Recent Advances in Preclinical Research Using PAMAM Dendrimers for Cancer Gene Therapy

Carriers of genetic material are divided into vectors of viral and non-viral origin. Viral carriers are already successfully used in experimental gene therapies, but despite advantages such as their high transfection efficiency and the wide knowledge of their practical potential, the remaining disadvantages, namely, their low capacity and complex manufacturing process, based on biological systems, are major limitations prior to their broad implementation in the clinical setting. The application of non-viral carriers in gene therapy is one of the available approaches. Poly(amidoamine) (PAMAM) dendrimers are repetitively branched, three-dimensional molecules, made of amide and amine subunits, possessing unique physiochemical properties. Surface and internal modifications improve their physicochemical properties, enabling the increase in cellular specificity and transfection efficiency and a reduction in cytotoxicity toward healthy cells. During the last 10 years of research on PAMAM dendrimers, three modification strategies have commonly been used: (1) surface modification with functional groups; (2) hybrid vector formation; (3) creation of supramolecular self-assemblies. This review describes and summarizes recent studies exploring the development of PAMAM dendrimers in anticancer gene therapies, evaluating the advantages and disadvantages of the modification approaches and the nanomedicine regulatory issues preventing their translation into the clinical setting, and highlighting important areas for further development and possible steps that seem promising in terms of development of PAMAM as a carrier of genetic material.

Comparative Study of Functionalized Carbosilane Dendrimers for siRNA Delivery: Synthesis, Cytotoxicity, and Biophysical Properties

Efficient and safe carriers of genetic material are crucial for advancing gene therapy. Three new series of cationic dendritic nanocarriers based on a carbosilane scaffold, differentiated by peripheral modifications: saccharide (CS-glyco), amine (CS-N), and phosphonium dendrimers (CS-P) were designed for binding, protecting, and releasing polyanionic compounds like therapeutic siRNA. Besides introducing synthetic methodology, this study brings a unique direct interstructural comparison of 16 dendritic nanovector's characteristics, addressing a gap in typical research that focuses on uniform structural types. The study evaluates the dendrimer's in vitro cytotoxicity, biophysical properties, and complexation capabilities in comparison with widely used PAMAM dendrimers. CS-glyco and PAMAMs were significantly less toxic to MCF-7 and THP-1 cell lines than were CS-N and CS-P, despite having the same peripheral charge density. Notably, CS-glyco maintained biocompatibility comparable to analogous neutral CS glycodendrimers, underscoring the exceptional capability of sugar coating to reduce toxicity. Dendriplexes formed from these nanocarriers protected siRNA from RNase degradation and facilitated its release in the presence of heparin, highlighting its potential in gene delivery applications. The study provides a background for future in-depth investigations into the introduced dendritic nanocarriers, which show significant potential for advancing drug delivery.