Biodegradable PAMAM ester for enhanced transfection efficiency with low cytotoxicity.
We synthesized biodegradable polycationic PAMAM (polyamidoamine) esters (e-PAM-R, e-PAM-K) that contain arginines or lysines at the peripheral ends of PAMAM-OH dendrimer through ester bond linkages. The PAMAM esters were readily degradable under physiological conditions (pH 7.4, 37 degrees C), with more than 50% of the grafted amino acids hydrolyzed within 5h. However, polyplexes were very stable and were hardly degraded in the endosomal pH range. Moreover, these amino-acid-modified polymers showed excellent buffering capacities between pH 5.1 and 7.4, facilitating endosomal escape of polyplexes. While the lysine-grafted PAMAM ester did not display significant improvement in transfection efficiency, the arginine-conjugated PAMAM ester-mediated transfection of a luciferase gene showed better transfection efficiency than the branched 25 kDa PEI (polyethylenimine) and PAM-R (peptide bond), and lower cytotoxicity, especially with primary cells such as HUVECs (human umbilical vein endothelial cells) and SMCs (primary rat aorta vascular smooth muscle cells). Furthermore, after DNA release, free e-PAM-R degraded completely into nontoxic PAMAM-OH and arginines by hydrolysis, which resulted in lower cytotoxicity in contrast to the poorly degradable arginine-modified PAMAM with amide bonds. These findings demonstrated that the arginine-grafted biodegradable PAMAM dendrimer, e-PAM-R, is a potential candidate as a safe and efficient gene delivery carrier for gene therapy.
Nam
Hye Yeong
HY
School of Chemistry and Molecular Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-747, Republic of Korea.
Nam
Kihoon
K
Hahn
Hwa Jeong
HJ
Kim
Bo Hye
BH
Lim
Hyun Jung
HJ
Kim
Hyun Jin
HJ
Choi
Joon Sig
JS
Park
Jong-Sang
JS
D000818:Animals; D001120:Arginine; D002021:Buffers; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D050091:Dendrimers; D004587:Electrophoresis, Agar Gel; D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008239:Lysine; D018613:Microscopy, Confocal; D010957:Plasmids / Q000378:metabolism; D011073:Polyamines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011108:Polymers; D051381:Rats; D017186:Titrimetry; D014162:Transfection
D002021:Buffers; D050091:Dendrimers; D004952:Esters; C104700:PAMAM Starburst; D011073:Polyamines; D011108:Polymers; D001120:Arginine; D008239:Lysine