Mesoporous bioactive glass nanoparticles exhibit intrinsic angiogenic potential in the chorioallantoic membrane assay, without the addition of exogenous cells

Angiogenesis is an essential part of bone regeneration, as neovascularisation supports the supply of necessary oxygen, nutrients, and cellular transport. Bioactive glasses (BGs) have shown promise in enhancing both angiogenesis and bone regeneration. For the evaluation of the angiogenic potential of BGs, the chorioallantoic membrane (CAM) assay constitutes an attractive experimental model and has already gained increasing attention in BG-focused research. However, there is conflicting evidence as to whether the addition of cells, such as bone-marrow-derived mesenchymal stromal cells (BMSCs) to the CAM is necessary to facilitate the evaluation of the angiogenic potency of BGs. Therefore, in this study, the angiogenic potential of mesoporous bioactive glass nanoparticles (MBGNs; molar composition = 70% silica (SiO₂) and 30% calcium oxide (CaO)) was assessed by using the <i>in ovo</i> CAM assay, both in the presence and the absence of exogenous BMSCs. Compared to the BMSC-free and MBGN-free control groups, both BMSCs alone and MBGNs without the addition of BMSCs were able to induce an equally strong, significantly enhanced angiogenic response on the CAM. The combination of MBGNs with BMSCs did not yield a more pronounced angiogenic response, as compared to MBGNs without the addition of cells. Thus, MBGNs exhibit a strong intrinsic angiogenic potential that is not dependent on the presence of exogenous BMSCs. Therefore, the CAM assay without added cells can be used as a simplified, reproducible and cost-effective method for accurate preclinical testing of the angiogenic potential of BGs.