The particles zeta potential was 13.4 ± 2.6mV, and echogenicity properties were tested using ultrasound imaging, which revealed a similar acoustic activity as standard Definity microbubble particles. Definity particles are lipid-encapsulated microbubbles containing
perfluoropropane gas ranging in size from 1.1 to 3.3μm [42] and manufactured by Bristol-Myers Squibb Medical Imaging, US. The overexpression of the β-gal reporter gene delivered was examined by X-gal staining and Western blot, and at least an 8-fold increase was observed Inhibitors,research,lifescience,medical in cell transfection efficiency in irradiated tumors compared to nonirradiated control. Negligible cell death was produced by ultrasonication and we determined the pDNA condensed by PEI was protected from degradation even under US
conditions. These results indicated that this selleck screening library formulation is promising for in vivo Inhibitors,research,lifescience,medical gene delivery of plasmid DNA using sonoporation. PLGA and PEI each are formulation choices that have certain advantageous chemical and structural characteristics that can enhance pDNA delivery in tumor cells. The advantage of PLGA, as discussed earlier, is the biodegradability profile and echogenicity Inhibitors,research,lifescience,medical of the prepared NP. The advantage of the in vivo jetPEI, as shown by our data, was its ability to protect pDNA from any potential US-induced damage. Also, PEI could further enhance NP translation potential as this polymer already has been utilized in clinical trials for bladder cancer [43]. Moreover, an important Inhibitors,research,lifescience,medical rationale for using PEI to condense pDNA and complex it to the surface of echogenic PLGA NP is to enable delivery of a large amount of pDNA (≥50μg) [3], which is usually necessary to achieve efficacy in
in vivo gene therapy settings [4], while still preserving the nanoscale dimensions of the chimeric NP (~200nm). In some cases, pDNA can be loaded inside the PLGA NP, but usually this results in minimal encapsulation (5%) for this NP type, requiring a microparticle production. For example, IL-10 is an anti-inflammatory molecule that has achieved interest as a therapeutic for neuropathic pain. Inhibitors,research,lifescience,medical In one recent study, encapsulation of plasmid was low (only ~8μg pIL-10) when PLGA microparticles of ~4.6μm were utilized to deliver these IL-10 [44]. And although this PLGA:pIL-10 therapy was able to relieve neuropathic pain for greater than 74 days in an animal model following direct intrathecal administration, a micron-sized particle such as this may be less desirable for tumor therapy and targeting, for example, as penetration and retention into tumor vasculature is desired with or without using sonoporation for gene delivery. However, refinements are possible that will allow incorporation of other choices of cationic polymers for DNA condensation and loading onto echogenic PLGA NP for further reductions in any potential PEI in vivo toxicity [38, 45], and potential approaches will be discussed as follows.