gms | German Medical Science

Introduction: In order to enhance vascularisation, the combination of gene therapy and scaffolds for tissue regeneration offers the opportunity to temporarily induce angiogenesis in vivo. In this study we developed a new approach to activate biomaterials by combining their use with non viral gene vectors encoding for therapeutic proteins.

Materials and methods: Copolymer-protected polyethylenimine (PEI)-DNA vectors were incorporated in a commercially available collagen scaffold for dermal regeneration (Integra Matrix). Vectors encoding for Metridia luciferase and NIH 3T3 mouse fibroblasts were used to determine the optimal DNA concentration in the scaffolds. Next scaffolds were activated with vectors encoding for VEGF¹⁶⁵ and cells were seeded. After, cell distribution and their attachment to the scaffolds were evaluated by fluorescence microscopy, cell viability and proliferation by metabolic MTT assays, and the release of VEGF¹⁶⁵ was evaluated by ELISA.

Results: DNA was incorporated at concentrations of 6.25, 12.5, 25 and 50 µg per scaffold (28 mg). No toxicity effects were observed in seeded cells and release of Metridia luciferase was detected in vitro for at least 10 weeks. A peak of expression was observed at day 5 to 9 and maximum release was obtained with the use of 12.5 µg of DNA per 28 mg of scaffold. After, vector encoding for VEGF¹⁶⁵ was incorporated in Integra matrix in a concentration of 2.3 µg DNA/mg scaffold. Results show that after seeding, NIH 3T3 fibroblasts were homogeneously distributed forming focal adhesions with the scaffold. Moreover, the presence of DNA-Polyplexes did not affect cell viability and proliferation. Finally, transient release of VEGF was observed for up to 3 weeks with a peak of expression of 7 ng/ml at day 5.

Conclusion: Combined use of collagen scaffolds and copolymer-protected polyethylenimine (PEI)-DNA vectors, allows inducing local release of therapeutic proteins without cell toxicity in vitro. Such technologies may have tremendous impact in the field of tissue engineering and regenerative medicine. Preclinical studies with the use of genetically activated scaffolds are already under evaluation.