Effects of pore orientation on in-vitro properties of retinoic acid-loaded PLGA/gelatin scaffolds for artificial peripheral nerve application.

Different manufacturing processes of scaffolds affect their main properties by altering the microstructure of pores. In this study, poly (lactic-co-glycolic acid) (PLGA) scaffolds were synthesized by both freeze casting and freeze drying methods. Scanning electron microscopy (SEM) micrographs demonstrated a unidirectional microstructure in the freeze-cast and a number of random pores in the freeze-dried scaffolds. According to the results, the formation of a lamellar microstructure increased the mechanical strength, swelling ratio, biodegradation behavior and drug release level. Addition of gelatin to the PLGA freeze-cast constructs led to an increase in the average diameter of pores, hydrophilicity and cellular spreading. The gelatin-containing scaffolds showed a decreased mechanical strength, but at the same time, an enhanced swelling ratio, biodegradation rate and drug release level. Differentiation of P19 cells and expression of β-tubulin III, Pax-6 and Nestin were improved by incorporating retinoic acid in PLGA-Gelatin freeze-cast scaffolds. This is a good option with initial necessary features for regenerating peripheral nervous system (PNS).