Cell recruitment and transfection in gene activated collagen matrix

Realization of systems able to both recruit cells and influence their fate (affecting their processes) represents a new approach for tissue regeneration. We investigated the potency of gene activated matrix (GAM) and implemented the GAM strategy in order to achieve a control of gene expression, as well as a specific cell recruitment. To this aim we developed a 3D DNA bio-activated collagen matrix by Poly (ethylenimine) (PEI)/DNA complex immobilization in the matrix through biotin/avidin bond. Moreover, we realised a serum based chemotactic gradient within the matrix in order to directionally attract NIH3T3 cells. In this system, cells are recruited and forced to migrate through the matrix where they find the bound PEI/DNA complexes and are transfected. The transfected cells can act as local in vivo bioreactors, secreting plasmid encoded proteins that augment tissue repair and regeneration. 3D cell migration and cell transfection were monitored through time-lapse video microscopy and fluorescence microscopy. Cell transfection was also quantified through FACS analysis. Results show that our engineered matrix is able to recruit external cells and transfect them once internalized, therefore it could help in tissue repairing strategy.