Takashi Hirukawa

Evaluation of bioartificial renal tubule device prepared with lifespan-extended human renal proximal tubular epithelial cells

BACKGROUND Acute kidney injury (AKI), accompanied by the development of systemic inflammatory response syndrome and multiorgan dysfunction syndrome, is associated with a high risk of death. Bioartificial renal tubule device (BTD) is a cell therapy that improves the conditions common to artificial kidney recipients treated for kidney diseases. In this paper, we describe the establishment of BTD with lifespan-extended human renal proximal tubular epithelial cells. METHODS AKI goats were established by performing bilateral nephrectomy followed by lipopolysaccharide administration. The AKI goats were treated with BTD or sham-BTD, and the two groups of animals were compared by measuring the respective life spans and the levels of blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and serum electrolytes. The expression levels of inflammatory cytokines were detected by reverse transcription-polymerase chain reaction, and plasma interleukin (IL)-6 levels were measured by enzyme-linked immunosorbent assay. RESULTS The life span of AKI goats was extended: the lifetime with the BTD treatment compared with sham-BTD. BTD and sham-BTD showed a similar degree of small solute clearance. The expression levels of inflammatory cytokines and plasma IL-6 levels were decreased by the BTD treatment. CONCLUSIONS BTD treatment results in less damage from endotoxin shock and increased life span in AKI goats. These results suggest that BTD may be a useful component of bioartificial kidneys and should be considered in the next generation of renal replacement therapies.

Can cinacalcet replace parathyroid intervention in severe secondary hyperparathyroidism

A 6‐month observational study was conducted in 61 patients (33 men and 28 women, mean age 54.8 ± 12.4 years) treated with cinacalcet in whom parathyroid intervention was indicated. Thirty‐seven patients had baseline intact parathyroid hormone (iPTH) levels of >500 pg/mL, but only five still had levels this high after 6‐month cinacalcet therapy. No patients had phosphorus (P), calcium (Ca), or iPTH levels within the target range at baseline, but six patients (9.8%) reached all three target ranges after treatment. The stratum with many patients who had 2–4 enlarged parathyroid glands shifted toward the low PTH groups (iPTH < 300 pg/mL) with treatment. There was less of a tendency for patients with more enlarged glands, that is, 10 mm or larger at baseline, to have a higher PTH level after cinacalcet treatment. There was no significant difference in the total volume of parathyroid glands after treatment, since some glands enlarged while others shrank. These findings indicate cinacalcet to be a potentially useful treatment. Our results suggest that 80% of cases indicated for parathyroid intervention could avoid such interventional therapies with cinacalcet administration. However, the variability in the gland‐shrinking effect of cinacalcet on parathyroid glands merits further study.

Characterization and quantification of proliferating cell patterns in endocapillary proliferation

BACKGROUND Endocapillary proliferation (EP) is a common pathological finding in proliferative glomerulonephritis (GN). Its appearance indicates the presence of active lesions of GN. In this study, we reinvestigated the pathological features of EP. METHODS Cell markers that included CD15, CD68, CD45RO, CD31 and alpha-smooth muscle actin (alpha-SMA) were used to identify the intraglomerular cells in renal biopsy tissues collected from patients with post-streptococcal acute GN (PSAGN), methicillin-resistant Staphylococcus aureus-associated GN (MRSAGN) with or without EP, membranoproliferative GN (MPGN) with or without EP, Henoch-Schönlein nephritis, immunoglobulin A nephropathy, membranous nephropathy and minimal change nephrotic syndrome. Proliferating cells and apoptotic cells were investigated simultaneously. RESULTS The glomerular infiltrating polymorphonuclear leukocytes, macrophages, T cells, mesangial cells and endothelial cells were enumerated. In PSAGN, the glomerulus was enlarged and all cell types were greatly increased. In MRSAGN EP, the glomerulus was slightly enlarged with abundant infiltrating leukocytes and monocyte/macrophages and had moderate mesangial cell proliferation with negligible endothelial cell proliferation. In MPGN, the glomerulus markedly enlarged with multiple monocyte/macrophages and remarkable mesangial proliferation. The mesangial cells in EP glomeruli were highly activated as evidenced by alpha-SMA expression, particularly in PSAGN. CONCLUSIONS This is the first report to use monoclonal antibodies specific for cell markers to quantitatively analyze and compare the proliferating cell types in EP glomeruli in different forms of GN. The results suggest that identification of the presence of polymorphonuclear leukocytes in the capillary lumen might help in differentiating between glomerular global and segmental EP.

Mineral and bone disorders in kidney transplant recipients: reversible, irreversible, and de novo abnormalities

Given the advances in medical technologies related to kidney transplantation, the post-transplant graft survival rate and quality of life have improved dramatically. Nevertheless, post-transplant mortality rate still remains high as compared to the general population due to the development of cardiovascular events. It has recently been widely recognized that chronic kidney disease-mineral and bone disorders (CKD-MBD) significantly contribute to such poor prognosis at least in part. In the majority of kidney recipients, abnormal serum parameters for mineral and bone disorder (MBD), such as phosphorus, calcium, 1,25-dihydroxyvitamin D, parathyroid hormone and fibroblast growth factor 23, gradually return toward acceptable levels following the re-establishment of kidney function after transplantation; however, some irreversible abnormalities, developed as the result of long-term dialysis, persist, require treatment, or even progress after kidney transplantation. Thus, better management of CKD-MBD during pre-dialysis and dialysis period as well as after kidney transplantation is highly appreciated.

Kidney Diseases Enhance Expression of Tetraspanin-8: A Possible Protective Effect against Tubular Injury

Background/Aims:TSPAN8 encoding tetraspanin-8 was identified as a candidate gene for immunoglobulin A nephropathy (IgAN) by a genome-wide association study using microsatellites in the Japanese population. Tetraspanin-8 is a cell surface protein that contributes to the migration and invasion of epithelial cells. Methods: We performed immunohistochemistry for tetraspanin-8 on human renal biopsy specimens associated with IgAN, antineutrophil cytoplasmic antibody-associated nephropathy and interstitial nephritis, as well as normal renal tissue. Furthermore, to study the potential function of tetraspanin-8, we performed cell migration and invasion assays using human renal tubule cells transfected with tetraspanin-8. Results: Tetraspanin-8 was often expressed in vascular smooth muscle cells and occasionally in tubule cells in normal kidney. In the kidneys of all types of nephropathy, tetraspanin-8 staining in the arteries was unaffected, but that in the tubules was enhanced. The degree of tubular staining negatively correlated with the estimated glomerular filtration rate, independently of the type of nephropathy. Tetraspanin-8-expressing tubule cells were found predominantly in distal and collecting tubules, identified by cytokeratin 7 or aquaporin 2 staining. In vitro studies using cultured tubule cells revealed that tetraspanin-8 promoted migration by 2.7-fold without laminin, by 2.8-fold with laminin and invasion into Matrigel by 3.5-fold, suggesting that enhanced tetraspanin-8 may be involved in the repair of tubules. Conclusion: The obtained findings indicate that tetraspanin-8 expression is enhanced in injured distal tubules, which may be involved in the repair of tubules by facilitating migration and invasion.

En Bloc Cadaver Kidney Transplantation From a 9-Month-Old Donor to an Adult Recipient: Maturation of Glomerular Size and Podocyte in the Recipient

Background Favorable outcomes of en bloc pediatric donor kidney transplantation to adult recipients are attributed primarily to grafting of twice the nephron mass of a single kidney. Methods The kidneys of a 9-month-old male infant were transplanted en bloc in a 56-year-old man. Biopsies were performed 1 hour postreperfusion, 6 months and 3.5 years posttransplant. Results Warm and cold ischemia times were 21 and 426 minutes, respectively. The recipient was released from hemodialysis 10 days posttransplant and discharged 91 days posttransplant when serum creatinine was 0.9 mg/dL. At 4 years and 9 months posttransplant, serum creatinine was 1.0 mg/dL, and estimated glomerular filtration rate was 58.0 mL/min per 1.73 m2. The grafts increased in size until they reached adult size by 3 months posttransplant. The glomerular area and volume, respectively, increased from 5.9 × 103 &mgr;m2 and 0.34 × 106 &mgr;m3 at 1 hour postreperfusion to 14.9 × 103 &mgr;m2 and 1.27 × 106 &mgr;m3 at 3.5 years posttransplant, both of which were less than half of adult size. At 1 hour postreperfusion, podocytes were structurally immature. At 6 months posttransplant, podocyte immaturity was still evident. At 3.5 years posttransplant, podocytes were mature. Conclusions These findings suggest that podocytes and glomerular size of pediatric donor kidneys can continue to mature in adult recipients at rates appropriate for donor age when transplanted en bloc. The maturational levels of podocytes and glomeruli may also be a factor involved in favorable outcomes of en bloc pediatric donor kidney transplantation.