(693e) Use of Fibrin Hydrogels for Localized and Cell-Controlled Lentiviral Gene Transfer

Recombinant lentiviruses are efficient gene delivery vehicles with the ability to infect non-dividing cells including neurons, hematopoietic and embryonic stem cells. In addition to high efficiency several applications may require localized and cell-controlled gene transfer to a subset of cells in a local microenvironment. To this end, we developed a strategy of lentivirus delivery using fibrin hydrogels. Our preliminary studies indicate that fibrin-mediated gene transfer is more efficient than traditional lentivirus transduction and that transduction efficiency depends on the properties of fibrin gels and the interaction of target cells with the matrix. Specifically, lentiviral transduction is optimum at intermediate concentrations of fibrinogen but independent of thrombin. Interestingly, fibrinolytic inhibitors decreased lentivirus transduction in a dose dependent manner, suggesting that matrix degradation is necessary for virus uptake. Surprisingly, at low fibrinogen concentrations lentiviral particles can diffuse out of the fibrin gels decreasing the transduction efficiency. To avoid this problem and obtain highly localized gene delivery we developed a novel method to covalently conjugate lentiviral particles into fibrin and achieve gene delivery in a cell-controlled manner. Using this strategy we engineered microarrays with immobilized lentivirus to express multiple genes in a single transduction step. This high throughput gene delivery strategy will have significant impact on many biological studies including profiling of adult and embryonic stem cells.