The control of alginate degradation to dynamically manipulate scaffold composition for in situ transfection application.

In this study, nanofibrous scaffolds were used for in situ transfection application. Polyethylenimine (PEI)/DNA complexes adsorbed to alginate nanofibers, so the more alginate fibers resulted in the higher transfection efficiency. However, alginate was not favorable for cell adhesion. Therefore, poly (ε­caprolactone) (PCL) nanofibers were electrospun with alginate to improve biocompatibility. The in situ transfection results demonstrated that although the incorporated PCL fibers effectively improved cell morphology, the bioactivity and proliferation rates of surface cells were not significantly increased due to the high ratio of alginate fibers. However, the reduction of the alginate ratio may decrease transfection efficiency because the immobilization of nonviral vectors linearly depended on the density of alginate fibers. To maintain transfection efficiency and increase biocompatibility, the stability of alginate fibers were manipulated by adjusting the concentrations of calcium ions during crosslinking. These partially crosslinked alginate fibers were initially intact to allow nanoparticle adsorption for cell uptake, and then gradually degraded in days to create an appropriate environment for cell survival. This dynamic system successfully fulfilled the requirements of both gene delivery and biocompatibility. To our knowledge, this study may be the first one which dynamically regulates scaffold composition for substrate-mediated gene delivery.

The development of an alginate/polycaprolactone composite scaffold for in situ transfection application.

Alginate and polycaprolactone (PCL) were coelectrospun using a dual-jet system to prepare composite nanofibers in defined ratios, and hence both chemical properties and hydrophobicity of scaffolds can be manipulated. These nanofibers were applied in gene immobilization: positively charged polyethyleneimine (PEI)/DNA polyplexes were adsorbed onto anionic alginate fibers, and the higher ratios of alginate resulted in the more immobilized nonviral vectors. Through the incorporation of PCL, biocompatibility of scaffolds was highly improved. Finally, these scaffolds were used for in situ transfection application. Compared to pure alginate fibers, composite fibers not only successfully transferred target genes to adhered cells but also enhanced cell morphology and viability, suggesting that alginate/PCL nanofibers were multifunctional with gene delivery capability and biocompatibility, and the manipulation of their composition can balance and optimize both requirements. To our knowledge, this approach might be the first one using electrostatic interactions to immobilize genes onto nanofibrous scaffolds for in situ transfection application.