Hydrogel-mediated DNA delivery confers estrogenic response in nonresponsive osteoblast cells

Oligo(polyethylene glycol) fumarate (OPF) hydrogel has been employed in musculoskeletal tissue engineering for photoencapsulation of chondrocytes and as a matrix for marrow stromal cells differentiation. In this study, we have studied the application of OPF hydrogel for coencapsulation of DNA and bone cells and examined whether coencapsulation can enhance gene transfer by maintaining the DNA within the cellular microenvironment. Our results showed that plasmid DNA encoding green fluorescence protein (GFP), coencapsulated with bone tumor cells, was capable of transfecting the cells, and the transfected tumor cells continuously expressed GFP protein over the time course of study (21 days). Furthermore, we have examined the coencapsulation of estrogen receptor (ER) encoding plasmid DNA and human fetal osteoblast cells (hFOB) that lack endogenous ER. Our results show that the transfected cells responded to estrogen as alkaline phosphatase (ALP), and estrogen response element (ERE)-directed luciferase enzyme activities increased with estrogen treatment. Taken together, these studies show that OPF hydrogel could be further explored for targeted gene delivery in bone and other tissues encapsulated within the hydrogels.