Promoting reconstruction of blood flow of urinary tissue engineering grafts by endothelial progenitor cells with adipose stem cells in diabetes model

Abstract

Objective Silk fibroin scaffolds (SFSs) were loaded with rabbit endothelial progenitor cells (EPCs) and adipose derived stem cells (ADSCs) in vitro to build composite grafts, which were then implanted into diabetic model rabbit, and after the degree of vascularization of grafts being evaluated, we investigated the feasibility of using this method to promote reconstruction of blood flow in diabetes condition. Methods EPCs were isolated, cultured and proliferated in vitro, which were identified by immunofluorescence methods of DiI-Ac-LDL and fluorescein isothiocyanate (FITC)-UEA-1 staining, and ADSCs were obtained and proliferated in vitro, which were identified by flow cytometry. In experimental group (n=24), after loading proliferative EPCs and ADSCs on SFSs, the compounds were cultured for 7 days before being transplanted into diabetic rabbits. SFSs only loaded with ADSCs served as the control group (n=24). At 8 and 16 weeks, animals were sacrificed and vascularization of obtained transplants was evaluated with histological methods. Results Seeded cells were successfully acquired and proliferated. EPCs and ADSCs were confirmed by immunofluorescence and flow cytometry respectively. Rabbit ADSCs expressed mesenchymal stem cell-specific antigen CD105 (96.39%), CD44 (94.73%), and CD73 (97.19%), rather than the expression of hematopoietic stem cell surface markers CD34 (0.97%) and CD45 (2.91%). Seeded cells proliferated well on SFSs after loading, and SFSs had no toxic effect on cells. At time points of 8 and 16 weeks, all animals were alive. Histologic sections of grafts in experimental group showed obvious neovascularization, and there was no obvious formation of vessels in control group (P<0.05). Conclusion SFSs loaded with EPCs and ADSCs provided a new experimental basis to promote reconstruction of blood flow of urinary tissue engineering grafts in diabetic condition. Key words: Endothelial progenitor cells; Adipose derived stem cells; Silk fibroin scaffolds; Tissue engineering; Diabetes; Reconstruction of blood flow