Electrospun poly(lactide-co-glycolide) scaffold with high grade of fibers alignment mimics tendon extracellular matrix influencing amniotic epithelial stem cells phenotype and orientation

Poly(lactide-co-glycolide) (PLGA) is a copolymer known for its biodegradability and biocompatibility, and when electrospun, it becomes a fibrous device that can be engineered with stem cells. In this study, electrospun PLGA were engineered with amniotic derived stem cells (AECs). These type of stem cells are already known for their easy retrieval, non-ethical concerns, non-tumorigenic and immunomodulatory properties, thus ideal in allo and xenotransplantation settings. Moreover, they are able to differentiate toward the tenocyte linage when co-cultivated in vitro with tendon explants or when transplanted in vivo in a tendon injury model. In fact, when transplanted, oAECs are able to direct tissue remodeling either indirectly, thanks to their ability to release paracrine factors, and directly by producing Collagen Type 1 (COL1), which is the major protein expressed in a tendon. Thus, 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 in order to verify their biocompatibility and if the high degree of fiber alignment could influence cell phenotype and orientation mimicking a tendon tissue structure. To this aim, oAECs were seeded on scaffolds and cultivated for 48h. The results obtained in this study demonstrate that oAECs are biocompatible with the analyzed scaffolds. In fact, Calcein AM and PKH26 vital dyes and Ki67, a cell proliferation marker, immunostaining show that nearly all cells were alive and able to proliferate on electrospun PLGA. Additionally, these fluorescent dyes proved that oAECs spatial distribution and orientation was influenced by scaffold fibers’ alignment. In fact, when oAECs were cultivated on these 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 of these oAECs, were able to express in their cytoplasm COL1 after 48h of culture 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, thus acquiring an early tenogenic-like phenotype. In conclusion, electrospun PLGA scaffolds engineered with oAECs appears to be a good synergy that can be used for future clinical application in the treatment of tendon disorders.