Indocyanine Green Clearance Research Articles

Assessment of Hepatic Function, Operative Candidacy, and Medical Management after Liver Resection in the Patient with Underlying Liver Disease

Liver resection in patients with underlying liver disease remains a formidable challenge. It requires adequate patient selection, a precise surgical plan, and avoidance of additional ischemic insults during surgery. Precise estimation of the residual liver volume using computed tomography or magnetic resonance imaging and computer-assisted volumetry allows the calculation of residual to total liver volume (RLV/TLV) ratios. Although RLV/TLV ratios over 20 to 25% are considered sufficient in healthy livers, patients with cirrhosis may only tolerate resections that result in RLV/TLV ratios over 40% and higher. Conventional laboratory tests may not be able to sufficiently predict liver reserve after resection. Dynamic tests such as indocyanine green clearance have been used to assess residual liver function and assist in deciding about operability of patients with underlying liver disease undergoing extensive resections. Intraoperative management should focus on avoiding blood loss and ischemic injury to the liver. Low central venous pressure may reduce blood loss and is recommended if tolerated without impeding renal perfusion. Portal vein and hepatic artery occlusion during resection can reduce blood loss, but will cause ischemic insult to the liver that may jeopardize residual liver function and induce postoperative hepatic failure. When feasible, vascular occlusion should be avoided in patients with underlying liver disease. The postoperative recovery is usually fast if sufficient liver remains. However, vigilance is required to detect liver dysfunction and treat its complications.

Spatially resolved assessment of hepatic function using 99mTc‐IDA SPECT

99mTc-iminodiacetic acid (IDA) hepatobiliary imaging is usually quantified for hepatic function on the entire liver or regions of interest (ROIs) in the liver. The authors presented a method to estimate the hepatic extraction fraction (HEF) voxel-by-voxel from single-photon emission computed tomography (SPECT)∕CT with a 99mTc-labeled IDA agent of mebrofenin and evaluated the spatially resolved HEF measurements with an independent physiological measurement. Fourteen patients with intrahepatic cancers were treated with radiation therapy (RT) and imaged by 99mTc-mebrofenin SPECT before and 1 month after RT. The dynamic SPECT volumes were with a resolution of 3.9 × 3.9 × 2.5 mm(3). Throughout the whole liver with approximate 50 000 voxels, voxelwise HEF quantifications were estimated and compared between using arterial input function (AIF) from the heart and using vascular input function (VIF) from the spleen. The correlation between mean of the HEFs over the nontumor liver tissue and the overall liver function measured by Indocyanine green clearance half-time (T1∕2) was assessed. Variation of the voxelwise estimation was evaluated in ROIs drawn in relatively homogeneous regions of the livers. The authors also examined effects of the time range parameter on the voxelwise HEF quantification. Mean of the HEFs over the liver estimated using AIF significantly correlated with the physiological measurement T1∕2 (r = 0.52, p = 0.0004), and the correlation was greatly improved by using VIF (r = 0.79, p < 0.0001). The parameter of time range for the retention phase did not lead to a significant difference in the means of the HEFs in the ROIs. Using VIF and a retention phase time range of 7-30 min, the relative variation of the voxelwise HEF in the ROIs was 10% ± 6% of respective mean HEF. The voxelwise HEF derived from 99mTc-IDA SPECT by the deconvolution analysis is feasible to assess the spatial distribution of hepatic function in the liver.

Indocyanine green clearance and INR: strong predictors of 1-month mortality in patients undergoing orthotopic liver transplantation

Indocyanine green clearance and INR: strong predictors of 1-month mortality in patients undergoing orthotopic liver transplantation

Predictive Models for Regional Hepatic Function Based on 99mTc-IDA SPECT and Local Radiation Dose for Physiologic Adaptive Radiation Therapy

High-dose radiation therapy (RT) for intrahepatic cancer is limited by the development of liver injury. This study investigated whether regional hepatic function assessed before and during the course of RT using 99mTc-labeled iminodiacetic acid (IDA) single photon emission computed tomography (SPECT) could predict regional liver function reserve after RT. Fourteen patients treated with RT for intrahepatic cancers underwent dynamic 99mTc-IDA SPECT scans before RT, during, and 1 month after completion of RT. Indocyanine green (ICG) tests, a measure of overall liver function, were performed within 1 day of each scan. Three-dimensional volumetric hepatic extraction fraction (HEF) images of the liver were estimated by deconvolution analysis. After coregistration of the CT/SPECT and the treatment planning CT, HEF dose-response functions during and after RT were generated. The volumetric mean of the HEFs in the whole liver was correlated with ICG clearance time. Three models, dose, priori, and adaptive models, were developed using multivariate linear regression to assess whether the regional HEFs measured before and during RT helped predict regional hepatic function after RT. The mean of the volumetric liver HEFs was significantly correlated with ICG clearance half-life time (r=-0.80, P<.0001), for all time points. Linear correlations between local doses and regional HEFs 1 month after RT were significant in 12 patients. In the priori model, regional HEF after RT was predicted by the planned dose and regional HEF assessed before RT (R=0.71, P<.0001). In the adaptive model, regional HEF after RT was predicted by regional HEF reassessed during RT and the remaining planned local dose (R=0.83, P<.0001). 99mTc-IDA SPECT obtained during RT could be used to assess regional hepatic function and helped predict post-RT regional liver function reserve. This could support individualized adaptive radiation treatment strategies to maximize tumor control and minimize the risk of liver damage.

Liver Stiffness Measurement by Transient Elastography as a Predictor on Posthepatectomy Outcomes

Liver fibrosis and cirrhosis are well-known risk factors for morbidity after hepatectomy. Liver stiffness measurement (LSM) using transient elastography is a new method for detection of hepatic fibrosis and cirrhosis with high accuracy. Whether LSM can predict posthepatectomy outcomes has not been studied. This was a prospective cohort study in which consecutive patients underwent hepatectomy for various indications from February 2010 to July 2011. All patients received detailed preoperative assessments including LSM and indocyanine green (ICG) clearance test. The primary outcome was major postoperative complication. One hundred five patients with a mean age of 59 years were included; 75 (71.4%) had chronic viral hepatitis and 76 (72.4%) had hepatocellular carcinoma. Thirty-four patients (32.4%) received major hepatectomy. The median ICG retention rate at 15 minutes was 4.2 (0.1%-32%) and the median LSM was 9.4 (3.3-75 kPa). For posthepatectomy outcomes, only LSM but not ICG showed significant correlation with major postoperative complications on receiver operating characteristic curves, with area under the curve of 0.79 (P < 0.001). Using the calculated cutoff at 12.0 kPa, LSM had sensitivity of 85.7% and specificity of 71.8% in the prediction of major postoperative complications. It was also an independent prognostic factor for major postoperative complications by multivariate analysis. The operative blood loss and transfusion rate were also significantly higher in patients with LSM >12.0 kPa. High LSM (>12.0 kPa) predicted worse posthepatectomy outcomes. Preoperative LSM was better than ICG test in the prediction of major postoperative complications. It was a useful preoperative investigation for risk stratification before hepatectomy.

Calcium receptors located in fibrotic septa: a new target to reduce portal pressure in liver cirrhosis

In rats with experimental liver cirrhosis, the kidney contains reduced amounts of membrane-bound CaRs (calcium-sensing receptors), and the specific stimulation of CaRs causes the generation of PGE2 (prostaglandin E2), renal vasodilation and increased natriuresis. CaR content and function in the liver of cirrhotic rats are unknown. To assess the activity of this Ca2+-dependent vasomotor system, we evaluated the effects of intravenous administration of PolyAg (poly-L-arginine), a selective CaR agonist, on hormonal status, portal haemodynamics, MAP (mean arterial pressure) in rats with liver cirrhosis induced by chronic CCl4 (carbon tetrachloride) administration. Two groups of eight control rats received intravenously 1 ml of 5% (w/v) glucose solution alone or containing 0.5 mg of PolyAg; two groups of ten cirrhotic rats were administered vehicle or PolyAg. Compared with controls, at baseline cirrhotic rats showed higher portal pressure (P<0.01), lower estimated functional liver plasma flow, measured as CICG (Indocyanine Green clearance) (P<0.03) and reduced hepatic protein content of CaRs (P<0.03), which were located mainly in sub-endothelial layers of portal venules and in myofibroblasts of fibrotic septa (immunohistochemistry and indirect immunofluorescence staining of liver sections). In cirrhotic animals, 0.5 mg of PolyAg decreased portal pressure (P<0.01) and increased CICG (P<0.05), without effects on arterial pressure and hormonal status. In conclusion, the present study provides evidence that in experimental cirrhosis agonists of liver CaRs elicit beneficial portal hypotensive effects by reducing intrahepatic resistance to portal flow. Moreover, these drugs are devoid of effects on systemic haemodynamics.

Preoperative liver function assessments to estimate the prognosis and safety of liver resections

Liver function assessment is important to ensure safe surgical procedures in patients with hepatocellular disease. Because the liver influences a wide variety of functions, including protein synthesis and metabolic, immune and storage functions, no single parameter is sufficient to adequately address all of these functions. We reviewed the relevant literature concerning the scoring systems, functional tests, plasma parameters and imaging modalities currently used to evaluate the liver function in an attempt to determine which parameters provide the most comprehensive and useful results. While the Child-Pugh scoring system is the gold standard for liver disease assessment, the liver damage grading system recommended by the Liver Cancer Study Group of Japan is also useful. Various models for end-stage liver disease scoring are used for organ allocation. While the indocyanine green clearance test is widely accepted throughout the world, other assessments have not been used routinely for clinical evaluations. The levels of plasma proteins, including albumin, prealbumin, retinol binding protein, apolipoprotein, coagulation factors and antithrombin III, represent the liver productivity. Liver fibrotic markers also correlate with liver function. Imaging modalities such as (99m)Tc-galactosyl serum albumin scintigraphy, (99m)Tc-mebrofenin hepatobiliary scintigraphy and transient elastography are also available, but future studies are needed to validate their clinical efficacy.

Effects of Prolonged Pneumoperitoneum on Hepatic Perfusion During Laparoscopy

To assess the influence of prolonged pneumoperitoneum (PP) on liver function and perfusion in a clinically relevant porcine model of laparoscopic abdominal insufflation. PP during laparoscopic surgery produces increased intra-abdominal pressure, which potentially influences hepatic function and microcirculatory perfusion. Six pigs (49.6 ± 5.8 kg) underwent laparoscopic intra-abdominal insufflation with 14 mm Hg CO2 gas for 6 hours, followed by a recovery period of 6 hours. Two animals were subjected to 25 mm Hg CO2 gas. Hemodynamic parameters were monitored, and damage parameters in the blood were measured to assess liver injury. Liver total blood flow and function were determined by the indocyanine green (ICG) clearance test. Intraoperative hepatic hemodynamics were measured by simultaneous reflectance spectrophotometry (venous oxygen saturation StO2 and relative tissue hemoglobin concentration rHb) and laser Doppler flowmetry (blood flow and flow velocity). Postmortem liver samples were collected for histological evaluation. A decrease in microvascular perfusion was observed during PP. After 6 hours of PP, ICG clearance increased (P < 0.001), indicating a compensatory improvement of overall liver blood flow resulting in concomitantly improved microcirculatory perfusion (P = 0.024). Minimal parenchymal damage (aspartate aminotransferase) of the liver was seen after 6 hours of PP (P = 0.006), which seemed related to PP pressure. Minor histological damage was observed. The liver sustains no additional damage due to prolonged PP during laparoscopic surgery. Our findings suggest that prolonged PP does not hamper liver function or cause liver damage after extended laparoscopic procedures.

A prospective experimental study of liver fibrosis with ultrasound and its correlation with hepatic reserve function and hemodynamics

BackgroundProgressive hepatic fibrosis is the eventual cause of liver cirrhosis. Doppler ultrasound has been used to detect hemodynamic changes that are known to be present during the pre-cirrhotic stages of hepatic fibrogenesis. However, the relationship between the Doppler ultrasound parameters and the impairment of the liver function has not been fully investigated. The purpose of this study was to explore the hepatic function reserve and its relationship with the hepatic hemodynamics in a rabbit model of liver fibrosis using Doppler ultrasound.MethodsA prospective study was performed. Sixty healthy New Zealand rabbits were included in this study. Eleven of them served as controls and were normally fed and provided with water drink; the rest of 49 rabbits that served as fibrosis group were normally fed but provided with 1.2 g/L of thioacetamide to create liver fibrosis model. Doppler measurements were performed in the portal trunk, proper hepatic artery and proper splenic artery. The hepatic circulation index (HCI) was calculated. Hepatic function reverse was evaluated by measuring the indocyanine green clearance and retention rate at 15 min (ICG R15) test. Portal venous pressure (PVP) was measured using the portal vein punctuation equipment.ResultsHCI was significantly decreased and PVP increased in the advanced fibrotic stage (F4) compared to mild and moderate fibrotic stage (F1-3), respectively (p<0.05). PVP and ICG R15 in the fibrotic group were significantly higher than that in the control group (ICG: 0.209±0.086 vs. 0.093±0.023, p<0.01). Within the fibrotic groups, PVP was higher in advanced fibrotic stage (F4) than those in mild (F1-2) or moderate (F3) fibrotic stages (p<0.05). Both HCI and PVP correlated well with ICG R15 (r = −0.890, and r = 0.780, p <0.01).ConclusionsHepatic function reserve closely relates to the hepatic hemodynamics in the rabbit model of liver fibrosis. Doppler Ultrasound could be reliably used to assess the hepatic function reserve and hemodynamic changes in different stages of liver fibrosis.

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Acquired Liver Injury in the Intensive Care Unit

HE liver plays a key role in the synthesis of proteins, metabolism of toxins and drugs, and in modulation of immunity. In critically ill patients, hypoxic, toxic, and inflammatory insults can affect hepatic excretory, synthetic, and/or purification functions, leading to systemic complications such as coagulopathy, increased risk of infection, hypoglycemia, and acute kidney injury. In severe cases, hepatic encephalopathyorbraindysfunction(acuteliverfailure)may occur. Because of the lack of specificity of standard laboratory investigations, identifying liver injury or dysfunction in critically ill patients remains a significant challenge. In addition, the great heterogeneity of criteria used to define the consequences of liver insults increases the difficulties for the clinician to properly interpret hepatic biochemical abnormalities. In this review, we choose to defineliver injuryas an elevation in serum concentrations of routinely measured hepatic enzymes, including aminotransferases (aspartate aminotransferase [AST]; alanine aminotransferase, [ALT]), alkaline phosphatase (ALP), or!-glutamyl transpeptidase. Hepatic dysfunctionrefers to derangement of pathways related to synthetic or clearance function, including international normalized ratio (INR) and bilirubin.Hepatotoxicity refers to hepatic injury and dysfunction caused by a drug or another noninfectious agent. 1 Acute liver failuredesignates

Assessment of safety in hepatic resection for hepatocellular carcinoma focusing on indirect hyperbilirubinemia

The indications for hepatic resection for hepatocellular carcinoma (HCC) patients with total bilirubin (T-Bil) equal to or higher than 1.2 mg/dl remain controversial. The aim of this study was to investigate the safety of hepatic resection for HCC patients who showed high T-Bil (≥1.2 mg/dl) with low direct bilirubin (D-Bil ≤ 0.5 mg/dl). Thirty-four HCC patients showing high T-Bil with low D-Bil were treated with mono- to tri-segmentectomy between January 2000 and December 2010. The perioperative clinical parameters and prognosis of the high T-Bil/low D-Bil patients were compared with those of 253 HCC patients showing normal T-Bil. In addition, complication rates of the patients with high T-Bil/high D-Bil (n = 4) were analyzed. The prothrombin time activity, indocyanine green clearance test, asialo-scintigraphy, and platelet count were similar in the two groups. The mean serum albumin in high T-Bil/low D-Bil patients was significantly higher than that of normal T-Bil patients (4.2 ± 0.5 vs. 4.0 ± 0.4 g/dl, P = 0.004). There were no significant differences in operation time, intraoperative bleeding, red cell concentrate transfusion rate, postoperative complication rate, and disease-free and overall survivals between the two groups. Postoperative hyperbilirubinemia (T-Bil >5 mg/dl) with ascites was observed in one of four high T-Bil/high D-Bil patients (25 %). Mono- to tri-segmentectomy can be performed in patients with low D-Bil (≤0.5 mg/dl) similarly to patients with low T-Bil (<1.2 mg/dl), even in HCC patients showing high T-Bil (≥1.2 mg/dl).

Limitations of Use of the Noninvasive Clearance of Indocyanine Green as a Prognostic Indicator of Graft Function in Liver Transplantation

AimTo assess the prognostic value of noninvasive indocyanine green (ICG) clearance (ICG-pulse-densitometric method [PDR]) for the outcome of liver grafts after transplantation. MethodsICG-PDR, hepatic artery resistance index, cardiac output, transaminases, prothrombin time, bilirubin, albumin, hematocrit at 48 to 72 hours after transplantation were analyzed with reference to outcome among 59 liver graft recipients. ResultsTwo grafts were lost at 10 and 88 days during the initial hospitalization. These two patients only differed from the other recipients in the need for packing (1/2 versus 3/57) and degree of hypoproteinemia (46 ± 0 versus 51 ± 7.8 g/L), whereas they had similar ICG-PDR values (16.7%/min and 21.8%/min versus 17.3%/min ± 7.2%/min). Seven patients showed an ICG-PDR ≤ 8.8%/min, a previously identified cutoff for early postoperative complications. These patients versus the other 52 significantly differed in prothrombin index (47.9% ± 15.9% versus 64.3% ± 11.7%, P = .001) and bilirubin (8.3 ± 3.2 versus 3.3 ± 2.9 mg/dL, P = .0001). Early postoperative complications—primary graft nonfunction, hepatic artery thrombosis, or septic shock— responsible for an ICG-PDR ≤ 8.8%/min were observed in 2/7 patients. Interestingly, six cases developed an early (range: 3–15 days) rejection episode. In all the cases rejection suspected by analytical abnormalities was confirmed by liver biopsy. Among the overall series of patients, ICG-PDR significantly correlated with serum albumin (r = 0.345; P = .007), bilirubin (r = −0.514; P = .0001), and hematocrit (r = 0.462; P = .0001) but not with transaminases, prothrombin index, cardiac output, or hepatic artery resistance index. Actuarial 72-month probability of graft survival was 75%. Overall, 14 grafts were lost over a median follow-up of 78 months (range 1–99 m). There were no significant differences among early ICG-PDR values among grafts lost vs retained upon follow-up. ConclusionICG-PDR measured once early after liver transplantation did not offer relevant information to predict individual patient outcomes in the immediate postoperative phase. This lack of prognostic value may have been due to the multiple confounding factors involved in ICG metabolism after liver transplantation.

Indocyanine green clearance test (using spectrophotometry) and its correlation with Model for End Stage Liver Disease (MELD) score in Indian patients with cirrhosis of liver

Child Turcotte Pugh (CTP) score and Model for End Stage Liver Disease (MELD) are used commonly to assess the prognosis of liver disease but the disadvantage of these static tests is their inability to identify the functional reserve of the liver. Among all quantitative liver function tests indocyanine green (ICG) clearance test is most widely used and has been used to determine operative risk before hepatectomy and to assess prognosis of patients with cirrhosis. To correlate indocyanine green (ICG) clearance test with MELD score in patients with cirrhosis of liver. Forty patients with cirrhosis of liver were included and divided into two groups according to their CTP scores. Group A had 20 patients with CTP class A and group B had 20 patients with CTP class B. After ICG injection, ICG retention at 15 minutes (ICGR 15) and ICG clearance rate were calculated. In group A, the mean ICGR15 was 32.86% +/- 6.4% while in group B it was 51.08% +/-12.8% (p <0.001). ICG clearance rates were 4.3% +/- 2.8% and 3.5% +/- 3.8% per minute in group A and B respectively. MELD score had a strong positive correlation with ICGR15 but a negative correlation with ICG clearance rate. On ROC curve analysis, AUC for MELD was 0.805 vs. 0.88 for ICGR15 in assessing prognosis of patients with cirrhosis. The sensitivity and specificity of MELD score was 60% and 80% respectively while that of ICGR15 was 85% and 90% respectively. ICGR15 has a higher sensitivity and specificity than MELD score in assessing the prognosis of patients with cirrhosis of liver.

Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which could aid in individualizing therapy, particularly for patients at risk for liver injury after RT.

Decreased lymphangiogenesis in mice with osteoarthritis under high fat diet

Purpose: We have reported that lymphatic drainage plays a critical role in limiting the severity of joint tissue injury in mouse model of rheumatoid arthritis by removing catalytic factors and inflammatory cells from interstitial fluids to the local draining lymph nodes. However the implication of lymphatic in the pathogenesis of osteoarthritis (OA) is un-known, especially in OA with diabetic because patients with diabetic often have abnormal micro-vasculature. Currently, there is no method to assess lymphatic draining function in mouse knee as an outcome measure to study lymphatic in OA. Here we examined lymphatic vessels in joint sections from a mouse model of OA with diabetes, and developed a near-infrared lymphatic image technique to monitor lymphatic drainage from knee to local draining lymph nodes in real time. Methods: OA was initiated by a meniscall-ligamentous injury (MLI) procedure in the right knee joint. Type 2 diabetic was induced by feeding mice with high fat (HF, 60% kcal) diet. Controls included mice with sham-operation in the left knee and fed by low fat diet (LF, 10% kcal). 5 wks-old C57/BL/6 mice were placed on HF or LF for 8 wks and then received MLI or sham-operation to initiate OA. Mice were sacrificed 16 wks after the MLI. The knee joints were subjected to histology and IHC stain with anti-podoplanin antibody to identify lymphatic vessels and anti-alpha smooth muscle actin (aSM) antibody to identify aSM covered vessels. A group of 12-wks-old mice were received intra-articular injection of the infrared dye, indocyanine green (ICG), the path and signal intensity of ICG in the knee were recorded under an infrared lymphatic imaging system at 1, 2, 4, 6, and 24 hrs. The ICG clearance was calculated. Results: MLI induced OA-like changes in right knee joints, including increased Chamber score, decreased cartilage thickness and osteophyte formation, which was more severe in the HF group. IHC detected that podoplanin+ vessels had thin wall with large lumen, a feature of lymphatic vessels. These podoplanin+ lymphatic vessels were localized in the connective tissue around joint capsules and periosteam. aSM+ vessels appeared to have thick wall and did not overlap with the podoplanin+ lymphatic vessels, suggesting that they are likely small blood vessels. Interestingly, the density of lymphatic and blood vessels were similar among sham-LF, OA-LF, and sham-HF groups, but remarkably decreased in OA-HF group. Decreased podoplanin+ vessels were more obvious than those of aSM+ vessels. Lymphatic imaging revealed that lymph drains from knee tissues to iliac lymph nodes via a single collecting lymphatic vessel. No lymphatic pulse was observed. The ICG signal intensity declined rapidly after injection. The ICG clearance (vs time 0) was 15% at 2 hrs, 60% at 4 hrs, 80% at 6 hrs and 100% at 24 hrs, indicating an efficient lymphatic drainage in WT mice. Conclusions: HF diet accelerates the progression of OA in a type 2 diabetic mouse model, which is associated with decreased lymphatic vessel formation. The near-infrared lymphatic image can be used to monitor lymphatic draining function in mouse knees longitudinally. The involvement of lymphatic in OA pathology is currently under investigation.

Indocyanine green clearance after cardiac surgery: the impact of cardiopulmonary bypass

Plasma clearance of indocyanine green has recently been established as a tool to monitor hepatic function and perfusion non-invasively. Reduced indocyanine green clearance has been associated with adverse outcome in cardiac surgery patients, and cardiopulmonary bypass has been hypothesized to be one important triggering factor. We performed a prospective observational study comparing the influence of off-pump and on-pump coronary surgery on perioperative indocyanine green clearance. Twenty-five consecutive adult patients without known pre-existing hepatic diseases scheduled for off-pump coronary artery bypass grafting were evaluated for hepatic dysfunction pre- and postoperatively with serial measurements of indocyanine green plasma clearance, specific laboratory values and liver function scores. Twenty-five matched patients who underwent coronary artery bypass grafting surgery with cardiopulmonary bypass in the same period served as controls. Parameters of postoperative hepatic function, including measurements of indocyanine green plasma clearance and specific laboratory values and scores, did not differ significantly between patients undergoing off-pump coronary artery bypass grafting and patients undergoing coronary artery bypass grafting with extracorporeal circulation. In patients without pre-existing hepatic diseases, a significant influence of cardiopulmonary bypass on perioperative indocyanine green plasma clearance as well as on liver specific laboratory parameters and scores cannot be proven.

Hepatic dysfunction and Indocyanine green clearance (LiMON) after coronary surgery: Impact of cardiopulmonary bypass

Aims: Hepatic dysfunction is a rare but serious complication after cardiac surgery. Plasma clearance of indocyanine green has recently been established as an excellent tool to measure even small changes in hepatic function. Reduced indocyanine green clearance has been associated with adverse outcome in cardiac surgery patients, and cardiopulmonary bypass (CPB) has been hypothesized to be one important triggering factor. Thus, we performed a prospective observational study comparing the influence of off-pump and on-pump coronary surgery on perioperative indocyanine green clearance.

Derivation of High-Purity Definitive Endoderm from Human Parthenogenetic Stem Cells Using an in Vitro Analog of the Primitive Streak

Human parthenogenetic stem cells (hpSCs) are pluripotent stem cells with enormous potential as cell sources for cell-based therapies: hpSCs may have histocompatibilty advantages over human embryonic stem cells (hESCs) and derivation of hpSCs does not require viable blastocyst destruction. For translation of all pluripotent stem cell-based therapies, derivation of differentiated cell products that are not contaminated with undifferentiated cells is a major technical roadblock. We report here a novel method to derive high-purity definitive endoderm (DE) from hpSCs, based on reproducing features of the normal human embryonic microenvironment. The method mimics the developmental process of transition through a primitive streak, using a differentiation device that incorporates a three-dimensional extracellular matrix (ECM) combined with a porous membrane. Treatment of undifferentiated hpSCs above the membrane results an epithelial-to-mesenchymal transition (EMT); thus, responsive cells acquire the ability to migrate through the membrane into the ECM, where they differentiate into DE. Importantly, the resultant DE is highly purified, and is not contaminated by undifferentiated cells, as assessed by OCT4 expression using immunocytochemistry and flow cytometry. The functional properties of the DE are also preserved by the process: DE differentiated in the device can generate a highly enriched population of hepatocyte-like cells (HLCs) characterized by expression of hepatic lineage markers, indocyanine green clearance, glycogen storage, cytochrome P450 activity, and engraftment in the liver after transplantation into immunodeficient mice. The method is broadly applicable and we obtained purified DE using hESCs, as well as several hpSC lines. The novel method described here represents a significant step toward the efficient generation of high-purity cells derived from DE, including hepatocytes and pancreatic endocrine cells, for use in regenerative medicine and drug discovery, as well as a platform for studying cell fate specification and behavior during development.

Ex vivo evaluation of porcine livers post-hypothermic machine perfusion at 4-6ºC and 12-14ºC

Background: The goal of our research is the development of a clinical hypothermic machine perfusion method and device for liver preservation during storage and transport prior to transplantation. The purpose of this study was comparison of two hypothermic temperature ranges. Methods: Heart beating donor pig livers with 2h of static cold storage on ice were employed. Thirteen experimental livers were perfused, at either 4-6oC or 12-14oC with oxygenation, employing a prototype device. They were compared with six control 2h static cold stored livers during normothermic ex vivo blood perfusion. Physiological measurements and biochemical perfusate analyses were performed to assess the impact of storage conditions on liver functions. Statistics were assessed by one way analysis of variance, p<0.05 was regarded as significant. Results: During hypothermic perfusion perfusate solutes (Na + , K + and Ca ++ ) varied little with time. A single 12-14oC perfused liver exhibited a Ca ++ spike at 22 hours. Temperature dependent metabolic activity was observed in both groups. Lactate levels were ≤4.5mmol/L for 22h. During normothermic ex vivo testing most controls and perfusion-treated experimental livers produced bile within an hour. 10h perfusion liver lactate dehydrogenase, hyaluronic acid uptake, and total bile production were not significantly different from controls. There were trends for albumin, glucose and lactate. Significantly different Factor V, indocyanine green clearance, and blood urinary nitrogen concentrations were observed in both 10h perfusion groups. Bilirubin kinetics was perturbed in all perfusion groups, however the peak concentrations in the 10h perfusion groups were not significantly different, while the 22h 12-14oC perfusion group was significantly less than controls. A significant difference in alanine aminotransferase values between the 2 perfusion groups, was observed, however this may be due to washout during 12-14°C perfusion. Lactate dehydrogenase was doubled in both perfusion groups at 22h and individual 22h livers exhibited other assay values outside control and 10h perfusion ranges. Conclusions: Significant differences were observed between controls and both perfused groups during post hypothermic storage ex vivo assessment. These results suggest that both temperature ranges tested, with further optimization, may be suitable for liver support for up to 10h of oxygenated hypothermic perfusion. Since there were no clear advantages to 12-14°C perfusion we will continue development of a 4-6°C perfusion device for storage and transport of livers for transplantation.