title: Efficient gene delivery targeted to the brain using a transferrin-conjugated polyethyleneglycol-modified polyamidoamine dendrimer.
abstract: The blood-brain barrier (BBB) poses great difficulties for gene delivery to the brain. To circumvent the BBB, we investigated a novel brain-targeting gene vector based on the nanoscopic high-branching dendrimer, polyamidoamine (PAMAM), in vitro and in vivo. Transferrin (Tf) was selected as a brain-targeting ligand conjugated to PAMAM via bifunctional polyethyleneglycol (PEG), yielding PAMAM-PEG-Tf. UV and nuclear magnetic resonance (NMR) spectroscopy were used to evaluate the synthesis of vectors. The characteristics and biodistribution of gene vectors were evaluated by fluorescent microscopy, flow cytometry, and a radiolabeling method. The transfection efficiency of vector/DNA complexes in brain capillary endothelial cells (BCECs) was evaluated by fluorescent microscopy and determination of luciferase activity. The potency of vector/DNA complexes was evaluated by using frozen sections and measuring tissue luciferase activity in Balb/c mice after i.v. administration. UV and NMR results demonstrated the successful synthesis of PAMAM-PEG-Tf. This vector showed a concentration-dependent manner in cellular uptake study and a 2.25-fold brain uptake compared with PAMAM and PAMAM-PEG in vivo. Transfection efficiency of PAMAM-PEG-Tf/DNA complex was much higher than PAMAM/DNA and PAMAM-PEG/DNA complexes in BCECs. Results of tissue expression experiments indicated the widespread expression of an exogenous gene in mouse brain after i.v. administration. With a PAMAM/DNA weight ratio of 10:1, the brain gene expression of the PAMAM-PEG-Tf/DNA complex was approximately 2-fold higher than that of the PAMAM/DNA and PAMAM-PEG/DNA complexes. These results suggested that PAMAM-PEG-Tf can be exploited as a potential nonviral gene vector targeting to brain via noninvasive administration.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Fudan University, P.O. Box 130, 200032, Shanghai, China.
authors.forename: Rong-Qin
authors.initials: RQ
authors.lastname: Huang
authors.forename: Ying-Hua
authors.initials: YH
authors.lastname: Qu
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Ke
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhu
authors.forename: Yuan-Ying
authors.initials: YY
authors.lastname: Pei
authors.forename: Chen
authors.initials: C
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002412:Cations; D002460:Cell Line; D050091:Dendrimers; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000295:instrumentation* / Q000379:methods; D005822:Genetic Vectors; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011073:Polyamines / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000378:metabolism*; D014168:Transferrin / Q000494:pharmacology*
chemical_list: D001672:Biocompatible Materials; D002412:Cations; D050091:Dendrimers; C104700:PAMAM Starburst; D011073:Polyamines; D014168:Transferrin; D011092:Polyethylene Glycols