The Study of 3D Printing-Assisted Electrospinning Technology in Producing Tissue Regeneration Polymer-Fibroin Scaffold for Ureter Repair.

Abstract

Long segment ureteral lesion with obstruction is a clinically difficult issue for recovering and maintaining organ or tissue function. Regeneration medicine using various biomaterials as a scaffold in supporting tissue regrowth is emerging. We developed this customized scaffold using electrospinning and 3-dimensional assistance and expected that it may provide an alternative biomaterial for ureter defect repair. Our study synthesized polycaprolactone and silk fibroin combination as biomaterial scaffolds. The differences in physicochemical properties and biocompatibility of polycaprolactone-silk fibroin bio-scaffolds prepared by electrospinning alone and 3-dimensional printing combined with electrospinning in proper ratios were compared and characterized. SV-HUC-1 uroepithelial cells cultured in polycaprolactone-silk fibroin (4 : 6) scaffolds were observed under a scanning electron microscope and using calcein-acetomethoxy and propidium iodide stain. The ex vivo resected healthy human ureteral segment tissue was anastomosed with the polycaprolactone-silk fibroin scaffolds and cultured in an ex vivo bath for 2 weeks. The cellular growth on the polycaprolactone-silk fibroin scaffold was observed microscopically. In the New Zealand white rabbit model, we performed a 1/5 ratio (2 cm out of 10 cm) defect replacement of the unilateral ureter. After 7 weeks, the rabbits were sacrificed and the implanted ureter scaffolds were resected for tissue sectioning and the cellular growth was observed by hematoxylin and eosin and Masson staining. When the proportion of silk fibroin was increased and the 3-dimensional electrospinning method was used, both the size and diameter of nanofiber holes were increased in the polycaprolactone-silk fibroin scaffold. Scanning electron microscope and fluorescent stain revealed that cultured 3T3 and SV-HUC-1 uroepithelial cells could electively penetrate inside the polycaprolactone-silk fibroin (4 : 6) nanofibrous scaffolds in 3 days. The polycaprolactone-silk fibroin scaffold anastomosis in an ex vivo bath showed cellular growth stably along the scaffold for 2 weeks, and most of the cells grow along with the outboard of the scaffold in layers. In an animal model, different layered cells can be observed to grow along with the outboard of the scaffold with mucosa, submucosa, muscular layer, and the serosa layer order after 7 weeks. Mucosa and muscular layer growth along the scaffold inner wall were seen simultaneously. 3-dimensional electrospinning synthesized 4 : 6 polycaprolactone-silk fibroin nanofiber scaffolds that are feasible for tissue growth and achieve the purpose of ureteral reconstruction in animal experiments. This new form of 3-dimensional electrospinning constructed polycaprolactone-silk fibroin nanofiber scaffold may be considered as a clinical urinary tract tissue reconstruction alternative in the future.