Discussion
Mainly, cells for use in cell and gene therapy are modified by viral vectors, but these might carry safety risks for patients. They potentially can promote severe immune response or activate oncogenes due to the integration into the host genome. A safe but challenging alternative to viral vectors are synthetic nanoparticle-based systems for gene delivery. Therefore, a biocompatible, biodegradable and ligand-functionalized nanoparticular delivery system was developed, optimized and evaluated. These human serum albumin-based nanoparticles (HSA-NP) were loaded with DNA-vectors encoding either a suicide gene for their use in cell and cancer therapy or transcription factors for the reprogramming of primary somatic cells to pluripotent stem cells (iPS). To promote cellular uptake of the HSA-NP, they were ligand-functionalized with the peptides RGD or TAT. The transfection efficiency as well as cellular uptake, intracellular distribution and gene expression of the differently modified HSA-NP were evaluated in vitro. Flow cytometry analysis and confocal laser scanning microscopy (CLSM) studies revealed efficient binding and uptake of the RGD- and TAT-modified HSA-nanoparticles by human mesenchymal stem cells (hMSC) and BJ-fibroblasts. RGD-modified HSA-NP led to considerable gene expression of the reporter gene eGFP. In comparison, TAT-modification remarkably increased eGFP expression in HEK293T cells and hard-to-transfect BJ-fibroblasts qualifying Tat-modified HSA-NP for further promising studies with functional genes.
Both applications, stem cell based cancer therapy as well as iPS generation, have an enormous clinical impact. The use of non-viral nanoparticle-based gene delivery systems will allow safer clinical application and opens up broad future possibilities and markets.
