Is cyclin D2 a marker of B-cLL cell activation?

The most recent studies emphasize a link between B-cell proliferation in vivo and clinical outcome of B-cell chronic lymphocytic leukemia (B-CLL). The expression of cyclin D2 in B-CLL cells isolated from the peripheral blood of 27 untreated patients in relation to the apoptosis ratio both before and 72 h after culture in the absence of growth factors was analyzed by immunocytochemistry. The significant associations between cell death in culture and both cyclin D2 expression in freshly isolated cells and the rate of its decrement in culture found in this study confirm the special role of cyclin D2 in enhancing the longevity of these cells in vivo. As cyclin D2 is inducible in the early G1 phase, its increased expression might also reflect the activation of cells attempting to replicate in vivo. Furthermore, the finding that B-CLL progression positively correlates with the gradual increase in the proportion of apoptotic B lymphocytes in culture seems to support the notion of cells striving to undergo division in the absence of growth factors. All together, these results indicate the possibility that cyclin D2+ cells represent a pool of leukemic cells with the potential to enter the dividing compartment.

Characterization of human hepatocytes isolated from non-transplantable livers.

INTRODUCTION: The successful use of hepatocytes depends on a reliable demonstration of the functional and morphological integrity of isolated cells. Herein we investigated whether the isolation and cryopreservation of primary human hepatocytes can compromise cell viability and liver-specific characteristics. MATERIAL/METHODS: Hepatocytes were isolated from encapsulated human liver segments by a modified 2-step perfusion technique. Isolated cells were Percoll-purified, cryopreserved, and stored in liquid nitrogen for 1-12 months. For rapid assessment of fresh and cryopreserve/thawed hepatocyte yield and viability, the cells were stained with trypan blue or labeled with fluorochromes. For immunocytochemical analysis, the cells were labeled with monoclonal antibodies for the presence of the following antigens and chemokines: CD3, CD45Ro, CD45Ra, CD34, CD68, CD90, CD95, CD20, HLA-DR, Ki67, PCNA, Bcl-2, p53, CXCR3, CXCR4, and SDF-1. The cells were tested for several specific functions, such as ureagenesis, energy status, MTT activity, lactate dehydrogenase leakage, and total CYP450 content. RESULTS: Assessment of both freshly isolated (Percoll-purified) and cryopreserved/thawed hepatocytes revealed a low constitutive level of contamination by non-parenchymal cells compared with crude (unpurified) preparations and tissue sections. All viable hepatocytes showed intact morphology and retained CYP450 protein, energy status, and urea synthesis. CONCLUSIONS: Modifications in hepatocyte preparations, such as depletion of dead, damaged, and nonparenchymal cells, improves cell purity, which can be adapted to further evaluation of hepatocyte immunogenicity. These data illustrate the importance and feasibility of human hepatocyte banking.

Enrichment of normal progenitors in counter-flow centrifugal elutriation (CCE) fractions of fresh chronic myeloid leukemia leukapheresis products.

OBJECTIVES: The aim of this study was to assess the suitability of a technique based on counter-flow centrifugal elutriation (CCE), which should allow one to enrich chronic myeloid leukemia (CML) patients' unstimulated native leukapheresis product (nLP) in CD34+ HLADR- cells and BCR-ABL negative cells. METHODS: Six newly diagnosed CML patients were subjected to leukapheresis, and the products were subfractionated with the use of CCE. nLP and all fractions were studied for the presence of CD34+ cells and a proportion of BCR-ABL fluorescence in situ hybridization (FISH)+ cells. RESULTS: CCE fractions with a high flow rate contained the highest proportion of CD34+ cells [mean (SEM) 6.89% (3.88)]. However, CD34+ cells present in low-rate CCE fractions showed a higher proportion of HLADR-[49.6% (13.5 in 70 mL min-1) and 21.5% (11.6 in 110 mL min-1)] than those in 170 mL min-1[3.2% (2.5)] and "rotor off" [3.4% (1.9)]. This was associated with lower proportions of BCR-ABL FISH+[8.1% (4.8) and 1.9 (1.7)] and smaller BCR-ABL to ABL transcript ratios [0.58 (17) and 0.26 (0.08) in 70 and 110 mL min-1] fractions as compared to 140 and 170 mL min-1 fractions [21.6% (5.2) and 31.6% (15.3) for BCR-ABL FISH+ cells and 0.75 (0.16) and 0.90 (0.24) for BCR-ABL/ABL]. Fractions with the lowest proportions of BCR-ABL-positive cells and the lowest BCR-ABL/ABL transcript ratios (110 mL min-1) contained from 1.3 x 106 to 82.7 x 106 (median: 3.97 x 106) CD34+ cells. CONCLUSIONS: In the present study we have shown that CCE may be used effectively to obtain nLP fractions enriched in normal hematopoietic progenitors.