Search PubMed⌕ Search

Biomedical subjects

Malcolm Alison

Publications and source records attributed to Malcolm Alison.

6 recordsLinked to original sources
PubMed2006

Characterization and clinical application of human CD34+ stem/progenitor cell populations mobilized into the blood by granulocyte colony-stimulating factor.

A phase I study was performed to determine the safety and tolerability of injecting autologous CD34(+) cells into five patients with liver insufficiency. The study was based on the hypothesis that the CD34(+) cell population in granulocyte colony-stimulating factor (G-CSF)-mobilized blood contains a subpopulation of cells with the potential for regenerating damaged tissue. We separated a candidate CD34(+) stem cell population from the majority of the CD34(+) cells (99%) by adherence to tissue culture plastic. The adherent and nonadherent CD34(+) cells were distinct in morphology, immunophenotype, and gene expression profile. Reverse transcription-polymerase chain reaction-based gene expression analysis indicated that the adherent CD34(+) cells had the potential to express determinants consistent with liver, pancreas, heart, muscle, and nerve cell differentiation as well as hematopoiesis. Overall, the characteristics of the adherent CD34(+) cells identify them as a separate putative stem/progenitor cell population. In culture, they produced a population of cells exhibiting diverse morphologies and expressing genes corresponding to multiple tissue types. Encouraged by this evidence that the CD34(+) cell population contains cells with the potential to form hepatocyte-like cells, we gave G-CSF to five patients with liver insufficiency to mobilize their stem cells for collection by leukapheresis. Between 1 x 10(6) and 2 x 10(8) CD34(+) cells were injected into the portal vein (three patients) or hepatic artery (two patients). No complications or specific side effects related to the procedure were observed. Three of the five patients showed improvement in serum bilirubin and four of five in serum albumin. These observations warrant further clinical trials.

Antigens, CD34↗
PubMed2004

Mesenchymal stem cells are renotropic, helping to repair the kidney and improve function in acute renal failure.

Injury to a target organ can be sensed by bone marrow stem cells that migrate to the site of damage, undergo differentiation, and promote structural and functional repair. This remarkable stem cell capacity prompted an investigation of the potential of mesenchymal and hematopoietic stem cells to cure acute renal failure. The model of renal injury induced in mice by the anticancer agent cisplatin was chosen. Injection of mesenchymal stem cells of male bone marrow origin remarkably protected cisplatin-treated syngeneic female mice from renal function impairment and severe tubular injury. Y chromosome-containing cells localized in the context of the tubular epithelial lining and displayed binding sites for Lens culinaris lectin, indicating that mesenchymal stem cells engraft the damaged kidney and differentiate into tubular epithelial cells, thereby restoring renal structure and function. Mesenchymal stem cells markedly accelerated tubular proliferation in response to cisplatin-induced damage, as revealed by higher numbers of Ki-67-positive cells within the tubuli with respect to cisplatin-treated mice that were given saline. Hematopoietic stem cells failed to exert beneficial effects. These results offer a strong case for exploring the possibility that mesenchymal stem cells by virtue of their renotropic property and tubular regenerative potential may have a role in the treatment of acute renal failure in humans.

Acute Kidney Injury↗
PubMed2002

Assessment of proliferation in vivo using 2-[(11)C]thymidine positron emission tomography in advanced intra-abdominal malignancies.

The purpose of this study was to determine the relationship between 2-[(11)C]thymidine positron emission tomography (PET) in vivo-derived parameters and the ex vivo Ki-67 index of proliferation in human tumors. The study comprised 17 treatment-naïve patients with advanced intra-abdominal malignancies. Tumor thymidine kinetics were measured using 2-[(11)C]thymidine PET. Tissue data were analyzed to give the standardized uptake value, the area under the time activity curve, and the fractional retention of thymidine (FRT) obtained by kinetic modeling. For the latter, the contribution of labeled metabolites was accounted for by measuring thymidine metabolites in arterial plasma. To examine the influence of tumor blood flow on the thymidine PET data, a perfusion scan using inhaled [(15)O]CO(2) was carried out in a subset of 11 patients. Biopsies were stained with a MIB1 antibody to obtain a Ki-67 index, and correlations with the PET-derived parameters were investigated. There was no relationship between tumor blood flow and the thymidine PET data, showing that the retention of 2-[(11)C]thymidine in tumors was independent of tumor perfusion. There was no correlation between the Ki-67 index and either standard uptake value or area under the curve. There was a correlation between the Ki-67 index and FRT (r = 0.58; P = 0.01). The correlation between the Ki-67 index and FRT in this dataset was not influenced by the interval between biopsy and imaging (0.1-126 weeks), the origin of the biopsy for Ki-67 staining (primary tumor or metastasis), or whether the biopsy was from an imaged or a nonimaged tumor. This is the first report in human tumors showing that 2-[(11)C]thymidine PET-derived parameters correlate with the level of tumor proliferation measured using Ki-67 immunohistochemistry. The study shows that the in vivo measurement of 2-[(11)C]thymidine in tumors using PET can provide a surrogate marker of proliferation and supports the potential use of the technique in the early assessment of response to antiproliferative cancer treatment.

Abdominal Neoplasms↗
PubMed2002

Hepatic stem cells.

The liver in an adult healthy body maintains a balance between cell gain and cell loss. Though normally proliferatively quiescent, hepatocyte loss such as that caused by partial hepatectomy, uncomplicated by virus infection or inflammation, invokes a rapid regenerative response to restore liver mass. This restoration of moderate cell loss and 'wear and tear' renewal is largely achieved by hepatocyte self-replication. Furthermore, hepatocyte transplants in animals have shown that a certain proportion of hepatocytes can undergo significant clonal expansion, suggesting that hepatocytes themselves are the functional stem cells of the liver. More severe liver injury can activate a potential stem cell compartment located within the intrahepatic biliary tree, giving rise to cords of bipotential so-called oval cells within the lobules that can differentiate into hepatocytes and biliary epithelial cells. A third population of stem cells with hepatic potential resides in the bone marrow; these haematopoietic stem cells can contribute to the albeit low renewal rate of hepatocytes, make a more significant contribution to regeneration, and even completely restore normal function in a murine model of hereditary tyrosinaemia. How these three stem cell populations integrate together to achieve a homeostatic balance is not known. This review focuses on two major aspects of liver stem cell biology: firstly, the identity of the liver stem cells, and secondly, their potential value in the treatment of major liver disease.

Animals↗
PubMed2002

Variable nuclear localization of alpha-catenin in colorectal carcinoma.

The E-cadherin/catenin complex plays a major role in epithelial cell-cell adhesion. Both beta-catenin and gamma-catenin bind directly to the cytoplasmic domain of E-cadherin whereas alpha-catenin links the bound beta-catenin or gamma-catenin to the actin microfilament network of the cellular cytoskeleton. Significant changes in the expression and/or structure of members of the complex can occur in neoplasia. Several studies have reported on the nuclear localization of beta- and gamma-catenin and on their role in influencing the transcriptional activity of several proto-oncogenes. The cellular localization of alpha-catenin has not been studied in detail. The aim of this study was to investigate the cellular localization of alpha-catenin in colorectal carcinoma both in vitro and in vivo and to assess whether it might be relevant to tumor behavior. The expression of alpha-catenin was examined in a panel of colorectal carcinoma cell lines (SW480, SW620, HCT116, HT29, and Caco-2) using a combination of immunohistochemistry, confocal fluorescence microscopy, and Western blotting. The expression of alpha-catenin was also studied by immunohistochemistry in 15 sporadic colorectal adenomas, 30 sporadic colorectal adenocarcinomas, and their 13 lymph node metastases. From familial adenomatous polyposis patients, 20 adenomas and 5 adenocarcinomas were studied. Nuclear localization of alpha-catenin was detected in the colorectal carcinoma cell lines when the cells were dispersed rather than confluent. alpha-catenin was not detected in the nuclei in any of the sporadic or familial adenomas. However, it was detected in one sporadic and one familial adenocarcinoma but not in any of the lymph node deposits. alpha-catenin can localize to the nuclei of colorectal tumor cells, and this may be related to lack of perception of connection to adjacent cells.

Cell Nucleus↗