Cell-Triggered DNA Release From a Fibrin Gel

The efficiency of bolus gene delivery is currently limited by mass transport issues and deactivation processes. The inclusion of vectors within 3D scaffold enables localized delivery; however, because they are diffusion-controlled, many of these systems still have burst effect release profiles. Immobilization of gene delivery vectors on biomaterial surfaces may avoid these problems. To this end, we are exploring the use of fibrin matrix as a scaffold upon which DNA can be immobilized. In our system, plasmid DNA is bound to fibrin via an enzymatically-labile peptide sequence, allowing for cell-responsive gene delivery. We functionalize plasmid DNA using a peptide nucleic acid (PNA) clamp. Coupling peptides that include a fibrin-binding sequence and a matrix metalloproteinase-1 (MMP-1) degradable sequence are attached to this conjugate forming DNA-PNA-peptide (DPP) conjugates. In this work, we demonstrate the formation of the DPP conjugates and binding to a fibrin surface. Through the completion of cell transfection studies, we present a system that promotes cell-responsive gene delivery via cellular production of both matrix metalloproteinase and plasminogen. The effects of surface coverage and fibrinogen concentration are being explored.