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.

High-purity magnesium screws modulate macrophage polarization during the tendon-bone healing process in the anterior cruciate ligament reconstruction rabbit model.

Magnesium (Mg) screws perform clinical potential in anterior cruciate ligament (ACL) reconstruction, and promote fibrocartilaginous entheses regeneration at the femoral entrance. We aim to prove that high-purity Magnesium (HP Mg) screws modulate macrophage polarization in fibrocartilage interface regeneration both in vitro and in vivo. HP Mg extracts performed good cytocompatibility and significantly promoted M2 macrophage polarization in the flow cytometry and ELISA assays. M2 macrophages stimulated fibrochondrocyte differentiation of co-cultured hBMSCs, and HP Mg extracts had synergistic effect on the process. Then we applied HP Mg screws, with Ti screws as control, in the ACL reconstruction rabbit model. In the histological and immunofluorescence analysis, HP Mg screws inhibited M1 polarization at 2 weeks and highly promoted M2 polarization at 2 and 4 weeks at the tendon-bone interface. Furthermore, regeneration of fibrocartilaginous entheses, rather than the fibrovascular scar interface, was detected in the HP Mg group at 12 weeks. For further mechanism study via RNA-seq detection and WB assays, we found that AKT1 was highly activated in M2 polarization, and HP Mg could stimulate AKT1 expression, rather than AKT2, in the early phase of tendon-bone healing. Our study elucidated macrophage polarization during tendon-bone healing process and emphasized HP Mg on M2 polarization and fibrocartilage interface regeneration via the selective activation of AKT1 and PI3K/AKT pathway.

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.

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.

Ferulic acid improves self-renewal and differentiation of human tendon-derived stem cells by upregulating early growth response 1 through hypoxia.

We aimed to investigate the potential beneficial effect of ferulic acid (FA) on stemness of human tendon-derived stem cells (hTSCs) in vitro and to elucidate the underlying molecular mechanism. The self-renewal ability of hTSCs was evaluated by colony formation and cell proliferation was determined by CCK-8 kit. Adipogenesis, osteogenesis, and chondrogenesis were determined by Oil Red O, Alizarin Red, and Alcian Blue stainings, respectively. Relative mRNA levels of PPARγ, Col2A1, Acan, Runx2, HIF1α, and EGR1 were measured with real-time PCR. Protein levels of HIF1α and EGR1 were detected by western blot. Direct binding of HIF1α with EGR1 promoter was analyzed by ChIP assay. Hypoxia-induced expression of EGR1 was interrogated by luciferase reporter assay. We demonstrated that FA treatment improved both self-renewal ability and multi-differentiation potential of hTSCs. FA induced hypoxia which in turn upregulated EGR1 expression via direct association with its hypoxia response element consensus sequence. Furthermore, we showed that both HIF1α and EGR1 were required for the enhancing effects of FA on hTSC self-renewal and differentiation. We hereby characterize the beneficial effect of FA on the stemness of hTSCs and highlight the critical role of HIF1α-EGR1 axis in this process.

Von Hippel-Lindau (VHL) Protein Antagonist VH298 Improves Wound Healing in Streptozotocin-Induced Hyperglycaemic Rats by Activating Hypoxia-Inducible Factor- (HIF-) 1 Signalling.

AIMS: The purpose of the present research is to investigate the effects of the VHL protein antagonist, VH298, on functional activities of fibroblasts and vascular endothelial cells and the effects on the wound healing process in a streptozotocin-induced hyperglycaemic rat model. METHODS: HIF-1α and hydroxy-HIF-1α protein levels in VH298-treated rat fibroblasts (rFb) were measured by immunoblotting, rFb proliferation was detected by the CCK-8 assay, and mRNA levels of related genes were measured by quantitative RT-PCR. In vitro wound healing was simulated by the scratch test; angiogenesis was measured by the human umbilical vein endothelial cell (hUVEC) tube formation assay. VH298 or PBS was locally injected into wounds in rat models with streptozotocin- (STZ-) induced hyperglycaemia, the wound tissues were harvested, and haematoxylin-eosin (HE) and Masson trichrome staining and immunohistochemical processes were conducted. RESULTS: HIF-1α and hydroxy-HIF-1α levels increased in VH298-treated rFb, in a time- and dose-dependent manner. Thirty micromolar VH298 could significantly increase cell proliferation, angiogenesis, and gene expression of type I collagen-α1 (Col1-α1), vascular endothelial growth factor A (VEGF-A), and insulin-like growth factor 1 (IGF-1). The VH298-treated wound had a better healing pattern, activation of HIF-1 signalling, and vascularization. CONCLUSIONS: Taken together, VH298 activated the HIF-1 signalling pathway by stabilizing both HIF-1α and hydroxy-HIF-1α. VH298 enhanced rFb functions, promoted hUVEC angiogenesis, and accelerated wound healing in the rat model mimicking diabetes mellitus.