Synthesis, characterization and evaluation of transfection efficiency of dexamethasone conjugated poly(propyleneimine) nanocarriers for gene delivery#

Abstract

Context: Polypropylenimine (PPI), a cationic dendrimer with defined structure and positive surface charge, is a potent non-viral vector. Dexamethasone (Dexa) conveys to the nucleus through interaction with its intracellular receptor. Objective: This study develops efficient and non-toxic gene carriers through conjugation of Dexa at various percentages (5, 10 and 20%) to the fourth and the fifth generation PPIs (PPIG4s and PPIG5s). Materials and methods: The 21-OH group of Dexa (0.536 mmol) was modified with methanesulfonyl chloride (0.644 mmol) to activate it (Dexa-mesylate), and then it was conjugated to PPIs using Traut's reagent. After dialysis (48 h) and lyophilization, the physicochemical characteristics of products (PPI-Dexa) including zeta potential, size, buffering capacity and DNA condensing capability were investigated and compared with unmodified PPIs. Moreover, the cytotoxicity and transfection activity of the Dexa-modified PPIs were assessed using Neuro2A cells. Results: Transfection of PPIG4 was close to PEI 25 kDa. Although the addition of Dexa to PPIG4s did not improve their transfection, their cytotoxicity was improved; especially in the carrier to DNA weight ratios (C/P) of one and two. The Dexa conjugation to PPIG5s enhanced their transfection at C/P ratio of one in both 5% (1.3-fold) and 10% (1.6-fold) Dexa grafting, of which the best result was observed in PPIG5-Dexa 10% at C/P ratio of one. Discussion and conclusions: The modification of PPIs with Dexa is a promising approach to improve their cytotoxicity and transfection. The higher optimization of physicochemical characteristics, the better cell transfection and toxicity will be achieved.

High-throughput screening of clinically approved drugs that prime nonviral gene delivery to human Mesenchymal stem cells

“…These anti-inflammatory genes could then rescue hMSCs from transfection-induced inflammation and cytotoxicity, leading to the observed increase in transgene production. Furthermore, this screen demonstrated that glucocorticoids can also have potent priming effects at high doses, suggesting that glucocorticoids at higher concentrations may be imparting additional nongenomic effects [36], such as modulating mitochondrial function [39], which our previous screen in HEK 293 T cells has suggested may be key for modulating nonviral gene delivery [17], or dilating nuclear pores [30], as others have shown increased transfection efficiency when glucocorticoids are conjugated to nonviral carriers [31][32][33]. However, further investigations into the specific mechanism of transfection enhancement seen in this screen with higher concentrations of glucocorticoids are needed in order to fully understand glucocorticoid priming in hMSCs.…”

“…Binding of the GR then rescues transfection-induced cellular metabolic decline [15], prevents transfection-mediated protein synthesis inhibition [16], and inhibits apoptosis [16], allowing for increased translation and expression of transgenic protein [15,16] while maintaining hMSCs differentiation potential [15]. Furthermore, the increase in translation and transgenic protein expression mediated by glucocorticoid priming was shown to be independent of nuclear pDNA internalization [16], even though glucocorticoids have been shown to alter nuclear membrane permeability [28][29][30] and increase nuclear pDNA internalization when conjugated to the cationic carrier [31][32][33], suggesting that the priming effect of dexamethasone is mediated by other mechanisms, potentially by modulating endoplasmic reticulum stress responses or upregulating genes that modulate oxidative conditions, as others have shown that dexamethasone can modulate these responses in other cell types [34,35].…”

A comparative study on solubility improvement of tetracycline and dexamethasone by poly(propylene imine) and polyamidoamine dendrimers: An insight into cytotoxicity and cell proliferation

“…Cationic PPI and PAMAM dendrimers showed relatively high cytotoxicity due to their surface amine functional groups those can affect the cell membrane (Malaekeh‐Nikouei, Rezaee, Gholami, Mousavi, & Oskuee, ). However, their cytotoxicity depended on their concentration and generation as reported previously (Malik et al, ; Parimi, Barnes, Callen, & Prestidge, ; Roberts, Bhalgat, & Zera, ).…”

Dexamethasone Conjugates: Synthetic Approaches and Medical Prospects

“…The second is that Traut’s reagent can be used to conjugate DEX to amine-containing carriers. This method is most often used for the synthesis of gene delivery systems [ 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 ].…”

“…Malaekeh-Nikouei et al [ 99 ] developed gene carriers via conjugation of DEX (5, 10, and 20%) to the polypropylenimines (PPI) of 4 and 5 generations (cationic dendrimers with terminal amino groups, potent non-viral vectors) the 21-OH group of DEX was first modified with methanesulfonyl chloride to activate it, and it was then conjugated to PPI using Traut’s reagent (2-iminothiolane; a thiolating reagent that reacts with primary amine groups to form sulfhydryl groups). The DEX degrees of substitution were 4, 8, and 15%.…”