Reperfusion injury after critical intestinal ischemia and its correction with perfluorochemical emulsion "perftoran"

AIM： To investigate the anti-ischemic properties of perfluorochemical emulsion ＂perftoran＂ in mesenteric region. METHODS： Experiments were conducted on 146 nonlinear white male rats weighing 200-350 g. Partial critical intestinal ischemia was induced by thorough atraumatic strangulation of 5-6 cm jejunal loop with its mesentery for 90 rain. Global critical intestinal ischemia was made by atraumatic occlusion of the cranial mesenteric artery （CMA） for 90 rain also. Perftoran （PF, 0.8-1.0 mL per 100 g） in experimental groups or 0.9% sodium chloride in control groups was injected at 75 rain of ischemic period. Mean systemic arterial blood pressure （BPM） registration, intravital microscopy and morphological examination of ischemic intestine and its mesentery were performed in both groups. RESULTS： During 90 min of reperfusion, BPM progressively decreased to 27.3±7.4% after PF administration vs 38.6±8.0% in the control group of rats with partial intestinal ischemia （NS） and to 50.3±6.9% vs 53.1±5.8% in rats after global ischemia （NS）. During the reperfusion period, full restoration of microcirculation was never registered; parts with restored blood flow had leukocyte and erythrocyte stasis and intra-vascular clotting, a typical ＂non-reflow＂phenomenon. The reduction of mesenteric 50-400 μm feeding artery diameter was significantly less in the PF group than in the control group （24±5.5% vs 45.2±3.6%, P〈0.05） 5 min after partial intestinal ischemia. This decrease progressed but differences between groups minimized at the 90th min of reperfusion （41.5±4.2% and 50.3±2.8%, respectively）. In reperfusion of rat＇s intestine, a significant mucosal alteration was registered. Villous height decreased 2.5-3 times and the quantity of crypts decreased more than twice. In the group of rats administered PF, intestinal mucosal layer was protected from irreversible post-ischemic derangement during reperfusion. Saved cryptal epithelial cells were the source of regeneration of the epithelium, which began to cover renewing intestinal villi after 24 h of blood flow restoration. View of morphological alterations was more heterogeneous in CMA groups. CONCLUSION： Systemic administration of perftoran promotes earlier and more complete structural regeneration during reperfusion in rats after partial and global critical intestinal ischemia.

Development of fluorinated polyplex nanoemulsions for improved small interfering RNA delivery and cancer therapy

We report the development of a small interfering RNA （siRNA） delivery vector based on cationic perfluorocarbon nanoemulsions. We have prepared perfluorodecalin （PFD） emulsions with a positive surface charge provided by a fluorinated poly（ethylenimine） （F-PEI）. The fluorinated emulsion （F-PEI@PFD） reduced cytotoxicity of F-PEI and demonstrated effective binding with siRNAs to form nanosized emulsion polyplexes. The prepared emulsion polyplexes enhanced cellular uptake and improved endosomal escape of the siRNA. In addition to increased reporter gene silencing in multiple cancer cell lines, when compared with control F-PEI and PEI polyplexes, the siR_NA emulsion polyplexes showed an excellent resistance to serum deactivation and maintained high activity, even in high-serum conditions. The F-PEI@PFD emulsion polyplexes carrying an siRNA to silence the expression of Bcl2 gene induced apoptosis and inhibited tumor growth in a melanoma mouse model in vivo and showed potential for in vivo ultrasound imaging. This study demonstrates the potential of F-PEI@PFD emulsions as a multifunctional theranostic nanoplatform for safe siRNA delivery, with integrated ultrasound imaging functionality.