Portal Hypertension in Children: A Tertiary Center Experience in Turkey.

Purpose: Portal hypertension (PH) and its complications have a significant impact on morbidity and mortality. This study aimed to evaluate the etiology; clinical, laboratory, and endoscopic findings; treatment approaches; long-term outcomes; and prognosis of pediatric PH. Methods: This retrospective study included 222 pediatric patients diagnosed with PH between 1998 and 2016, and data encompassing clinical, laboratory, and radiological features; treatments; and complications were analyzed. Results: The most common causes of PH were portal vein thrombosis (20.3%), progressive familial intrahepatic cholestasis (18.9%), and biliary atresia (12.2%). Among the enrolled patients, 131 (59.0%) were included in the cirrhotic group and 91 (41.0%) in the non-cirrhotic group. Hepatomegaly and increased transaminase levels were more frequent in the cirrhotic group than in the non-cirrhotic group. Additionally, portal gastropathy, esophageal varices, and variceal bleeding were more frequent in the non-cirrhotic group, whereas ascites, hepatopulmonary syndrome and hepatic encephalopathy were more common in the cirrhotic group. The incidence of hepatomegaly was higher in the presinusoidal group than in the prehepatic group (p<0.001). Hyperbilirubinemia was more frequent in the prehepatic group (p=0.046). The frequency of esophageal varices was similar between the prehepatic and presinusoidal groups; however, variceal bleeding was more frequent in the prehepatic group (p=0.002). Conclusion: Extrahepatic portal vein obstruction, genetic-metabolic diseases, and biliary atresia were the most prevalent causes of PH in our country. In patients with PH, hepatomegaly, increased transaminase levels, and synthesis dysfunction were suggestive of cirrhotic PH. Notably, PH in patients without cirrhosis might be more severe than that in those with cirrhosis.

Long-Term Outcomes of Patients With Progressive Familial Intrahepatic Cholestasis After Biliary Diversion.

OBJECTIVES: Progressive familial intrahepatic cholestasis is a heterogeneous group of genetic disorders characterized by disrupted bile homeostasis. Patients with this disease typically present with cholestasis and pruritus early in life and often progress to end-stage liver disease. The clinical symptoms that patients with progressive familial intrahepatic cholestasis encounter are usually refractory to medical treatment. Although the effects of biliary diversion surgery on native liver survival are not exactly known, this procedure may provide a positive impact on pruritus and laboratory parameters in these patients. MATERIALS AND METHODS: We retrospectively evaluated the clinical and laboratory characteristics of patients with progressive familial intrahepatic cholestasis who underwent partial external biliary diversion between 2002 and 2020 at our center. Diagnosis of progressive familial intrahepatic cholestasis was made by clinical, biochemical, and histopathological characteristics as well as genetic testing. RESULTS: Nine patients were included in the study. Five patients required liver transplant during follow-up, with 4 having liver transplant as a result of endstage liver disease (median interval of 5 years). In 1 patient, partial external biliary diversion was performed 1.5 years after liver transplant for severe diarrhea, metabolic acidosis, and hepatic steatosis. Four patients did not require liver transplant during follow-up (median follow-up time of 7.6 years). Pruritus responded well to partial external biliary diversion in all patients. Among laboratory values evaluated 6 months after biliary diversion, only albumin showed significant improvement. CONCLUSIONS: Partial external biliary diversion had favorable results on long-term follow-up. This procedure can provide the relief of pruritus and delay the requirement for liver transplant in patients with progressive familial intrahepatic cholestasis. In our view, partial external biliary diversion should be considered the first-line surgical management for patients with this disease.

Kidney transplantation from elderly donors: single-center experience / Trasplante renal de donantes añosos: experiencia de un centro

ABSTRACT Introduction: The shortage of deceased donor kidneys for transplantation has forced the re-evaluation of the limits on donor age acceptability. Thus, marginal donors such as elderly donors have been progressively increasing in recent years for organ transplantation around the world. Aim: In this study, it was aimed to contribute to the elimination of question marks about the using elderly donors for kidney transplantation. Methods: In this retrospective cohort study, prospectively recorded data of patients who underwent kidney transplantation between January 1996 and January 2020 were evaluated. The inclusion criteria for the study were deceased or living donor, donor aged 55 years and older. Results: Of the total 392 kidney transplantation, 64 donors met the study criteria. The mean age of the donors was 59 ± 3.86 years (range, 55-69). Twenty-one (87.5%) out of 24 deceased donors and 1 (2.5%) living related recipients presented DGF. There was no mortality in the living donors. Overall, 1, 5, 10 years of recipient and graft survivals for this study 91%, 88%, 81% and 84%, 82%, 75%, respectively. Same rates for living donor 96%, 96%, 96% and 90%, 88%, 80%, respectively, and for deceased donor 81%, 74%, 70% and 78%, 74%, 67%, respectively. Conclusion: Transplantation from the donors with age 55 and up, might be related to decreased kidney function and graft survival, compared to the transplantations from the standard donors. However, when the long-term graft survival and patient survival is observed, the group of elderly donors cannot be subject to exclusion.

RESUMEN Introducción: La escasez de riñones de donantes fallecidos para trasplante ha obligado a reevaluar los límites de aceptabilidad de la edad de los donantes. Así, los donantes marginales como los donantes de edad avanzada han ido aumentando progresivamente en los últimos años para el trasplante de órganos en todo el mundo. Objetivo: En este estudio se buscó contribuir a la eliminación de interrogantes sobre el uso de donantes ancianos para trasplante renal. Material y métodos: En este estudio de cohorte retrospectivo, se evaluaron datos registrados prospectivamente de pacientes que se sometieron a trasplante renal entre enero de 1996 y enero de 2020. Como criterio de inclusión para el estudio se tomó la edad de los donantes y se incluyeron aquellos donantes mayores de 55 años tanto fallecidos como vivos relacionados. Resultados: Del total de 392 trasplantes renales, 64 donantes cumplieron con los criterios del estudio. La edad media de los donantes fue de 59 ± 3,86 años (rango, 55-69). Veinte y un receptorde 24 donantes fallecidos (87,5%) y solo un receptor de donante vivo relacionado (2,5%)presentaron DGF. No hubo mortalidad en los donantes vivos. En términos generales, la supervivencia del receptor y del injerto a 1, 5 y 10 años en este estudio fue de 91 % - 88 %, 81 % - 84 % y 82 % - 75 %, respectivamente. Se observaron las tasas similares para donante vivo 96%- 96%, 96% - 90% y 88% - 80%, respectivamente, y para donante fallecido 81% - 74%, 70% - 78%y 74% - 67%, respectivamente. Conclusión: El trasplante de riñones provenientes de donantes de 55 años en adelante, podría estar relacionado con la disminución de la función renal y la supervivencia del injerto, en comparación con los trasplantes de los donantes estándar. Sin embargo, cuando se observa la supervivencia del injerto a largo plazo y la supervivencia del paciente, el grupo de donantes de edad avanzada no puede ser objeto de exclusión.

Surgical Complications After Deceased Donor Renal Transplant.

OBJECTIVES: Deceased donor renal transplant is an accepted treatment for patients with end-stage renal disease. We retrospectively analyzed urological and surgical complications and outcomes in our series. MATERIALS AND METHODS: Since 2016, we have performed 263 renal transplants at the Gazi University Transplantation Center, Ankara, and 92 of these were from deceased donors. We retrospectively analyzed outcomes of these 92 deceased donor transplants from our database records. There were 45 female and 47 male recipients, and 20 were pediatric recipients. Mean recipient and donor ages were 36 ± 14 and 38 ± 18 years old, respectively. Immunosuppression therapy consisted of steroids, mycophenolate, and calcineurin inhibitors. Induction therapy was 20 mg basiliximab (Simulect) on day 0 and day 4. Antithymocyte globulin (2 mg∕kg) was used in steroid-resistant acute rejection cases. RESULTS: There were 13 surgical complications (14.1%) after 92 consecutive deceased donor renal transplants, and 4 of these were classified as miscellaneous surgical complications. Four of 9 cases were early, and the rest were classified as late complications. Postoperative early complications were bleeding (n = 2), urine leak (n = 1), and renal artery thrombosis (n = 1). Lymphoceles (n = 4) and urine leak (n = 1) occurred as late complications. Postoperative median follow-up was 78 months, during which 11 grafts (12%) were lost and 7 patients (7.6%) died from sepsis (n = 4), myocardial infarction, aortic dissection, and fungal pneumonia. No patients died from any surgical complications. The 1-year, 5-year, and 10-year survival rates of patients were 98%, 94%, and 94% and for grafts were 97%, 94%, and 88%, respectively. CONCLUSION: Despite the limited number of deceased donor organs, improvements of surgical techniques at our center have facilitated success with deceased donor renal transplant at rates similar to other successful centers in the world.

First Reported Case of Echinococcal Disease on a Renal Graft Successfully Treated With Albendazole.

Echinococcal disease is an endemic disease for eastern Mediterranean countries. Various types of kidney involvement have been reported. Here, we report the first case of echinococcal disease on a transplanted kidney in a patient who was successfully treated with albendazole alone. The patient (a 38-year-old female) was evaluated for elevated creatinine levels 7 months after receiving a living-donor allograft. Standard immunosuppression therapy protocols were applied. Tacrolimus level was normal, and the patient was compliant with treatment. Creatinine level was 1.91 mg/dL (baseline: 1.2 mg/dL); proteinuria level was 1300 mg/day. The graft was found to be normal, as evaluated with standard sonographic methods. A kidney biopsy was performed, which showed that part of the cortical parenchyme was infiltrated by echinococcal protoscolices with hooklets. Because there were no cysts present on the graft, we concluded that disease was at an early stage. The patient was given albendazole for 3 months. After therapy, all echinococcal structures disappeared. Her creatinine level dropped to baseline, and proteinuria resolved. Echinococcal disease can affect transplanted kidneys. Albendazole is a valuable treatment option for patients who are not candidates for surgical resection.

Evaluation of patients with lympocele after renal transplantation / Evaluación de pacientes con linfocele luego de trasplante renal

Abstract Introduction: The lymphocele is a common complication following renal transplantation and may cause significant clinical problems especially when reachs to big volumes. The aim of this study is to present the clinical characteristics, diagnostic approaches, and therapeutic strategies of lymphocele formations in a group of Turkish patients. Methods: A total of 244 renal transplantations were included in this retrospective study. Data of patients who were diagnosed with lymphocele during the postoperative period were analyzed. Results: Ten (2.4%) patients have been diagnosed with lymphocele. There were six males and 4 females, with a mean age of 46 years. The median onset was 19 days posttransplantation. The median size of the lymphoceles was 53 mm. All lymphoceles were localizated between the lower pole of the transplanted kidney and urine bladder. On presentation, one patient had hydronephrosis and three patients had elevated serum creatinine while the remaining six ones were asymptomatic. Five patients were successfully treated by percutaneous aspiration whereas two patients required surgery. Three patients' lymphoceles dissolved spontaneously. Conclusion: Preventive strategies including preserving the lymphatics of the recipient, careful organ retrieval and 'back table' work are of great importance to reduce the incidence of lymphocele. Early decision of radiological or surgical intervention should be considered in patients with symptomatic lymphoceles in order to prevent further complications.

Resumen Introducción: El linfocele es una complicación frecuente luego de un trasplante renal y puede ocasionar problemas clínicos importantes, especialmente, cuando alcanza volúmenes elevados. El objetivo de este estudio es presentar las características clínicas, métodos de diagnóstico y estrategias para el tratamiento del linfocele en un grupo de pacientes turcos. Material y métodos: Se incluyeron 244 pacientes en este estudio retrospectivo. Se analizaron los datos de pacientes diagnosticados con linfocele durante el período postoperatorio. Resultados: Se diagnosticó linfocele a diez pacientes (2,4%). Eran seis hombres y cuatro mujeres con una edad promedio de 46 años. El comienzo promedio fue 19 días luego del trasplante. El tamaño medio de los linfoceles fue de 53 mm. Todos se encontraban entre el polo inferior del riñón trasplantado y la vejiga urinaria. En la consulta, un paciente presentó hidronefrosis, y tres pacientes, creatinina sérica elevada, mientras que los seis restantes eran asintomáticos. Cinco pacientes fueron tratados con éxito por aspiración percutánea; en cambio, otros dos pacientes requirieron cirugía. Tres pacientes mostraron disolución espontánea de los linfoceles. Conclusión: Las estrategias preventivas, que incluyen la preservación de los vasos linfáticos del receptor, la extracción cuidadosa de los órganos y la preparación de estos antes de realizar el trasplante, son de gran importancia para reducir la incidencia de linfocele. Debe considerarse tempranamente la intervención radiológica o quirúrgica en pacientes con linfoceles sintomáticos para prevenir complicaciones adicionales.

Predictable and Unusual Adverse Effects of Immunosuppression in Pediatric Liver Transplant Patients.

OBJECTIVES: Our aim was to determine potentially adverse effects of immunosuppressive protocols after liver transplantation in children. MATERIALS AND METHODS: The medical records of 60 children who underwent liver transplant retrospectively analyzed. Corticosteroid, tacrolimus, and mycophenolate mofetil were the primary immunosuppressive agents used in our center. RESULTS: The mean age of children was 6.1 years, ranging from 3 months to 17 years (34 boys, 26 girls). The most common indication for liver transplant was biliary atresia (26.7%). Thirty-nine patients (65%) received livers from living donors, and 21 patients (35%) received from livers from deceased donors. The main complications of immunosuppressive therapy were diarrhea associated with mycophenolate mofetil, hyperglycemia and hypertension associated with corticosteroid, and seizures and tremors associated with tacrolimus. Two patients developed post transplant lymphoproliferative disorder. The diagnosis was based on histologic findings of cervical lymphadenopathy and duodenal biopsy. One patient was diagnosed with acute lymphoblastic lymphoma. In addition to these predictable adverse effects, unusual adverse effects of immunosuppression were also observed. Hemolytic anemia (n = 3) (one was also diagnosed with Evans syndrome), eosinophilic gastroenteritis (n = 2), de novo food allergy (n = 2), posttransplant lymphoproliferative disorder (n = 2), Burkitt lymphoma (n = 1), and renal tubular acidosis (n = 1) were thought to be related to tacrolimus therapy. CONCLUSIONS: Adverse effects of immunosuppression represent a major cause of postoperative morbidity. The common effects of immunosuppression are recognized easily by clinicians. It should be kept in mind that unexpected symptoms and signs may be related to immunosuppression in pediatric liver transplant patients.

Surgical Complications After Pediatric Renal Transplant.

OBJECTIVES: Renal transplant is the most appropriate treatment for both adult and pediatric patients with end-stage renal failure. Here, we analyzed surgical complications after pediatric renal transplant at our center. MATERIALS AND METHODS: We retrospectively analyzed data from patient files and hospital charts of pediatric patients who had renal transplant at our center (Gazi University, Ankara, Turkey). Our immunosuppression protocol, a calcineurin inhibitor-based triple regimen, was applied to all recipients (steroids, mycophenolic acid). For neoureterocystostomy anastomosis, we used the corner-saving, open-loop continuous suture technique with double J stent for all patients, except when faced with an unfavorable situation. Catheters were removed within 4 weeks after transplant. RESULTS: Among 40 pediatric renal transplant procedures performed at our center since 2006, we had 6 documented surgical complications (15%), with 3 being early and 3 being late complications. In the early transplant period, there were 2 surgical and 1 urologic complications. Eight patients (20%) lost their kidney grafts over the 10-year follow-up. The main reasons for graft loss were chronic allograft nephropathy in 4 patients (10%), BK virus nephropathy in 3 patients (7.5%), and hyperacute rejection in 1 patient (2.5%). Two patients died; however, no patient deaths or graft losses were from surgical complications. Overall graft and patient survival rates were 97% and 100% at 1 year, 94% and 98% at 5 years, and 68% and 95% at 10 years. CONCLUSIONS: Renal transplant in pediatric patients is a safe procedure in our department, based on patient and graft survivals, with a low rate of graft loss from surgical problems. As a result, our center is showing success with pediatric renal transplant procedures in accordance with the developed centers in the world.

Urologic Complications After Renal Transplant: A Single-Center Experience.

OBJECTIVES: Urologic complications after kidney transplant are associated with significant morbidity, mortality, and prolonged hospital stay. An intervention or second surgical procedure is frequently required. Here, we report urologic complications in adult kidney recipients. MATERIALS AND METHODS: Since 2006, 171 adult kidney transplant procedures have been performed at the Gazi University Transplantation Center (Ankara, Turkey). Among these patients, there were 65 adult female (38%) and 106 adult male (62%) recipients. Donor source included 61 deceased donations (36%) and 110 living related donations (64%). The Haberal corner-saving technique was used for ureteroneocystostomy anastomosis. All recipients received a calcineurin-based triple immunosuppression regimen. All recipients also received trimethoprim/sulfamethoxazole prophylaxis for 3 months after transplant. RESULTS: In the 171 adult kidney recipients analyzed for urologic complications, mean age was 32.5 ± 14.1 years (median: 32.5 y; range, 18-67 y); mean donor age was 41 ± 14.2 years (median: 42 y). We focused on 3 specific urologic complications: urine leak, ureteric stenosis, and symptomatic vesicoureteral reflux. In our study group, urologic complications were encountered in 7 patients (4%), with 5 complications detected in the early period and 2 complications detected in the late period. No symptomatic vesicoureteral reflux complications were shown in this study group. Urologic complications did not result in any patient deaths or graft loss. CONCLUSIONS: In this study, the Haberal corner-saving suture technique with double J stent seemed to have a protective effect for development of urologic complications.

Outcome of the Double-J Stent Placement in Pediatric Kidney Transplant: A Single Center Experience.

OBJECTIVES: Double J stent placement at kidney transplant may reduce stenosis or leakage complication rates. However, placement may also increase risk for early urinary tract infection (ie, < 3 mo after transplant). In children, the usefulness of double J stent placement is not well defined. MATERIALS AND METHODS: We analyzed retrospective data from children who received transplants at the Gazi University Transplantation Center and Pediatric Nephrology (Ankara, Turkey) for outcomes related to double J stents. At our center, double J stent placement decision is made by the transplant surgery team during operation. Placements were routinely performed in all transplant recipients. Stent removal occurs within 6 week after transplant. RESULTS: Among 42 transplants since 2006, early urinary tract infection was seen in 7% and stenosis in 3.6% of patients, with no leakage reported. Mean stent removal time was 6 ± 0.5 weeks. Early urinary tract infection was seen in 3 recipients with posterior urethral valve and neurogenic bladder (2 recipients) and meningoma cells and neurogenic bladder (1 recipient). All 3 recipients with early urinary tract infection received clean intermittent catheterization after transplant for adequate emptying of the bladder. In our study group, stent complications such as migration (2 patients) and hematuria (1 patient) were seen, but crusting, breakage, and stone formation were not seen. The 3 patients with urinary tract infection had neurogenic bladder types, complicating the urine outflow system. Stent placement was not a significant risk factor for early urinary tract infection and but had a protective effect. CONCLUSIONS: In our study group, we observed no risk factors for routine double J stent placement in pediatric renal transplant procedures. Stent placement was not a risk factor for early urinary tract infection. However, regardless of stent placement, when a recipient had complicated urologic outflow problems, infection became a long-term hurdle.

Chylous ascites after a living-donor liver graft, effectively treated in a child with octreotide.

Chylous ascites after a liver transplant is a rare complication of surgery. We report a 11-month-old girl with biliary atresia who was presented with chylous ascites after a liver transplant. On the seventh day after surgery, while being fed, chylous ascites was observed. Besides fasting and diuretics, total parenteral nutrition and somatostatin analogue (octreotide) were initiated. Chylous ascites resolved in 3 weeks. Abdominal distention recurred 1 week later; fasting and total parenteral nutrition, combined with octreotide, were administered again for 2 more weeks. Thereafter, enteral feeding was started without any complications.

Resistance to the induction of mixed chimerism in spontaneously diabetic NOD mice depends on the CD40/CD154 pathway and donor MHC disparity.

Blockade of CD40/CD154 pathway has proven effective in promoting the induction of allogeneic mixed chimerism. Using NOD mouse model of human type 1 diabetes, we investigated whether allogeneic mixed chimerism can be induced in prediabetic NOD mice and in spontaneously diabetic NOD mice under nonmyeloablative and irradiation-free conditioning therapy and anti-CD154 mAb as a short-term posttransplant treatment. We found that spontaneously diabetic NOD mice are more resistant to the induction of allogeneic mixed chimerism than prediabetic NOD mice under our nonmyeloablative and irradiation-free conditioning therapy. This alloresistance in spontaneously diabetic NOD mice is dependent on the CD40/CD154 pathway and donor MHC disparity.

Analysis of postsurgical complications in 75 living liver transplantation donors.

Seventy-five living donor liver hepatectomies were performed at our transplantation center between April 1990 and December 2004. We collected the data from patient charts, files, and the Baskent University Liver Registry. There were 39 male and 36 female donors (mean age, 35.1 +/- 9.3 years). We have performed 29 (38.6%) left hepatic lobectomies, 18 (24%) left lateral segmentectomies, 26 (34.6%) right lobectomies, and two (2.6%) donors had simultaneous living donor nephrectomy plus left lobe hepatectomy. The mean remnant liver volume was 598 +/- 168 cm(3) (range, 410-915 cm(3)). The mean percentage of remnant liver for the donor was 55.2%. Mean postoperative hospital stay was 10 +/- 4.4 days. After surgery, there was no mortality or reoperation. We saw 15 (20%) postsurgical complications in 14 donors. Intra-abdominal collection was seen in five (6.6%) patients. Biliary leak was seen in four patients. Portal vein thrombosis was seen in one patient, and a pulmonary embolus developed in one liver donor. Patient safety must be the primary focus in living-donor liver transplantation. These donors face significant risks, including substantial morbidity and death. More experience, improved surgical techniques, and meticulous donor evaluation will help minimize morbidity and mortality for both living liver donors and recipients.

Plasma homocysteine levels in living kidney donors before and after uninephrectomy.

An increased prevalence of hyperhomocysteinemia has been observed among patients with end-stage renal disease, and numerous studies have demonstrated that kidney function is one of the most important determinants of plasma total homocysteine (tHcy) concentration. In an effort to understand the mechanism of hyperhomocysteinemia in renal disease, we chose, as our model, living kidney donors who had undergone uninephrectomy. We studied 10 living kidney donors and measured fasting plasma tHcy, plasma creatinine, folate, vitamins B(12) and B(6), and high-sensitivity C-reactive protein (hsCRP) 24 hours before nephrectomy and 2 days, 6 weeks, and 6 months after nephrectomy compared to the values 24 hours before nephrectomy. Mean fasting tHcy and creatinine concentrations were significantly higher in donors 2 days, 6 weeks and 6 months after nephrectomy they were 24 hours before nephrectomy. Both the increases in tHcy levels 2 days after nephrectomy and subsequent decreases 6 weeks and 6 months after are paralleled by the changes in plasma creatinine values, although neither returned to its presurgery value. Decreases in tHcy are significantly correlated with decreases in creatinine values. The B vitamins were unchanged, and the hsCRP level was increased 2 days after surgery but had returned to the baseline level after 6 weeks. We conclude that tHcy and creatinine levels parallel each other after uninephrectomy and that the gradual decrease in tHcy is accounted for by hypertrophy of the remaining kidney. Our results, the first to be obtained from living kidney donors, support the hypothesis that renal metabolism of tHcy is the mechanism responsible for the correlation between renal function and plasma tHcy level.

A substantial level of donor hematopoietic chimerism is required to protect donor-specific islet grafts in diabetic NOD mice.

BACKGROUND: Mixed chimerism can induce tolerance to alloantigens and restore self-tolerance to autoantigens, thereby permitting islet transplantation. However, the minimal level of donor chimerism that is required to prevent islet allograft rejection and recurrence of autoimmune diabetes has not been established. METHODS: We investigated whether allogeneic Balb/c donor chimerism can be induced in C57BL/6 mice, in prediabetic NOD mice, and in diabetic NOD mice after transplantation of a modest dose of bone marrow by using purine nucleoside analogue, fludarabine phosphate and cyclophosphamide conditioning therapy, followed by short-term anti-CD40 ligand monoclonal antibody and rapamycin posttransplant treatment. We also investigated whether the induced donor chimerism is sufficient to prevent the onset of diabetes in prediabetic NOD mice and protect donor islet grafts in diabetic NOD mice. RESULTS: Allogeneic donor chimerism could be induced under the authors' approach that is nonmyeloablative and radiation-free. Diabetes onset was prevented in chimeric prediabetic NOD mice. The induction of mixed chimerism protected donor-specific islet grafts in diabetic NOD mice. At 60 days after islet transplantation, all donor Balb/c islet grafts survived in diabetic NOD mice whose level of donor-derived lymphocytes was higher than 30% at the time of islet transplantation (n=8). In contrast, Balb/c islet grafts were rejected in five of seven diabetic NOD mice whose level was lower than 30%. CONCLUSIONS: Our data demonstrate that a donor lymphocyte chimerism (>30%) at the time of islet transplantation is required to protect donor-specific islet grafts, and indicate that a strictly non-irradiation-based protocol can be used to achieve this goal.

Inducing tolerance to MHC-matched allogeneic islet grafts in diabetic NOD mice by simultaneous islet and bone marrow transplantation under nonirradiative and nonmyeloablative conditioning therapy.

BACKGROUND: Human type 1 diabetes is associated with defects in the hematopoietic stem cells. Simultaneous donor islet and bone marrow transplantation may be an ideal therapeutic approach for inducing tolerance to islet allogeneic antigens and restoring self-tolerance to islet autoimmune antigens. METHODS: Using a nonobese diabetic (NOD) mouse model of human type 1 diabetes, we investigated whether tolerance to MHC-matched allogeneic islet grafts from male nonobese diabetes-resistant (NOR) donors can be induced in female NOD recipients by simultaneous islet and bone marrow transplantation under fludarabine phosphate-based nonmyeloablative and irradiation-free conditioning therapy. Donor-specific chimerism in the peripheral blood of tolerant mice (n=7) was measured by semiquantitative polymerase chain reaction for a male-specific marker (SRY). RESULTS: Donor-specific tolerance to NOR islet grafts was induced in all diabetic NOD mice after simultaneous islet and bone marrow transplantation and treated with fludarabine phosphate, cyclophosphamide, anti-mouse lymphocyte serum, and rapamycin. At 100 days and 200 days after transplantation, the average percentage of male NOR marker in DNA derived from the peripheral blood of NOD recipients that had long-term islet graft survival was over 10%. CONCLUSION: Our data suggest that this approach may induce donor-specific tolerance in clinical islet transplantation and living-related donor solid organ transplantation.