The enhanced angiogenesis effect of VEGF-silk fibroin nanospheres-BAMG scaffold composited with adipose derived stem cells in a rabbit model

We report a study to determine whether a vascular endothelial growth factor (VEGF)-silk fibroin (SF) nanospheres-bladder acellular matrix graft (BAMG) scaffold composited with adipose derived stem cells (ADSCs) could enhance angiogenesis in bladder regeneration in rabbits. Rabbit ADSCs were isolated and identified by flow cytometry. The morphology and release behaviour of VEGF-SF nanospheres were detected. After the composite scaffolds were successfully used in bladder reconstruction, the bladder capacity, H&E staining and immunohistochemical staining were studied at different time points. ADSCs exerts high expression rates of CD29, CD90, and CD44, accompanied with low expression rates of CD34 and CD45. SF nanospheres with diameters of 200–1000 nm were prepared to load VEGF, and they contributed to maintain the release of VEGF. The reconstructed bladder with VEGF-SF nanospheres-BAMG plus ADSCs had more regular smooth muscle tissue and blood vessels. Moreover, instead of differentiating into epithelial or vascular endothelial cells, ADSCs may be more likely to provide additional cytokines to enhance angiogenesis in the bladder regeneration process. The tissue engineered bladder constructed by BAMG modified by VEGF-SF nanospheres possessed high bio-compatibility and an enhanced angiogenesis effect, and could be used as an ideal biological material to repair bladder defects after being composited with ADSCs.