Abstract
BackgroundRestoration of massive bone defects remains a huge challenge for orthopedic surgeons. Insufficient vascularization and slow bone regeneration limited the application of tissue engineering in bone defect. The effect of electromagnetic field (EMF) on bone defect has been reported for many years. However, sinusoidal EMF (SEMF) combined with tissue engineering in bone regeneration remains poorly investigated.MethodsIn the present study, we investigated the effect of SEMF and vascular endothelial growth factor (VEGF) on osteogenic and vasculogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs). Furthermore, pretreated rBMSC- laden polycaprolactone-hydroxyapatite (PCL/HA) scaffold was constructed and implanted into the subcritical cranial defect of rats. The bone formation and vascularization were evaluated 4 and 12 weeks after implantation.ResultsIt was shown that SEMF and VEGF could enhance the protein and mRNA expression levels of osteoblast- and endothelial cell-related markers, respectively. The combinatory effect of SEMF and VEGF slightly promoted the angiogenic differentiation of rBMSCs. The proteins of Wnt1, low-density lipoprotein receptor-related protein 6 (LRP-6), and β-catenin increased in all inducted groups, especially in SEMF + VEGF group. The results indicated that Wnt/β-catenin pathway might participate in the osteogenic and angiogenic differentiation of rBMSCs. Histological evaluation and reconstructed 3D graphs revealed that tissue-engineered constructs significantly promoted the new bone formation and angiogenesis compared to other groups.ConclusionThe combinatory effect of SEMF and VEGF raised an efficient approach to enhance the osteogenesis and vascularization of tissue-engineered constructs, which provided a useful guide for regeneration of bone defects.
Highlights
Restoration of massive bone defects remains a huge challenge for orthopedic surgeons
Cell morphology After 1 week induction with or without sinusoidal EMF (SEMF) or vascular endothelial growth factor (VEGF), third generation rat bone marrow-derived mesenchymal stem cells (rBMSCs) showed some morphological changes between different groups. rBMSCs showed a typical shape of spindle in control and SEMF-inducted groups, while cells in VEGF-inducted group revealed a short spindle or pebble morphology and in SEMF/VEGF-inducted group observed a cobble-like morphology (Fig. 2a)
The results showed that the PCL/HA/rBMSCs/SEMF/VEGF group had significantly higher ultimate force and ultimate stress compared to other implantation groups (p < 0.05; Fig. 9a, b)
Summary
Restoration of massive bone defects remains a huge challenge for orthopedic surgeons. Insufficient vascularization and slow bone regeneration limited the application of tissue engineering in bone defect. Restoration of massive bone defects resulted from significant trauma, tumor excision, inflammation, osteoporosis, or pathological fractures remains an unfulfilled challenge for orthopedic surgeons [1]. Autogenous bone grafting remains the gold standard for bony defect repair. This approach is limited by numerous drawbacks, such as finite supply, donor site morbidity, pain, and risk of infection [5]. Deficiencies, including host rejection, risk of disease transmission, high cost, lacking osteogenicity, and vascularization, limited the application of xeno/allografts in clinic [4]. Bone tissue engineering has shown great potentials in bone regeneration and attracted great interests in the past decades [6]
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