Overall survival from tebentafusp versus nivolumab plus ipilimumab in first-line metastatic uveal melanoma: a propensity score-weighted analysis.

BACKGROUND: Tebentafusp demonstrated a superior overall survival (OS) benefit [hazard ratio (HR) 0.51] compared to investigator's choice (82% pembrolizumab) in a randomized, phase III trial (IMCgp100-202; N = 378) in untreated metastatic uveal melanoma (mUM). The 1-year OS rates for tebentafusp and pembrolizumab were 73% and 59%, respectively. In the single-arm GEM1402 (N = 52), the 1-year OS rate for nivolumab plus ipilimumab (N+I) in mUM was 52%. Due to limitations in conducting randomized trials in mUM, we compared OS on tebentafusp or pembrolizumab (IMCgp100-202) to N+I (GEM1402) in untreated mUM using propensity scoring methods. PATIENTS AND METHODS: Analyses were adjusted using propensity score-based inverse probability of treatment weighting (IPTW), balancing age, sex, baseline lactate dehydrogenase (LDH), baseline alkaline phosphatase, disease location, Eastern Cooperative Oncology Group status, and time from primary diagnosis to metastasis. OS was assessed using IPT-weighted Kaplan-Meier and Cox proportional hazard models. Sensitivity analyses using alternative missing data and weights methods were conducted. RESULTS: The primary IPTW analysis included 240 of 252 patients randomized to tebentafusp from IMCgp100-202 and 45 of 52 N+I-treated patients from GEM-1402. Key baseline covariates, including LDH, were generally well balanced before weighting. The IPTW-adjusted OS favored tebentafusp, HR 0.52 [95% confidence interval (CI) 0.35-0.78]; 1-year OS was 73% for tebentafusp versus 50% for N+I. Sensitivity analyses showed consistent superior OS for tebentafusp with all IPTW HRs ≤0.61. IPTW analysis of pembrolizumab versus N+I showed no significant difference in OS (HR 0.72; 95% CI 0.50-1.06). CONCLUSIONS: Tebentafusp was previously shown to provide an OS benefit compared to checkpoint inhibitors or chemotherapy in untreated mUM. Propensity score analysis demonstrated a similar OS benefit for tebentafusp compared with N+I. These data further support tebentafusp as the standard of care in previously untreated human leukocyte antigen (HLA)-A∗02:01+ adult patients with mUM.

Micro RNA expression profiles as adjunctive data to assess the risk of hepatocellular carcinoma recurrence after liver transplantation.

Donor livers are precious resources and it is, therefore, ethically imperative that we employ optimally sensitive and specific transplant selection criteria. Current selection criteria, the Milan criteria, for liver transplant candidates with hepatocellular carcinoma (HCC) are primarily based on radiographic characteristics of the tumor. Although the Milan criteria result in reasonably high survival and low-recurrence rates, they do not assess an individual patient's tumor biology and recurrence risk. Consequently, it is difficult to predict on an individual basis the risk for recurrent disease. To address this, we employed microarray profiling of microRNA (miRNA) expression from formalin fixed paraffin embedded tissues to define a biomarker that distinguishes between patients with and without HCC recurrence after liver transplant. In our cohort of 64 patients, this biomarker outperforms the Milan criteria in that it identifies patients outside of Milan who did not have recurrent disease and patients within Milan who had recurrence. We also describe a method to account for multifocal tumors in biomarker signature discovery.

Analysis of cell viability using time-dependent increase in fluorescence intensity.

We report the use of resazurin (AlamarBlue) dye in a robust assay for cell viability of primary cells. Human mononuclear cells were used here for immunological studies, but the method can be applied to monitor reduction potential of any living cell. Reduction of AlamarBlue dye is widely used in several commercial assays of cell viability. Although it is fast and easy with immortal cell lines, the method is impractical for the primary cells due to their slower metabolic activity. We propose that the viability of human primary cells can be determined with AlamarBlue by monitoring the increase in fluorescence intensity in a matter of a few hours. In the presence of AlamarBlue, the dynamic increase in cellular reduction capacity is linear for several hours or, alternatively, the assay can be repeated to monitor the viability at any time point of cell culture. In addition to testing cellular growth rates and cytotoxicity, the application can be used to compare sample quality of cells that have been frozen or represent a pool of multiple donors. This application of the AlamarBlue cell viability assay is simple, rapid, and cost-effective, and therefore it is also well suited for high-throughput studies.

Modulation of the uptake and metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by nicotine in hamster lung.

The tobacco-specific carcinogenic nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is formed during the curing and processing of tobacco by nitrosation of nicotine. Nicotine and NNK have structural similarities, and they are both metabolized extensively by lung tissue via several steps known to require oxidative enzyme systems, such as cytochrome P450. On the other hand, nicotine exerts many biological effects similar to those caused by the physiological neurotransmitter acetylcholine, a phenomenon mediated through selective uptake mechanisms via nicotinic cholinergic cell membrane receptors. The aim of this study was to determine if nicotine modulates NKK metabolism in hamster lung explants and if NNK competes with nicotine for binding sites on nicotinic cholinergic receptors in the hamster lung in vivo. Our data show a concentration-dependent inhibition of NNK metabolism in vitro by alpha-carbon hydroxylation and pyridine N-oxidation, whereas the carbonyl reduction of NNK remained unchanged. Radioreceptor assays with membrane receptor fractions of hamster lung after exposure to radiolabeled (S)-(-)-nicotine revealed significant numbers of nicotinic binding sites only in the lungs of hamsters with hyperplasia of pulmonary neuroendocrine cells caused by 4-wk preexposure to hyperoxia. In such animals, radiolabeled nicotine was displaced from the receptor binding sites by NNK. Our data suggest that nicotine can potentially interfere with the carcinogenicity of NNK by competition for enzyme systems essential for the metabolic activation of the nitrosamine and by competition as ligand for nicotinic cholinergic receptors.

Beta-adrenergic mitogenic signal transduction in peripheral lung adenocarcinoma: implications for individuals with preexisting chronic lung disease.

Peripheral adenocarcinoma (PAC) of the lung has increased dramatically over the last 20 years and is today the leading histological type of lung cancer in smokers and nonsmokers in industrialized countries. There is no apparent explanation for the steep rise in the number of individuals developing this cancer type. Using assays for the assessment of cell proliferation, receptor binding, and production of cyclic AMP (cAMP), we have identified a beta-adrenergic receptor-mediated mitogenic pathway, which activates cAMP down-stream, in cell lines derived from human peripheral adenocarcinomas that express features of Clara cells. Agonists of beta-adrenergic receptors strongly stimulated cell proliferation, whereas antagonists of this receptor and its associated second messenger, cAMP, were potent inhibitors of this effect. Agonists of beta-adrenergic receptors are the active ingredients of many decongestants and bronchodilators, and such medications are, therefore, likely to stimulate this pathway in vivo. Patients suffering from chronic upper and lower respiratory tract diseases and treated with such medications over many years may, therefore, be at a higher risk than the average population to develop PAC, particularly when simultaneously exposed to carcinogenic environmental factors such as smoking. Because the incidence of chronic respiratory tract diseases has risen in industrialized countries during the same time frame as PAC, a potential etiological link between the therapy of such nonneoplastic diseases with beta-adrenergic agonists and the risk for PAC should be investigated.

Successful chemotherapy of experimental neuroendocrine lung tumors in hamsters with an antagonist of Ca2+/calmodulin.

The chemotherapeutic effect of B859-35, the (-)-enantiomer of dihydropyrine 3-methyl-5-3-(4,4-diphenyl-1-piperidinyl)-propyl-1,4-dihydro-2,6-dimethy l-4- (3-nitrophenyl)-pyridine-3,5-dicarboxylate-hydrochloride (niguldipine), was tested on tumors induced in Syrian golden hamsters by N-nitrosodiethylamine (DEN). Peripheral pulmonary adenomas/adenocarcinomas were induced in hamsters maintained under ambient air conditions by multiple s.c. injections of DEN for 20 weeks. We have reproducibly shown that within this time interval lung adenomas develop in a significant number of the animals. The carcinogen treatment was discontinued at this point and one group of these hamsters was given B859-35 intragastrically 5 days/week for 20 weeks while the second group of such tumor-bearing hamsters were kept for an identical time interval without further treatment. Neuroendocrine lung tumors were induced in hamsters maintained in an atmosphere of 60% O2 by multiple s.c. injections of DEN for 8 weeks. We have reproducibly shown that within this short time interval neuroendocrine lung tumors develop in a significant number of the animals. The carcinogen treatment was discontinued at this point and the animals were returned to ambient air conditions. One group of these tumor-bearing hamsters was then given B859-35 intragastrically 5 days/week for 20 weeks while a second group of these hamsters was kept untreated for an identical time interval. A control group was given s.c. injections of saline for 20 weeks under ambient air conditions. A dramatic and selective anticarcinogenic effect of B859-35 was observed on the neuroendocrine lung tumors and nasal cavity tumors induced by DEN/hyperoxia while tumors of larynx/trachea were not affected. B859-35 had no effect on peripheral adenomas/adenocarcinomas, nasal cavity tumors, papillary polyps of larynx/trachea, or liver tumors induced by DEN under ambient air conditions.

Case Report Demonstrating the Safe and Effective Means of Expanding the Donor Pool With Livers Recovered From Brain-Dead Donors After Ethylene Glycol Toxicity.

The growing disparity between organ supply and demand has become the greatest hurdle facing transplant professionals and life-saving transplants. Because the organ shortage has become the rate-limiting step to effective transplants, it is critical for the transplant community to identify viable mechanisms to expand the donor pool and use every available allograft. Although using kidneys from deceased donors whose demise was secondary to ethylene glycol (EG) toxicity requires great deliberation and precise timing as described by Barbas et al [5], using hepatic allografts in this setting involves far less risk. The following is a discussion of a 61-year-old male who was diagnosed with end-stage liver disease secondary to non-alcoholic steatohepatitis and ultimately underwent a life-saving transplant with a liver recovered from a donor with EG-induced brain death and allocated nationally due to trepidation by local and regional centers to use the liver from a donor after EG toxicity.

Reversal of mesangial enlargement in rats with long-standing diabetes by whole pancreas transplantation.

An important unanswered question about clinical use of pancreas transplantation is: can pancreas transplants reverse or, at least, stabilize well-established lesions of insulin-dependent diabetes mellitus (IDDM)? To answer this question, we performed whole pancreas transplantations in 190 highly inbred rats 6, 9, 12, 15, 18, and 21 mo after induction of diabetes mellitus (DM) with alloxan. We then studied the effect on renal mesangial enlargement (ME) for 24 mo after onset of DM by a quantitative morphologic technique in which camera lucida tracings of the mesangium were made at X 1250 and were analyzed using an electronic planimeter connected to a calculator/computer. A pretransplant kidney biopsy was obtained so that the rats served as their own controls. In addition, studies were performed for 28 mo in 57 untreated diabetic controls and in 55 nondiabetic controls. Monthly metabolic studies showed that whole pancreas transplantation maintained very tight, lifelong metabolic control of diabetes. Kidney sections obtained for 2 yr from diabetic controls and for 21 mo from diabetic rats before transplantation showed highly significant increases in total mesangial area, nuclear-free mesangial area, and percentage of glomerular area occupied by nuclear-free mesangial area. Pancreas transplantation consistently produced a highly significant reversal of well-established ME, regardless of when it was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival outcome after hepatic retransplantation for hepatitis C virus-positive and -negative recipients.

INTRODUCTION: Hepatitis C virus (HCV)-related liver disease is the most common indication for liver transplantation in the United States. Recurrence of HCV infection in these recipients is almost uniform. The currently available antiviral treatment is known to cause significant side effects, and the rate of sustained viral response is low. There is still controversy about whether such patients should undergo subsequent transplantations for HCV disease. This study compared outcomes for hepatic retransplantation performed in HCV(+) and HCV(-) recipients at a single center. PATIENTS AND METHODS: From December 1994 through November 2003, 68 patients at our institution received a second liver allograft. Nineteen of the recipients were HCV(+) (group A) and 49 were HCV(-) (group B). All patients were followed until January 2004. The mean follow-up time after initial retransplantation was 37 +/- 29 months. Patient and graft survival for the two groups were compared. RESULTS: Seven recipients in group A (36.8%) and 22 recipients in group B (44.9%) died during follow-up. The actuarial 3-year patient survival after initial retransplantation for groups A and B were 61.7% and 51.6%, respectively. Nine patients required a second retransplantation, 3 (15.8%) in group A and 6 (12.2%) in group B. The actuarial 3-year graft survival from initial retransplantation for groups A and B were 56.3% and 45.7%, respectively. CONCLUSION: We observed slightly better patient and graft survivals at 3 years from initial retransplantation in HCV(+) recipients compared to HCV(-) recipients. This may be due to younger donor age and better selection of HCV(+) recipients in this series.

Transplantation of liver grafts from older donors: impact on recipients with hepatitis C virus infection.

INTRODUCTION: Older donor allografts are being accepted for liver transplantation (LTx) due to shortage of organs. Hepatitis C virus (HCV) infection-related disease is presently the most common indication of LT in the United States. We studied the impact of donor age on patient and graft survivals in patients with HCV infection. PATIENTS AND METHODS: One hundred fifty four consecutive HCV(+) LTx recipients (117 men, 37 women) were studied. The mean follow-up period was 41.0 +/- 30.2 months. The population was divided into four groups according to donor age: group I (< or =20 years); group II (21 to 40 years); group III (41 to 60 years); group IV (>60 years). RESULTS: Thirty-two (20.8%) patients died during follow-up and 16 patients (10.4%) required retransplantation. The actuarial 7-year patient survivals for groups I, II, III, and IV were 87.1%, 73.7%, 69.3%, and 68.5%, respectively (P = .4). Patient survivals for donor age groups III + IV (n = 95) and groups I + II (n = 59) were 68.9% and 77.2%, respectively (P = .19). The 7-year graft survivals for groups I, II, III, and IV were 82.7%, 71.8%, 65.8%, and 62.5%, respectively (P = .17). Graft survivals for groups III + IV and groups I + II were 58.4% and 76.2%, respectively (P = .03). CONCLUSION: Patient and graft survivals for HCV-positive liver transplant recipients in this study decreased progressively as the donor age increased. Patient and graft survivals were best for group I recipients. There were significant differences in graft survivals when recipients were grouped with a cutoff donor age of 40 years.

Change in oral absorption of tacrolimus in a liver transplant recipient after reversal of jejunoileal bypass: case report.

INTRODUCTION: Jejunoileal bypass (JIB) was, at one time, a popular surgical technique for the treatment of morbid obesity. However, this operation was also associated with major complications. Consequently, many such procedures were eventually reversed. One of the most serious of these complications was liver failure. For those patients who developed cirrhosis, liver transplantation was one therapeutic alternative. Tacrolimus is one of the primary immunosuppressive agents used in liver transplantation. It is effective to prevent acute rejection episodes, but shows a narrow therapeutic index and can cause nephrotoxicity and neurotoxicity. This report describes the change in tacrolimus absorption that was observed after JIB reversal in a 57-year-old female liver transplant recipient. RESULTS: Prior to JIB reversal, the mean tacrolimus dose was 7 mg twice daily with a whole-blood tacrolimus concentration ranging from 5.2 to 6.4 ng/mL. There was no appreciable peak in tacrolimus concentration, and the area under the concentration-time curve (AUC) was 10.9 ng/mL/h. After reversal, the daily tacrolimus dose was decreased to 5 mg twice daily, with a now-discernable peak concentration at 3 hours postdose. Furthermore, the AUC increased 90% to 20.7 ng/mL/h. CONCLUSION: After JIB reversal, the patient showed higher systemic levels of tacrolimus and required lower steady-state doses. It is therefore imperative that such patients be monitored closely to avoid tacrolimus-related toxicity.

Use of hepatitis B core antibody-positive liver allograft in hepatitis C virus-positive and -negative recipients with use of short course of hepatitis B immunoglobulin and Lamivudine.

INTRODUCTION: With the shortage of donor organs, increasing number of hepatitis B core antibody (HBcAb)-positive [HBcAb(+)] liver allografts are being used for liver transplantation (LTx) in patients who are HBcab-negative [HBsAb(-)]. This study was aimed at assessing outcomes for hepatitis C virus (HCV)-positive [HCV(+)] and HCV-negative [HCV(-)] patients who received HBcAb(+) liver grafts from deceased donors and also received a short course of hepatitis B immunoglobulin (HBIg) with long-term lamivudine therapy after LTx. MATERIALS AND METHODS: From February 1995 through February 2003, 28 patients (mean age 53.8 +/- 10.2 years, 19 men and nine women, 16 HCV[-]; 12 HCV[+]) received HbcAb(+) liver allografts. All recipients received a short course of HBIg prophylaxis (10,000 units/day for 4 days) and long-term lamivudine 100 mg/d after LTx in addition to a tacrolimus-based immunosuppressive regimen. RESULTS: Seven (25%) of the 28 recipients died during follow-up and three recipients required retransplantation. Three recipients (10.7%) developed HBV infection during follow-up, one of whom died 36 months after LTx and the other two had YMDD mutant HBV. The overall 6-year actuarial patient survival after transplantation was 74.4% and those for HCV(-) and HCV(+) recipients were 81.3% and 66.6%, respectively (P = .46). The overall 6-year actuarial graft survival was 63.9% and those for HCV(+) and HCV(-) recipients were 68.8% and 57.1%, respectively (P = .6). CONCLUSION: We conclude that HBcAb(+) liver grafts can be used for both HCV(+) patients and HCV(-) patients who are critically ill, have early hepatocellular carcinoma, or have been exposed to HBV in the past. A short course of HBIg-lamivudine combination therapy provides effective prophylaxis against HBV infection in 89% of recipients of HBcAb(+) grafts.

Does valganciclovir hydrochloride (valcyte) provide effective prophylaxis against cytomegalovirus infection in liver transplant recipients?

INTRODUCTION: Cytomegalovirus (CMV) infection after solid organ transplantation is one of the most common viral infections, causing significant morbidity and mortality if not treated promptly. Ganciclovir has proven to be effective for the prophylaxis and treatment of CMV. However, oral absorption of ganciclovir is poor. Recently, oral administration of valganciclovir hydrochloride (Valcyte) has been observed to display 10-fold better absorption than oral ganciclovir. Valganciclovir has increasingly been used as prophylaxis against CMV after solid organ transplantation. The purpose of this study was to examine the efficacy of valganciclovir prophylaxis therapy after primary liver transplantation. PATIENTS AND METHODS: Between July 2001 and May 2003, 203 consecutive liver transplant recipients, including 129 men and 74 women of overall mean age 53 +/- 11 years, received valganciclovir (900 mg/d or 450 mg every other day depending on renal function) for 3 to 6 months after primary liver transplantation. All patients were followed up for a minimum of 6 months. Mean follow-up was 19 +/- 5.8 months. CMV DNA in peripheral blood was tested using polymerase chain reaction (PCR) amplification. Symptomatic CMV was stratified according to the CMV immunoglobulin (Ig)G status of the donor and recipient at the time of liver transplantation. Donors and recipients were classified preoperatively into groups according to the presence or absence of CMV as follows: group 1 (n = 73; donor CMV+, recipient CMV+); group 2 (n = 41; donor CMV-, recipient CMV+); group 3 (n = 54; donor CMV+, recipient CMV-; high-risk group); and group 4 (n = 35; donor CMV-, recipient CMV-). RESULTS: Twenty-nine patients (14.3%) developed symptomatic CMV disease at 169 +/- 117 days after liver transplantation: group 1, 16.4% versus group 2, 7.3% versus group 3, 25.9% versus group 4, 0%. Of these patients, 5 also had invasive CMV on liver biopsy, which was performed owing to abnormal liver functions. All 29 patients were treated with intravenous ganciclovir. One patient died owing to disseminated CMV, whereas the remaining 28 patients responded to treatment. Interestingly, 8 patients, including 1 who had invasive CMV hepatitis, developed symptomatic CMV within 90 days of liver transplantation even while on prophylactic valganciclovir. CONCLUSION: Valganciclovir failed to provide adequate prophylaxis following liver transplantation in our patients. The overall rate of CMV in seropositive donors and/or recipients was 17%, and in the high-risk group was 26%. Further prospective studies with measurement of ganciclovir concentrations are needed to elucidate the reasons for this unexpected failure.

Alloxan diabetic neuropathy: electron microscopic studies.

Peripheral nerves of diabetic rats were studied 2 years after alloxan injection. We observed demyelination and remyelination, axonal degeneration and regeneration, reduplication of basal laminae around vessels and Schwann's cells, as well as onion bulb formation by proliferated Schwann's cells. Crystalline deposits composed of aggregates of fibrillary electron dense material often occurred in vessel walls and endoneurium of diabetic animals but rarely were seen in nerves from age-matched control animals. Glycogen accumulated in myelinated and unmyelinated axons within mitochondria. Axoplasmic inclusions resembling Lafora's bodies and the inclusions of glycogenosis type IV were frequent and often were accompanied by deposits of particulate glycogen. The findings suggest that the neuropathy in alloxan diabetes is caused by metabolic impairment of anxons, Schwann's cells, and vessels, leading to segmental demyelination and axonal degeneration.

Comparison of the metabolic control of diabetes achieved by whole pancreas transplantation and pancreatic islet transplantation in rats.

To compare the long-term effectiveness of whole pancreas transplantation and pancreatic islet transplantation in controlling the metabolic disorders of alloxan diabetes, metabolic studies were performed monthly for 2 years in 4 groups of highly inbred rats: (1) NC-116 nondiabetic controls; (2) DC-273 untreated alloxan-diabetic controls; (3) PDT-182 rats that received syngeneic pancreaticoduodenal transplants shortly after induction of diabetes with alloxan; and (4) IT-92 rats that received an intraportal injection of at least 1500, but usually 2000, syngeneic pancreatic islets shortly after induction of diabetes with alloxan. Whole pancreas transplantation maintained strict metabolic control throughout the 2 years of study. In group PDT, hyperglycemia was abolished; plasma glucose concentration was maintained tightly within the normal range; markedly depressed plasma insulin levels were raised to above normal; glucose tolerance tests had insulin levels above normal and glucose levels that increased less and declined more rapidly than normal; and body weight gain and growth approached normal. In contrast, pancreatic islet transplantation failed to maintain precise metabolic control. In group IT, plasma glucose concentration initially fell to normal but then was elevated significantly above normal beginning with the 3rd posttransplant month; plasma insulin level declined progressively after the 6th posttransplant month; glucose tolerance tests had a diabetic glucose tolerance curve as a result of a markedly deficient plasma insulin response; and body weight gain and growth were significantly less than in group PDT. The results of these long-term metabolic studies may explain the effectiveness of whole pancreas transplantation and the ineffectiveness of pancreatic islet transplantation in preventing diabetic nephropathy.

Lifelong reversal of the metabolic abnormalities of advanced diabetes in rats by whole-pancreas transplantation.

Evidence suggests that metabolic abnormalities are responsible for the widespread microvascular complications of insulin-dependent diabetes mellitus (IDDM). Interest in endocrine pancreas replacement therapy, including pancreas transplantation, is based on the hope that such treatment will reverse the complications of IDDM by providing more precise metabolic control than conventional therapy. To determine if whole pancreas transplantation is capable of reversing well-established metabolic abnormalities of diabetes mellitus (DM) and maintaining strict metabolic control for life, we performed monthly metabolic studies for 2 years in 141 nondiabetic control rats, 273 diabetic control rats with alloxan-induced DM, and 267 diabetic rats that received syngeneic whole pancreaticoduodenal transplants 6, 9, 12, 15, 18, and 21 months after induction of DM with alloxan. Whole-pancreas transplantation in rats with long-standing DM permanently reversed the metabolic disorders. Elevated plasma glucose concentrations were permanently reduced to normal, depressed plasma insulin levels were permanently increased to normal, elevations of BUN and serum creatinine were permanently normalized, and there was a striking gain in body weight. Hyperglycemia during glucose tolerance tests was of lesser magnitude and shorter duration than normal, as a result of greater-than-normal plasma insulin levels. The only abnormality that persisted was hyperglucagonemia, but it did not interfere with control of hyperglycemia and is of unknown significance. These results indicate that whole-pancreas transplantation produces the most complete and sustained correction of the metabolic abnormalities of experimental DM of any available therapeutic modality.

En bloc transplantation of liver, pancreas, duodenum, and spleen in the rat. Description of technique and histological findings.

En bloc transplantation involving liver, spleen, pancreas, and duodenum was successfully carried out in the rat. While operative mortality due to technical failure was 31%, of those that survived over 95% of the isografts had normal histology up to 4.5 months. Rejection reaction in the allografts first appeared in the liver and the spleen, followed by the pancreas and the duodenum, and was complete by day 14. No gross evidence of graft-versus-host reaction was observed.

A simplified model for heterotopic rat heart transplantation.

A technique for simplified heterotopic rat heart transplantation having only aorto-aortic anastomosis is presented. The heterotopic rt heart survives and functions well when one lung lobe is attached t the transplantation and functions as a reservoir. Iso- and allotransplants are compared by electrocardiogram (ECG) determination and histological examination. Isotransplants exhibited normal heart and lung throughout the 6-month observation period. allotransplants ceased to function by the 16th postoperative day, with the cessation of palpable heart beat over the abdominal wall by the 10th postoperative day. This simplified heterotopic rat heart transplantation model can be operated by nonsurgeons in an unhurried manner with minimal training in microvascular surgery, and can be applied to various transplantation immunological studies.

Prevention of chronic rejection and graft arteriosclerosis by tolerance induction.

Chronic rejection is a major cause of graft failure in solid organ transplants after the first year. A characteristic lesion in a variety of chronically rejecting organs is a fibrointimal proliferative arteriosclerosis. It has been speculated that approaches to tolerance induction may be effective in obviating not only acute, but also chronic, rejection. A picture of chronic rejection develops naturally in heart grafts transplanted from the Lewis-to-F-344 strain of rat. We examined whether tolerance induction by bone marrow transplantation and development of hematopoietic chimerism or tolerance induction by intrathymic inoculation of alloantigen could effectively prevent chronic rejection in an established model of chronic rejection. Bone marrow chimeras were developed in F-344 hosts by transplantation of T cell-depleted allogeneic marrow (TCD A BMT). Another set of F-344 hosts was inoculated with intrathymic allogeneic bone marrow cells. Heart grafts in these animals demonstrated tolerance for 120 days after transplantation. Control F-344 animals treated with a short course of cyclosporine consistently developed chronic rejection by 120 days following heart transplantation. Strikingly absent from the tolerant animals was any sign of graft arteriosclerosis, which was demonstrated in the vast majority of control animals. Analysis of cytokine mRNA profiles at 30 days following heart transplantation demonstrated differences between control and tolerant animals. These results suggest that tolerance induction can effectively prevent chronic rejection.

Tolerance induced by bone marrow chimerism prevents transplant vascular sclerosis in a rat model of small bowel transplant chronic rejection.

BACKGROUND: The major impediment to success in solid organ transplantation is chronic rejection (CR). The characteristic lesion of CR is transplant vascular sclerosis (TVS). Although the mechanism of TVS is thought to have an immunologic basis, in humans immunosuppression does not prevent or reverse it. One possible therapy to prevent TVS is induction of donor-specific tolerance. Bone marrow chimerism has been successful in inducing tolerance in acute and chronic rejection heart and kidney transplant models. The highly immunogenic small bowel (SB) allograft provides a rigorous test of the efficacy of this tolerance regimen. We examined whether induction of tolerance by bone marrow chimerism could prevent TVS in a model of Fisher 344 (F344) to Lewis (LEW) rat SB transplantation. METHODS: Bone marrow chimeras (BMC) were created by transplantation of T-cell-depleted F344 bone marrow into irradiated LEW rats. Chimerism was assessed by flow cytometric method. F344 SB, heterotopically transplanted into the chimeras, was clinically and histologically assessed for CR. F344 SB grafts, transplanted into cyclosporine-A-treated LEW recipients, served as control grafts for CR. RESULTS: Cyclosporine-A-treated LEW rats chronically rejected F344 SB grafts. By contrast, the BMC group demonstrated tolerance and had long-term SB graft survival (>120 days) without TVS. The BMC demonstrated immunocompetence by prompt rejection of third party ACI (RT1av1) SB allografts. CONCLUSIONS: Bone marrow chimerism prevents chronic graft failure secondary to TVS in a model of chronic SB rejection. TVS fails to develop when tolerance is established, suggesting that the mechanisms involved in TVS are, in part, immunologically mediated.