Amniotic epithelial stem cells phenotype and orientation can be influenced using electrospun poly(lactide-co-glycolide) scaffolds with high grade of fibers alignment mimicking tendon extracellular matrix

OBJECTIVE: Electrospun poly(lactide-co-glycolide) (PLGA) is a biocompatible copolymer, and can be engineered with amniotic derived stem cells (AECs) (Russo et al, Mater Sci Eng C Mater Biol Appl 2016 69:321). AECs are known for their easy retrieval, non-ethical concerns, non-tumorigenic and immunomodulatory properties, thus ideal in allo and xenotransplantation settings. They are able to differentiate toward the tenogenic linage when co-cultivated in vitro with tendon explants or when transplanted in vivo in a tendon injury model. Indeed, when transplanted, AECs contribute to tissue remodeling also directly by producing Collagen Type 1 (COL1), which is the major protein expressed in a tendon. In this study, PLGA electrospun scaffolds were fabricated with a high degree of aligned fibers, in order to mimic tendon extracellular matrix (ECM), and with random fibers (control). Then, these scaffolds were cultured with ovine AECs verifying their biocompatibility and if fiber alignment, mimicking a tendon structure, could influence cell phenotype and orientation. MATERIALS AND METHODS: To this aim, oAECs were seeded on scaffolds and cultivated for 48h. Then, scaffold ultrastructure (SEM), Calcein AM, PKH26 vital dyes and Ki67, a cell proliferation marker, and COL1 mRNA and protein expression were analyzed. RESULTS: Immunostaining showed that nearly all cells were alive and able to proliferate (20% cells of highly aligned fibers vs. 15% random fibers, p<0.05). Additionally, oAECs spatial distribution and orientation was influenced by scaffold fibers’ alignment. In fact, when oAECs were cultivated on highly aligned electrospun PLGA fibers they changed their morphology acquiring a spindle tenocyte-like shape, and were able to align along the longitudinal axis of the fibers, whereas in random electrospun PLGA scaffolds oAECs maintained their cuboidal morphology. Moreover, several oAECs were able to express in their cytoplasm COL1 only on aligned fibers scaffolds and not on the random oriented fibers ones. These findings indicate that when oAECs are seeded on electrospun PLGA scaffolds with highly aligned fibers, their phenotype and orientation are influenced by this artificial tendon ECM structure acquiring an early tenogenic-like phenotype. CONCLUSION: Electrospun PLGA scaffolds engineered with oAECs could be used for future clinical application in the treatment of tendon disorders.