Hydrogel bioink formulation for 3D bioprinting: Sustained delivery of PDGF-BB and VEGF in biomimetic scaffolds for tendon partial rupture repair

In the evolving field of tissue engineering, the power of three-dimensional (3D) bioprinting technology can be harnessed by innovative methodologies to address the complex challenges of treating partial tendon injuries. In order to engineer a solution for this type of musculoskeletal injuries, a biomimetic bioink and a scaffold developed using 3D bioprinting technology and capable of delivering cells and growth factors were investigated. For the development of the bioink, a hydrogel type structure was selected based on a strategic combination of alginate, hyaluronic acid, gelatin, and fibrinogen. This tailored combination exhibited favorable rheological behavior and impeccable printability. The bioink, demonstrating promising characteristics, was then employed to fabricate both acellular scaffolds and tissue constructs. The structures possessed mechanical properties suitable and adequate for addressing partial tendon injuries and achieved a microenvironment that allowed good metabolic activity of tenocytes, maintenance of their phenotype, and overexpression of genes related to macromolecules of tendon extracellular matrix. Regarding growth factors delivery, vascular endothelial growth factor (VEGF165) and platelet-derived growth factor (PDGF-BB) were successfully incorporated into the bioink. Their release profile was thoroughly studied, and their activity once released was demonstrated. Together, these results suggest that the developed bioink and the resulting 3D structures can have an important impact on tendon partial injury therapies. The multifaceted capabilities of the bioink and the developed tissue constructs position them as crucial contributors to the advancement of tendon injury therapies, marking a significant stride toward enhanced patient outcomes and regenerative medicine practices.