Electrospun nanoyarn and exosomes of adipose-derived stem cells for urethral regeneration: Evaluations in vitro and in vivo.

Regeneration of urethral defects has been difficult in the clinic. To address it, the collagen/ poly (L-lactide-co-caprolactone) (P(LLA-CL)) nanoyarn scaffold delivering adipose-derived stem cells' exosomes (ADSC-exos) was fabricated. The multipotential differentiation potential of ADSCs were confirmed by Adipogenic, osteogenic, and chondrogenic differentiation. The 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide assay shows that 50% concentration of ADSC-exos nanoyarn scaffold dramatically enhanced the cell viability of fibroblasts. The ADSC-exos nanoyarn scaffold for human foreskin fibroblasts (HFFs) and human urethral scar fibroblasts (HSFs) shows good biocompatibility: theproduction of inflammatory factors IL-6 and Col 1A1 was less, indicating that ADSC-exos had the minimal inflammatory effect of cells. Besides, the cells on the ADSC-exos nanoyarn scaffold did not appear to contribute to DNA damage in the same way as the normal cell's growth did. The HFFs seeding on the ADSC-exos nanoyarn scaffold shows a typical morphology of extending outwards. Urethral repair with ADSC-exos nanoyarn scaffold did not lead to either a sign of urethral stricture or scar formation after 4 weeks post-surgery. The deposition of collagen was less and the epithelial cells formed multiple layer epithelium. The treatment of ADSC-exos stimulated epithelization and vascularization. And the transition from an inflammatory state to a regenerative state was promoted. The ADSC-exos-treated group did not promote the over-proliferation of fibroblasts and the expression of Collagen I. Therefore, the ADSC-exos nanoyarn scaffold has evident, positive effects on wound healing and tissue fibrosis inhibition.