Repetitive allogeneic intraarticular injections of synovial mesenchymal stem cells promote meniscus regeneration in a porcine massive meniscus defect model

OBJECTIVE

A new strategy is required in order to regenerate a meniscus for extensive defects. Synovial mesenchymal stem cells (MSCs) are an attractive cell source for meniscus regeneration due to their high proliferation and chondrogenic potential. We examined the effect of repetitive intraarticular injections of synovial MSCs on meniscus regeneration in a massive meniscal defect of pigs. We followed up the efficacy using MRI evaluation in addition to macroscopic and histological observations.

DESIGN

Two weeks before the injection of synovial MSCs, the anterior half of the medial menisci was resected in both knees of pigs. Fifty million allogeneic synovial MSCs were injected into the right knee at 0, 2, and 4 weeks and followed up by sequential MRI. The regenerated meniscus, adjacent articular cartilage, and subchondral bone were evaluated by MRI at 2, 4, 8, 12 and 16 weeks. They were also evaluated macroscopically and histologically at 16 weeks (n = 7).

RESULTS

The resected meniscus regenerated significantly better in the MSC group than in the control group based on histological and MRI analyses. Macroscopically, the meniscal defect already appeared to be filled with synovial tissue at 2 weeks. Articular cartilage and subchondral bone at the medial femoral condyle were also significantly more preserved in the MSC group based on MRI, macroscopic, and histological analyses.

CONCLUSIONS

Intraarticular injections of allogeneic synovial MSCs appeared to promote meniscus regeneration and provide protection at the medial femoral articular cartilage in a porcine massive meniscal defect model.

A case of successful enteroscopic balloon dilation for late anastomotic stricture of choledochojejunostomy after living donor liver transplantation

Biliary complications remain a major concern after living donor liver transplantation. We describe a pediatric case who underwent a successful endoscopic balloon dilatation of biliary-enteric stricture following living donor liver transplantation using a newly developed method of enteroscopy. The 7-year-old boy with late biliary stricture of choledochojejunostomy was admitted 6 years after transplantation. Since percutaneous transhepatic cholangiography was technically difficult in this case, endoscopic retrograde cholangiography was performed using a double-balloon enteroscope under general anesthesia. The enteroscope was advanced retrograde through the duodenum, jejunum, and the leg of Roux-Y by the double-balloon method, and anastomotic stricture of choledochojejunostomy was clearly confirmed by endoscopic retrograde cholangiography and endoscopic direct vision. Balloon dilatation was performed and the anastomosis was expanded. Restenosis was not noted as of 2 years after the treatment. In conclusion, endoscopic balloon dilation of biliary-enteric anastomotic stricture using a new enteroscopic method can be regarded as an alternative choice to percutaneous transhepatic management and surgical re-anatomists.

Arthroscopic, histological and MRI analyses of cartilage repair after a minimally invasive method of transplantation of allogeneic synovial mesenchymal stromal cells into cartilage defects in pigs

BACKGROUND AIMS

Transplantation of synovial mesenchymal stromal cells (MSCs) may induce repair of cartilage defects. We transplanted synovial MSCs into cartilage defects using a simple method and investigated its usefulness and repair process in a pig model.

METHODS

The chondrogenic potential of the porcine MSCs was compared in vitro. Cartilage defects were created in both knees of seven pigs, and divided into MSCs treated and non-treated control knees. Synovial MSCs were injected into the defect, and the knee was kept immobilized for 10 min before wound closure. To visualize the actual delivery and adhesion of the cells, fluorescence-labeled synovial MSCs from transgenic green fluorescent protein (GFP) pig were injected into the defect in a subgroup of two pigs. In these two animals, the wounds were closed before MSCs were injected and observed for 10 min under arthroscopic control. The defects were analyzed sequentially arthroscopically, histologically and by magnetic resonance imaging (MRI) for 3 months.

RESULTS

Synovial MSCs had a higher chondrogenic potential in vitro than the other MSCs examined. Arthroscopic observations showed adhesion of synovial MSCs and membrane formation on the cartilage defects before cartilage repair. Quantification analyses for arthroscopy, histology and MRI revealed a better outcome in the MSC-treated knees than in the non-treated control knees.

CONCLUSIONS

Leaving a synovial MSC suspension in cartilage defects for 10 min made it possible for cells to adhere in the defect in a porcine cartilage defect model. The cartilage defect was first covered with membrane, then the cartilage matrix emerged after transplantation of synovial MSCs.

Intramyocardial Transplantation of Human iPS Cell-Derived Cardiac Spheroids Improves Cardiac Function in Heart Failure Animals

The severe shortage of donor hearts hampered the cardiac transplantation to patients with advanced heart failure. Therefore, cardiac regenerative therapies are eagerly awaited as a substitution. Human induced pluripotent stem cells (hiPSCs) are realistic cell source for regenerative cardiomyocytes. The hiPSC-derived cardiomyocytes are highly expected to help the recovery of heart. Avoidance of teratoma formation and large-scale culture of cardiomyocytes are definitely necessary for clinical setting. The combination of pure cardiac spheroids and gelatin hydrogel succeeded to recover reduced ejection fraction. The feasible transplantation strategy including transplantation device for regenerative cardiomyocytes are established in this study.

Double-balloon enteroscopy for bilioenteric anastomotic stricture after pediatric living donor liver transplantation

Bilioenteric anastomotic stricture after liver transplantation is still frequent and early detection and treatment is important. We established the management using double-balloon enteroscopy (DBE) and evaluated the intractability for bilioenteric anastomotic stricture after pediatric living donor liver transplantation (LDLT). We underwent DBE at Jichi Medical University from May 2003 to July 2009 for 25 patients who developed bilioenteric anastomotic stricture after pediatric LDLT. The patients were divided into two types according to the degree of dilatation of the anastomotic sites before and after interventional radiology (IVR) using DBE. Type I is an anastomotic site macroscopically dilated to five times or more, and Type II is an anastomotic site dilated to less than five times. The rate of DBE reaching the bilioenteric anastomotic sites was 68.0% (17/25), and the success rate of IVR was 88.2% (15/17). There were three cases of Type I and 12 cases of Type II. Type II had a significantly longer cold ischemic time and higher recurrence rate than Type I (P = 0.005 and P = 0.006). In conclusion, DBE is a less invasive and safe treatment method that is capable of reaching the bilioenteric anastomotic site after pediatric LDLT and enables IVR to be performed on strictures, and its treatment outcomes are improving. Type II and long cold ischemic time are risk factors for intractable bilioenteric anastomotic stricture.

Elevated blood concentrations of calcineurin inhibitors during diarrheal episode in pediatric liver transplant recipients: involvement of the suppression of intestinal cytochrome P450 3A and P-glycoprotein

We encountered two cases of pediatric living-related liver transplant recipients who showed increases in blood concentration of cyclosporine or tacrolimus, a dual substrate for cytochrome P450 (CYP) 3A and P-glycoprotein (P-gp), during a diarrheal episode. To investigate the effect of intestinal inflammation on the metabolic and efflux pump activities, we conducted the experiments using the lipopolysaccharide (LPS)-induced intestinal damage model. Intestinal epithelial CYP3A activity was assessed by nifedipine oxidation using intestinal epithelial microsomes in rat. Drug efflux by P-gp was tested using digoxin flux with the excised intestine perfusion system in rats. Intraperitoneal injection of LPS (0.3 mg/kg) significantly reduced the intestinal epithelial CYP3A activity by 41% (p < 0.01). In the proximal jejunal segment of the rats treated with LPS, mucosal to serosal flux of digoxin was significantly enhanced compared to that of control (p < 0.05). Efflux of digoxin, which was taken up by intestinal epithelium, to mucosal perfusate was significantly blunted in the jejunum treated with LPS (p < 0.05), which indicates that the LPS treatment reduced the P-gp activity in rat small intestine. These findings suggest that the suppression of CYP3A and P-gp activities may be involved in the mechanism of elevated blood concentrations of cyclosporine and tacrolimus during enteritis-induced diarrhea. To prevent a drug-induced adverse effect, dose of a drug, which is a substrate of CYP3A or P-gp, should be reduced during such an episode.

Living donor liver transplantation for neonates using segment 2 monosubsegment graft

The prognosis of liver transplantation for neonates with fulminant hepatic failure (FHF) continues to be extremely poor, especially in patients whose body weight is less than 3 kg. To address this problem, we have developed a safe living donor liver transplantation (LDLT) modality for neonates. We performed LDLTs with segment 2 monosubsegment (S2) grafts for three neonatal FHF. The recipient age and body weight at LDLT were 13-27 days, 2.59-2.84 kg, respectively. S2 or reduced S2 grafts (93-98 g) obtained from their fathers were implanted using temporary portacaval shunt. The recipient portal vein was reconstructed at a more distal site, such as the umbilical portion, to have the graft liver move freely during hepatic artery (HA) reconstruction. The recipient operation time and bleeding were 11 h 58 min-15 h 27 min and 200-395 mL, respectively. The graft-to-recipient weight ratio was 3.3-3.8% and primary abdominal wall closure was possible in all cases. Although hepatic artery thrombosis occurred in one case, all cases survived with normal growth. Emergency LDLT with S2 grafts weighing less than 100 g can save neonates with FHF whose body weight is less than 3 kg. This LDLT modality using S2 grafts could become a new option for neonates and very small infants requiring LT.

Growth curves of pediatric patients with biliary atresia following living donor liver transplantation: factors that influence post-transplantation growth

We evaluated the growth curves of children with BA after LDLT, and identified factors influencing growth velocity one-yr after LDLT (DeltaZ). The clinical data of 51 children with BA, who had an LDLT at our center from 2001 to 2005, were retrospectively reviewed. The Z scores for height and weight, and DeltaZ were studied. The correlation between DeltaZ and various clinical factors was evaluated statistically. Multivariate stepwise analyses were performed for DeltaZ. The average height and weight Z scores at the time of LDLT were -1.34 +/- 1.36 (+/-s.d.) and -0.78 +/- 1.15, respectively. Among 30 BA recipients with stable liver function after transplant, weight returned to normal one-yr post-transplantation. However, height did not return to normal even by the third post-transplantation year. On multivariate analyses, 73% of the variance in height DeltaZ could be accounted for by factors such as standardized height at the time of LDLT (proportion of variance: 38%), number of steroid pulse treatments (17%), donor age (10%), and the presence of HVS (9%). Fifty-four percentage of the variance in weight DeltaZ could be accounted for by factors such as standardized weight at the time of LDLT (37%) and the total steroid dose given (17%). Height and weight status at the time of LDLT likely have the strongest impact on DeltaZ. Additional factors include steroid exposure, age of the living donor, and presence of HVS, all of which should be considered to improve post-transplantation growth.

Living-donor liver transplantation in 126 patients with biliary atresia: single-center experience

OBJECTIVES

To describe our experience with 126 consecutive living-donor liver transplantation (LDLT) procedures performed because of biliary atresia and to evaluate the optimal timing of the operation.

PATIENTS AND METHODS

Between May 2001 and January 2010,126 patients with biliary atresia underwent 130 LDLT procedures. Mean (SD) patient age was 3.3 (4.2) years, and body weight was 13.8 (10.7) kg. Donors included 64 fathers, 63 mothers, and 3 other individuals. The left lateral segment was the most commonly used graft (75%). Patients were divided into 3 groups according to body weight: group 1, less than 8 kg (n = 40); group 2,8 to 20 kg (n = 63); and group 3, more than 20 kg (n = 23). Medical records were reviewed retrospectively. Follow up was 4.5 (2.7) years.

RESULTS

All group 3 donors underwent left lobectomy, and all group 1 donors underwent left lateral segmentectomy. No donors required a second operation or died. Comparison of the 3 groups demonstrated that recipient Pediatric End-Stage Liver Disease score in group 1 was highest, operative blood loss in group 2 was lowest (78 mL/kg), and operative time in group 3 was longest (1201 minutes). Hepatic artery complications occurred more frequently in group 1 (17.9%), and biliary stenosis (43.5%) and gastrointestinal perforation (8.7%) occurred more frequently in group 3. The overall patient survival rates at 1, 5, and 9 years was 98%, 97%, and 97%, respectively. Five-year patient survival rate in groups 1,2, and 3 were 92.5%, 100%, and 95.7%, respectively. Gastrointestinal perforation (n = 2) was the primary cause of death.

CONCLUSIONS

Living-donor liver transplantation is an effective treatment of biliary atresia, with good long-term outcome. It seems that the most suitable time to perform LDLT to treat biliary atresia is when the patient weighs 8 to 20 kg.

Living donor liver transplantation for ornithine transcarbamylase deficiency

Ornithine transcarbamylase deficiency, the most common urea cycle disorder, causes hyperammonemic encephalopathy and has a poor prognosis. Recently, LT was introduced as a radical OTCD treatment, yielding favorable outcomes. We retrospectively analyzed LT results for OTCD at our facility. Twelve children with OTCD (six boys and six girls) accounted for 7.1% of the 170 children who underwent LDLT at our department between May 2001 and April 2010. Ages at LT ranged from nine months to 11 yr seven months. Post-operative follow-up period was 3-97 months. The post-operative survival rate was 91.7%. One patient died. Two patients who had neurological impairment preoperatively showed no alleviation after LT. All patients other than those who died or failed to show recovery from impairment achieved satisfactory quality-of-life improvement after LT. The outcomes of LDLT as a radical OTCD treatment have been satisfactory. However, neurological impairment associated with hyperammonemia is unlikely to subside even after LT. It is desirable henceforth that more objective and concrete guidelines for OTCD management be established to facilitate LDLT with optimal timing while avoiding the risk of hyperammonemic episodes.

Mannequin Simulation Improves the Confidence of Medical Students Performing Tube Thoracostomy: A Prospective, Controlled Trial

This study was undertaken to determine the educational benefits of mannequin simulation for performance of tube thoracostomy in a porcine model by medical students. Thirty medical students were randomized into two groups; the first performed tube thoracostomy on a mannequin simulator and then a porcine model; the second used only the porcine model. Performance measures included completion of subtasks, time to perform the procedure, a global score assigned by faculty raters, and a self-evaluation survey. Subtask completion rate was similar in both groups ( P > 0.05). Mean time to perform the procedure was 9.8 minutes (±0.9, simulator), and 9.3 minutes (± 1.0, nonsimulator, P > 0.05). Global scores were 12.3 (±1.3, simulator) and 11.0 (±1.4, non-simulator, P > 0.05). Self-evaluation of confidence (1= “very”, 7= “not at all”) showed the simulator group was significantly more confident (3.4 ± 0.42) than the nonsimulator group (4.7 ± 0.49, P < 0.05). All students met basic competencies to perform tube thoracostomy. The simulator group felt significantly more confident to subsequently perform the procedure on a patient, whereas performance was not statistically significantly different for the two groups. Further trials may be needed to delineate the optimal role for these simulators in teaching tube thoracostomy.

The role of operative intervention in management of congenital extrahepatic portosystemic shunt

BACKGROUND AND AIMS

Congenital extrahepatic portosystemic shunt (CEPS) is a rare venous malformation in which mesenteric venous blood drains directly into the systemic circulation. It is still a matter of debate whether conservative or operative strategies should be used to treat symptomatic CEPS. The aim of this study was to evaluate the role of operative intervention in the management of CEPS.

METHODS

Between June 2004 and August 2010, 6 consecutive patients with symptomatic CEPS were treated in our department. There were 3 male and 3 female patients, with a median age of 3.5 years (range, 1-8). Their demographic, clinical, and laboratory data were analyzed. All patients were scheduled to undergo shunt ligation or liver transplantation (LT).

RESULTS

Living donor LT was carried out in 4 patients, and shunt ligation in 2. After a median follow-up of 25 months, all the patients are alive currently with marked relief of symptoms.

CONCLUSION

Shunt ligation or LT for symptomatic CEPS is potentially curative.

Risk factors and treatments for hepatic arterial complications in pediatric living donor liver transplantation

BACKGROUND

Hepatic artery complications (HAC) are a serious complication in pediatric liver transplant recipients because its incidence is high and it can occasionally lead to graft liver failure. We herein present a retrospective analysis of our 10-year experience with pediatric living donor liver transplantation (LDLT) focusing on the risk factors and treatments for HAC.

METHODS

Between May 2001 and November 2011, 209 LDLTs were performed for 203 pediatric recipients. We performed the multivariate analyses to identify the factors associated with HAC and showed the therapeutic strategy and outcome for HAC.

RESULTS

The overall incidence of HAC was 7.2%, and the graft survival of recipients with HAC was 73.3%. The multivariate analysis showed that the pediatric end-stage liver disease score (≥20), post-transplant laparotomy except for HAC treatment and extra-anatomical hepatic artery reconstruction were independent risk factors for HAC (P = 0.020, P = 0.015 and P = 0.002, respectively). Eleven surgical interventions and 13 endovascular interventions were performed for 15 recipients with HAC. The serum aspartate aminotransferase levels pre- and post-treatment for HAC were significantly higher in the surgical group than in the endovascular group (P = 0.016 and P = 0.022, respectively).

CONCLUSIONS

It is important for recipients with risk factors to maintain strict post-transplant management to help prevent HAC and detect it in earlier stages. Endovascular intervention can be a less invasive method for treating HAC than surgical intervention, and can be performed as an early treatment.

Organ ischemia during partial resuscitative endovascular balloon occlusion of the aorta: Dynamic 4D Computed tomography in swine

Resuscitative endovascular balloon occlusion of the aorta (REBOA) increases proximal pressure, and simultaneously induces distal ischemia. We aimed to evaluate organ ischemia during partial REBOA (P-REBOA) with computed tomography (CT) perfusion in a swine model. The maximum balloon volume was recorded as total REBOA when the distal pulse pressure ceased. The animals (n = 4) were scanned at each 20% of the maximum balloon volume, and time-density curve (TDC) were analysed at the aorta, portal vein (PV), liver parenchyma, and superior mesenteric vein (SMV, indicating mesenteric perfusion). The area under the TDC (AUTDC), the time to peak (TTP), and four-dimensional volume-rendering images (4D-VR) were evaluated. The TDC of the both upper and lower aorta showed an increased peak and delayed TTP. The TDC of the PV, liver, and SMV showed a decreased peak and delayed TTP. The dynamic 4D-CT analysis suggested that organ perfusion changes according to balloon volume. The AUTDC at the PV, liver, and SMV decreased linearly with balloon inflation percentage to the maximum volume. 4D-VR demonstrated the delay of the washout in the aorta and retrograde flow at the inferior vena cava in the highly occluded status.

Impact of acute cellular rejection on coagulation and fibrinolysis biomarkers within the immediate post-operative period in pediatric liver transplantation

We studied restoration of the coagulation and fibrinolysis system in pediatric patients following liver transplantation and biomarkers of blood coagulation and fibrinolysis for suspecting the occurrence of acute cellular rejection. Coagulation activity recovered rapidly within two days following transplantation, but it took approximately 21-28 days for full recovery of the coagulation and fibrinolysis factors synthesized in the liver. PAI-1 levels were significantly higher in patients at the time of acute cellular rejection compared with levels after control of AR, and levels on days 14 and 28 in patients without AR. Plasma protein C and plasminogen levels at the time of rejection were significantly lower than those on day 14 in patients without AR. Statistical analysis suggested that an increase in plasma PAI-1 at a single time point in the post-operative period is a reliable marker among the coagulation and fibrinolysis factors for suspecting the occurrence of acute cellular rejection. These data suggested that appropriate anticoagulation may be required for 14 days after liver transplantation in order to avoid vascular complications and measurement of plasma PAI-1 levels may be useful for suspecting the occurrence of acute cellular rejection in pediatric patients following liver transplantation.

Production and rearing of germ-free X-SCID pigs

Pigs with X-linked severe combined immunodeficiency (X-SCID) caused by a mutation of the interleukin-2 receptor gamma chain gene (IL2RG) are of value for a wide range of studies. However, they do not survive longer than 8 weeks because of their susceptibility to infections. To allow longer survival of X-SCID pigs, the animals must be born and reared under germ-free conditions. Here, we established an efficient system for piglet derivation by hysterectomy and used it to obtain and maintain a germ-free X-SCID pig. In four trials using pregnant wild-type pigs, 66% of piglets after hysterectomy started spontaneous breathing (range of 20-100% per litter). The resuscitation rate was found to negatively correlate with elapsed time from the uterus excision to piglet derivation (r=-0.97, P<0.05). Therefore, it is critical to deliver piglets within 5 min to achieve a high resuscitation rate (82% estimated from regression analysis). In a fifth trial with an IL2RG^+/- pig, four piglets were delivered within 4.2 min of uterus excision and three were alive (75%). One of the live born piglets was genotypically and phenotypically determined to be X-SCID and was reared for 12 weeks. The X-SCID piglet was free from both bacteria and fungi at all time points tested by microbial culture and grew without any abnormal signs or symptoms. This study showed successful production and rearing of germ-free pigs, enabling experiments involving long-term follow-up of X-SCID pigs.

Pediatric living donor liver transplantation for biliary atresia with hepatopulmonary syndrome: the gift of a second wind

PURPOSE

Hepatopulmonary syndrome (HPS) is a progressive, deteriorating complication of end-stage liver disease (ESLD) that occurs in 13-47% of liver transplant candidates. Although LT is the only therapeutic option for HPS, it has a high morbidity and mortality, especially in patients with severe hypoxemia before transplantation, but the course of HPS after living donor liver transplantation (LDLT), especially for biliary atresia (BA) patients is not well established.

PATIENTS AND METHODS

The present study evaluated 122 patients who received an LDLT for BA and of these, 3 patients had HPS at the time of LDLT in a single-center series.

RESULTS

Two patients of the HPS patients them had biliary and/or vascular complications, but they recovered uneventfully with interventional treatment. None of the patients required supplemental oxygen and had no residual cardiopulmonary abnormalities at a follow-up of more than 24 months.

CONCLUSION

Although a series of three patients is too small for definitive conclusion and further investigations must be conducted, pediatric LDLT can be a favorable therapeutic option for HPS.

Pediatric liver retransplantation from living donors can be considered as a therapeutic option for patients with irreversible living donor graft failure

Liver retransplantation (re-LT) is required in patients with irreversible graft failure, but it is a significant issue that remains medically, ethically, and economically controversial, especially in living donor liver transplantation (LDLT). The aim of this study was to evaluate the outcome, morbidity, mortality, safety and prognostic factors to improve the outcome of pediatric living donor liver retransplantation (re-LDLT). Six of 172 children that underwent LDLT between January 2001 and March 2010 received a re-LDLT and one received a second re-LDLT. The overall re-LDLT rate was 3.5%. All candidates had re-LDLT after the initial LDLT. The overall actuarial survival of these patients was 83.3% and 83.3% at one and five yr, respectively. These rates are significantly worse than the rates of pediatric first LDLT. Vascular complications occurred in four patients and were successfully treated by interventional radiologic therapy. There were no post-operative biliary complications. One case expired because of hemophagocytic syndrome after re-LDLT. Although pediatric re-LDLT is medically, ethically, and economically controversial, it is a feasible option and should be offered to children with irreversible graft failure. Further investigations, including multicenter studies, are therefore essential to identify any prognostic factors that may improve the present poor outcome after re-LDLT.

Diurnal variation in the biliary excretion of flomoxef in patients with percutaneous transhepatic biliary drainage

AIMS

To examine diurnal variation in biliary excretion of flomoxef.

METHODS

Flomoxef (1 g) was injected intravenously in eight patients with percutaneous transhepatic cholangiography with drainage at 09.00 h and 21.00 h by a cross-over design with a 36 h washout period. Drained biliary fluid was collected for 6 h after each dosing. These patients still had mild to moderate hepatic dysfunction.

RESULTS

Bile flow and bile acid excretion for 6 h after dosing did not differ significantly between the 09.00 h and 21.00 h treatments. The maximum concentration of biliary flomoxef was significantly greater and its total excretion for 6 h tended to be greater after the 21.00 h dose [maximum concentration (microg ml(-1)): 34.2 +/- 29.9 (09.00 h dose) vs 43.5 +/- 28.3 (21.00 h dose) (95% confidence interval for difference: 2.6 approximately 15.9, P = 0.013); total excretion (mg 6 h(-1)): 1.4 +/- 1.3 (09.00 h dose) vs 1.6 +/- 1.2 (21.00 h dose) (95% confidence interval for difference: -26.8, 313.7, P = 0.087)]. The period that biliary flomoxef remained above the minimal inhibitory concentration did not differ significantly between the two treatment times.

CONCLUSIONS

These results suggest that biliary excretion of flomoxef shows diurnal variation. However, as the difference was relatively small, flomoxef could be given at any time of day without any dosage adjustments.

Recurrence of hepatic artery thrombosis following acute tacrolimus overdose in pediatric liver transplant recipient

Acute overdose of tacrolimus appears to cause no or minimal adverse clinical consequences. We encountered a pediatric case who underwent liver transplantation associated with hepatic artery thrombosis (HAT), which recurred following acute tacrolimus overdose. A 10-month-old girl underwent living-related liver transplantation because of biliary atresia. To reconstruct the hepatic artery, the right gastroepiploic artery of the donor was interposed between the right hepatic artery of the recipient (2.5 mm in diameter) and the left hepatic graft artery (1 mm in diameter) under microscopy. On postoperative day 4, Doppler ultrasonography showed a remarkable reduction in hepatic arterial flow, which was consistent with HAT. The patient underwent immediate hepatic arteriography and balloon angioplasty. The stenotic sites were dilated by the procedure. Tacrolimus was infused intravenously after transplantation and the infusion rate was adjusted to achieve a target concentration of 18-22 ng/mL, which remained stable until the morning of day 6. An unexpectedly high blood concentration of tacrolimus (57.4 ng/mL) was detected at 6:00 PM on day 6, and tacrolimus was discontinued at 9:00 PM; however, the tacrolimus level reached 119.5 ng/mL at 0:00 h on day 7. While the concentration decreased to 55.2 ng/mL on the morning of day 7, the hepatic arterial flow could not be observed by Doppler ultrasonography. Emergent hepatic arteriography showed stenosis of the artery at the proximal site of the anastomosis. Balloon angioplasty was again performed and the stenotic site was successfully dilated. High level of tacrolimus exposure to the hepatic artery with injured endothelium by preceding angioplasty may have been related to the recurrence of HAT in the present case.