The additive effects of photobiomodulation and bioactive glasses on enhancing early angiogenesis

Abstract

Early angiogenesis is important to facilitate biomaterials’ osteogenic effects and avoid the bone regeneration failure for large-sized bone defects. Bioactive glasses (BG) have been widely utilized as a biomaterial for bone repair. However, the early angiogenesis of BG may be inadequate. In this study, we explored the effects of photobiomodulation (PBM) combined with BG on early angiogenesis to solve this bottleneck problem of insufficient early angiogenesis. In vitro, human umbilical vein endothelial cells (HUVECs) were cultured with BG extracts and treated with PBM using 1 J/cm2. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) and tubule formation assay were utilized to detect HUVECs’ proliferation, vascular growth factor genes expression and tubules formation. In vivo, bone defects at the femoral metaphysis in Sprague-Dawley rats were treated with BG particulates and PBM at 120 J/cm2. Immunohistochemical staining was applied to observe the vascular-like structure formation. In vitro results showed that PBM combined with BG significantly promoted HUVECs’ proliferation, genes expression and mature tubules formation. On days 2, 4 and 7, the VEGF gene expression in BG+PBM group was 2.70-, 2.59- and 3.05-fold higher than control (P<0.05), and higher than PBM and BG groups (P<0.05). On days 4 and 7, the bFGF gene expression in BG+PBM group was 2.42- and 1.82-fold higher than control (P<0.05), and also higher than PBM and BG groups (P<0.05). Tube formation assay showed that mature tubules formed in BG+PBM and PBM groups after 4 hours. The tubules number in BG+PBM group was significantly higher than other groups (P<0.05). In vivo results further confirmed that PBM induced early angiogenesis. More vascular-like structures were observed in BG+PBM and PBM groups 2-week post surgery. In conclusion, with the optimum PBM fluence and BG concentration, PBM combined with BG exerted additive effects on enhancing early angiogenesis.

The additive effects of bioactive glasses and photobiomodulation on enhancing bone regeneration

“…On the other hand, the osteoinductivity of BG also overcomes the application limitations of the PBM. Our previous study [ 22 ] found that the combination of BG and PBM could additively promote early angiogenesis. Therefore, we preliminarily explored their additive effects on promoting bone regeneration in the current study.…”

“…Secondly, the enhanced early angiogenesis may promote bone regeneration and accelerate bone defect healing. In our recently published paper, we used BG and PBM in combination to observe their effects on angiogenesis [ 22 ]. We found that the superiority of PBM on angiogenesis could overcome the inadequacy of BG in early angiogenesis, and the combination of both would generate additive effects on enhancing human umbilical vein endothelial cells’ proliferation, angiogenic-related growth factors’ gene expression and tubules formation in vitro , as well as promoting early angiogenesis in vivo [ 22 ].…”

“…In our recently published paper, we used BG and PBM in combination to observe their effects on angiogenesis [ 22 ]. We found that the superiority of PBM on angiogenesis could overcome the inadequacy of BG in early angiogenesis, and the combination of both would generate additive effects on enhancing human umbilical vein endothelial cells’ proliferation, angiogenic-related growth factors’ gene expression and tubules formation in vitro , as well as promoting early angiogenesis in vivo [ 22 ]. Therefore, the sufficient newly blood provided by PBM and BG on the early stage will supply rich nutrients to cells and tissues, which will further enhance the cell activities and promote the bone repair.…”

“…Compared to adding proangiogenic microelements into BG particles, the combined application of PBM avoids biosafety issues caused by the microelements’ concentration and release rate [ 46 ]. Moreover, the results of our previous study showed that PBM could reduce the inflammatory reaction caused by materials implantation [ 22 ], which can avoid excessive harmful inflammation damaging cells, and facilitate an environment conducive to tissue regeneration [ 47 ]. Therefore, it’s feasible to combine BG and PBM in bone tissue engineering.…”

“…Based on the respective characteristics of BG and PBM, we hypothesized that with the combined application of BG and PBM, there would be additive effects on the enhancement of bone regeneration. Our previous study indicated that the combination of BG and PBM could additively promote the early angiogenesis [ 22 ]. In this research, we explored the effects of BG in combination with PBM on human bone marrow mesenchymal stem cells’ (hBMMSCs) proliferation, osteogenic-related genes expression and mineralization in vitro , as well as their additive effects on bone defects repair in vivo , aiming at investigating the osteogenic effect of their combined application.…”