using alkaline phosphatase (ALP) and alizarin red s (ARS) staining. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence staining were used to assay angiogenic markers, osteogenic markers, and FAK-extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. In vivo, a rat tibia DO model was established to verify the effects of ZN27 on neovascularization and bone regeneration using radiological and histological analyses. Results: ZN27 promoted the migration and angiogenesis of HUVECs. Additionally, ZN27 facilitated the osteogenic differentiation of BMSCs, as revealed by increased ALP activity, calcium deposition, and expression of osteogenesis-specific markers. The ERK1/2-specific inhibitor PD98059 significantly hindered the effects of ZN27, suggesting the participation of FAK-ERK1/2 signaling in ZN27-enhanced angiogenesis and osteogenesis. As indicated by improved radiological and histological features, ZN27 induced active angiogenesis within the distraction area and accelerated bone regeneration in a rat DO model. Conclusion: Our results show that ZN27 targets FAK-ERK1/2 signaling to stimulate both angiogenesis and osteogenesis, and ZN27 accelerates bone regeneration in DO, suggesting the therapeutic potential of ZN27 for repairing large bone defects in the mechanobiological environment during DO.

Black Phosphorus/MnO2 Nanocomposite Disrupting Bacterial Thermotolerance for Efficient Mild-Temperature Photothermal Therapy.

The emergence of multi-drug resistant (MDR) pathogens is a major public health concern, posing a substantial global economic burden. Photothermal therapy (PTT) at mild temperature presents a promising alternative to traditional antibiotics due to its biological safety and ability to circumvent drug resistance. However, the efficacy of mild PTT is limited by bacterial thermotolerance. Herein, a nanocomposite, BP@Mn-NC, comprising black phosphorus nanosheets and a manganese-based nanozyme (Mn-NZ) is developed, which possesses both photothermal and catalytic properties. Mn-NZ imparts glucose oxidase- and peroxidase-like properties to BP@Mn-NC, generating reactive oxygen species (ROS) that induce lipid peroxidation and malondialdehyde accumulation across the bacterial cell membrane. This process disrupts unprotected respiratory chain complexes exposed on the bacterial cell membrane, leading to a reduction in the intracellular adenosine triphosphate (ATP) content. Consequently, mild PTT mediated by BP@Mn-NC effectively eliminates MDR infections by specifically impairing bacterial thermotolerance because of the dependence of bacterial heat shock proteins (HSPs) on ATP molecules for their proper functioning. This study paves the way for the development of a novel photothermal strategy to eradicate MDR pathogens, which targets bacterial HSPs through ROS-mediated inhibition of bacterial respiratory chain activity.

Injectable hypoxia-preconditioned cartilage progenitor cells-laden GelMA microspheres system for enhanced osteoarthritis treatment.

Osteoarthritis (OA) is the most common age-related degenerative joint disease mainly characterized by the destruction of articular cartilage. Owing to its native avascular property, intrinsic repair of articular cartilage is very limited. Thus, a chondrogenic microenvironment in the joint is essential to the preservation of healthy chondrocytes and OA treatment. Recently, cartilage progenitor cells (CPCs)-based therapy is emerging as a promising strategy to repair degenerated and damaged articular cartilage. In this study, injectable hypoxia-preconditioned three-dimensional (3D) cultured CPCs-laden gelatin methacryloyl (GelMA) microspheres (CGMs) were constructed and characterized. Compared to normoxia-pretreated 3D CPCs and two-dimensional (2D) cultured CPCs, hypoxia-preconditioned 3D cultured CPCs exhibited enhanced cartilage extracellular matrix (ECM) secretion and greater chondrogenic ability. In addition, hypoxia-preconditioned 3D cultured CPCs more effectively maintained cartilage matrix metabolism balance and attenuated articular cartilage degeneration in subacute and chronic rat OA models. Mechanistically, our results demonstrated hypoxia-preconditioned 3D cultured CPCs exerted chondro-protective effects by inhibiting inflammation and oxidative stress via NRF2/HO-1 pathway in vitro and in vivo. Together, through the 3D culture of CPCs using GelMA microspheres (GMs) under hypoxia environment, our results proposed an efficient articular cartilage regeneration strategy for OA treatment and could provide inspiration for other stem cells-based therapies.

FAR591 promotes the pathogenesis and progression of SONFH by regulating Fos expression to mediate the apoptosis of bone microvascular endothelial cells.

The specific pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) is still not fully understood, and there is currently no effective early cure. Understanding the role and mechanism of long noncoding RNAs (lncRNAs) in the pathogenesis of SONFH will help reveal the pathogenesis of SONFH and provide new targets for its early prevention and treatment. In this study, we first confirmed that glucocorticoid (GC)-induced apoptosis of bone microvascular endothelial cells (BMECs) is a pre-event in the pathogenesis and progression of SONFH. Then, we identified a new lncRNA in BMECs via lncRNA/mRNA microarray, termed Fos-associated lincRNA ENSRNOT00000088059.1 (FAR591). FAR591 is highly expressed during GC-induced BMEC apoptosis and femoral head necrosis. Knockout of FAR591 effectively blocked the GC-induced apoptosis of BMECs, which then alleviated the damage of GCs to the femoral head microcirculation and inhibited the pathogenesis and progression of SONFH. In contrast, overexpression of FAR591 significantly promoted the GC-induced apoptosis of BMECs, which then aggravated the damage of GCs to the femoral head microcirculation and promoted the pathogenesis and progression of SONFH. Mechanistically, GCs activate the glucocorticoid receptor, which translocates to the nucleus and directly acts on the FAR591 gene promoter to induce FAR591 gene overexpression. Subsequently, FAR591 binds to the Fos gene promoter (-245∼-51) to form a stable RNA:DNA triplet structure and then recruits TATA-box binding protein associated factor 15 and RNA polymerase II to promote Fos expression through transcriptional activation. Fos activates the mitochondrial apoptotic pathway by regulating the expression of Bcl-2 interacting mediator of cell death (Bim) and P53 upregulated modulator of apoptosis (Puma) to mediate GC-induced apoptosis of BMECs, which leads to femoral head microcirculation dysfunction and femoral head necrosis. In conclusion, these results confirm the mechanistic link between lncRNAs and the pathogenesis of SONFH, which helps reveal the pathogenesis of SONFH and provides a new target for the early prevention and treatment of SONFH.

Cobalt-Doped Mesoporous Silica Coated Magnetic Nanoparticles Promoting Accelerated Bone Healing in Distraction Osteogenesis.

Introduction: Large bone abnormalities are commonly treated using distraction osteogenesis (DO), but it is not suitable for a long-term application; therefore, there is an urgent need for adjuvant therapy that can accelerate bone repair. Methods: We have synthesized mesoporous silica-coated magnetic nanoparticles doped with cobalt ions (Co-MMSNs) and assessed their capacity to quicken bone regrowth in a mouse model of DO. Furthermore, local injection of the Co-MMSNs significantly accelerated bone healing in DO, as demonstrated by X-ray imaging, micro-CT, mechanical tests, histological evaluation, and immunochemical analysis. Results: In vitro, the Co-MMSNs exhibited good biocompatibility and induced angiogenic gene expression and osteogenic development in bone mesenchymal stem cells. And the Co-MMSNs can promote bone regeneration in a rat DO model. Discussion: This study demonstrated the significant potential of Co-MMSNs to shorten the DO treatment duration and effectively reduce the incidence of complications.

LncAABR07053481 inhibits bone marrow mesenchymal stem cell apoptosis and promotes repair following steroid-induced avascular necrosis.

The osteonecrotic area of steroid-induced avascular necrosis of the femoral head (SANFH) is a hypoxic microenvironment that leads to apoptosis of transplanted bone marrow mesenchymal stem cells (BMSCs). However, the underlying mechanism remains unclear. Here, we explore the mechanism of hypoxic-induced apoptosis of BMSCs, and use the mechanism to improve the transplantation efficacy of BMSCs. Our results show that the long non-coding RNA AABR07053481 (LncAABR07053481) is downregulated in BMSCs and closely related to the degree of hypoxia. Overexpression of LncAABR07053481 could increase the survival rate of BMSCs. Further exploration of the downstream target gene indicates that LncAABR07053481 acts as a molecular "sponge" of miR-664-2-5p to relieve the silencing effect of miR-664-2-5p on the target gene Notch1. Importantly, the survival rate of BMSCs overexpressing LncAABR07053481 is significantly improved after transplantation, and the repair effect of BMSCs in the osteonecrotic area is also improved. This study reveal the mechanism by which LncAABR07053481 inhibits hypoxia-induced apoptosis of BMSCs by regulating the miR-664-2-5p/Notch1 pathway and its therapeutic effect on SANFH.

Distal Ulnar Bifurcation Arthroplasty in the Treatment of Bayne and Klug Types 3 and 4 Radial Club Hands: Preliminary Outcomes.

BACKGROUND: The treatment of Bayne and Klug types 3 and 4 radial club hands (RCHs) remains challenging and controversial. In this study, the authors reported a new procedure called distal ulnar bifurcation arthroplasty and reviewed the preliminary results. METHODS: Between 2015 and 2019, 11 patients with 15 affected forearms having type 3 or 4 RCHs underwent distal ulnar bifurcation arthroplasty. The mean age was 55.5 months (range, 29 to 86 months). The surgical protocol consisted of (1) bifurcation of the distal ulna to accommodate the wrist with stable support; (2) pollicization to treat hypoplastic or absent thumb; and (3) in the case of significant bowed ulna, ulnar corrective osteotomy. In all patients, clinical and radiologic parameters including hand-forearm angle, hand-forearm position, ulnar length, wrist stability, and motion were recorded. RESULTS: The mean duration of follow-up was 42.2 months (range, 24 to 60 months). The average correction of hand-forearm angle was 80.2 degrees. The overall range of active wrist motion was approximately 87.5 degrees. Ulna growth per year was 6.7 mm (range, 5.2 to 9.2 mm). No major complications were recorded during follow-up. CONCLUSIONS: The distal ulnar bifurcation arthroplasty offers a technically feasible alternative for the treatment of type 3 or 4 RCH, which enables satisfactory appearance, provides stable support to the wrist, and maintains wrist function. Despite the promising preliminary results, longer follow-up is necessary to evaluate this procedure. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Monorail External Fixation in Humeral Lengthening and Deformity Correction with Glenohumeral Reduction: A Case Report.

CASE: External fixation has an established use in humeral lengthening and deformity correction. An 11-year-old boy presented with left-sided humeral shortening, proximal varus deformity, and glenohumeral dislocation. Anatomical and functional corrections were achieved through innovative monorail external fixation, including bifocal osteotomies of the surgical neck and diaphysis proximal to the deltoid insertion. CONCLUSION: Monorail external fixation with bifocal osteotomies of the surgical neck and diaphysis proximal to the deltoid insertion may improve the anatomical and functional outcomes in humeral shortening and proximal varus deformity with glenohumeral dislocation.

Detection of type III effector-induced transcription factors that regulate phytohormone content during symbiosis establishment in soybean.

Soybean is a pivotal protein and oil crop that utilizes atmospheric nitrogen via symbiosis with rhizobium soil bacteria. Rhizobial type III effectors (T3Es) are essential regulators during symbiosis establishment. However, how the transcription factors involved in the interaction between phytohormone synthesis and type III effectors are connected is unclear. To detect the responses of phytohormone and transcription factor genes to rhizobial type III effector NopAA and type III secretion system, the candidate genes underlying soybean symbiosis were identified using RNA sequencing (RNA-seq) and phytohormone content analysis of soybean roots infected with wild-type Rhizobium and its derived T3E mutant. Via RNA-seq analysis the WRKY and ERF transcription factor families were identified as the most differentially expressed factors in the T3E mutant compared with the wild-type. Next, qRT-PCR was used to confirm the candidate genes Glyma.09g282900, Glyma.08g018300, Glyma.18g238200, Glyma.03g116300, Glyma.07g246600, Glyma.16g172400 induced by S. fredii HH103, S. fredii HH103ΩNopAA, and S. fredii HH103ΩRhcN. Since the WRKY and ERF families may regulate abscisic acid (ABA) content and underlying nodule formation, we performed phytohormone content analysis at 0.5 and 24 h post-inoculation (hpi). A significant change in ABA content was found between wild Rhizobium and type III effector mutant. Our results support that NopAA can promote the establishment of symbiosis by affecting the ABA signaling pathways by regulating WRKY and ERF which regulate the phytohormone signaling pathway. Specifically, our work provides insights into a signaling interaction of prokaryotic effector-induced phytohormone response involved in host signaling that regulates the establishment of symbiosis and increases nitrogen utilization efficiency in soybean plants.

Endocrine modulation of brain-skeleton axis driven by neural stem cell-derived perilipin 5 in the lipid metabolism homeostasis for bone regeneration.

Factors released from the nervous system always play crucial roles in modulating bone metabolism and regeneration. How the brain-driven endocrine axes maintain bone homeostasis, especially under metabolic disorders, remains obscure. Here, we found that neural stem cells (NSCs) residing in the subventricular zone participated in lipid metabolism homeostasis of regenerative bone through exosomal perilipin 5 (PLIN5). Fluorescence-labeled exosomes tracing and histological detection identified that NSC-derived exosomes (NSC-Exo) could travel from the lateral ventricle into bone injury sites. Homocysteine (Hcy) led to osteogenic and angiogenic impairment, whereas the NSC-Exo were confirmed to restore it. Mecobalamin, a clinically used neurotrophic drug, further enhanced the protective effects of NSC-Exo through increased PLIN5 expression. Mechanistically, NSC-derived PLIN5 reversed excessive Hcy-induced lipid metabolic imbalance and aberrant lipid droplet accumulation through lipophagy-dependent intracellular lipolysis. Intracerebroventricular administration of mecobalamin and/or AAV-shPlin5 confirmed the effects of PLIN5-driven endocrine modulations on new bone formation and vascular reconstruction in hyperhomocysteinemic and high-fat diet models. This study uncovered a novel brain-skeleton axis that NSCs in the mammalian brain modulated bone regeneration through PLIN5-driven lipid metabolism modulation, providing evidence for lipid- or bone-targeted medicine development.

Promotion of the genipin crosslinked chitosan-fiber hydrogel loaded with sustained release of clemastine fumarate in diabetic wound repair.

Diabetic skin disorders are lingering and refractory clinical diseases. In this study, a genipin-crosslinked porous chitosan fiber (CSF) hydrogel was fabricated to achieve rapid wound healing. By embedding clemastine fumarate (CF) in the CSF hydrogel pores, we synthesised a CSF/CF hydrogel for the treatment of diabetic wounds. The microstructure, chemical elements, spectral variation, mechanical properties, swelling ratios, degradability, and toxicity of the CSF/CF hydrogels were studied. Compared with the typical CS power hydrogel, the porous CSF hydrogel crosslinked with genipin possesses a stable structure and improved physicochemical properties. Moreover, CF was slowly released from the CSF hydrogel. Molecular simulation also showed that CF was evenly embedded inside the cavity formed by the novel CSF hydrogel. The results suggested that CF can resist damage from high glucose levels and promote proliferation, tube formation, and migration of endothelial cells (ECs) and fibroblasts. The CSF/CF hydrogel promoted wound healing in a rat model. Mechanistically, the beneficial effect of CF on wound healing may be related to activation of the MEK/ERK and PI3K/Akt signalling pathways. In conclusion, genipin-crosslinked CSF/CF hydrogel can accelerate wound healing and may be an effective therapeutic method for treating diabetic skin lesions.

Triplanar osteotomy combined with proximal tibial transverse transport to accelerate healing of recalcitrant diabetic foot ulcers.

BACKGROUND: Management of recalcitrant diabetic foot ulcers remains challenging. Tibial transverse transport (TTT) is an effective method for enhancing the healing of foot ulcers. This retrospective study reports a novel triplanar osteotomy in the tibia and assesses the clinical outcomes of TTT for diabetic foot ulcers. METHODS: Fifty-nine patients with recalcitrant diabetic foot ulcers were divided into the TTT (32 patients) and control (27 patients) groups. In the TTT group, the patients underwent triplanar osteotomy of the proximal tibia, followed by 2 weeks of medial distraction and 2 weeks of lateral distraction. In the control group, the patients received conventional management, including debridement, revascularization, and reconstruction. Ulcer healing and healing time, amputation, recurrence, and complications were assessed at an 18-month follow-up visit. Computed tomography angiography (CTA) was used to evaluate vessel changes in the lower limbs of patients in the TTT group. RESULTS: The TTT group was superior to the control group in the healing rate (90.6% [29/32] vs. 66.7% [18/27]) and the healing time (4.6 ± 1.7 months vs. 7.4 ± 2.5 months), respectively. The proportions of amputation and recurrence in the TTT group were lower than that in the control group, without statistical difference. After triplanar osteotomy and transverse distraction, CTA demonstrated an increase in small vessels in the wound and ipsilateral limb. All patients achieved satisfactory union of the osteotomized bone fragment after removal of the external fixator. CONCLUSIONS: Triplanar osteotomy combined with proximal tibial transverse distraction accelerates wound healing and limb salvage caused by severe and recalcitrant diabetic foot ulcers. Triplanar osteotomy not only increases the bone contact area, which is beneficial for rapid bone reconstruction, but also preserves the vascularization of the bone fragment and substantially facilitates capillary angiogenesis during distraction. These results suggest that triplanar osteotomy followed by tibial transverse distraction is an effective method for treating diabetic foot ulcers.

Specific deletion of Axin1 leads to activation of ß-catenin/BMP signaling resulting in fibular hemimelia phenotype in mice.

Axin1 is a key regulator of canonical Wnt signaling pathway. Roles of Axin1 in skeletal development and in disease occurrence have not been fully defined. Here, we report that Axin1 is essential for lower limb development. Specific deletion of Axin1 in limb mesenchymal cells leads to fibular hemimelia (FH)-like phenotype, associated with tarsal coalition. Further studies demonstrate that FH disease is associated with additional defects in Axin1 knockout (KO) mice, including decreased osteoclast formation and defects in angiogenesis. We then provide in vivo evidence showing that Axin1 controls limb development through both canonical ß-catenin and BMP signaling pathways. We demonstrate that inhibition of ß-catenin or BMP signaling could significantly reverse the FH phenotype in mice. Together, our findings reveal that integration of ß-catenin and BMP signaling by Axin1 is required for lower limb development. Defect in Axin1 signaling could lead to the development of FH disease.

Outcomes of Eight-Plate Epiphysiodesis for Residual Clubfoot Deformities.

OBJECTIVE: The outcome of congenital clubfoot treatment is still challenging if the feet deformities are not completely corrected. Here we explore a minimal invasive procedure with an eight-plate implant to correct the residual forefoot adduction deformity after treatment of neglected or relapsed clubfoot. METHODS: We retrospectively reviewed patients with residual forefoot adduction deformity after clubfoot treatment between January 2013 and June 2016. The patients underwent temporary epiphysiodesis of the lateral column of the mid-foot, which in detail, an eight-plate was placed on each side of the calcaneocuboid joint. The foot deformities were recorded according to the weight-bearing radiographic measurements including talo-first metatarsal angle, calcaneo-fifth metatarsal angle and medial-to-lateral column length. RESULTS: A total of 13 patients (20 feet) with an average age of 7.8 years old were located with an average duration of 40.8 months follow-up (range, 28 to 54 months). The average talo-first metatarsal angle improved from 28.3° (range, 19° to 47°) preoperatively to 8.3° (range, 3° to 18°) and the calcaneo-fifth metatarsal angle improved from 29.1° (range, 19° to 40°) preoperatively to 8.4° (range, 0° to 21°) at final follow-up. The mean ratio of the medial-to-lateral column length improved from 1.14 ± 0.06 to 1.55 ± 0.09 with statistical significance (t = 3.566; P < 0.001). CONCLUSIONS: Eight-plate epiphysiodesis is an easy and effective method for the correction of residual forefoot adduction deformity after clubfoot treatment in growing children without the need of osteotomy.

In vivo prevascularization strategy enhances neovascularization of ß-tricalcium phosphate scaffolds in bone regeneration.

Background: Neovascularization is critical for bone regeneration. Numerous studies have explored prevascularization preimplant strategies, ranging from calcium phosphate cement (CPC) scaffolds to co-culturing CPCs with stem cells. The aim of the present study was to evaluate an alternative in vivo prevascularization approach, using preimplant-prepared macroporous beta-tricalcium phosphate (ß-TCP) scaffolds and subsequent transplantation in bone defect model. Methods: The morphology of ß-TCPs was characterized by scanning electron microscopy. After 3 weeks of prevascularization within a muscle pouch at the lateral size of rat tibia, we transplanted prevascularized macroporous ß-TCPs in segmental tibia defects, using blank ß-TCPs as a control. Extent of neovascularization was determined by angiography and immunohistochemical (IHC) evaluations. Tibia samples were collected at different time points for biomechanical, radiological, and histological analyses. RT-PCR and western blotting were used to evaluate angio- and osteo-specific markers. Results: With macroporous ß-TCPs, we documented more vascular and supporting tissue invasion in the macroporous ß-TCPs with prior in vivo prevascularization. Radiography, biomechanical, IHC, and histological analyses revealed considerably more vascularity and bone consolidation in ß-TCP scaffolds that had undergone the prevascularization step compared to the blank ß-TCP scaffolds. Moreover, the prevascularization treatment remarkably upregulated mRNA and protein expression of BMP2 and vascular endothelial growth factor (VEGF) during bone regeneration. Conclusion: This novel in vivo prevascularization strategy successfully accelerated vascular formation to bone regeneration. Our findings indicate that prevascularized tissue-engineered bone grafts have promising potential in clinical applications. The translational potential of this article: This study indicates a novel in vivo prevascularization strategy for growing vasculature on ß-TCP scaffolds to be used for repair of large segmental bone defects, might serve as a promising tissue-engineered bone grafts in the future.

Plating after lengthening in treating phalangeal and metacarpal deficiency: An alternative method.

OBJECTIVES: This study aims to investigate whether plating after lengthening in patients with phalanges and metacarpals deficiency could significantly shorten the duration of external fixation and decrease bone healing index. PATIENTS AND METHODS: Between February 2010 and December 2018, 11 phalanges in nine patients (6 males, 3 females; mean age: 28.4±4.4 years; range, 22 to 35 years) and nine metacarpals in six patients (2 males, 4 females; mean age: 21.0±2.9 years; range, 16 to 25 years) were lengthened at a rate of 0.25 mm in two increments. A unilateral external fixator was applied in all cases. A locking compression plate was applied at the end of the distraction period before the external fixator was removed. Removal of the plate was considered two years after the internal fixation. RESULTS: The desired length and bone consolidation were achieved in all cases. The additional lengths achieved in the phalanges and metacarpals group were 18.3 mm and 27.7 mm on average, respectively. The bone healing indexes in the phalanges and metacarpals were 1.33 and 1.44 mo/cm, respectively. No significant difference was observed in the pre- and postoperative range of motion of involved metacarpophalangeal joint of both phalangeal (95% CI: -0.469~1.014, t=0.820, p=0.432) and metacarpal (95% CI: -0.689~0.975, t=0.420, p=0.689) lengthening cases. Only one case of minor complication (track infection) occurred. CONCLUSION: Plating after lengthening is an ideal method for phalanges and metacarpals deficiency. Its advantages include shorter duration of external fixation, lower complication rate, and early functional recovery.