Percutaneous CO2 Treatment Accelerates Bone Generation During Distraction Osteogenesis in Rabbits

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.

An Inexpensive 3D Printed Mouse Model of Successful, Complication-free Long Bone Distraction Osteogenesis

Distraction osteogenesis (DO) is used for skeletal defects; however, up to 50% of cases exhibit complications. Previous mouse models of long bone DO have been anecdotally hampered by postoperative complications, expense, and availability. To improve clinical techniques, cost-effective, reliable animal models are needed. Our focus was to develop a new mouse tibial distractor, hypothesized to result in successful, complication-free DO.

Methods

A lightweight tibial distractor was developed using CAD and 3D printing. The device was fixed to the tibia of C57Bl/6J mice prior to osteotomy. Postoperatively, mice underwent 5 days latency, 10 days distraction (0.15 mm every 12 hours), and 28 days consolidation. Bone regeneration was examined on postoperative day 43 using micro-computed tomography (μCT) and Movat's modified pentachrome staining on histology (mineralized volume fraction and pixels, respectively). Costs were recorded. We compared cohorts of 11 mice undergoing sham, DO, or acute lengthening (distractor acutely lengthened 3.0 mm).

Results

The histological bone regenerate was significantly increased in DO (1,879,257 ± 155,415 pixels) compared to acute lengthening (32847 ± 1589 pixels) (P < 0.0001). The mineralized volume fraction (bone/total tissue volume) of the regenerate was significantly increased in DO (0.9 ± 0.1) compared to acute lengthening (0.7 ± 0.1) (P < 0.001). There was no significant difference in bone regenerate between DO and sham. The distractor was relatively low cost ($11), with no complications.

Conclusions

Histology and µCT analysis confirmed that the proposed tibial DO model resulted in successful bone formation. Our model is cost-effective and reproducible, enabling implementation in genetically dissectible transgenic mice.

Osteolytic metatarsal osteomyelitis regenerated by combined treatment of artificial carbon dioxide foot bathing and povidone-iodine sugar ointment: a case report

BACKGROUND

In recent years, the number of patients with ischemic skin ulcers due to diabetes mellitus and arteriosclerosis obliterans are increasing. Accordingly, endovascular therapy, drugs, and various wound dressings have been developed and applied to diabetic foot ulcers, and negative-pressure wound therapy, which often requires expensive and burdensome procedures for medical personnel, has also become popular. So simple and minimal invasive home treatment by the patient or their caregiver is required.

CASE PRESENTATION

The present patient (77 years old, male, Asian) had developed left sole ulcers with draining pus that were resistant to conventional treatment, and he suffered from gait disturbance. We report a case of metatarsal osteomyelitis in a patient with diabetes mellitus and arteriosclerosis obliterans, in whom artificial carbon dioxide foot bathing and povidone-iodine sugar ointment were used continuously to promote bone and joint regeneration, and skin ulcer healing.

CONCLUSIONS

A simple therapeutic intervention with artificial carbon dioxide foot bathing and povidone-iodine sugar ointment can improve not only ischemic skin ulcers, but also the bone and joint regeneration of ischemic limbs. This therapy can lead to a reduction in healthcare costs for a huge number of diabetic patients.

Overview of Physical and Pharmacological Therapy in Enhancing Bone Regeneration Formation During Distraction Osteogenesis

Distraction osteogenesis (DO) is a kind of bone regeneration technology. The principle is to incise the cortical bone and apply continuous and stable distraction force to the fractured end of the cortical bone, thereby promoting the proliferation of osteoblastic cells in the tension microenvironment and stimulating new bone formation. However, the long consolidation course of DO presumably lead to several complications such as infection, fracture, scar formation, delayed union and malunion. Therefore, it is of clinical significance to reduce the long treatment duration. The current treatment strategy to promote osteogenesis in DO includes gene, growth factor, stem-cell, physical and pharmacological therapies. Among these methods, pharmacological and physical therapies are considered as safe, economical, convenience and effective. Recently, several physical and pharmacological therapies have been demonstrated with a decent ability to enhance bone regeneration during DO. In this review, we have comprehensively summarized the latest evidence for physical (Photonic, Waves, Gas, Mechanical, Electrical and Electromagnetic stimulation) and pharmacological (Bisphosphonates, Hormone, Metal compounds, Biologics, Chinese medicine, etc) therapies in DO. These evidences will bring novel and significant information for the bone healing during DO in the future.

Hypoxia During the Consolidation Phase of Distraction Osteogenesis Promotes Bone Regeneration

Background

Hypoxia is the critical driving force for angiogenesis and can trigger the osteogenic-angiogenic coupling followed by the enhancement of bone regeneration. While lots of studies showed that hypoxia administration can accelerate bone formation during distraction osteogenesis (DO), the therapeutic timing for the osteogenic purpose was concentrated on the distraction phase. The outcomes of hypoxia administration in the consolidation phase stay uncertain. The purpose of this study was to determine the osteogenic effectiveness of hypoxia therapy during the consolidation phase, if any, to enhance bone regeneration in a rat femoral DO model.

Methods

A total of 42 adult male Sprague-Dawley rats underwent right femoral mid-diaphysis transverse osteotomy and were randomly divided into Control (NS administration, n = 21) and Group1 (deferoxamine therapy, n = 21) after distraction. During the consolidation phase, Group1 was treated with local deferoxamine (DFO) injection into the distraction zone, while the Control underwent the same dosage of NS. Animals were sacrificed after 2, 4, and 6 weeks of consolidation. The process of bone formation and remodeling was monitored by digital radiographs, and the regenerated bone was evaluated by micro-computed tomography (micro-CT), biomechanical test, and histological analysis. The serum content of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) were measured by enzyme linked immunosorbent assay (ELISA) for further analysis.

Results

Bone regeneration was significantly enhanced after hypoxia therapy during the consolidation phase. The digital radiograph, micro-CT, and biomechanical evaluation showed better effects regarding volume, continuity, and mechanical properties of the regenerated bone in Group1. The histomorphological evaluation also revealed the hypoxia treatment contributed to accelerate bone formation and remodeling during DO. The higher positive expression of angiogenic and osteogenic markers were observed in Group1 after hypoxia administration according to the immunohistochemical analysis. The serum content of HIF-1α and VEGF was also increased after hypoxia therapy as evidenced from ELISA.

Conclusion

Hypoxia administration during the consolidation phase of distraction osteogenesis has benefits in enhancing bone regeneration, including accelerates the bone formation and remodeling.

The RNA Methyltransferase METTL3 Promotes Endothelial Progenitor Cell Angiogenesis in Mandibular Distraction Osteogenesis via the PI3K/AKT Pathway

Distraction osteogenesis (DO) is used to treat large bone defects in the field of oral and maxillofacial surgery. Successful DO-mediated bone regeneration is dependent upon angiogenesis, and endothelial progenitor cells (EPCs) are key mediators of angiogenic processes. The N6-methyladenosine (m⁶A) methyltransferase has been identified as an important regulator of diverse biological processes, but its role in EPC-mediated angiogenesis during DO remains to be clarified. In the present study, we found that the level of m⁶A modification was significantly elevated during the process of DO and that it was also increased in the context of EPC angiogenesis under hypoxic conditions, which was characterized by increased METTL3 levels. After knocking down METTL3 in EPCs, m⁶A RNA methylation, proliferation, tube formation, migration, and chicken embryo chorioallantoic membrane (CAM) angiogenic activity were inhibited, whereas the opposite was observed upon the overexpression of METTL3. Mechanistically, METTL3 silencing reduced the levels of VEGF and PI3Kp110 as well as the phosphorylation of AKT, whereas METTL3 overexpression reduced these levels. SC79-mediated AKT phosphorylation was also able to restore the angiogenic capabilities of METTL3-deficient EPCs in vitro and ex vivo. In vivo, METTL3-overexpressing EPCs were additionally transplanted into the DO callus, significantly enhancing bone regeneration as evidenced by improved radiological and histological manifestations in a canine mandibular DO model after consolidation over a 4-week period. Overall, these results indicate that METTL3 accelerates bone regeneration during DO by enhancing EPC angiogenesis via the PI3K/AKT pathway.

EGFL6 regulates angiogenesis and osteogenesis in distraction osteogenesis via Wnt/β-catenin signaling

Background

Osteogenesis is tightly coupled with angiogenesis during bone repair and regeneration. However, the underlying mechanisms linking these processes remain largely undefined. The present study aimed to test the hypothesis that epidermal growth factor-like domain-containing protein 6 (EGFL6), an angiogenic factor, also functions in bone marrow mesenchymal stem cells (BMSCs), playing a key role in the interaction between osteogenesis and angiogenesis.

Methods

We evaluated how EGFL6 affects angiogenic activity of human umbilical cord vein endothelial cells (HUVECs) via proliferation, transwell migration, wound healing, and tube-formation assays. Alkaline phosphatase (ALP) and Alizarin Red S (AR-S) were used to assay the osteogenic potential of BMSCs. qRT-PCR, western blotting, and immunocytochemistry were used to evaluate angio- and osteo-specific markers and pathway-related genes and proteins. In order to determine how EGFL6 affects angiogenesis and osteogenesis in vivo, EGFL6 was injected into fracture gaps in a rat tibia distraction osteogenesis (DO) model. Radiography, histology, and histomorphometry were used to quantitatively evaluate angiogenesis and osteogenesis.

Results

EGFL6 stimulated both angiogenesis and osteogenic differentiation through Wnt/β-catenin signaling in vitro. Administration of EGFL6 in the rat DO model promoted CD31^hiEMCN^hi type H-positive capillary formation associated with enhanced bone formation. Type H vessels were the referred subtype involved during DO stimulated by EGFL6.

Conclusion

EGFL6 enhanced the osteogenic differentiation potential of BMSCs and accelerated bone regeneration by stimulating angiogenesis. Thus, increasing EGFL6 secretion appeared to underpin the therapeutic benefit by promoting angiogenesis-coupled bone formation. These results imply that boosting local concentrations of EGFL6 may represent a new strategy for the treatment of compromised fracture healing and bone defect restoration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02487-3.

Monobloc Distraction and Facial Bipartition Distraction with External Devices

Monobloc and bipartition advancement by external distraction plays a major role in the treatment of syndromic craniosynostosis. They can reverse the associated facial deformity and play a role in the management of ocular exposure, intracranial hypertension, and upper airway obstruction. Facial bipartition distraction corrects the intrinsic facial deformities of Apert syndrome. Both procedures are associated with relatively high complication rates principally related to ascending infection and persistent cerebrospinal fluid leaks. Modern perioperative management has resulted in a significant decline in complications. External distractors allow fine tuning of distraction vectors and improve outcome but are less well tolerated than internal distractors.

Evaluation of Effects of Systemic Zoledronic Acid Application on Bone Maturation in the Consolidation Period in Distraction Osteogenesis

ABSTRACT

Distraction osteogenesis (DO) is a physiological process that generates new bone tissue formation, using progressively separated bone fragments. Recently, several techniques have been investigated to develop the maturation of the new bone tissue. Bisphosphonates was an effective material for the acceleration of bone formation in DO procedures. The purpose of this study was to evaluate the effects of the systemic zoledronic acid application at the beginning of the consolidation period on new bone genesis in a DO model of rat femurs. The rats were divided randomly into 3 groups, as follows: Control group (CNT group) (n = 10), zoledronic acid dosage-1 (n = 10), and dosage-2 (n = 10) groups (ZA-D-1 and ZA-D-2). No treatment was administered in controls, but DO was applied to the rat femurs. A single dose of 0.1 mg/kg and 0.2 mg/kg of zoledronic acid was administered systematically at the beginning of the consolidation period after the distraction in treatment groups, respectively. Histomorphometric analyses were performed on the original distracted bone area and the surrounding bone tissue. Osteoblasts, new bone formation, and fibrosis were scored. New bone formation in the ZA-D-1 and ZA-D-2 groups, when compared with the control group, was detected highly (P < 0.05). The numbers of osteoblasts in the ZA-D-1 and ZA-D-2 groups were higher when compared with the controls (P < 0.05). Fibrosis in the controls, when compared with the ZA-D-1 and ZA-D-2 groups, was found to be higher (P < 0.05). Zoledronic acid application is an effective method for bone maturation in consolidation period in DO.