Eco‐Sustainable Approaches in Bone Tissue Engineering: Evaluating the Angiogenic Potential of Different Poly(3‐Hydroxybutyrate‐Co‐3‐Hydroxyhexanoate)–Nanocellulose Composites with the Chorioallantoic Membrane Assay

Abstract

Additive manufacturing (AM) has opened new frontiers in precision medicine, giving the possibility of fabricating patient‐customized scaffolds to replace damaged tissues. In particular, bone tissue engineering (BTE) has benefited the most from the introduction of AM. In contrast, the impelling environmental issues are moving all the industrial sectors toward a sustainable development, avoiding the use of nonrenewable resources. Since thermoplastic polymers, such as poly(lactic acid) (PLA) and polycaprolactone (PCL), are massively used in the biomedical field, the primary objective of this study is to encourage the use of biodegradable and compostable materials also in BTE. Focusing on poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH), an eco‐friendly material with good biocompatibility and biodegradability, reinforced with cellulose nanocrystals (CNCs), 3D‐printed scaffolds through fused filament fabrication (FFF) are realized. Since vascularization is mandatory for bone regeneration processes and for a successful scaffold integration, the angiogenic potential of different PHBH–CNC formulations in vitro is tested, evaluating the colonization of the scaffolds by endothelial cells, and in ovo with the chorioallantoic membrane (CAM) assay. The final goal is to define the best geometry of the scaffold and PHBH–CNC composition that can trigger vascularization in BTE applications, with the ultimate aim of giving greater guarantees of osseointegration.

CAM Model: Intriguing Natural Bioreactor for Sustainable Research and Reliable/Versatile Testing

“…The vascularized environment of the CAM of avian species offers the possibility to study a variety of molecules and materials; in particular, a CAM assay can be used to test pro/anti-angiogenic potential, to perform cancer studies, to test molecules and materials [ 66 , 67 ], to verify transplant reactions, and to test some drug effects.…”

“…Specifically, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) reinforced witch cellulose nanocrystals (CNCs) has been tested in CAM in the form of a porous scaffold. The CAM assay enabled the identification of the scaffold pore size, which is more optimal for endothelial cell colonization and blood vessel formation [ 67 ]. Bioactive glasses, in the TE field, have also received a significant amount of interest.…”