Background 60–75% of HIV-infected children develop static or progressive encephalopathy. Drug delivery to the central nervous system is one of the most challenging fields of research and development.

Objective To investigate the role of a carbosilane dendrimer (2G-NN16) to bind and transport siRNA to the interior of the astrocytoma and to study the capacity of siRNA against HIV-1.

Methods We tested 2G-NN16 for cytotoxicity in U-87-MG astrocytoma by MTT, LDH and microarrays. The ability to transfect U-87-MG with 2G-NN16 was tested by flow cytometry and confocal microscopy. HIV inhibition assays using 2G-NN16 and dendriplexes formed with siRNA were determined by quantification viral load in supernatants.

Results 2G-NN16 does not produce a toxicity effect on U-87-MG by MTT and LDH screening, being of 2G-NN16 concentration for biological assays between 1 and 5 μmol. Our result reveals that 2G-NN16 does not produce changes in gene expression using the whole genome human microarrays. U-87-MG were seen to be successfully transfected by fluorochrome-labelled siRNA complexed with 2G-NN16 using flow cytometry and confocal microscopy. Dendriplexes with ratio 1 : 8 were determined to have the highest transfection efficiency. Finally, siRNA p24-2G-NN16/dendriplexes were shown to reduce HIV replication in U-87-MG >85% and siRNA Nef-2G-NN16 approximately 50%. 2G-NN16 by itself or siRNA random were not able to inhibit HIV replication.

Conclusion Our results indicate the possibility of utilising dendrimers such as 2G-NN16 to deliver and transfect siRNA into astrocytoma cells allowing the use of siRNA as a strong candidate for new treatment of HIV-1-associated dementia.