Direct sprayed endothelialization, basement membrane and cell junction development on biological and artificial products are highly substrate-dependent and require optimized biofunctionalization

Abstract

Background: Optimizing endothelialization of medical implants requires deep mechanistic insight into cellular adhesion, cell junction and physiological basement membrane development at the endothelial cell-to-scaffold substrate interface. Methods and results: We employed and standardized endothelial cells and fibrin hydrogel for simultaneous cell-plus-fibrin (EC-Fib) spray application using the Maslanka® spray pen. Quality assessment illustrated excellent structural integrity of EC-Fib. Acellular SynerGraft® showed improved intimal endothelial recellularization after short-term physical and chemical preconditionings including dry-freezing, sodium desoxycholate, Triton-X, acetic acid and collagenase treatments. Artificial substrates poly-L-lactic acid (PLLA), and polyamide-6 (PA-6) were tested regarding their mechanical appropriateness, revealed complete endothelialization following EC-Fib application and showed partially physiological basement membrane development. Additional laminin 1 biofunctionalization on PA-6 moderately enhanced basement membrane gene and protein expression. However, scanning electron microscopy, immunohistology and PCR analyses underlined immature endothelialization, basement membrane and cell junction development on all substrates with clear substrate-dependent differences. Conclusions: Direct sprayed endothelialization outlined the necessity for preconditioning acellular SynerGraft® prostheses for adequate recellularization. Laminin 1 biofunctionalization could slightly improve endothelialization of PA-6 substrates whereas physiological organization of the microenvironment remained immature and seemed highly substrate dependent.