Gene delivery through cell culture substrate adsorbed DNA complexes.
ABSTRACT Efficient gene delivery is a fundamental goal of biotechnology and has numerous applications in both basic and applied science. Substrate-mediated delivery and reverse transfection enhance gene transfer by increasing the concentration of DNA in the cellular microenvironment through immobilizing a plasmid to a cell culture substrate prior to cell seeding. In this report, we examine gene delivery of plasmids that were complexed with cationic polymers (polyplexes) or lipids (lipoplexes) and subsequently immobilized to cell culture or biomaterial substrates by adsorption. Polyplexes and lipoplexes were adsorbed to either tissue culture polystyrene or serum-adsorbed tissue culture polystyrene. The quantity of DNA immobilized increased with time of exposure, and the deposition rate and final amount deposited depended upon the properties of the substrate and complex. For polyplexes, serum modification enhanced reporter gene expression up to 1500-fold relative to unmodified substrates and yielded equivalent or greater expression compared to bolus delivery. For lipoplexes, serum modification significantly increased the number of transfected cells relative to unmodified substrates yet provided similar levels of expression. Immobilized complexes transfect primary cells with improved cellular viability relative to bolus delivery. Finally, this substrate-mediated delivery approach was extended to a widely used biomaterial, poly(lactide-co-glycolide). Immobilization of DNA complexes to tissue culture polystyrene substrates can be a useful tool for enhancing gene delivery for in vitro studies. Additionally, adapting this system to biomaterials may facilitate application to fields such as tissue engineering.
Article: Nanofiber-mediated controlled release of siRNA complexes for long term gene-silencing applications.[show abstract] [hide abstract]
ABSTRACT: Nanofiber scaffold-mediated delivery of small-interfering RNA (siRNA) holds great potential in regenerative medicine by providing biomimicking topographical signals and enhanced gene silencing effects to seeded cells. While the delivery of naked siRNA was demonstrated previously using poly (ε-caprolactone) (PCL) nanofibers, the resulting siRNA release kinetics and gene knockdown efficiencies were sub-optimal. In this study, we investigated the feasibility of encapsulating siRNA and transfection reagent (TKO) complexes within nanofibers comprising of a copolymer of caprolactone and ethyl ethylene phosphate (PCLEEP, diameter ∼ 400 nm). Sustained release of bioactive naked siRNA and siRNA/TKO complexes were obtained for at least 28 days. By copolymerizing EEP with caprolactone, siRNA release was significantly enhanced (total siRNA that was released by day 49 was ∼ 89.3-97.2% as compared to previously reported 3% by plain PCL nanofiber delivery). Using GAPDH as the model protein, bioactivity analyses by supernatant transfection revealed the partial retention of bioactivity of naked siRNA and siRNA/TKO complexes for at least 30 days. In particular, GAPDH siRNA/TKO supernatant alone induced significant gene silencing (∼40%), indicating the feasibility of co-encapsulating siRNA and transfection reagent within a single scaffold construct for sustained delivery. Direct culture of cells on siRNA incorporated scaffolds for scaffold-mediated gene transfection revealed significant gene knockdown even in the absence of transfection reagent (21.3% knockdown efficiency by scaffolds incorporating naked siRNA only). By encapsulating siRNA/TKO complexes, more significant gene knockdown was obtained (30.9% knockdown efficiency as compared to previously reported 18% by plain PCL scaffold-mediated transfection). Taken together, the results demonstrated the feasibility of co-encapsulating siRNA-transfection reagent complexes within a single nanofiber construct for sustained siRNA delivery and enhanced gene knockdown efficiency. The study also highlights the potential of PCLEEP as a platform for tailoring siRNA release kinetics for long-term gene silencing applications.Biomaterials 09/2011; 32(25):5915-23. · 7.40 Impact Factor
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ABSTRACT: Integrating viral gene delivery with engineered biomaterials is a promising strategy to overcome a number of challenges associated with virus-mediated gene delivery, including inefficient delivery to specific cell types, limited tropism, spread of vectors to distant sites, and immune responses. Viral vectors can be combined with biomaterials either through encapsulation within the material or immobilization onto a material surface. Subsequent biomaterial-based delivery can increase the vector's residence time within the target site, thereby potentially providing localized delivery, enhancing transduction, and extending the duration of gene expression. Alternatively, physical or chemical modification of viral vectors with biomaterials can be employed to modulate the tropism of viruses or reduce inflammatory and immune responses, both of which may benefit transduction. This review describes strategies to promote viral gene delivery technologies using biomaterials, potentially providing opportunities for numerous applications of gene therapy to inherited or acquired disorders, infectious disease, and regenerative medicine.Molecular Therapy 05/2011; 19(8):1407-15. · 6.87 Impact Factor