Various types of induced pluripotent stem (iPS) cells have been established by different methods, and each type exhibits different biological properties. Before iPS cell-based clinical applications can be initiated, detailed evaluations of the cells, including their differentiation potentials and tumorigenic activities in different contexts, should be investigated to establish their safety and effectiveness for cell transplantation therapies. Here we show the directed neural differentiation of murine iPS cells and examine their therapeutic potential in a mouse spinal cord injury (SCI) model. "Safe" iPS-derived neurospheres, which had been pre-evaluated as nontumorigenic by their transplantation into nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse brain, produced electrophysiologically functional neurons, astrocytes, and oligodendrocytes in vitro. Furthermore, when the safe iPS-derived neurospheres were transplanted into the spinal cord 9 d after contusive injury, they differentiated into all three neural lineages without forming teratomas or other tumors. They also participated in remyelination and induced the axonal regrowth of host 5HT + serotonergic fibers, promoting locomotor function recovery. However, the transplantation of iPSderived neurospheres pre-evaluated as "unsafe" showed robust teratoma formation and sudden locomotor functional loss after functional recovery in the SCI model. These findings suggest that preevaluated safe iPS clone-derived neural stem/progenitor cells may be a promising cell source for transplantation therapy for SCI.neural stem/progenitor cell | cell transplantation | regenerative medicine | remyelination | axonal regrowth

The resectable liver volume is strictly limited and this reduces the number of patients who may be treated. Recently, “tissue/organ decellularization”, a new approach in bioengineering, has been investigated for its ability to produce a native organ scaffold by removing all the viable cells. Such a scaffold may support the repair of damaged or injured tissue. The purpose of this study was to evaluate the potential contribution of liver scaffolds to hepatic regeneration after hepatectomy. We sutured the partial liver scaffolds onto the surfaces of partially hepatectomized porcine livers and assessed their therapeutic potential by immune histological analysis at various time points. Animals were sacrificed after surgery and the implanted scaffolds were evaluated for the infiltration of various types of cells. Immune histochemical study showed that blood vessel-like structures, covered with CD31 positive endothelial cells and ALB positive cells, were present in all parts of the scaffolds at days 10 and 28. Blood inflow was observed in some of these ductal structures. More interestingly, CK19 and EpCAM positive cells appeared at day 10. These results suggest that the implantation of a decellularized organ scaffold could promote structural reorganization after liver resection.

Unlimited organ availability would represent a paradigm shift in transplantation. Longterm in vivo engraftment and function of scaled-up bioengineered liver grafts have not been previously reported. In this study, we describe a human-scale transplantable liver graft engineered on a porcine liver-derived scaffold. We repopulated the scaffold parenchyma with primary hepatocytes and the vascular system with endothelial cells. For in vivo functional testing, we performed auxiliary transplantation of the repopulated scaffold in pigs with induced liver failure. It was observed that the auxiliary bioengineered liver graft improved liver function for 28 days and exhibited upregulation of liver-specific genes. This study is the first of its kind to present 28 days of posttransplant evaluation of a bioengineered liver graft using a preclinical large animal model. Furthermore, it provides definitive evidence for the feasibility of engineering human-scale transplantable liver grafts for clinical applications.

A feasible large animal model to evaluate regenerative medicine techniques is vital for developing clinical applications. One such appropriate model could be to use retrorsine (RS) together with partial hepatectomy (PH). Here, we have developed the first porcine model using RS and PH. RS or saline control was administered intraperitoneally to Göttingen miniature pigs twice, two weeks apart. Four weeks after the second dose, animals underwent PH. Initially, we tested different doses of RS and resection of different amounts of liver, and selected 50 mg/kg RS with 60% hepatectomy as our model for further testing. Treated animals were sacrificed 3, 10, 17 or 28 days after PH. Blood samples and resected liver were collected. Serum and liver RS content was determined by Liquid Chromatograph-tandem Mass Spectrometer. Blood analyses demonstrated liver dysfunction after PH. Liver regeneration was significantly inhibited 10 and 17 days after PH in RS-treated animals, to the extent of 20%. Histological examination indicated hepatic injury and regenerative responses after PH. Immunohistochemical staining demonstrated accumulation of Cyclin D1 and suppression of Ki-67 and PCNA in RS-treated animals. We report the development of the first large animal model of sustained liver injury with suppression of hepatic regeneration.

It has not been considered that nephrons regenerate in adult mammals. We present that an organ-derived extracellular matrix in situ induces nephron regeneration in a preclinical model. A porcine kidney-derived extracellular matrix was sutured onto the surface of partial nephrectomy (PN)-treated kidney. Twenty-eight days after implantation, glomeruli, vessels, and renal tubules, characteristic of nephrons, were histologically observed within the matrix. No fibrillogenesis was observed in the matrix nor the matrix-sutured kidney, although this occurred in a PN kidney without the matrix, indicating the structures were newly induced by the matrix. The expression of renal progenitor markers, including Sall1, Six2, and WT-1, within the matrix supported the induction of nephron regeneration by the matrix. Furthermore, active blood flow was observed inside the matrix using computed tomography. The matrix provides structural and functional foundations for the development of cell-free scaffolds with a remarkably low risk of immune rejection and cancerization.

BACKGROUND Cytomegalovirus (CMV) remains a critical complication after solid-organ transplantation. The CMV antigenemia (AG) test is useful for monitoring CMV infection. Although the AG-positivity rate in CMV gastroenteritis is known to be low at onset, almost all cases become positive during the disease course. We treated a patient with transverse colon perforation due to AG-negative CMV gastroenteritis, following a living donor liver transplantation (LDLT). CASE SUMMARY The patient was a 52-year-old woman with decompensated liver cirrhosis as a result of autoimmune hepatitis who underwent a blood-type compatible LDLT with her second son as the donor. On day 20 after surgery, upper and lower gastrointestinal endoscopy (GE) revealed multiple gastric ulcers and transverse colon ulcers. The biopsy tissue immunostaining confirmed a diagnosis of CMV gastroenteritis. On day 28 after surgery, an abdominal computed tomography revealed transverse colon perforation, and simple lavage and drainage were performed along with an urgent ileostomy. Although the repeated remission and aggravation of CMV gastroenteritis and acute cellular rejection made the control of immunosuppression difficult, the upper GE eventually revealed an improvement in the gastric ulcers, and the biopsy samples were negative for CMV. The CMV-AG test remained negative, therefore, we had to evaluate the status of the CMV infection on the basis of the clinical symptoms and GE. CONCLUSION This case report suggests a monitoring method that could be useful for AG-negative CMV gastroenteritis after a solid-organ transplantation.

BackgroundTolvaptan, an antagonist of the vasopressin V2 receptor is a novel oral diuretic that promotes water excretion selectively. We have used furosemide as a primary diuretic and added human atrial natriuretic peptide (hANP) if necessary for fluid management postoperatively in living-donor liver transplantation (LDLT) recipients. Recently we introduced tolvaptan and used both tolvaptan and furosemide as primary diuretics.Material/MethodsClinical outcomes were compared between LDLT recipients whose postoperative fluid management was performed before (control group, n=10) and after (tolvaptan group, n=16) introduction of tolvaptan.ResultsPreoperative and intraoperative demographic data did not differ significantly between the groups except for the period of post-surgical follow-up and total ischemic time. Urine volume was 1,242±692, 2,240±1307, and 2,268±1262 mL on postoperative day 1, 3, and 7, respectively, in the tolvaptan group. These volumes did not significantly differ from those in control group (1,027±462, 1,788±909, and 2,057±1216 mL on day 1, 3, and 7 postoperatively, respectively). Body weight gain and fluid volume from abdominal drainage tubes postoperatively did not differ significantly between groups. The time from hANP initiation to discontinuation and the time to removal of central vein catheters were significantly reduced in tolvaptan-treated patients. No severe side effects directly related to tolvaptan were observed. The survival rate at month 6 was 90.0% in control patients versus 93.8% in tolvaptan-treated patients.ConclusionsThe outcomes of this investigation indicate that tolvaptan in combination with furosemide provides an adequate diuretic for fluid management subsequent to LDLT without causing adverse effects.

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