Fatemeh Nouri - Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran
Hossein Sadeghpour - Department of Medicinal Chemistry, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
Reza Heidari - Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
Ali Dehshahri - Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. Center for Nanotechnology in Drug Delivery, Shiraz School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.

Background and Objective:In the present investigation, we sought to enhance low molecular weight PEI (LMW PEI) transfection efficiency while maintaining low toxicity by cross-linking of LMW PEI via a succinic acid linker. These modifications were designed to improve the hydrophilic-hydrophobic balance of the polymer as well as enhance the buffering capacity and maintain the low cytotoxic effects of the final conjugate. Since the reduced expression of CD200 in CNS has been considered as one of the proposed mechanism associated with multiple sclerosis, the plasmid encoding CD200 gene was selected to be transferred using the modified PEI derivatives.Materials and Methods:To characterize the polyplexes, DNA condensation ability, particle size, zeta potential, buffering capacity, cytotoxicity and resistance to DNase I digestion carried out. Also, flow cytometry analysis and real-time PCR to confirm the protein expression and finally biodistribution of nanoparticles in multiple sclerosis (MS) mice model during 24 h were performed.Results:Dynamic light scattering experiments demonstrated that the modified PEIs were able to form polyplexes in the size range of around 100 nm. The highest level of CD200 expression was achieved by the PEI derivatives at the C/P ratio of 8 where the expression level was increased 1.5 fold in SH-SY5Y cell line, an in vitro model of neurodegenerative disorders. Also, the results of in vivo imaging of the nanoparticles in a mouse model of multiple sclerosis revealed that fluorescently labeled CD200 plasmid distributed in various organs including liver, brain, and kidneys. The nanoparticles also showed the ability to pass the blood-brain barrier and enter the periventricular area.Conclusion:These results indicate that hydrophobic modification of low-toxicity PEI is an effective strategy to increase levels of CD200 and could have a therapeutic potential to regulate inflammation in human neurodegenerative diseases.

Polyethylenimine, Nanoparticle, Transfection, CD200, Gene Delivery