Date Published: April 5, 2017
Publisher: Public Library of Science
Author(s): Tatjana Perisic, Ziyang Zhang, Peter Foehr, Ursula Hopfner, Kathrin Klutz, Rainer H. Burgkart, Alexei Slobodianski, Moritz Goeldner, Hans-Günther Machens, Arndt F. Schilling, Hélder A. Santos.
Recent advances in gene delivery into cells allow improved therapeutic effects in gene therapy trials. To increase the bioavailability of applied cells, it is of great interest that transfected cells remain at the application site and systemic spread is minimized. In this study, we tested clinically used biodegradable poly(lactic acid-co-glycolic acid) (PLGA) scaffolds (Vicryl & Ethisorb) as transient carriers for genetically modified cells. To this aim, we used human fibroblasts and examined attachment and proliferation of untransfected cells on the scaffolds in vitro, as well as the mechanical properties of the scaffolds at four time points (1, 3, 6 and 9 days) of cultivation. Furthermore, the adherence of cells transfected with green fluorescent protein (GFP) and vascular endothelial growth factor (VEGF165) and also VEGF165 protein secretion were investigated. Our results show that human fibroblasts adhere on both types of PLGA scaffolds. However, proliferation and transgene expression capacity were higher on Ethisorb scaffolds most probably due to a different architecture of the scaffold. Additionally, cultivation of the cells on the scaffolds did not alter their biomechanical properties. The results of this investigation could be potentially exploited in therapeutic regiments with areal delivery of transiently transfected cells and may open the way for a variety of applications of cell-based gene therapy, tissue engineering and regenerative medicine.
New generation non-viral gene delivery systems, such as nanoparticles, novel cationic lipids and polymers, chemically coupling the nucleic acid to peptides and polymers [1–9] have shown to overcome some of the limitations of viral gene transfer and offer advantages in use of recombinant proteins [10, 11]. On the other side, the localized delivery of genetically modified cells themselves poses another major barrier for efficient and area-specific therapeutic protein expression in gene therapy applications. Challenges regarding the reduction of off-target effects remain to be addressed . Thus, biodegradable synthetic polymer scaffolds may offer a safe and effective option for targeted cell delivery.
Due to significant advances in recombinant DNA technology, cell-based gene therapy is increasingly recognized as an ideal tool to deliver therapeutic proteins to target sites. A typical way of administering genetically modified cells is the direct injection of cells in target areas. However, this mode of administration is accompanied by the spread away from the injection site. The spreading of transfected cells can reduce vector levels at the target site and also lead to low-grade systemic spread in off-target regions . There are different strategies in addressing those concerns. For example, in adoptive T cell therapy, new generation of chimeric antigen receptors called TRUCKs (T cells redirected for universal cytokine killing) are used as vehicles to produce and release a transgenic product that accumulates in the targeted tissue  and this strategy can potentially yield effective and localized therapeutic effects. Another approach in targeted cancer gene therapy of solid tissues is based on local delivery of NK4 (hepatocyte growth factor antagonist) secreted from an NK4 gene-transduced oral mucosal epithelial cell . A similar technique by using cellular vehicle for delivery of bone morphogenetic protein-2 has been used to promote bone regeneration . Thus, genetically transfected cells can be used for delivery of therapeutic cells to the intended area in the body.
Bioresorbable PLGA scaffolds can be used as vehicle for the delivery of transiently transfected cells and may open the way for a variety of applications of gene therapy, tissue engineering and regenerative medicine. Scaffolds with a condensed structure and smaller pore size might lead to a better cell-scaffold interaction and thus lead to a higher yield of the desired recombinant therapeutic proteins.