Adaptive regulation of taurine transport in two continuous renal epithelial cell lines

Taurine is actively transported by a beta-amino acid transporter located on the proximal tubule apical surface. We have characterized taurine transport into confluent monolayers of two continuous renal epithelial cell lines: LLC-PK1, a cell of porcine proximal tubular origin, and the Madin-Darby canine kidney cell line (MDCK) of distal origin. Taurine uptake is linear up to 90 minutes in LLC-PK1 cells and 180 minutes in MDCK cells. This process is highly dependent upon Na+ as the cation and either Cl- or Br- as the anion. Taurine uptake is inhibited by another beta-amino acid, beta-alanine, to a greater extent than the alpha-analog, L-alanine or other alpha-amino acids. Incubation of cell monolayers with taurine-free medium (0 microM taurine) induces an increase in Na(+)-dependent taurine uptake when compared to cells exposed to standard medium (50 microM taurine). When cells were incubated in medium containing high taurine (500 microM), uptake was decreased as compared to control cells. This adaptive response is evident by 12 hours in both cell lines and is the result of changes in the apparent transport maximum (Jmax) rather than the apparent Km for taurine. The changes in transport observed after manipulation of medium taurine concentration were not associated with differences in taurine efflux. In summary, taurine is transported by a beta-specific, Na-Cl dependent process in both renal epithelial cell lines. Although the factors which regulate taurine transport are not known, an increased transport maximum is observed in cells which have been taurine-starved, and a decreased Jmax is seen in cells supplied with excess taurine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intracellular Ca2+ regulation in a human prostate stromal cell culture

AIMS: Prostate stromal cell cultures are used in vitro to study the cellular pathophysiology of benign prostatic hyperplasia (BPH), but their functional properties are poorly understood. This study characterized intracellular Ca2+ ([Ca2+]i) regulation in a cultured cell line in comparison to freshly isolated cells, as a background to understanding contractile regulation and cellular proliferation in this tissue. METHODS: Prostate stromal cells were isolated from either PrS6 cell cultures, with an extended life span by transfection with the SV40 T-antigen, tsA58-U19, or freshly obtained transition zone prostate samples, primary cells. [Ca2+]i was measured in vitro with the indicator Fura-2 by epifluorescence microscopy. RESULTS: Phenylephrine, high-K+, and caffeine induced Ca2+-transients in primary cells (resting [Ca2+]i 94 +/- 8 nM, n = 29; peak 193 +/- 26 nM, n = 19). In PrS6 cells resting [Ca2+]i was 96 +/- 8 nM (n = 78) and in 34 of these 78 cells, 30 microM phenylephrine increased [Ca2+]i to 296 +/- 28 nM. 5-methyl-urapidil (10-30 microM) inhibited this response in 10 of 16 cells. Spontaneous Ca2+-transients were also observed in 91% of phenylephrine-responsive cells, but in only 20% of non-responsive cells (P < 0.01). Ca2+-transients were also induced by high-K+ solution, and 20 mM caffeine. The latter abolished the response to subsequent phenylephrine application. Depletion of intracellular Ca2+ stores by caffeine or restoration from a Ca2+-free superfusate caused a substantial rise of [Ca2+]i. CONCLUSIONS: PrS6 prostate stromal cells express functional alpha1-adrenoceptors associated with spontaneous intracellular Ca2+-transients. They exhibit functional Ca2+ channels, intracellular Ca2+ stores, and Ca2+ entry induced by store depletion. Stromal cultures can therefore be used to characterize the cellular physiology of prostate stromal cell contraction and proliferation.     

Stem cell therapy-present status

Stem cell research is a new field that is advancing at an incredible pace with new discoveries being reported from all over the world. Scientists have for years looked for ways to use stem cells to replace cells and tissues that are damaged or diseased. Stem cells are the foundation cells for every organ, tissue, and cell in the body. Stem cells are undifferentiated, "blank" cells that do not yet have a specific function. Under proper conditions, stem cells begin to develop into specialized tissues and organs. They are self-sustaining and can replicate themselves for long periods of time. Embryonic stem cells are pluripotent cells, isolated from the inner cell mass of the blastocyst-stage mammalian embryo. They have the ability to differentiate into several somatic or somatic-like functional cells such as neurons, hepatocytes, cardiomyocytes, and others. Adult stem cells are specialized cells found within many tissues of the body where they function in tissue homeostasis and repair. They are precursor cells capable of differentiation into several different cells. The knowledge of stem cells from various sources offered a new hope for the treatment of various diseases.     

Derivation of osteoclasts from hematopoietic colony-forming cells in culture.

The osteoclast is known to be derived from the hematopoietic stem cell, but its lineage remains controversial. There is evidence that osteoclastic differentiation is induced through a contact-dependent interaction between bone marrow stromal cells and hematopoietic precursors. To analyze osteoclastic lineage, colonies were generated in semisolid medium from mouse spleen cells in the presence of Wehi-conditioned medium, interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), or macrophage colony-stimulating factor (M-CSF) with or without erythropoietin (epo). After 5-8 days colonies were picked and phenotyped and incubated with 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] on bone slices or coverslips with bone marrow-derived cell lines (ts8 or ST2) that induce osteoclastic differentiation. Cells of osteoclastic phenotype [as judged by calcitonin receptor (CTR) expression or bone resorption] were observed only in multilineage colonies. The ability of cells that generate macrophage colonies (CFU-M) to generate osteoclasts was tested by incubating alveolar or peritoneal macrophages on ts8 or ST2 cells. Despite colony formation, no osteoclastic differentiation was detectable. Last, individual cells from blast cell colonies were incubated (1 cell per culture well) on ts8 or ST2 cells in the presence of 1,25-(OH)2D3 and epo (to expose the lineage potential of the plated cell). We found CTR-positive (CTRP) cells in 6 of 66 macrophage colonies, 7 of 12 granulocyte-macrophage (GM) colonies, and 49 of 50 colonies containing multiple lineages other than GM colonies. No single-lineage CTRP colonies were observed. Although most macrophage colonies did not contain CTRP, no CTRP were observed in colonies from which macrophages were absent. These results suggest that osteoclasts are derived from a multilineage precursor rather than from CFU-M.     

Stem cell therapies in reparative medicine

The future implementation of stem cell therapies to treat conditions thus far considered incurable has been envisioned as logical consequence of the fast-paced progress in stem cell research over the last few years. Still, many practical obstacles stand in the way to the routine application of these novel technologies in medicine. The conference "Stem Cell Therapies in Reparative Medicine," held aboard the cruise vessel Majesty of the Seas (Miami, USA-Nassau, Bahamas, April 19-22, 2002), focused on the analysis of these problems from different perspectives, including developmental biology (cell proliferation, fate determination, and enrichment), immunology (allorejection and prevention of autoimmunity recurrence), and clinical therapy, emphasizing the impact of stem cell technologies on the emerging field of tissue engineering and the treatment of alpha-1 antitrypsin deficiency.     

Stem cell strategies in burns care

The prospect of being able to replace damaged tissue by the process of regeneration would dramatically and irrevocably change the impact, management and outcome of burns. The current understanding of stem cell-based modulation and therapy together with their potential developments do bring this prospect ever closer to a clinical reality. This paper gives a background to stem cell strategies in burns care and identifies actual or prospective applications which, collectively, will forever change burns care throughout the world.     

Acute kidney injury in hematopoietic cell transplantation

Hematopoietic cell transplantation is becoming an increasingly common treatment modality for a variety of diseases. However, patient survival may be limited by substantial treatment-related toxicities, including acute kidney injury (AKI). AKI can develop in approximately 70% of patients posttransplant and is associated with an increased risk of morbidity and mortality. The development of AKI varies depending on the type of conditioning regimen used and the donor cells infused at the time of transplant, and the etiology often is multifactorial. Epidemiology, risk factors for development, pathogenesis, and potential treatment options for AKI in the hematopoietic cell transplantation population are reviewed as well as newer data on early markers of renal injury. As the indications for and number of transplants performed each year increases, nephrologists and oncologists will have to work together to identify patients who are at risk for AKI to both prevent its development and initiate therapy early to improve outcomes.     

Renal dysfunction in allogeneic hematopoietic cell transplantation

BACKGROUND: Allogeneic hematopoietic cell transplantation (HCT), formerly called bone marrow transplantation, can potentially cure various malignant and non-malignant diseases, but it is associated with a high risk of toxicity. We have previously shown an overall 21% incidence of severe acute renal failure in patients undergoing autologous HCT. The present study evaluated renal dysfunction in patients undergoing allogeneic HCT. METHODS: The clinical course of 88 adult patients who received allogeneic HCT at the University of Colorado Health Science Center was analyzed. Renal dysfunction was classified as follows: Grade 0 = normal renal function; Grade 1 =>25% decrement in GFR but twofold increase in serum creatinine; Grade 3 =>twofold increase in serum creatinine and need for dialysis. RESULTS: Of the 88 patients, 81 (92%) patients had some degree of renal dysfunction (Grade 1, 20 patients; Grade 2, 32 patients; Grade 3, 29 patients). Severe nephrotoxicity (Grade 2 and Grade 3 renal dysfunction) was associated with significantly higher frequencies of sepsis, hepatic toxicity and hepatic veno-occlusive disease (VOD), and lung toxicity. The overall mortality rate at the end of 6 months was 58%. Grade 3 renal dysfunction was associated with a significantly increased risk of mortality (82.6%). CONCLUSION: A 92% incidence of renal dysfunction in allogeneic HCT patients was found. Lung and liver toxicities were significantly correlated with developing renal dysfunction, and the mortality rates for patients with Grade 3 renal failure exceeded 80%.     

Peripheral dendritic cell chimerism in allogeneic hematopoietic stem cell recipients

BACKGROUND: Relapse and graft-versus-host disease (GVHD) represent major causes of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Although leukocyte and T-cell chimerism analyses are performed routinely suggesting a predictive value on the patients outcome, little is known about chimerism of dendritic cells (DC) representing strong initiators of immune responses. METHODS: In this prospective study, peripheral DC1 (CD11c+) and DC2 (CD123+) chimerism was determined in hematopoetic stem cell recipients. DCs were isolated from peripheral blood by fluorescence activated cell sorting. Chimerism analyses were performed by fluorescent in situ hybridization or by polymerase chain reaction-based typing of short tandem repeats. RESULTS: At time of engraftment, DC chimerism analyses showed complete chimerism in 76.3% (DC1)/79.5% (DC2), mixed chimerism (MC) in 21.0% (DC1)/17.9% (DC2) and no chimerism in 2.7% (DC1)/2.6% (DC2) of the patients. Peripheral DC chimerism had no significant effect on relapse-free or overall survival. Although acute GVHD was observed more often in patients with MC for DC1/DC2 and chronic GVHD occurred more often in patients with MC for DC2, there was no statistically significant correlation. CONCLUSIONS: Although DCs as antigen presenting cells are supposed to have an impact on the induction of GVHD, there was no significant correlation between incidence of GVHD and DC chimerism after HSCT.     

Acute renal failure in hematopoietic cell transplantation

Hematopoietic cell transplantation is a common procedure for the treatment of malignancies and some non-malignant hematologic disorders. In addition to other transplant-related organ toxicities, acute renal failure is a common complication following transplantation. This review discusses the incidence, timing, etiologies, risk factors, and prognosis of renal failure associated with three commonly used transplantation procedures - myeloablative autologous, myeloablative allogeneic, and non-myeloablative allogeneic transplantation. It is important to note that the epidemiology and prognosis of renal failure are distinct with these three transplantation procedures. However, the common theme is that mortality increases with worsening renal failure with all three procedures. Moreover, mortality is >80% for patients with renal failure requiring dialysis. It also appears that surviving patients have an increased risk of chronic kidney disease after renal failure. The reduction of acute renal failure will have several advantages, including reducing mortality and the burden of chronic kidney disease following transplantation.     

干细胞与肾脏修复

目前,对于慢件肾脏疾病(Chronic kidney disease,CKD),肾脏移植和维持透析仍是最基本的治疗手段.干细胞疗法为现代医学提供了一个新的途径,同时也为肾脏疾病的治疗提供的新的契机.本文就各类十细胞在肾脏病研究中的应用作一综述.     

Stem cell use in critical limb ischemia

The following paper gives an overview of the current status of stem cell use in vascular medicine. The role of endothelial progenitor cells (EPCs) is discussed. Different approaches to use cellular based concepts are outlined: among these are the treatment of patients with critical ischemia with bone marrow derived mononuclear cells as well as our own experience with purified and highly selected CD133 and CD34 cells. The pro and cons of these different treatment regimens are discussed. An outlook is given discussing a combination of gene therapy and stem cell injections. The clinical and laboratory results of 15 patients with end-stage critical ischemia are discussed with implications for future clinical trials. We conclude that, despite all open questions, the outlook for EPC-based therapies for tissue ischemia and blood vessel repair appears promising.     

干细胞与肾脏再生

干细胞研究是一项新兴研究，在一些领域已应用于临床治疗疾病。在肾脏疾病尤其急性肾损伤修复方面，干细胞也显示了巨大的应用前景。研究显示多种干细胞可参与肾损伤后修复和肾脏再生。本文对近年来关于干细胞和肾损伤修复、肾脏再生的文献进行了回顾。     

Epithelial and hematopoietic cell chimerism in intestinal allografts

BACKGROUND: In intestinal transplantation recipient lymphocytes infiltrate the allograft soon after reperfusion. Recently, it has been demonstrated that long-surviving small bowel transplants bear enterocytes of recipient origin. We investigated whether epithelial cells (enterocytes) persisted in long-term allografts based on studies of biopsies. METHODS: The biopsies of four male intestinal transplant recipients of female grafts with a previous graft biopsy positive for recipient enterocytes were examined at least 6 months after previous positive assessment. Using the FISH technique, we searched for Y-chromosome-positive enterocytes in the female allograft. RESULTS: Recipient male enterocytes were identified in all biopsies at low percentages ranging from 0.18 to 0.26. The lymphocytes within the graft were of both recipient (male) and donor (female) origin. CONCLUSION: The four types of cells-enterocytes and lymphocytes of recipient and donor origin-coexist in long-term graft biopsies.     

Liver disease after hematopoietic cell transplantation in adults

Liver-related complications constitute a large component of the overall morbidity and mortality associated with hematopoietic cell transplantation. Affecting up to 80% of allogeneic HCT recipients, prompt recognition and treatment are essential. The differential diagnosis is broad and is best categorized by time of onset after transplantation. Early complications include drug-induced liver injury, sinusoidal obstruction syndrome, and graft-versus-host disease. Late complications include infectious sequelae, cirrhosis, and hepatic malignancies. Patients being considered for hematopoietic cell transplantation should be screened and evaluated for liver-related complications to help improve outcomes.