Increased CD133 expression in bone marrow of myelodysplastic syndromes

Endothelial progenitor cells: current issues on characterization and challenging clinical applications

Since their discovery about a decade ago, endothelial precursor cells (EPC) have been subjected to intensive investigation. The vision to stimulate respectively suppress a key player of vasculogenesis opened a plethora of clinical applications. However, as research opened deeper insights into EPC biology, the enthusiasm of the pioneer era has been damped in favour of a more critical view. Recent research is focused on three major questions: The fact that the number of EPC in peripheral blood is exceedingly low has consistently raised suspicion whether these cells can plausibly have an impact on physiological or pathophysiological processes. Secondly, whereas the key role of EPC in tumourigenesis has been strongly emphasized by various groups in the past, recent publications are challenging this hypothesis. Thirdly, the lack of consensus on EPC-defining markers and standardized protocols for their detection have repeatedly led to difficulties concerning comparability between papers. In this current review, an overview on recent findings on EPC biology is given, their challenging clinical implications are discussed and the perplexity underlying the current controversial debate is illustrated.

Detection of molecular targets on the surface of CD34+CD38- bone marrow cells in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) is a kind of clonal stem-cell disorder in which aberration within a hematopoietic stem cell (HSC) gives rise to the entire disease as in acute myeloid leukemia (AML). Studies have showed that contrasting normal stem cells, AML stem cells express CD96 and CD123, but lack of CD90, although both of them reside within the CD34(+)CD38(-) population. So far, little is known about expression of the markers on MDS HSC. In this study, we analyzed the immunophenotypic characteristics of CD34(+)CD38(-) bone marrow (BM) cells by multicolor flow cytometry in 38 patients with MDS and 10 control patients. We found that CD34(+)CD38(-) BM cells coexpressed CD13, CD33, CD117, CD133, and HLA-DR almost in all patients, but in MDS they expressed higher amounts of CD13 (79% +/- 16% vs. 36% +/- 13%, P < 0.05) and CD133 (66% +/- 20% vs. 25% +/- 13%, P < 0.05). CD90 was expressed in all control patients but just in 63% of patients with MDS. No control patients had an expression of CD2, CD5, CD7, CD44, CD96, and CD123, which expressed variable amounts in 17-53% of patients with MDS. The level of CD13 in RCMD (89% +/- 7%), RAEB-1 (88% +/- 11%), and RAEB-2 (81% +/- 13%) were obviously higher than that of RA (63% +/- 16%, P < 0.05). CD2, CD5, and CD7 were more frequently observed in RAEB or INT and HIGH-R cases. Taken together, we demonstrate MDS stem cells display deranged phenotypic abnormalities that may make them particularly difficult to eradicate using therapies targeted against surface antigens, and the percentage of cells expressing CD13 is notably higher in patients with high-grade MDS that may be a potential prognostic indicator of MDS in the future.

Flow cytometric scoring system (FCMSS) assisted diagnosis of myelodysplastic syndromes (MDS) and the biological significance of FCMSS-based immunophenotypes

In the myelodysplastic syndromes (MDS), the haematopoietic cells show various levels of abnormal maturation and differentiation, which can be detected by flow cytometry. Testing the anomalies of stage- or lineage-specific surface antigens in CD34+ blasts can distinguish MDS from non-clonal cytopenic diseases, and also reflect the pathological characteristics of MDS as a class of clonal diseases for providing new clues to basic research. The present study established a flow cytometric scoring system (FCMSS) based on theproportion and antigenic co-expression of CD34+ blasts. This FCMSS showed good sensitivity and specificity (77.8% and 100%) in the assisted diagnosis of low-risk MDS without chromosome anomalies, ringed sideroblasts and excess marrow blasts. Moreover, we explored and reported different modes of abnormal expression of CD34+ blasts antigens in different disease stages and analyzed the biological significance of the immunotypes for the first time. We found expression of mature myeloid antigens and lymphoid antigens gradually decreased, and early functional antigens gradually increased from low-risk MDS with normal karytype to low-risk MDS with abnormal karyotype then to high-risk MDS. The patients with higher FCM scores were generally accompanied with HLA-DR15 allele or hypocellular marrow. Evolution of clones and immunological factors might have influence on expression of antigens in CD34+ blasts.

Expression and clinical significance of the stem cell marker CD133 in hepatocellular carcinoma

BACKGROUND

Although the primitive haematopoietic and neuronal stem cell marker CD133 is known to be present in cancer stem cells (CSCs) in hepatocellular carcinoma (HCC), the postresection prognostic impact of CD133 in HCC patients remains limited.

METHODS

Sixty-three resected specimens were collected from HCC patients. The expression of CD133 protein was analysed by immunohistochemistry and the association of CD133 expression with clinicopathological characteristics, tumour recurrence and survival of the patients was evaluated.

RESULTS

Immunohistochemical analysis of 63 HCC tissue specimens revealed that CD133 positive tumour cells were frequently present in HCC. Increased CD133 immunostaining was found in 26 specimens (41.3%). Increased CD133 expression levels were correlated with increased tumour grade, advanced disease stage, and elevated serum alpha-fetoprotein levels. Kaplan-Meier analysis indicated that patients with increased CD133 levels had shorter overall survival and higher recurrence rates compared with patients with low CD133 expression. Multivariate analyses revealed that increased CD133 expression was an independent prognostic factor for survival and tumour recurrence in patients with HCC.

CONCLUSIONS

These findings suggest that reactivated CD133 positive cells are frequently present in HCC. Additionally, increased CD133 expression corresponds with higher stage tumours in HCC, thus indicating a poor prognosis for patients. These data support the CSC hypothesis.

Detection of hematopoietic maturation abnormalities by flow cytometry in myelodysplastic syndromes and its utility for the differential diagnosis with non-clonal disorders

The diagnosis of myelodysplastic syndromes (MDS) is based on peripheral cytopenias, bone marrow (BM) morphology and karyotyping. This may be difficult in cases with few dysplastic elements in BM and a normal karyotype. We examined the utility of flow cytometric analysis for the differential diagnosis between MDS and non-clonal disorders (NCD) presenting peripheral cytopenias. Quantitative assessment of CD45, CD16, CD13, CD11b, CD10 and CD64 in granulocytes and monocytes, and CD71 and glycophorin A in erythroblasts besides CD34+ cell count was performed in BM of 31 consecutive newly diagnosed patients with MDS, 11 patients with NCD and 11 healthy controls (BM donors). In MDS, the median number of phenotypic abnormalities found was 3 (1-8). The WPSS score showed a correlation with the total number of changes per case (r=0.48; p=0.002). Decreased SSC in promyelocytes correlated with the peripheral neutrophil count (r=-0.46; p=0.007). In NCD, the normal variation of antigen expression along granulocytic and erythroblast maturation was always maintained. In the discriminant analysis, SSC of CD34+ cells, together with that of promyelocytes and metamyelocytes were able to correctly classify 87% of the cases as clonal or non-clonal. Our quantitative approach permitted to detect at least one abnormality in antigen expression in every case of MDS. However, the most important parameters for differential diagnosis with NCD were the analysis of the granularity in immature cells, especially of the granulocytic series.