Tuning Surface Charge and PEGylation of Biocompatible Polymers for Efficient Delivery of Nucleic Acid or Adenoviral Vector

Abstract

As an effective and safe strategy to overcome the limits of therapeutic nucleic acid or adenovirus (Ad) vectors for in vivo application, various technologies to modify the surface of vectors with nonimmunogenic/biocompatible polymers have been emerging in the field of gene therapy. However, the transfection efficacy of the polymer to transfer genetic materials is still relatively weak. To develop more advanced and effective polymers to deliver not only Ad vectors, but also nucleic acids, 6 biocompatible polymers were newly designed and synthesized to different sizes (2k, 3.4k, or 5k) of poly(ethylene) glycol (PEG) and different numbers of amine groups (2 or 5) based on methoxy poly(ethylene glycol)-b-poly{N-[N-(2-aminoethyl)-2-aminoethyl]-l-glutamate (PNLG). We characterized size distribution and surface charge of 6 PNLGs after complexation with either nucleic acid or Ad. Among all 6 PNLGs, the 5 amine group PNLG showed the strongest efficacy in delivering nucleic acid as well as Ad vectors. Interestingly, cellular uptake results showed higher uptake ability in Ad complexed with 2 amine group PNLG than Ad/5 amine group PNLG, suggesting that the size of Ad/PNLGs is more essential than the surface charge for cellular uptake in polymers with charges greater than 30 mV. Moreover, the endosome escape ability of Ad/PNLGs increased depending on the number of amine groups, but decreased by PEG size. Cancer cell killing efficacy and immune response studies of oncolytic Ad/PNLGs showed 5 amine group PNLG to be a more effective and safe carrier for delivering Ad. Overall, these studies provide new insights into the functional mechanism of polymer-based approaches to either nucleic acid or Ad/nanocomplex. Furthermore, the identified ideal biocompatible PNLG polymer formulation (5 amine/2k PEG for nucleic acid, 5 amine/5k PEG for Ad) demonstrated high transduction efficiency as well as therapeutic value (efficacy and safety) and thus has strong potential for in vivo therapeutic use in the future.

Systemic administration of human mesenchymal stromal cells infected with polymer-coated oncolytic adenovirus induces efficient pancreatic tumor homing and infiltration

“…S8; P < 0.05 or 0.001). These results suggest that increasing PCDP concentration and net cationic charge of Ad-PCDP complex at higher molar ratio either more tightly binds with Ad or condenses the nanocomplex, which is in agreement with our previous publication where higher cationic polymer concentration above threshold level promoted condensation of the nanocomplexes and decrease in average complex diameter [51].…”

“…To determine the optimal concentration of PCDP for complexation with Ad, transduction efficiency of GFP-expressing and non-replicating Ad (dAd/GFP) complexed with various molar ratios of PCDP (1 × 10 4 , 2 × 10 4 , 5 × 10 4 , 1 × 10 5 , or 2 × 10 5 ) was assessed in hMSCs. Branched 25K PEI was used as a control and complexed with dAd/GFP at a molar ratio of 1 × 10 5 , as this ratio was determined to be optimal for complexation in a previous report [50,51]. As shown in Fig.…”

Achieving systemic delivery of oncolytic viruses

“…Noncovalent methods using cationic polymers (e.g. polyacrylates [92], branched polyamine copolymers [93], and polypeptides [94][95][96][97]) to coat viruses were first reported in 1997 but achieved limited success due to their serum instability [98]. The modulation of complex surface charge using PEG or oligoethylene glycol blocks enabled the polymer-coated viruses to overcome their instability in serum.…”

Oncolytic Adenovirus: Strategies and Insights for Vector Design and Immuno-Oncolytic Applications

“…They subsequently produced a cationic polymer (mPEG-PEI-g-Arg-S-S-Arg-g-PEI-mPEG (PPSA) containing both bio-reducible disulphide bonds and functional arginine moieties that reduced cytotoxicity and enhanced cancer cell transduction both in vitro and in vivo . More recently, coating of two OAds with 5-amine polymers conjugated with 3.4K PEG (OAd/M3.4kPN5LG) or 5K PEG (OAd/M5kPN5LG) showed the strongest killing effects in cancer cells in comparison to OAds coated with biopolymer alone or naked Ad [ 172 ].…”