A PEG‐Based Biocompatible Block Catiomer with High Buffering Capacity for the Construction of Polyplex Micelles Showing Efficient Gene Transfer toward Primary Cells

Abstract

Nonviral gene vectors from synthetic catiomers (polyplexes) are a promising alternative to viral vectors. In particular, many recent efforts have been devoted to the construction of biocompatible polyplexes for in vivo nonviral gene therapy. A promising approach in this regard is the use of poly(ethylene glycol) (PEG)-based block catiomers, which form a nanoscaled core-shell polyplex with biocompatible PEG palisades. In this study, a series of PEG-based block catiomers with different amine functionalities were newly prepared by a simple and affordable synthetic procedure based on an aminolysis reaction, and their utility as gene carriers was investigated. This study revealed that the block catiomers carrying the ethylenediamine unit at the side chain are capable of efficient and less toxic transfection even toward primary cells, highlighting critical structural factors of the cationic units in the construction of polyplex-type gene vectors. Moreover, the availability of the polyplex micelle for transfection with primary osteoblasts will facilitate its use for bone regeneration in vivo mediated by nonviral gene transfection.

Incorporation of 2,3‐Diaminopropionic Acid into Linear Cationic Amphipathic Peptides Produces pH‐Sensitive Vectors

“…Such effects are observed in ethylenediamine units in PEG block catiomers. [18] The electron withdrawing effect of the two amide groups is acknowledged when using the pKa prediction tool MarvinView 5.1.4 which indicates that at 8.5, 8.3 and 8.1 the pKa of the β-NH 2 in compounds 1, 2 and 3 respectively are almost 2 units lower than that of lysine. The prediction tool however, does not take into account possible intramolecular hydrogen bonding that may stabilize an even lower pKa.…”

Biocompatible micellar nanovectors achieve efficient gene transfer to vascular lesions without cytotoxicity and thrombus formation

“…7,8 To resolve this issue, we recently designed biocompatible nonviral vectors constructed from newly synthesized cationic block copolymer. 9 The block copolymer thus synthesized is characterized by tandem alignment of a hydrophilic poly(ethylene glycol) (PEG) segment and a cationic polyaspartamide segment carrying an ethylenediamine unit at the side chain (PEG-b-P[Asp(DET)]) (Figure 1a), 10 leading to the formation of stable and biocompatible polyplex micelles with a core of tightly packed plasmid DNA (pDNA) surrounded by a dense shell layer of PEG (Figure 1b). Because of the hydrophilicity as well as the strong steric-repulsive propensity of the PEG shell, the polyplex micelles are assumed to be stable in physiological entities including harsh in vivo conditions.…”

“…12 A previous study indeed revealed that polyplex micelles made from PEG-b-P[Asp(DET)] accomplished appreciably high gene transfection efficacy with remarkably low cytotoxicity toward several cultured cell lines as well as primary osteoblasts. 10 In the present study, the utility of the polyplex micelle from PEG-b-P[Asp(DET)] for transfection to vascular lesions was investigated to evaluate its feasibility for vascular gene therapy. The polyplex micelle was revealed to have excellent colloidal stability even in proteinaceous medium and reduced interactions with blood components, showing appreciable gene transfection efficacy toward primary vascular smooth muscle cells (VSMC) under in vitro conditions.…”

Impact of polyplex micelles installed with cyclic RGD peptide as ligand on gene delivery to vascular lesions

“…21 Briefly, b-benzyl-L-aspartate N-carboxyanhydride was polymerized in N,N-dimethylformamide/CH 2 Cl 2 (1:10) at 35 1C by initiation from the primary amino group of acetal-PEG-NH 2 (Mw of PEG: 12 000 g mol À1 ). Acetal-PEG-b-poly(b-benzyl L-aspartate) was recovered by precipitation in an excess amount of n-hexane/ AcoEt (6:4) and the filtrate was dried in vacuo.…”

“…[18][19][20] In previous studies, we also designed PEG-block-polycation carrying ethylenediamine units (PEGPAsp(DET)) in the side chain and reported that polyplex micelles with PEG-PAsp(DET) accomplished appreciable gene transfer efficiency with low cytotoxicity. 20,21 After internalization of PEG-PAsp(DET) micelles into the intracellular compartment by endocytosis, the ethylenediamine units are expected to promote translocation of the polyplex micelles toward the cytoplasm due to endosomal membrane destabilization, resulting in improvement of gene transfer efficiency. 22,23 Furthermore, to increase cellular uptake of polyplex micelles, we recently attempted to introduce appropriate ligands into their surface.…”