That ANG stimulates endothelial cell proliferation and angiogenesis [7…

That ANG stimulates endothelial cell proliferation and angiogenesis [7, 28]. In the present study, the MTS and cytotoxicity assays showed that FB/ANG enhanced cell proliferation and was not cytotoxic. Furthermore, cell adhesion was analyzed in SEM images (Fig. 4c), which showed that a higher amount of cells grew and adhered on FB/ANG scaffolds than on FB scaffolds. These results indicate that cell adhesion was also enhanced by additionKim et al. Biomaterials Research (2015) 19:Page 8 ofof ANG to the scaffold because ANG supports the adhesion of endothelial cells [29]. Our in vitro results suggest that FB/ANG scaffolds could enable bone formation through enhanced angiogenesis. Therefore, in this study, we examined whether ANG-containing FB scaffolds could improve new bone formation using an in vivo rabbit calvarial defect model, which has been widely used to evaluate the performance of scaffolds in bone regeneration. In bone tissue engineering, several growth factors (e.g., VEGF, FGF2, and PDGF) have been used to provide increased vascularization because new vessels support bone regeneration [3]. Comez et al. [23] reported enhanced bone healing in rat calvarial bone defects using FGF2 and a poly-L/D-lactide scaffold. Kaigler et al. reported enhanced bone regeneration using VEGF and poly (L/D-lactide and glycolide) scaffolds in irradiated rat osseous defects [30]. These previous studies indicate that angiogenic growth factors not only increase angiogenesis but also improve bone regeneration. Given the pivotal role of ANG in angiogenesis, several studies have reported that neovascularization induced by ANG may enhance the healing of tissues such as the liver [31] and meniscus [32]. 4-Bromo-5-nitro-1H-indazole In addition, a previous study attempted the application of ANG with a collagen-chitosan scaffold for skin tissue engineering [33]. These previous reports suggest that ANG also can be used as a potential angiogenic growth factor in bone tissue engineering. In our in vivo study, the number of new blood vessels was significantly increased at 2 weeks in the group implanted with ANG-containing scaffolds. Furthermore, the regenerated bone volume was also significantly (S)-3-(tert-Butoxycarbonyl)-2,2-dimethyloxazolidine-4-carboxylic acid PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/13485127 increased by ANG treatment. Although the exact mechanism was not evaluated in this study, these results suggest that induced vascularization by scaffold-released ANG PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/9282946 improved new bone regeneration.Competing interests The authors declare that they have no competing interests. Authors' contributions BSK conducted the experiment and drafted the manuscript. KJS performed the in vivo experiment and analyzed. SSY helped to conduct the experiment. HWK and HJL participated in the design of the study. JL conceived in the design of experiments and help to draft the manuscript. All authors read and approved the final manuscript. Acknowledgement This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning (NRF-2015R1A2A2A01004888). Author details 1 Wonkwang Bone Regeneration Research Institute, Wonkwang University, Iksan 570-749, Korea. 2Bonecell Biotech Inc., Dunsan-dong, Seo-gu, Daejeon 302-830, Korea. ijms17122034 3Department of Herbal Crop Research, NIHHS, RDA, Eumseong 369-873, Korea. 4Department of Dentistry, Oral and Maxillofacial, Wonkwang University, Iksan 570-749, Korea. Received: 22 July 2015 Accepted: 4 AugustConclusions In summary, we prepared an ANG-containing FB scaffold. The scaffold not only provid.