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.

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.

Cartilage progenitor cells derived extracellular vesicles-based cell-free strategy for osteoarthritis treatment by efficient inflammation inhibition and extracellular matrix homeostasis restoration.

Osteoarthritis (OA) is a common degenerative joint disease which currently lacks of effective agents. It is therefore urgent and necessary to seek an effective approach that can inhibit inflammation and promote cartilage matrix homeostasis. Cartilage progenitor cells (CPCs) are identified as a cell population of superficial zone in articular cartilage which possess strong migration ability, proliferative capacity, and chondrogenic potential. Recently, the application of CPCs may represent a novel cell therapy strategy for OA treatment. There is growing evidence that extracellular vesicles (EVs) are primary mediators of the benefits of stem cell-based therapy. In this study, we explored the protective effects of CPCs-derived EVs (CPCs-EVs) on IL-1ß-induced chondrocytes. We found CPCs-EVs exhibited chondro-protective effects in vitro. Furthermore, our study demonstrated that CPCs-EVs promoted matrix anabolism and inhibited inflammatory response at least partially via blocking STAT3 activation. In addition, liquid chromatography-tandem mass spectrometry analysis identified 991 proteins encapsulated in CPCs-EVs. By bioinformatics analysis, we showed that STAT3 regulatory proteins were enriched in CPCs-EVs and could be transported to chondrocytes. To promoting the protective function of CPCs-EVs in vivo, CPCs-EVs were modified with cationic peptide ε-polylysine-polyethylene-distearyl phosphatidylethanolamine (PPD) for surface charge reverse. In posttraumatic OA mice, our results showed PPD modified CPCs-EVs (PPD-EVs) effectively inhibited extracellular matrix catabolism and attenuated cartilage degeneration. Moreover, PPD-EVs down-regulated inflammatory factors expressions and reduced OA-related pain in OA mice. In ex-vivo cultured OA cartilage explants, PPD-EVs successfully promoted matrix anabolism and inhibited inflammation. Collectively, CPCs-EVs-based cell-free therapy is a promising strategy for OA treatment.

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.

Hypoxic condition induced H3K27me3 modification of the LncRNA Tmem235 promoter thus supporting apoptosis of BMSCs.

Bone marrow mesenchymal stem cells (BMSCs) have strong regenerative potential and show good application prospects for treating clinical diseases. However, in the process of BMSC transplantation for treating ischemic and hypoxic diseases, BMSCs have high rates of apoptosis in the hypoxic microenvironment of transplantation, which significantly affects the transplantation efficacy. Our previous studies have confirmed the key role of long non-coding RNA Tmem235 (LncRNA Tmem235) in the process of hypoxia-induced BMSC apoptosis and its downstream regulatory mechanism, but the upstream mechanism by which hypoxia regulates LncRNA Tmem235 expression to induce BMSC apoptosis is still unclear. Under hypoxic conditions, we found that the level of LncRNA Tmem235 promoter histone H3 lysine 27 trimethylation modification (H3K27me3) was significantly increased by CHIP-qPCR. Moreover, H3K27me3 cooperated with LncRNA Tmem235 promoter DNA methylation to inhibit the expression of LncRNA Tmem235 and promote apoptosis of BMSCs. To study the mechanism of hypoxia-induced modification of LncRNA Tmem235 promoter H3K27me3 in the hypoxia model of BMSCs, we detected the expression of H3K27 methylase and histone demethylase and found that only histone methylase enhancer of zeste homolog 2 (EZH2) expression was significantly upregulated. Knockdown of EZH2 significantly decreased the level of H3K27me3 modification in the LncRNA Tmem235 promoter. The EZH2 promoter region contains a hypoxia-responsive element (HRE) that interacts with hypoxia-inducible factor-1alpha (HIF-1α), which is overexpressed under hypoxic conditions, thereby promoting its overexpression. In summary, hypoxia promotes the modification of the LncRNA Tmem235 promoter H3K27me3 through the HIF-1α/EZH2 signaling axis, inhibits the expression of LncRNA Tmem235, and leads to hypoxic apoptosis of BMSCs. Our findings improve the regulatory mechanism of LncRNA Tmem235 during hypoxic apoptosis of BMSCs and provide a more complete theoretical pathway for targeting LncRNA to inhibit hypoxic apoptosis of BMSCs.

A novel human anti-TIGIT monoclonal antibody with excellent function in eliciting NK cell-mediated antitumor immunity.

TIGIT is an emerging novel checkpoint target that is expressed on both tumor-infiltrating T cells and NK cells. Some current investigational antibodies targeting TIGIT have also achieved dramatic antitumor efficacy in late clinical research. Most recently, the relevance of NK cell-associated TIGIT signaling pathway to tumors' evasion of the immune system has been clearly revealed, which endows NK cells with a pivotal role in the therapeutic effects of TIGIT blockade. In this article, we describe a novel anti-TIGIT monoclonal antibody, AET2010, which was acquired from a phage-displayed human single-chain antibody library through a cell panning strategy. With emphasis on its regulation of NK cells, we confirmed the excellent ex vivo and in vivo antitumor immunity of AET2010 mediated by the NK-92MI cells. Intriguingly, our work also revealed that AET2010 displays a lower affinity but parallel avidity and activity relative to MK7684, an investigational monoclonal antibody from MSD, implying a reasonable balance of potency and potential side effects for AET2010. Together, these results are promising and warrant further development of AET2010.

Efficacy of the "Eiffel tower" double titanium elastic nailing in combined management of congenital pseudarthrosis of the tibia: preliminary outcomes of 17 cases with review of literature.

BACKGROUND: Difficulty in obtaining union, recurrent fractures, and residual deformities remain the problems challenging the management of congenital pseudarthrosis of the tibia (CPT). We applied the "Eiffel Tower" double titanium elastic nails (TENs) in the existing combined approach, which takes advantages of TEN's mechanical stability with the protection against refracture, Ilizarov's high fusion rate with alignment control and the biologic environment provided by bone grafting for bony union. The results of this procedure are presented and discussed. METHODS: Seventeen patients with CPT treated by combined surgery including pseudarthrosis resection, the "Eiffel Tower" double TENs technique, autogenous iliac bone grafting, and Ilizarov fixation between 2013 and 2019 were retrospectively investigated. Signs of bone union, limb length discrepancy (LLD), rate of refracture, and degree of residual deformities were reviewed. The AOFAS Ankle Hindfoot scale and measurement of ankle motion were used to evaluate ankle function. The mean follow-up time was 40.5 (11 to 91) months. RESULTS: The mean age at index surgery was 6.2 (2.5 to 15) years. Union of the pseudarthrosis was achieved in 100% of cases. Among them, 15 (88.2%) patients obtained union of the pseudarthrosis on the first attempt (primary union). The average time to primary union was 3.8 (2 to 6) months. The rest 2 cases achieved union after additional surgeries (secondary union). In terms of complications, refracture occurred in 2 patients (11.8%) and 4 patients (23.5%) developed pin infection. The mean limb length discrepancy at the final follow up was 33.4 (6-141) mm. The average AOFAS score improved from 38.2 (27 to 51) pre-operatively to 77 (63 to 87) post-operatively (p < 0.01). CONCLUSIONS: The "Eiffel Tower" double TENs technique is an ideal intramedullary fixation method in the surgical treatment of CPT. The combination of TENs technique with bone grafting and Ilizarov fixation has the advantages of early bone union, less injury on metaphysis, and early functional recovery. LEVEL OF EVIDENCE: Level IV.

Subacromial balloon spacer implantation for patients with massive irreparable rotator cuff tears achieves satisfactory clinical outcomes in the short and middle of follow-up period: a meta-analysis.

PURPOSE: This meta-analysis was performed systematically to evaluate the efficacy of subacromial balloon spacers for patients with massive, irreparable rotator cuff tears. METHODS: Electronic databases, including Medline/PubMed, Embase and Cochrane Library, were systematically searched to identify studies evaluating the efficacy of subacromial spacers for patients with irreparable or massive rotator cuff tears. Meta-analyses were performed to pool the outcome estimates of interest, such as the total constant score (TCS) and its sub-score (pain, activities of daily living [ADL], range of motion [ROM], and strength), Oxford shoulder score (OSS), American Shoulder and Elbow Society scores (ASES) and numeric rating scale (NRS), as well as different outcomes at different time points in the follow-up period. RESULTS: Ten studies with a total of 261 patients involving 270 shoulders were deemed viable for inclusion in the meta-analysis. The combined results demonstrated significant improvements in the TCS at the final follow-up (pooled mean difference = 26.4, 95% confidence intervals [CIs] 23.3 to 29.5). A sensitivity analysis and subgroup analysis, which were implemented based on two factors, different follow-up points and sub-scores (pain, ADL, ROM, and strength), revealed a consistent trend. The combined shoulder motion results demonstrated significant improvements in the forward flexion and external rotation (0° abduction) variables rather than in the abduction and external rotation (90° abduction) variables. Additionally, significant improvements in the OSS and ASES and a decrease in the NRS were observed in the middle of the follow-up period. CONCLUSION: This meta-analysis indicated that subacromial balloon spacer implantation for patients with massive irreparable rotator cuff tears may achieve satisfactory outcomes between 3 months and 3 years of follow-ups. Although the short- and middle- term effect is significant, the long-term effect needs to be confirmed by large-sample randomized controlled trial. LEVEL OF EVIDENCE: IV.

Exosomes Secreted by Young Mesenchymal Stem Cells Promote New Bone Formation During Distraction Osteogenesis in Older Rats.

Distraction osteogenesis (DO) is a clinically effective procedure to regenerate large bone defects. However, the treatment duration is undesirably lengthy, especially in elderly patients. Exosomes derived from mesenchymal stem cells (MSC-Exos) could exert the beneficial effects while avoiding the possible complications of stem cell transplantation. This study aimed to evaluate the effects of MSC-Exos on bone regeneration during DO in older rats. Exosomes were isolated from the supernatants of young bone marrow mesenchymal stem cells (BMSCs) through ultra-centrifugation, and characterized using transmission electron microscopy, western blot, and tunable resistive pulse sensing analysis. The effects of MSC-Exos on the proliferation and differentiation of older BMSCs were evaluated using CCK-8 assay, ALP and ARS staining, and qRT-PCR. Unilateral tibial DO model was established on older Sprague-Dawley rats and MSC-Exos or phosphate buffer saline was locally injected into the distraction gaps after distraction weekly. Bone regeneration were evaluated using X-ray, Micro-CT, mechanical test, and histological staining. The MSC-Exos were round or cup-shaped vesicles ranging from 60 to 130 nm in diameter and expressed markers including CD9, CD63, and TSG101. The in vitro results indicated that MSC-Exos could enhance the proliferation and osteogenic differentiation of older BMSCs. Bone regeneration was markedly accelerated in rats treated with MSC-Exos according to the results of X-ray, micro-CT, and histological analysis. The distracted tibias from the MSC-Exos group also demonstrated better mechanical properties. These results suggest that MSC-Exos promote DO-mediated bone regeneration in older rats through enhancing the proliferation and osteogenic capacity of BMSCs.

Identification of two novel COL10A1 heterozygous mutations in two Chinese pedigrees with Schmid-type metaphyseal chondrodysplasia.

BACKGROUND: Schmid-type metaphyseal chondrodysplasia (MCDS) is an autosomal dominant disorder caused by COL10A1 mutations, which is characterized by short stature, waddling gait, coxa vara and bowing of the long bones. However, descriptions of the expressivity of MCDS are rare. METHODS: Two probands and available family members affected with MCDS were subjected to clinical and radiological examination. Genomic DNA of all affected individuals was subjected to whole-exome sequencing, and candidate mutations were verified by Sanger sequencing in all available family members and in 250 healthy donors. A spatial model of the type X collagen (α1) C-terminal noncollagenous (NC1) domain was further constructed. RESULTS: We found that the phenotype of affected family members exhibited incomplete dominance. Mutation analysis indicated that there were two novel heterozygous missense mutations, [c.1765 T > A (p.Phe589Ile)] and [c.1846A > G (p.Lys616Glu)] in the COL10A1 gene in family 1 and 2, respectively. The two novel substitution sites were highly conserved and the mutations were predicted to be deleterious by in silico analysis. Furthermore, protein modeling revealed that the two substitutions were located in the NC1 domain of collagen X (α1), which potentially impacted the trimerization of collagen X (α1) and combination with molecules in the pericellular matrix. CONCLUSION: Two novel mutations were identified in the present study, which will facilitate diagnosis of MCDS and further expand the spectrum of the COL10A1 mutations associated with MCDS patients. In addition, our research revealed the phenomenon of incomplete dominance in MCDS.

Regeneration of large bone defects using mesoporous silica coated magnetic nanoparticles during distraction osteogenesis.

Distraction osteogenesis (DO) represents an effective but undesirably lengthy treatment for large bone defects. Both magnetic nanoparticles and silicon have been shown to induce osteogenic differentiation of mesenchymal stem cells (MSCs), the key participant in bone regeneration. We herein synthesized mesoporous silica coated magnetic (Fe3O4) nanoparticles (M-MSNs) and evaluated its potential for acceleration of bone regeneration in a rat DO model. The M-MSNs exhibited good biocompatibility and remarkable capability in promoting the osteogenic differentiation of MSCs via the canonical Wnt/ß-catenin pathway in vitro. More importantly, local injection of M-MSNs dramatically accelerated bone regeneration in a rat DO model according to the results of X-ray imaging, micro-CT, mechanical testing, histological examination, and immunochemical analysis. This study demonstrates the notable potential of M-MSNs in promoting bone regeneration during DO by enhancing the osteogenic differentiation of MSCs, paving the way for clinical translation of M-MSNs in DO to repair large bone defects.

Bifocal osteosynthesis to treat radial shortening deformity with dislocation of the inferior radioulnar joint.

BACKGROUND: Several methods have been reported to correct deformity and shortening of the distal radius. However, the results are not entirely satisfactory. The results of bifocal osteosynthesis were retrospectively analyzed in this study. METHODS: Eight patients treated with bifocal osteosynthesis were evaluated retrospectively. Pre-operative and post-operative clinical and radiographic examinations were performed. Subjective symptoms and objective joint function were assessed. Radiographic data of the extent of radial lengthening and distal radial articular angle were collected. RESULTS: The mean follow-up period was 46 months (37-68 months). Satisfactory wrist appearance and radial lengthening was achieved in all patients. All patients were satisfied with the wrist appearance and willing to undergo the same treatment again. The range of motion (ROM) of the forearm and wrist was significantly improved. Pin-track infections occurred in two patients, for which they received wound care and oral antibiotics. Complications such as fixation device failure, tendon rupture, fracture of regenerated bone or nerve impairment did not occur. The duration of lengthening depended on the shortening of the radius. Delayed union in the docking site was observed in two patients and union was achieved after bone grafting. CONCLUSIONS: Bifocal osteosynthesis using the Ilizarov method provides a useful method for correction of radial shortening deformity with dislocation of the inferior radioulnar joint. Despite the fact that we did not validate pre-and post-operation functional outcome scores, all patients were satisfied with the wrist appearance and function.

Humeral lengthening and proximal deformity correction with monorail external fixator in young adults.

PURPOSE: Several humeral lengthening or simultaneous deformity corrections through one osteotomy using various external fixators were reported, while literature regarding correction of shortening and proximal varus deformity is scarce. This retrospective clinical study evaluated the results of preforming an acute correction and delayed lengthening in young adults through two osteotomies using monorail external fixator. METHODS: We report seven patients with various pathologies who underwent humeral proximal deformity correction and lengthening between 2009 and 2015. Pre-operative and post-operative clinical and radiographic data were collected. The mean follow-up time was 33.4 months (25-46 months). RESULTS: The humeral neck-shaft angle improved from 97.9° (85-110°) to 138.6° (135-145°). The magnitude of lengthening achieved was average 7.6 cm (range, 6-10 cm) at an average healing index of lengthening of 30.2 days/cm (range, 27.7-35.4 days/cm). There was a significant increase in range of shoulder abduction, and active abduction improved from pre-operative 136.4° (range, 95-160°) to post-operative 166.4° (range, 150-180°). The DASH score improved significance from 23.29 ± 8.36 to 6.57 ± 3.65 (t = 4.848; p < 0.001). CONCLUSION: Acute deformity correction and gradual lengthening with the monorail external fixator can be used for humeral shortening and proximal varus angular deformity. Functional improvement is expected after surgery and post-operative therapy.

Effect of SDF-1/Cxcr4 Signaling Antagonist AMD3100 on Bone Mineralization in Distraction Osteogenesis.

Distraction osteogenesis (DO) is a widely applied technique in orthopedics surgery, which involves rapid stem cell migration, homing, and differentiation. Interactions between the chemokine receptor Cxcr4 and its ligand, stromal derived factor-1 (SDF-1), regulate hematopoietic stem cell trafficking to the ischemic area and induce their subsequent differentiation. Here, we examined SDF-1 expression and further investigated the role of SDF-1/Cxcr4 signaling antagonist AMD3100 during bone regeneration in rat DO model. The results showed that expression levels of SDF-1 and osteogenic genes were higher in DO zones than in the fracture zones, and SDF-1 expression level was the highest at the termination of the distraction phase. Radiological, mechanical, and histological analyses demonstrated that the local administration of AMD3100 (400 µM) to DO rats significantly inhibited new bone formation. In the rat bone marrow mesenchymal stem cells culture, comparing to the group treated with osteogenic induction medium, AMD3100 supplement led to a considerable decrease in the expression of alkaline phosphatase and early osteogenic marker genes. However, the amount of calcium deposits in rat MSCs did not differ between the groups. Therefore, our study demonstrated that the DO process induced higher expression of SDF-1, which collated to rapid induction of callus formation. Local application of SDF-1/Cxcr4 signaling antagonist AMD3100 significantly inhibited bone mineralization and osteogenesis in DO, which may represent a potential therapeutic approach to the enhancement of bone consolidation in patients undergoing DO.

Reverse-Flow Lateral Tarsal Island Flap for Covering the Great Toe Donor Site of Wraparound Flap.

BACKGROUND: Coverage of the great toe donor site of wraparound flap remains a challenge. This report presents the results of using an innervated pedicled reverse-flow lateral tarsal island flap for covering the great toe donor site of wraparound flap. PATIENTS AND METHODS: Between 2005 and 2010, 11 reverse-flow lateral tarsal island flaps were used to cover the great toe donor site of wraparound flap in 11 patients. This pedicled flap designed on the lateral tarsal area of foot was based distally on the dorsalis pedis artery; the lateral dorsal pedal cutaneous nerve was incorporated into the reverse-flow lateral tarsal island flap and coapted with the first plantar digital nerve. The donor sites of reverse-flow lateral tarsal island flap were covered with inguinal full-thickness skin grafts. RESULTS: All flaps achieved primary healing except for two that suffered from mild venous insufficiency which was managed by conservative intervention. All skin grafts covering the donor site of reverse-flow lateral tarsal island flap healed uneventfully. The mean follow-up was 24 months (range, 18-48 months). The mean hallux metatarsophalangeal-interphalangeal scale score was 92 points (range, 85-97 points) at 6 months postoperatively. The static 2-point discrimination of the reverse-flow lateral tarsal island flap ranged from 6 to 14 mm (mean 10 mm). None of the patients were restricted in standing or walking during follow-up. CONCLUSIONS: The reverse-flow lateral tarsal island flap based distally on the dorsalis pedis artery has a constant pedicle that is sufficiently long. This innervated pedicle flap is a reliable option to cover the great toe donor site of wraparound flap with satisfactory functional and cosmetic results and acceptable donor site morbidity.

Stimulation of Nitric Oxide Production Contributes to the Antithrombotic Effect of Stromal Cell-Derived Factor-1α in Preventing Microsurgical Anastomotic Thrombosis.

Background Intimal injury plays a critical role in initiating the pathogenesis of thrombosis formation after microsurgical anastomosis. Application of stromal cell-derived factor-1α (SDF-1α) is reported to promote early regeneration of injured intima through migration of endothelial cells and mobilization of endothelial progenitor cells. We therefore hypothesized that local transfer of SDF-1α gene would inhibit microsurgical anastomotic thrombosis. Methods Sixty Sprague-Dawley rats were used and divided randomly into three groups (SDF-1α group, plasmid group, and saline group) in this study. Plasmid DNA encoding SDF-1α, empty plasmid, and saline were injected into the left femoral muscles of rats from each group, respectively. Seven days after injection, peripheral blood samples were obtained to measure the plasma levels of SDF-1α and nitric oxide (NO). The left femoral artery of each rat was crushed, transected, and repaired by end-to-end microsurgical anastomosis. Vascular patency was assessed at 15, 30, and 120 minutes after reperfusion using milk test. Thrombosis formation was assessed with hematoxylin and eosin staining and scanning electron microscopy at 120 minutes postoperatively. Results The plasma levels of SDF-1α and NO in SDF-1α group were significantly higher than those in plasmid group and saline group (p < 0.01). The patency rate in SDF-1α group was significantly higher than that in control groups at 120 minutes after reperfusion (p < 0.05). Treatment of SDF-1α significantly reduced the size of thrombotic occlusion when compared with controls (p < 0.05). All SDF-1α recipients exhibited decreased thrombosis under scanning electron microscopy. Conclusions The current study demonstrated that local transfer of SDF-1α gene increases arterial patency and inhibits microsurgical anastomotic thrombosis in a crush model of femoral artery in rat. The antithrombotic effect of SDF-1α may be mediated through increased production of endogenous NO. These findings provide a novel approach for inhibition of microsurgical anastomotic thrombosis.

Developmental pattern of the hip in patients with hereditary multiple exostoses.

BACKGROUND: Coxa valga is a common clinical feature of hereditary multiple exostoses (HME). The current study aimed to determine the unique developmental pattern of the hip in patients with HME and evaluate the factors that influence its progression. METHODS: Thirty patients (57 hips) with HME were divided into two groups according to the Hilgenreiner epiphyseal angle (HEA). Twenty-two patients (44 hips) including 13 men and 9 women were assigned to group 1 (HEA <25°), and 8 patients (13 hips) including 3 men and 5 women were assigned to group 2 (HEA ≥25°). The mean age at the initial presentation was 6.0 (4-12) years with 6.8 (4-11) years of follow-up in group 1, and 10.4 (8-13) years with 5.4 (2-9) years of follow-up in group 2. We measured the HEA, neck-shaft angle (NSA), acetabular index (AI), center-edge angle (CEA), and migration percentage (MP) for radiographic evaluation. RESULTS: Among the hips, 50 (87.7%) hips had coxa valga and 27 (47.4%) hips had abnormal MP (42.1% were borderline and 5.3% were subluxated). There was a significant difference in the HEA and NSA between the groups (p < 0.001 and p < 0.05, respectively). The HEA significantly correlated with the development of the NSA and no correlation was found between the HEA and AI, CEA, and MP. CONCLUSIONS: There was a significant relationship between the HEA at the initial presentation and the NSA at skeletal maturity. We should consider guided growth for patients with lower HEA to prevent significant coxa valga deformity with close follow-up.

Combined Anterolateral Thigh and Anteromedial Thigh Flap for Extensive Extremity Reconstruction: Vascular Anatomy and Clinical Application.

BACKGROUND: The combined anterolateral thigh (ALT) and anteromedial thigh (AMT) flap has been previously reported for use in complicated head and neck reconstruction. However, it has not gained popularity due to the vascular variation. Here, we explore the vascular basis of this combined flap, and report its application in extremity reconstruction. METHODS: This study was divided into two parts: vascular anatomy and clinical application. In the anatomical study, 52 sides of adult thighs were dissected to identity vascular perforators supplying the combined ALT and AMT flap, with focus on sizeable perforators (larger than 0.5 mm) arising from the descending branch of the lateral circumflex femoral artery.Clinically, five male patients were treated by combined ALT and AMT flaps for extensive extremity reconstruction from January 2006 to December 2010. The mean age was 32 years (range, 23-45 years). The combined flap was used for covering large soft-tissue defects in forearm (n = 3) and calf (n = 2). For each patient, esthetic and functional results were recorded. RESULTS: The anatomical study showed that sizeable perforators supplying the ALT flap were present in 50 thighs (96.2%), and the perforators supplying the AMT flap were present in 32 thighs (61.5%). The combined ALT and AMT flaps were available in 30 thighs (57.7%).All five combined flaps survived completely. Skin grafts covering the donor sites healed uneventful. The mean follow-up was 9.6 months (range, 6-12 months). No complications were recorded during the follow-up. CONCLUSION: The combined ALT and AMT flap may be used for extensive extremity reconstruction in selected patients for its great maneuverability and acceptable donor-site morbidity.

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.