Hematopoietic stem cells.

The adequate production of blood cells is maintained by a set of immature hematopoietic stem cells (HSC) located in the bone marrow after birth. HSC are able to reconstitute the hematopoietic system in disease-related bone marrow failure and bone marrow aplasia. Nowadays, HSC cells can be mobilized from the bone marrow into the peripheral blood using hematopoietic cytokines, allowing a convenient harvest of these cells for clinical transplantation. This review outlines the development of the hematopoietic system in the embryo and in adults and the characterization, enumeration, purification and ex vivo expansion of HSC for clinical use. Future directions include the genetic manipulation of HSC and the identification/expansion of bone marrow-derived stem cells capable of generating non-hematopoietic tissues.     

Marginal zone lymphoma of the lacrimal gland spreading to the lung and the bone marrow 11 years after first symptoms

We report on the case of a 52-year-old male presenting with an extranodal marginal zone lymphoma of the mucosa-associated tissue (MALT lymphoma) in the lung 11 years after radiotherapy for a MALT lymphoma of the lacrimal gland, which was primarily diagnosed as dacryoadenitis. Both tumors were investigated by immunohistochemistry and molecular techniques demonstrating their clonal genetic relationship. Both harbored the t(14;18)(q32;q21) and a trisomy 3 and showed identical immunoglobulin heavy-chain gene rearrangements. At the time of pulmonary relapse, clonal CD20- and CD43-positive bone marrow B lymphocytes were detected as well. The elaboration of this case emphasizes the importance of the combined use of modern diagnostic methods for establishment of correct diagnosis of MALT lymphomas at late relapses, which is essential for proper patient management.     

CD34+/CD133- circulating endothelial precursor cells (CEP): characterization, senescence and in vivo application

Circulating endothelial precursor cells (CEP) are interesting candidates for the treatment of ischemic diseases and for tumor targeting/imaging. We isolated a homogeneous population of CEP from CD34(+)/CD133(-) cells of peripheral blood that can be expanded easily on collagen-type-I coated plastic. CEP displayed a phenotype of mature endothelial cells (vWF, CD31, CD34, VEGF-R2, CD105, CD146) similar to that of cord-blood CEP and umbilical vein endothelial cells. They bound UEA-1 lectin, incorporated acetylated LDL and formed tube-like structures with capillary lumens in vitro. Weibel-Palade bodies were observed by electron microscopy. After 40-60 cell population doublings, CEP cultures underwent a terminal growth arrest, had shorter telomeres, up-regulated cell cycle inhibitory proteins, such as p21(CIP1) and stained positive for senescence-associated-beta galactosidase. During the whole expansion period CEP retained their endothelial phenotype and a normal karyotype. CEP had the capacity to home to ischemic tissue in vivo after systemic injection in nude rats. The convenient expandability, the homogenous phenotype, the functional cellular senescence program, the regular karyotype and the homing capacity to ischemic myocardium suggest autologous CEP cultures as a safe and promising tool for cell-based therapeutic approaches in targeting ischemic tissue and tumors.     

Disseminated infection with Prototheca zopfii after unrelated stem cell transplantation for leukemia

Disseminated infection with Prototheca zopfii is a rare disease in immunosuppressed patients. We here report the first case of lethal infection with P. zopfii following unrelated stem cell transplantation for leukemia. Breakthrough protothecosis occurred during long-term administration of voriconazole in the case of pulmonary aspergillosis.     

Correlation of COX-2 and Ep-CAM overexpression in human invasive breast cancer and its impact on survival

Recent studies have demonstrated cyclooxygenase 2 (COX-2) overexpression in various human malignancies, especially in breast cancer, where COX-2 turned out to be a predictor of poor survival. To evaluate the relation of COX-2 and Ep-CAM overexpression and its prognostic significance, we performed a retrospective study on 212 breast cancer patients with a median follow-up time of 10.5 years. Overexpression of COX-2 in tumour tissue samples was assessed by immunohistochemistry. COX-2 overexpression was found in 48.6% of the tumour samples and was predictive for poor disease-free and overall survival. Univariate analysis revealed a strong correlation between COX-2 and Ep-CAM overexpression (P=0.009). Concurrent COX-2 and Ep-CAM overexpression was present in 21.7% of tumour specimens and had an additive negative impact on disease-free and overall survival. Determination of both tumour markers should help in guiding new therapeutic strategies in patients with invasive breast cancer.     

Evaluation of optimal survival of primitive progenitor cells (LTC-IC) from PBPC apheresis products after overnight storage

Optimal overnight (ON) storage of PBPC aphereses is becoming an increasingly important issue and different options for storing PBPC products exist. The survival of primitive progenitor cells is of major interest, as recent data suggest that these progenitors are not only important for long-term engraftment but also contribute significantly to the early phase of hematopoietic engraftment after myeloablative therapy. We therefore investigated the survival of primitive progenitor cells (ie long-term culture initiating cells, LTC-IC) before (ie within 2 h after finishing the apheresis procedure) and after ON storage lasting 16 to 20 h. In addition, we compared the % of recovery of LTC-IC with that of mature progenitors (ie colony-forming cells, CFC) and with the % viability of the mononuclear cells in the apheresis product. Aliquots of PBPC aphereses products were tested in collection bags at room temperature (RT), in EDTA tubes both at RT or 4 degrees C +/- the addition of autologous plasma (AP; 2.6-fold the apheresis volume) and +/- the possibility of gas exchange. Mean viable cell counts did not show strong differences between the different storage conditions and were poor predictors for the survival of CFC and LTC-IC. At RT (collection bags, EDTA tubes +/- gas exchange) recoveries (% of input) of both, CFC (18%, 18% and 31%) and LTC-IC (10%, 4%, 17%) were low. The addition of AP at RT improved the survival of CFC and LTC-IC to 66% and 38%, respectively. Optimal recoveries for both types of progenitors (CFC: 99%, LTC-IC: 109%) were obtained at 4 degrees C in the presence of AP. In addition, a good correlation between the survival of CFC and LTC-IC was obtained (r = 0.76) suggesting that the analysis of CFC may also allow some conclusions to be drawn on the survival of LTC-IC. Bone Marrow Transplantation (2000) 25, 197-200.     

Prognostic significance of Ep-CAM AND Her-2/neu overexpression in invasive breast cancer

To assess the frequency and prognostic impact of Ep-CAM and Her-2/neu overexpression in patients with breast cancer and to determine its relationship with other prognostic markers, 205 breast cancer patients with a median follow-up of 10.8 years were enrolled in this retrospective study. Overexpression of Ep-CAM and Her-2/neu in tumor tissue samples was assessed by immunohistochemistry. Tumors presenting a Her-2/neu 2+ staining were additionally analyzed by FISH to exclude false positive results. Ep-CAM and Her-2/neu overexpression was found in 35.6% and 19.5% of the tumor samples, respectively. Both Ep-CAM and Her-2/neu overexpression were predictive for poor disease-free (DFS) and disease-related overall survival (DROS). Concurrent Ep-CAM and Her-2/neu overexpression was present in 13.2% of tumor specimens and had an additive negative impact on DFS and DROS. This minority of patients had a median time to relapse of only 34 months, whereas the median time to relapse was not reached in the patient population without Her-2/neu and Ep-CAM overexpression. By multivariate analysis Ep-CAM overexpression proved to be an indicator of poor prognosis, independent of tumor size, histologic grade, hormone receptor expression and Her-2/neu overexpression. In conclusion, overexpression of Ep-CAM and Her-2/neu complement each other as predictors for poor prognosis in patients with invasive breast cancer. Determination of these tumor markers should help in assigning breast cancer patients to 1 of 3 distinct risk categories.