Tat-conjugated PAMAM dendrimers as delivery agents for antisense and siRNA oligonucleotides.
OBJECTIVE
PAMAM G5 dendrimer (P) was conjugated to Tat peptide (T), a cell penetrating peptide, in search of an efficient cellular delivery vehicle for antisense and siRNA oligonucleotides.


METHODS
PAMAM G5 dendrimer was reacted with 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionic acid, sulfosuccinimidyl ester, sodium salt (BODIPY) for visualization to yield the conjugate BP. Bifunctional sulfosuccinimidyl 6-[alpha-methyl-alpha-(2-pyridyldithio)toluamido]hexanoate (sulfo-LC-SMPT) was then used to conjugate primary amino groups of BP to cysteine derivatized Tat peptide to give the designed conjugate, BPT. This conjugate was complexed with antisense and siRNA oligonucleotides designed to inhibit MDR1 gene expression. NIH 3T3 MDR cells were used for the evaluation of biological activity of the conjugate.


RESULTS
Both antisense and siRNA readily formed complexes with the synthesized BPT, introduced into NIH 3T3 MDR cells, and primarily accumulated in intracellular vesicles. MDR1 gene expression was partially inhibited by the antisense-BPT complex and weakly inhibited by the siRNA-BPT complex when both were tested at nontoxic levels of dendrimer. Conjugation with Tat peptide did not improve the delivery efficiency of the dendrimer.


CONCLUSIONS
Dendrimer-oligonucleotide complexes were moderately effective for delivery of antisense and only poorly effective for delivery of siRNA. Conjugation of the dendrimer with the Tat cell penetrating peptide failed to further enhance the effectiveness of the dendrimer.
Kang
Hyunmin
H
Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
DeLong
Robert
R
Fisher
Michael H
MH
Juliano
Rudolph L
RL
D016475:3T3 Cells; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D001896:Boron Compounds; D002470:Cell Survival / Q000187:drug effects; D002850:Chromatography, Gel; D050091:Dendrimers; D016503:Drug Delivery Systems; D005456:Fluorescent Dyes; D015696:Gene Products, tat / Q000737:chemistry*; D019450:Genes, MDR / Q000235:genetics; D051379:Mice; D018613:Microscopy, Confocal; D009841:Oligonucleotides / Q000008:administration & dosage*; D011073:Polyamines / Q000737:chemistry*; D016372:RNA, Antisense / Q000008:administration & dosage*; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D012260:Ribonucleases / Q000378:metabolism
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001896:Boron Compounds; D050091:Dendrimers; D005456:Fluorescent Dyes; D015696:Gene Products, tat; D009841:Oligonucleotides; C104700:PAMAM Starburst; D011073:Polyamines; D016372:RNA, Antisense; D034741:RNA, Small Interfering; D012260:Ribonucleases