The chorioallantoic membrane (CAM) is a highly vascularized avian extraembryonic membrane widely used as an in vivo model to study angiogenesis and its inhibition in response to tissues, cells, or soluble factors. In recent years, the use of CAM has become an integral part of the biocompatibility testing process for developing biomaterials intended for regenerative strategies and tissue engineering applications. In this study, we used the chicken ex ovo CAM assay to investigate the angiogenic potential of innovative acellular biopolymer polyhydroxybutyrate/chitosan (PHB/CHIT) scaffold, which is intended for the treatment of hard tissue defects, depending on treatment with pro- and anti-angiogenic substances. On embryonic day (ED) 7, the experimental biomaterials were placed on the CAM alone or soaked in vascular endothelial growth factor (VEGF-A), saline solution (PHY), or tyrosine kinase inhibitor (SU5402). After 72 h, the formation of vessels was analyzed in the surrounding area of the scaffold and inside the pores of the implants, using markers of embryonic endothelium (WGA, SNA), myofibroblasts (α-SMA), and macrophages (KUL-01). The morphological and histochemical analysis showed strong angiogenic potential of untreated scaffolds without additional effect of the angiogenic factor, VEGF-A. The lowest angiogenic potential was observed in scaffolds soaked with SU5402. Gene expression of pro-angiogenic growth factors, i.e., VEGF-A, ANG-2, and VE-CAD, was upregulated in untreated scaffolds after 72 h, indicating a pro-angiogenic environment. We concluded that the PHB/CHIT has a strong endogenous angiogenic potential and could be promising biomaterial for the treatment of hard tissue defects.
Keywords: CAM assay; angiogenesis; biomaterial; bone tissue engineering; chitosan; polyhydroxybutyrate; regeneration.