Increased CD133 expression in bone marrow of myelodysplastic syndromes

Fresh frozen bone marrow biopsies were evaluated immunohistochemically, applying monoclonal antibodies against CD31, CD34, VEGFR-2 and CD133, a novel marker identifying human endothelial progenitor cells (EPCs). Specimens of 51 patients diagnosed with MDS were compared with 16 AML and 18 controls. The percentage of CD34 expressing cells was increased and CD31 expression was decreased in advanced stages of MDS compared with normal BM. VEGFR-2 expression was also raised in MDS. Here we show for the first time that increased numbers of CD133 positive cells are present in the majority of MDS patients. Additionally, those cells occasionally seem to contribute to capillary forming units in bone marrow.     

Screening for Aspergillus spp. using polymerase chain reaction of whole blood samples from patients with haematological malignancies

Sensitive screening for Aspergillus spp. using polymerase chain reaction (PCR) of whole blood samples in patients with haematological disorders has not been performed to date. In a 2-year study, 121 patients admitted to the University Hospital of Innsbruck for cancer chemotherapy without clinical signs of fungal infection were prospectively screened for Aspergillus spp. In 28 out of 121 (23%) patients, Aspergillus DNAaemia was detected. Of these patients, 16 (57%) were positive only once for Aspergillus DNA, but positivity was never associated with invasive aspergillosis. PCR positive episodes were short and resolved without antifungal treatment. Five patients (18%) had intermittent PCR positive results. Seven (25%) patients presented at least two consecutive positive PCR results; one of these patients developed invasive aspergillosis and another two were strongly suspected as having aspergillosis. Based on the criteria of the European Organization for Research and Treatment of Cancer case definitions, sensitivity and specificity of serial PCR monitoring were 75% and 96%. Positive PCR results became negative shortly after commencement of antifungal treatment, but the changes did not correlate with clinical responsiveness to treatment in three patients. Our results indicate the potential usefulness of PCR for screening for Aspergillus spp. in patients at risk, but without antifungal treatment.     

“Idiopathic Bence-Jones proteinuria”: a new characterization of an old entity

Idiopathic Bence-Jones proteinuria (BJP) is a rare plasma cell dyscrasia, of which the clinical and biological characteristics are yet unclear. Historical data suggested that they are at higher risk of progression to multiple myeloma or other related neoplasms, while recent findings are contradictory. To address these open questions, we evaluated a series of both BJP and monoclonal gammopathy of undetermined significance (MGUS) with production of an intact immunoglobulin plus Bence-Jones proteinuria (MGUS+BJP) with long-term follow-up, regarding their clinical characteristics and progression to multiple myeloma, amyloidosis or other related B cell lymphoproliferative disorders. Two hundred and twenty-nine persons fulfilling the 2004 criteria of MGUS were included in the final analyses: 31 had BJP and 198 had MGUS+BJP. At the time of diagnosis, significantly more persons in the BJP group had renal impairment, anaemia and polyneuropathy. A more detailed analysis revealed discrepancies between the serum and urine light chain type in nine cases, reflecting clonal heterogeneity. The number of disease progressions was higher in MGUS+BJP (n?=?30) when compared to BJP (n?=?1), with a rate of 1.6 and 0.4 progressions per 100 person-years, respectively. In conclusion, BJP has distinct clinical characteristics and a lower risk of progression when compared to MGUS+BJP. Our data suggest that MGUS+BJP being closer to malignant transformation may be due to the higher portion of genetically heterogeneous, pre-malignant plasma cell subclones.     

Defective DNA-mismatch repair: a potential mediator of leukemogenic susceptibility in therapy-related myelodysplasia and leukemia

We investigated the potential role of defective DNA-mismatch repair (MMR) as a mediator of leukemogenic susceptibility in patients with therapy-related myelodysplasia (t-MDS) and leukemia (t-leuk). Thirty-seven individuals with t-MDS/t-leuk were analyzed for microsatellite instability (MSI), the hallmark of defective DNA-MMR. Using standardized international criteria, 5/37 (14%) patients displayed high MSI, whereas 3 other patients had low MSI (8%). To determine the stage at which MSI had developed, we analyzed the primary tumors of 12 patients. Three of 4 patients with high MSI t-MDS/t-leuk also had microsatellite unstable primary tumors. Conversely, MSI was not detected in any primary malignancy of patients with low MSI or microsatellite stable t-MDS/t-leuk (P = 0.0182). In the high MSI group, we further investigated genes targeted by defective DNA-MMR (BAX, TGFBRII, IGFIIR, Caspase-5, APC, PTEN, E2F4, MBD4, MSH6, and MSH3) in both primary tumor and t-MDS/t-leuk. However, no mutation was found in any gene. The significant association of MSI in t-MDS/t-leuk and corresponding primary tumors suggests that defective DNA-MMR confers leukemogenic susceptibility to this cohort of patients.     

In vivo release of vascular endothelial growth factor from colorectal carcinomas

The formation of new blood vessels is essential for the growth of malignant tumors and their hematogenic spread. Tumor-induced neoangiogenesis occurs through sprouting of preexisting vessels. An alternative mechanism might be the recruitment of bone marrow-derived endothelial cells, or their precursors, to the tumor site by the release of vascular endothelial growth factor (VEGF) from cancer cells, i.e., tumor-induced postnatal vasculogenesis. To investigate if a significant amount of VEGF is released from malignant tumors in vivo, thus potentially mobilizing endothelial precursor cells (EPC) from the bone marrow, we measured plasma levels of soluble VEGF obtained from tumor-draining mesenteric veins (VEGF-M) during surgery and, simultaneously, in venous blood obtained distant from the tumor (VEGF-P). This analysis was performed in 29 patients with colorectal carcinoma. VEGF-M levels were substantially higher in patients with distant metastases (208 +/- 61 pg/ml) compared to patients with nonmetastatic disease (99 +/- 72 pg/ml, p = 0.003). Also, in patients with aggressive disease, i.e., histologically undifferentiated (G3) tumors, higher levels of VEGF-M were measured than in patients with tumors of lower histologic grading (196 +/- 46 vs. 107 +/- 80 pg/ml, p = 0.01). In conclusion, the release of significant amounts of soluble VEGF in vivo from clinically and/or histologically aggressive tumors might reflect their high angiogenic or vasculogenic potential, probably leading to the recruitment of EPC from the bone marrow.     

Thrombocytes are the major source for soluble vascular endothelial growth factor in peripheral blood

Serum levels of vascular endothelial growth factor (VEGF-S) have been reported to correlate with tumor stage and prognosis in various human malignancies. The source of soluble VEGF in peripheral blood remains obscure. We therefore measured the concentration of immunoreactive VEGF in 241 serum samples and 61 plasma samples (VEGF-P) from 20 subjects undergoing myeloablative chemotherapy and from 3 normal platelet donors. A significant correlation between the peripheral blood platelet count (PC) and VEGF-S (r = 0.86) but not VEGF-P was found. VEGF-S levels were 58.43 +/- 42.50 pg/ml (mean +/- SD) in patients with a PC < 50 x 10(9)/l, 203.29 +/- 176.56 pg/ml for a PC of 50-150 x 10(9)/l, and 457.42 +/- 475.41 pg/ml for a PC > 150 x 10(9)/l. Interestingly, VEGF-P levels were substantially lower than the corresponding VEGF-S values, namely below the detection limit in most cases. Supernatants from platelet-rich plasma contained no VEGF, but after in vitro lysis of the platelets very high VEGF levels were found. The VEGF content per 10(9) platelets was calculated at 2.51 +/- 2.39 pg and was dependent on the mean platelet volume. In summary, VEGF release from platelets during blood clotting was found to be the main source of VEGF in serum samples. Cancer patients in clinical remission have negligible amounts of soluble VEGF in peripheral blood, and myeloablative chemotherapy causes a significant drop in VEGF-S levels corresponding to the decrease in PC. Thus, studies addressing the diagnostic and prognostic value of VEGF-S in cancer patients must be interpreted with caution. Our data provide the basis for predicting VEGF-S in relation to PC in vivo, and for reevaluating former studies of VEGF-S in patients with malignant or nonmalignant disease.