Poly(d-lactide)/poly(caprolactone) nanofiber-thermogelling chitosan gel composite scaffolds for osteochondral tissue regeneration in a rat model

Macroporous nanostructured scaffolds that can be made to closely mimic skeletal tissue extracellular matrix as well as have the potential to support bone and cartilage tissue regeneration. Porous poly(d-lactide)/poly(caprolactone) nanofiber scaffolds were prepared by electrospinning respective polymer solutions along with salt crystals, which were sintered into fiber mats into cylindrical shape of 1.5 mm diameter and cut into 2–3 mm length followed by salt leaching in distilled water. The poly(d-lactide)/poly(caprolactone)–chitosan composite scaffolds were prepared by impregnating the porous structure of the electrospun scaffold with a thermosensitive chitosan solution. For in vivo evaluation, the scaffolds with and without chitosan gel were press fitted into osteochondral defects in a rat model. Hematoxylin and eosin staining 6 weeks post implantation showed new bone formation within the porous scaffolds with and without chitosan gel. Significant bone formation was observed within both the scaffolds at 15 weeks post implantation compared to the control group. The results show that macroporous poly(d-lactide)/poly(caprolactone) nanofiber scaffolds can be prepared with and without chitosan hydrogel and can serve as an osteochondral scaffold. The porous scaffolds showed the ability to promote new bone formation at the defect site, and incorporation of chitosan within the pores did not adversely affect the tissue in-growth. However, the scaffolds did not support significant cartilage formation even after 15 weeks, which indicates the need for the addition of cells or bioactive molecules within the scaffold to support effective osteochondral tissue regeneration.