Contrast-enhanced ultrasound of renal masses in the pre-transplant setting: literature review with case highlights.

With the rising incidence of chronic kidney disease worldwide, an increasing number of patients are expected to require renal transplantation, which remains the definitive treatment of end stage renal disease. Medical imaging, primarily ultrasonography and contrast-enhanced CT and/or MRI, plays a large role in pre-transplantation assessment, especially in the characterization of lesions within the native kidneys. However, patients with CKD/ESRD often have relative contraindications to CT- and MR-contrast agents, limiting their utilization within this patient population. Contrast-enhanced ultrasound (CEUS), which combines the high temporal and spatial resolution of ultrasonography with intravascular microbubble contrast agents, provides a promising alternative. This review aims to familiarize the reader with the literature regarding the use of CEUS in the evaluation of cystic and solid renal lesions and provide case examples of its use at our institution in the pre-transplant setting.

Magnetic Resonance Imaging of Macrophage Response to Radiation Therapy.

BACKGROUND: Magnetic resonance imaging (MRI) is a non-invasive imaging modality which, in conjunction with biopsies, provide a qualitative assessment of tumor response to treatment. Intravenous injection of contrast agents such as fluorine (19F) nanoemulsions labels systemic macrophages, which can, then, be tracked in real time with MRI. This method can provide quantifiable insights into the behavior of tumor-associated macrophages (TAMs) in the tumor microenvironment and macrophage recruitment during therapy. METHODS: Female mice received mammary fat pad injections of murine breast or colon cancer cell lines. The mice then received an intravenous 19F nanoemulsion injection, followed by a baseline 19F MRI. For each cancer model, half of the mice then received 8 Gy of localized radiation therapy (RT), while others remained untreated. The mice were monitored for two weeks for tumor growth and 9F signal using MRI. RESULTS: Across both cohorts, the RT-treated groups presented significant tumor growth reduction or arrest, contrary to the untreated groups. Similarly, the fluorine signal in treated groups increased significantly as early as four days post therapy. The fluorine signal change correlated to tumor volumes irrespective of time. CONCLUSION: These results demonstrate the potential of 19F MRI to non-invasively track macrophages during radiation therapy and its prognostic value with regard to tumor growth.

Liver Transplantation for Severe Hepatic Trauma: a multicenter analysis from the UNOS dataset.

BACKGROUND: Orthotopic liver transplantation (OLT) is rarely indicated after hepatic trauma but it can be the only therapeutic option in some patients. There are scarce data analyzing the surgical outcomes of OLT after trauma. METHODS: We used the UNOS dataset to identify patients who underwent OLT for trauma from 1987 to 2022, and compared them to a cohort of patients transplanted for other indications. Cox proportional hazard and multivariable logistic regression analyses were performed to assess predictors of graft and patient survival. RESULTS: 72 patients underwent OLT for trauma during the study period. Patients with trauma were more frequently on mechanical ventilation at the time of transplantation (26.4% vs. 7.6%, p < 0.001) and had a greater incidence of pre-transplant portal vein thrombosis (PVT) (12.5% vs. 4%, p = 0.002). Our 4:1 matched analysis showed that trauma patients had significantly shorter wait times, higher incidence of pre-transplant PVT and prolonged length of stay (LOS). Trauma was associated with decreased overall graft survival (HR = 1.42, 95% CI = 1.01-1.98), and increased LOS (p = 0.048). There were no significant differences in long term patient survival. CONCLUSION: Unique physiological and vascular challenges after severe hepatic trauma might be associated with decreased graft survival in patients requiring liver transplantation. LEVEL OF EVIDENCE: Retrospective cohort study, III.

Metabolic Disruption Induced by mTOR Signaling Pathway Inhibition in Regulatory T-Cell Expansion for Clinical Application.

BACKGROUND: Regulatory T cell (Treg) therapy is considered an alternative approach to induce tolerance in transplantation. If successful, this therapy may have implications on immunosuppression minimization/withdrawal to reduce drug-induced toxicity in patients. The aim of this study was to assess the efficacy of the mTORC1/C2 inhibitor, AZD8055, in the manufacturing of clinically competent Treg cells and compare the effects with those induced by rapamycin (RAPA), another mTOR inhibitor commonly used in Treg expansion protocols. METHODS: Primary human Treg cells were isolated from leukapheresis product. Cell viability, expansion rates, suppressive function, autophagy, mitochondrial unfolded protein response (mitoUPR), and cell metabolic profile were assessed. RESULTS: We observed a stronger inhibition of the mTORC2 signaling pathway and downstream events triggered by Interleukin 2 (IL2)-receptor in AZD8055-treated cells compared with those treated with RAPA. AZD8055 induced progressive metabolic changes in mitochondrial respiration and glycolytic pathways that disrupted the long-term expansion and suppressive function of Tregs. Unlike RAPA, AZD8055 treatment impaired autophagy and enhanced the mitoUPR cell stress response pathway. CONCLUSIONS: A distinct pattern of mTOR inhibition by AZD, compared with RAPA, induced mitochondrial stress response and dysfunction, impaired autophagy, and disrupted cellular bioenergetics, resulting in the loss of proliferative potential and suppressive function of Treg cells.

Liver transplantation for biliary cysts: perioperative and long-term outcomes.

BACKGROUND: Biliary cysts (BC) is a rare indication for orthotopic liver transplantation (OLT). METHODS: We queried the UNOS dataset to identify patients who underwent OLT for Caroli's disease (CD) and choledochal cysts (CC). All patients with BC (CD + CC) were compared to a cohort of patients transplanted for other indications. Patients with CC were also compared to those with CD. Cox proportional hazard model was performed to assess predictors of graft and patient survival. RESULTS: 261 patients underwent OLT for BC. Patients with BC had better pre-operative liver function compared to those transplanted for other indications. 5-year graft and patient survival were 72% and 81%, respectively, similar to those transplanted for other indications after matching. Patients with CC were younger and had increased preoperative cholestasis compared to those with CD. Donor age, race, and gender were predictors of poor graft and patient survival in patients transplanted for CC. CONCLUSIONS: Patients with BC have similar outcomes to those transplanted for other indications and more frequently require MELD score exception. In patients transplanted for choledochal cysts, female gender, donor age, and African-American race were independent predictors of poor survival. Pediatric patients transplanted for Caroli's disease had better survival compared to adults.

Anti-neoplastic sulfonamides alter the metabolic homeostasis and disrupt the suppressor activity of regulatory T cells.

Regulatory T cells (Tregs) are essential to maintain self-tolerance and immune homeostasis but, as components of the tumor microenvironment (TME), are also a major barrier to effective cancer immunosurveillance and immunotherapy. FH535 and its derivative Y3 are two N-aryl-benzene-sulfonamides (NABs) that inhibit HCC cell proliferation and tumor progression. However, the impact of NABs on the immune cells in the TME is not yet known. Analyses of explanted livers from patients with hepatocellular carcinoma (HCC) showed that high levels of tumor-infiltrating Tregs were associated with poor tumor differentiation. These results lead us to investigate the immunomodulatory effects of NABs in regulatory and effector T cells. Exposure of primary human Tregs to NABs induced a rapid but temporary increase of cell expansion, a gradual disruption of suppressor activity, and concomitant bioenergetics and autophagic flux dysregulations. In contrast to Tregs, no gross effects were observed in effector T cells. Addition of Rapamycin prevented the functional decay of Tregs and restored their metabolic profile, suggesting that NAB effects require the integrity of the mTOR pathway. This study revealed the immunomodulatory properties of NABs with a preferential impact on Treg activity and provided novel insights into the anti-tumor potential of sulfonamides.

Cell sorting microbeads as novel contrast agent for magnetic resonance imaging.

The success of several cell-based therapies and prevalent use of magnetic resonance imaging (MRI) in the clinic has fueled the development of contrast agents for specific cell tracking applications. Safe and efficient labeling of non-phagocytic cell types such as T cells nonetheless remains challenging. We developed a one-stop shop approach where the T cell sorting agent also labels the cells which can subsequently be depicted using non-invasive MRI. We compared the MR signal effects of magnetic-assisted cell sorting microbeads (CD25) to the current preclinical gold standard, ferumoxytol. We investigated in vitro labeling efficiency of regulatory T cells (Tregs) with MRI and histopathologic confirmation. Thereafter, Tregs and T cells were labeled with CD25 microbeads in vitro and delivered via intravenous injection. Liver MRIs pre- and 24 h post-injection were performed to determine in vivo tracking feasibility. We show that CD25 microbeads exhibit T2 signal decay properties similar to other iron oxide contrast agents. CD25 microbeads are readily internalized by Tregs and can be detected by non-invasive MRI with dose dependent T2 signal suppression. Systemically injected labeled Tregs can be detected in the liver 24 h post-injection, contrary to T cell control. Our CD25 microbead-based labeling method is an effective tool for Treg tagging, yielding detectable MR signal change in cell phantoms and in vivo. This novel cellular tracking method will be key in tracking the fate of Tregs in inflammatory pathologies and solid organ transplantation.

Predictors of Liver Failure in Non-Cirrhotic Patients Undergoing Hepatectomy.

BACKGROUND: Post-hepatectomy liver failure (PHLF) is associated with high mortality following liver resection. There have been limited studies evaluating predictors of PHLF and clinically significant PHLF in non-cirrhotic patients. METHODS: This was a retrospective cohort study using the National Surgical Quality Improvement Program database (NSQIP) to evaluate 8,093 non-cirrhotic patients undergoing hepatectomy from 2014 to 2018. Primary endpoints were PHLF and clinically significant PHLF (PHLF grade B or C). RESULTS: Among all patients, 4.74% (n = 383) developed PHLF and 2.5% clinically significant PHLF (n = 203). The overall 30-day mortality was 1.35% (n = 109), 11.5% (n = 44) in patients with PHLF, and 19.2% in those with clinically significant PHLF. Factors associated with PHLF were: metastatic liver disease (OR = 1.84, CI = 1.14-2.98), trisectionectomy (OR = 3.71, CI = 2.59-5.32), right total lobectomy (OR = 4.17, CI = 3.06-5.68), transfusions (OR = 1.99, CI = 1.52-2.62), organ/space SSI (OR = 2.84, CI = 2.02-3.98), post-operative pneumonia (OR = 2.43, CI = 1.57-3.76), sepsis (OR = 2.27, CI = 1.47-3.51), and septic shock (OR = 5.67, CI = 3.43-9.36). Patients who developed PHLF or clinically significant PHLF had 2-threefold increased risk of perioperative mortality. Post-hepatectomy renal failure (OR = 8.47, CI = 3.96-18.1), older age (OR = 1.04, CI = 1.014-1.063), male sex (OR = 1.83, CI = 1.07-3.14), sepsis (OR = 2.96, CI = 1.22-7.2), and septic shock (OR = 3.92, CI = 1.61-9.58) were independently associated with 30-mortality in patients with clinically significant PHLF. CONCLUSION: PHLF in non-cirrhotic patients increased the risk of perioperative mortality and is associated with the extent of hepatectomy and infectious complications. Careful evaluation of the liver remnant, antibiotic prophylaxis, nutritional assessment, and timely management of post-operative infections could decrease major morbidity and mortality following hepatectomy.

Untangling the Knots of Regulatory T Cell Therapy in Solid Organ Transplantation.

Numerous preclinical studies have provided solid evidence supporting adoptive transfer of regulatory T cells (Tregs) to induce organ tolerance. As a result, there are 7 currently active Treg cell-based clinical trials in solid organ transplantation worldwide, all of which are early phase I or phase I/II trials. Although the results of these trials are optimistic and support both safety and feasibility, many experimental and clinical unanswered questions are slowing the progression of this new therapeutic alternative. In this review, we bring to the forefront the major challenges that Treg cell transplant investigators are currently facing, including the phenotypic and functional diversity of Treg cells, lineage stability, non-standardized ex vivo Treg cell manufacturing process, adequacy of administration route, inability of monitoring and tracking infused cells, and lack of biomarkers or validated surrogate endpoints of efficacy in clinical trials. With this plethora of interrogation marks, we are at a challenging and exciting crossroad where properly addressing these questions will determine the successful implementation of Treg cell-based immunotherapy in clinical transplantation.

The Role of Alterations in Alpha-Klotho and FGF-23 in Kidney Transplantation and Kidney Donation.

Cardiovascular disease and mineral bone disorders are major contributors to morbidity and mortality among patients with chronic kidney disease and often persist after renal transplantation. Ongoing hormonal imbalances after kidney transplant (KT) are associated with loss of graft function and poor outcomes. Fibroblast growth factor 23 (FGF-23) and its co-receptor, α-Klotho, are key factors in the underlying mechanisms that integrate accelerated atherosclerosis, vascular calcification, mineral disorders, and osteodystrophy. On the other hand, kidney donation is also associated with endocrine and metabolic adaptations that include transient increases in circulating FGF-23 and decreases in α-Klotho levels. However, the long-term impact of these alterations and their clinical relevance have not yet been determined. This manuscript aims to review and summarize current data on the role of FGF-23 and α-Klotho in the endocrine response to KT and living kidney donation, and importantly, underscore specific areas of research that may enhance diagnostics and therapeutics in the growing population of KT recipients and kidney donors.

Outcomes in Elderly Patients Undergoing Liver Transplantation Compared with Liver-Directed Ablative Therapy in Early-Stage Hepatocellular Carcinoma.

BACKGROUND: Orthotopic liver transplantation (OLT) is the accepted treatment in patients with unresectable, early-stage hepatocellular carcinoma (HCC) in the setting of cirrhosis. Due to increasing waitlist demand for OLT, determining optimal groups for transplant is critical. Elderly patients are known to have poorer postoperative outcomes. Considering the effectiveness of liver-directed therapies for HCC, we sought to determine whether elderly patients received survival benefit from OLT over liver-directed therapy alone. STUDY DESIGN: The National Cancer Database participant use file was used to analyze data between 2004 and 2017. Only patients ≥70 years of age who received OLT or liver-directed therapy alone were included. Patients with alpha-fetoprotein >500 ng/mL or missing alpha-fetoprotein values were excluded. Baseline demographic variables, model for end-stage liver disease score, and overall survival from time of diagnosis were collected. Descriptive statistics, Kaplan-Meier survival, Cox proportional hazards model, and propensity score matching were used. RESULTS: A total of 2,377 patients received ablative therapy alone, and 214 patients received OLT. Multivariable analysis and Kaplan-Meier showed that OLT conferred a significant survival benefit compared to liver-directed therapy alone. Age was also associated with a yearly 3% increase in risk of mortality. Propensity-matched analysis adjusting also demonstrated a significant survival benefit for elderly patients receiving OLT compared to liver-directed therapy alone. CONCLUSION: Despite increased age and associated comorbidities being factors associated with poor outcomes, OLT confers a survival advantage compared to liver-directed ablative therapies alone in selected elderly patients with HCC. OLT should be offered in medically appropriate elderly patients with HCC.

Prognostic Value of Fluorine-19 MRI Oximetry Monitoring in cancer.

Hypoxia is a key prognostic indicator in most solid tumors, as it is correlated to tumor angiogenesis, metastasis, recurrence, and response to therapy. Accurate measurement and mapping of tumor oxygenation profile and changes upon intervention could facilitate disease progression assessment and assist in treatment planning. Currently, no gold standard exists for non-invasive spatiotemporal measurement of hypoxia. Magnetic resonance imaging (MRI) represents an attractive option as it is a clinically available and non-ionizing imaging modality. Specifically, perfluorocarbon (PFC) beacons can be externally introduced into the tumor tissue and the linear dependence of their spin-lattice relaxation rate (R1) on the local partial pressure of oxygen (pO2) exploited for real-time tissue oxygenation monitoring in vivo. In this review, we will focus on early studies and recent developments of fluorine-19 MRI and spectroscopy (MRS) for evaluation of tumor oximetry and response to therapy.

Hepatic Steatosis is Associated with an Increased Risk of Postoperative Infections and Perioperative Transfusion Requirements in Patients Undergoing Hepatectomy.

BACKGROUND: To determine the impact of hepatic steatosis on perioperative outcomes of patients undergoing hepatectomy. METHODS: We analyzed all hepatectomy patients with normal and fatty liver texture, between 2014 and 2018 using NSQIP. Main endpoints included perioperative transfusions (within 72 h) and infectious complications. RESULTS: A total of 8,237 patients underwent hepatectomy during the study period. The overall rate of fatty liver texture (FLG) was 31% (2,557). Operative duration was significantly longer; inflow occlusion was more common (Pringle maneuver), and the need of transfusions was significantly higher in the FLG compared to the normal liver group (NLG) (p = < 0.001). On multivariate analysis, patients in the FLG had increased risk of developing infectious complications (OR 1.22 [95%IC 1.05-1.41]) and transfusion requirements within 72 h after hepatectomy (OR 1.43 [95% CI 1.24-1.63]). CONCLUSIONS: Hepatic steatosis is an independent risk factor for the development of infectious complications and increased perioperative transfusion requirements in patients undergoing hepatectomy. Those requiring transfusions within 72 h had also an increased risk of infections after hepatectomy.

Perioperative Challenges in Patients Transplanted with Livers from Extreme Obese Donors.

The combination of rising rates of obesity and the shortage of deceased donor livers have forced the consideration of marginal liver donors in terms of body mass index (BMI) for liver transplantation (LT). To date, there are still conflicting data on the impact of donor obesity on post-LT outcomes. We analyzed all patients undergoing LT alone in the United States (US) from October 2005 through December 2019 using the United Network of Organ Sharing (UNOS) data set. We categorized donor BMI >40 kg/m2 as extremely obese (EO). Primary endpoints included 30-day perioperative mortality and early graft loss (EGL) within 7 days. A subgroup analysis was performed for the EO donor group to assess how macrovesicular steatosis (MaS) >30% affects 30-day mortality and EGL within 7 days. A total of 72,616 patients underwent LT during the study period. The 30-day perioperative mortality was significantly higher in the EO donor group (P = 0.02). On multivariate analysis, recipients undergoing LT with EO donors had a 38% higher 30-day mortality risk (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.21-1.69) and 53% increased risk of EGL (OR, 1.53; 95% CI, 1.22-1.90). MaS >30% was independently associated with a 2-fold increased risk of 30-day mortality (P = 0.003) and 3.5-fold increased risk of EGL within 7 days (P < 0.001). The impact of MaS >30% in EGL was 2-fold for all patients transplanted during the study period compared with 3.5-fold in the EO donor group. There is an increased risk of EGL and 30-day perioperative mortality in recipients transplanted with EO donors. Future studies are warranted in morbid and super obese donors to assess the possible effect of obesity-related proinflammatory factors in EGL.

Alcohol-related cirrhosis is associated with high coronary artery calcium scores in patients undergoing evaluation for orthotopic liver transplantation.

BACKGROUND AND AIMS: Coronary artery disease is a major cause of morbidity and mortality in liver transplant patients. Coronary artery calcium (CAC) score has been used to evaluate the risk of CAD in non-cirrhotic patients. However, its significance in cirrhotic patients is unknown. This study aimed to identify factors associated with elevated CAC scores in patients with end-stage liver disease undergoing liver transplant evaluation. METHODS: We retrospectively reviewed all patients who underwent liver transplantation evaluation and had coronary CT scan between January 2015 and December 2018. Patients with prior history of CAD were excluded. CAC score was calculated based on the method described by Agatston. RESULTS: Sixty-two patients were included. 37.1% had alcohol-related liver disease and 27.4% had NASH cirrhosis. Mean CAC score was 261.1 ± SD, 463.84. Alcohol-related liver disease, male gender, and hypertension were significantly associated with CAC score >100 and only alcohol-related liver disease was associated with CAC score >300. In logistic regression, patients with alcohol-related liver disease had more than sixfold increase in risk of having CAC scores >100 and 300 (OR 6.14, and 6.70, respectively). CONCLUSION: Alcohol-related liver disease, male gender, and hypertension were significantly associated with an increased CAC score >100. However, alcohol-related liver disease was the only factor associated with CAC score >300.

Younger Age Is Associated with Improved Survival in Patients Undergoing Liver Transplantation Alone for Metastatic Neuroendocrine Tumors.

BACKGROUND: Neuroendocrine tumor (NET) metastases are a major cause of morbidity and mortality. The role of liver transplantation to treat unresectable metastases from NET is controversial. METHODS: We evaluated outcomes of all patients undergoing "isolated" liver transplantation (LT) for metastatic NETs in the USA, from October 1988 through June 2018 using the UNOS dataset. RESULTS: During the study period, 160,360 LTs were performed. Two hundred six adult patients underwent "isolated" LT for metastatic NETs. The mean (SD) age was 48.2 (11.7) years, ranging from 19 to 75 years; 117 (56.8%) patients were male. Overall 1-, 3-, 5-, and 10-year patient survival rates were 89.1%, 75.3%, 64.9%, and 46.1%, respectively. Tumor recurrence was seen in 70 of 206 patients who underwent LT (34%). The median time to recurrence was 28 months (range, 1 to 192 months) and median wait time for LT was 112 days. Tumor recurrence was significantly higher in transplanted patients waiting less than 6 months compared with those waiting more than 6 months (74.3% vs. 25.7%). Patients' age ≤ 45 years had significantly better survival compared with those > 45 years (p = 0.03). Younger patients with carcinoid tumors had better survival but this trend was not observed in the non-carcinoid group. On multivariable analysis, recipient age, donor age, cold ischemic time MELD score, and tumor recurrence were significant predictors of poor patient survival. CONCLUSIONS: Waiting time longer than 6 months is associated to lower rates of tumor recurrence. Younger patients ≤ 45 years had significantly improved survival after LT for NET metastases.

Mitochondrial uncoupling and the disruption of the metabolic network in hepatocellular carcinoma.

BACKGROUND: Hepatocellular Carcinoma (HCC) is the third most common cause of cancer related death worldwide. Adequate treatment options for patients with advanced HCC are currently limited. MATERIALS AND METHODS: We studied the anti-HCC effect of FH535 and a novel derivative Y3, on proliferation, mitochondrial function and cellular metabolism focusing on the three key substrates, glutamine, glucose, and fatty acids. RESULTS: FH535 and Y3 disrupted mitochondrial redox control in HCC cells that resulted from uncoupling mechanisms that increased proton leakage and decreased ATP production leading to apoptosis. The uncoupling effects of the sulfonamides in HCC cells were supported by the loss of activity of the methylated analogs. The accumulation of ROS significantly contributed to cell damage after the impaired autophagic machinery. These sulfonamides, FH535 and Y3, targeted glutamine and fatty acid metabolism and caused HCC cell reprograming towards the preferential use of glucose and the glycolytic pathway. CONCLUSIONS: FH535, and Y3, demonstrated potent anti-HCC activity by targeting OXPHOS, increasing dangerous levels of ROS and reducing ATP production. These sulfonamides target glutamine and FA metabolic pathways significantly increasing the cellular dependency on glycolysis.