Collagen gel delivery of Tgf‐β3 non‐viral plasmid DNA in rat osteoblast and calvarial culture

Abstract

Different forms of collagen as a carrier for naked plasmid DNA have shown potential as vehicles for therapeutic gene delivery and tissue engineering. The objective of this study was to determine the suitability of a dense collagen gel as a vehicle for sustained delivery of plasmid DNA in cell and organ culture. Plasmid DNA encoding Tgf-beta(3) was combined with collagen gel. DNA released into the media was measured by Pico-Green spectrophotometry. Results showed that DNA was released from the collagen gel at a gradual rate for up to 14 days. To evaluate collagen-mediated transfection in tissue, calvariae were exposed to collagen containing plasmid encoding GFP or DsRed. Transfection was visualized by fluorescence localized to tissue adjacent to the vehicle. To evaluate protein production, fetal rat calvarial osteoblasts were cultured with a collagen/Tgf-beta(3) plasmid mixture or in media containing plasmid alone. Media was collected at various time points to measure Tgf-beta(3) protein production. ELISA assays showed that collagen-transfected osteoblasts demonstrated an elevated Tgf-beta(3) protein production for up to 14 days. Therefore, collagen delivery of viable plasmid DNA created a sustained transient transfection of calvarial osteoblasts resulting in prolonged and elevated growth factor production. Together, these results suggest that use of collagen gel as a vehicle may provide a strategy to achieve localized and controlled, non-viral gene delivery in vivo.