Preliminary Formulation-Dependent Angiogenesis-Related and Early Osteogenic Responses to Three-Dimensional Bioprinted Hydroxyapatite-Acrylated Palm Olein Scaffolds: An In Vitro Study.

Periodontal and alveolar bone regeneration requires coordinated angiogenic and osteogenic responses supported by biomimetic scaffolds. This study compared three-dimensional bioprinted hydroxyapatite-acrylated palm olein (3D-HA-APO) scaffold formulations containing 5%, 7% and 10% (w/v) hydroxyapatite (HA), designated F1, F2 and F3, respectively. Human umbilical vein endothelial cells were cultured on the scaffolds, and background-corrected soluble vascular endothelial growth factor (VEGF) concentrations in culture supernatants were quantified by enzyme-linked immunosorbent assay (ELISA). Angiogenic-related responses of human periodontal ligament stem cells were assessed by VEGF and cluster of differentiation 31 (CD31) immunofluorescence after endothelial induction, while alkaline phosphatase (ALP) activity in construct lysates was used as an indicator of early osteogenic activity. Soluble VEGF concentrations increased from F1 to F3, with significant differences between all formulations. VEGF-associated signal proportions differed among formulations, with F3 significantly higher than F1. CD31-associated signal proportions increased progressively from F1 to F3, with significant differences between all formulation pairs. ALP activity increased over time in all scaffold groups, and F3 generally showed the highest activity from Day 4 onwards. Overall, F3 showed the most favourable formulation-level profile across the selected angiogenic-related and early osteogenic outcomes.