Controlled basic fibroblast growth factor release device made of poly(ethyleneglycol) dimethacrylates for creating a subcutaneous neovascular bed for cell transplantation

Subcutaneous space is a potential site for the transplantation of cells such as islets for treatment of type 1 diabetes. To enhance engraftment, an optimal space for the growth of the transplanted cells is needed along with neovascularization. In this study, we developed a device using a photocurable resin, poly(ethyleneglycol) dimethacrylates (PEGDM), for controlled release of basic fibroblast growth factor (bFGF) to create a subcutaneous neovascular bed in rats. The device consists of a disk-shaped capsule with micropores and is composed of tri(ethyleneglycol) dimethacrylate (TEGDM) and a drug formulation of PEGDM. The release rate was tuned by changing the number of pores and the composition of water and PEGDM in the drug formulation. bFGF released from devices incubated in phosphate-buffered saline (PBS) enhanced the growth of fibroblasts, indicating bioactivity of bFGF after release. Histological evaluation showed a significant increase in the extent of vasculature that was dependent on the amount of bFGF loaded into the device. A perfusion study using fluorescein isothiocyanate dextran 2000 kDa showed linear and capillary staining patterns, indicating potent functional vasculature. In conclusion, the controlled bFGF releasing device could provide a neovascular bed with the required vascularization in the subcutaneous space.