Redefining the properties of an osmotic agent in an intestinal-specific preservation solution

AIM: To investigate the effects of dextrans of various molecular weights (Mw) during a 12 h cold storage time-course on energetics, histology and mucosal infiltration of fluorescein isothiocyanate (FITC)-dextran. METHODS: Rodent intestines were isolated and received a standard University of Wisconsin vascular flush followed by intraluminal administration of a nutrientrich preservation solution containing dextrans of varying Mw: Group D1, 73 kdal; Group D2, 276 kdal; Group D3, 534 kdal; Group D4, 1185 kdal; Group D5, 2400 kdal. RESULTS: Using FITC-labeled dextrans, fluorescent micrographs demonstrated varying degrees of mucosal infiltration; lower Mw (groups D1-D3: 73-534 kdal) dextrans penetrated the mucosa as early as 2 h, whereas the largest dextran (D5: 2400 kdal) remained captive within the lumen and exhibited no permeability even after 12 h. After 12 h, median injury grades ranged from 6.5 to 7.5 in groups D1-D4 (73-1185 kdal) representing injury of the regenerative cryptal regions and submucosa; this was in contrast to group D5 (2400 kdal) which exhibited villus denudation (with intact crypts) corresponding to a median injury grade of 4 (P < 0.05). Analysis of tissue energetics reflected a strong positive correlation between Mw and adenosine triphosphate (r 2 = 0.809), total adenylates (r 2 = 0.865) and energy charge (r 2 = 0.667).CONCLUSION: Our data indicate that dextrans of Mw > 2400 kdal act as true impermeant agents during 12 h ischemic storage when incorporated into an intraluminal preservation solution.

Protective effects of cyclosporine and its analog NIM-811 in a murine model of hepatic ischemia-reperfusion injury

Background and aim:The liver is susceptible to ischemia-reperfusion injury(IRI)during hepatic surgery,when the vessels are compressed to control bleeding,or liver transplantation,when there is an obligate period of ischemia.The hallmark of IRI comprises mitochondrial dysfunction,which generates reactive oxygen species,and cell death through necrosis or apoptosis.Cyclosporine(CsA),which is a well-known immunosuppressive agent that inhibits calcineurin,has the additional effect of inhibiting the mito-chondrial permeability transition pore(mPTP),thereby,preventing mitochondrial swelling and injury.NIM-811,which is the nonimmunosuppressive analog of CsA,has a similar effect on the mPTP.In this study,we tested the effect of both agents on mitigating warm hepatic IRI in a murine model.Materials and methods:Before ischemic insult,the mice were administered with intraperitoneal normal saline(control);CsA at 2.5,10,or 25 mg/kg;or NIM-811 at 10 mg/kg.Thereafter,the mice were subjected to partial warm hepatic ischemia by selective pedicle clamping for 60 min,followed by 6 h of recovery after reperfusion.Serum alanine transaminase(ALT)was measured,and the liver tissue was examined histologically for the presence of apoptosis and the levels of inflammatory cytokines.Results:Compared with the control mice,the mice treated with 10 and 25 mg/kg of CsA and NIM-811 had significantly lower ALT levels(P<0.001,0.007,and 0.031,respectively).Moreover,the liver tissue showed reduced histological injury scores after treatment with CsA at 2.5,10,and 25 mg/kg and NIM-811(P=0.041,<0.001,0.003,and 0.043,respectively)and significant decrease in apoptosis after treatment with CsA at all doses(P=0.012,0.007,and<0.001,respectively).Levels of the pro-inflammatory cyto-kines,particularly interleukin(IL)-1β,IL-2,IL-4,IL-10,and keratinocyte chemoattractant/human growth-regulated oncogene significantly decreased in the mice treated with the highest dose of CsA(25 mg/kg)than those in the control mice.Conclusions:Premedication with CsA or NIM-811 mitigated hepatic IRI in mice,as evidenced by the decreased ALT and reduced injury on histology.These results have potential implications on mitigating IRI during liver transplantation and resection.