Table 1.

The major types of NAs used in gene delivery applications and their specific features.

Nucleic Acid	Description	Site of Action	Applications/Pathway
pDNAs (also called chimeras) [1,9]	large circular dsDNAs (<10 kbp)	nucleus	nuclear localization followed by transgene expression under specific promoters to induce protein expression
mRNAs [1,9]	large ssRNAs (<10 kbp)	cytosol	positive regulation of protein expression
short regulatory RNAs (siRNAs/miRNAs/shRNA) [1,9]	short regulatory RNA (15–30 nt)	cytosol	RNA interference mechanisms to shorten mRNA half-life and downregulate translation
ASOs [10]	short DNA, RNA or analogs (15–30 nt)	cytosol and nucleus	RNA alteration to reduce, restore, or modify protein expression

dsDNA = double stranded DNA; bp = base pair; ssRNA = single stranded RNA; nt = nucleotide.