Delivery of Heme Oxygenase-1 gene using Dexamethasone conjugated low molecular weight Polyethylenimine for stroke gene therapy

Abstract

Polyethylenimine (PEI) is well known for non-viral vector for the gene delivery. It has high transfection efficiency due to proton sponge effect. However, a commonly used PEI with a molecular weight of 25 kDa is highly toxic to cells, which limits its clinical applications. In this study, thus, non-toxic low molecular weight PEI (2 kDa) was conjugated with Dexamethasone as a gene carrier. Dexamethasone is an anti-inflammatory glucocorticoid. When dexamethasone binds to a glucocorticoid receptor after cellular entry, the receptor/dexamethasone complex is subsequently translocated into the nucleus. Therefore, if a gene carrier is conjugated with dexamethasone, the transport of DNA into the nucleus may be facilitated. Dexamethsone conjugated low molecular weight PEI 2kDa (PEI2K-Dexa) may have dual functions as an anti-inflammatory reagent and nuclear-targeting gene carrier. Heme oxygenase-1 (HO-1) is considered a protective gene in various diseases including stroke. The pSV-HO-1/polymer complexes were injected v directly cortex. Middle cerebral artery occlusion (MCAO) was performed at 1 hour after injection. Brain infarct size 24 hours after MCAO were evaluated by 2% 2, 3, 5-triphenyltetrazolium hydrochloride (TTC) staining. The cytokine levels of TNF-α and IL-1β were measured by ELISA. Also, ELISA for HO-1 was performed in infarcted area. The brain infarct size in the pEmpty/PEI2K-Dexa group was reduced significantly, compared with the pEmpty/PEI2K groups. The pSV-HO-1/PEI2K-Dexa group further reduced infarct size, compared with the pEmpty/PEI2K-Dexa group. The results suggest that PEI2K-Dexa has synergistic protective effect with HO-1 gene. Therefore, pSV-HO-1/PEI2K-Dexa complex is a potential candidate for therapeutic gene delivery to stroke.