Biological properties of a bionic scaffold for esophageal tissue engineering research

Polyurethane is a good matrix material with wide application prospects in tissue engineering because of its adjustable and mechanical properties. A novel biodegradable crosslinked poly(ester urethane) (CPU) with flexible poly(caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) components has been synthesized using a ferric iron catalyst in our laboratory. In the present study, to promote the interaction between the CPU material and cells, the material was superficially modified by silk fibroin (SF) grafting using an aminolysis and glutaraldehyde crosslinking method to achieve a biocompatible material, CPU-SF. Considering the esophageal-specific architecture, three types of scaffolds were fabricated. S1 was a CPU-SF channel (200 μm in diameter and 30 μm in depth with 30 μm of wall thickness) to support muscle regeneration; S2 was the decellularized matrix of the esophageal mucosa/submucosa obtained by enzyme treatment; and S3 was a combination of S1 and S2, aiming to promote esophageal regeneration with histological structure and function. The biological properties and functions of the materials and scaffolds were investigated by qualitative and quantitative analyses using scanning electron microscopy, immunofluorescence staining, cell adhesion and proliferation measurements, and western blotting technology. The results showed that esophageal smooth muscle cells (SMCs) and epithelial cells (ECs) were very well supported by the scaffolds. In particular, SMCs exhibited guided directional growth and ECs infiltrated the acellular mucosa with retained biological functions when co-cultured on the composite scaffold S3. These findings suggest that the composite bionic scaffold will be a good alternative for esophageal replacement.