Abstract: One of the cardinal symptoms of type 1 Gaucher Disease (GD) is cytopenia, usually explained by bone marrow (BM) infiltration by Gaucher cells and hypersplenism. However, some cases of cytopenia in splenectomized or treated patients suggest possible other mechanisms. To evaluate intra-cellular glucocerebrosidase (GlcC) activity in immature progenitors and to prove the conduritol B epoxide (CBE)-induced inhibition of the enzyme, we used an adapted flow cytometric technique before assessing the direct effect of GlcC deficiency in functional assays. Among haematopoietic cells from healthy donors, monocytes showed the highest GlcC activity but immature CD34(+) and mesenchymal cells also had significant GlcC activity. CBE greatly inhibited the enzyme activity of all cell categories. GlcC-deficient CD34(+) cells showed impaired ability to proliferate and differentiate in the expansion assay and had lower frequency of erythroid burst-forming units, granulocyte colony-forming units (CFU) and macrophage CFU progenitors, but the effect of GlcC deficiency on megakaryocyte CFU lineage was not significant. GlcC deficiency strongly impaired primitive haematopoiesis in long-term culture. Furthermore, GlcC deficiency progressively impaired proliferation of mesenchymal progenitors. These data suggest an intrinsic effect of GlcC deficiency on BM immature cells that supplements the pathophysiology of GD and opens new perspectives of therapeutic approach.
Abstract: Our purpose was to assess success rates in children of achieving optimal hematopoietic progenitor cells (HPCs) harvest after mobilization with 300 microg/kg pegfilgrastim. Between January 2005 and January 2007, 26 children with solid malignancies who were referred for HPC collection were consecutively included. Hematopoietic progenitor cell mobilization consisted of one s.c. injection of 300 microg/kg body weight (BW) of pegfilgrastim. The success criterion was defined as at least 5 x 10(6) CD34+ cells/kg during the first standard apheresis (less than 3 blood volumes processed (BVP)). After 26 inclusions, the Bayesian analysis gave a mean estimated success rate of 60.7% (95% credibility interval: 42.0-78.0%). The first apheresis allowed the collection of 8.3 x 10(6) CD34+ cells/kg BW (range 0.6-37.8), with a median of 2.8 BVP (range 1.4-3.0). Overall, the median of CD34+ cells collected was 12.4 x 10(6)/kg (range 2.7-37.8). The cumulative dose of anthracyclin was the only variable associated with the total number of CD34+ collected cells (P<0.05). Mobilization was clinically well tolerated in 20 patients. No drug-related adverse events of grade > or =3 occurred. We conclude that a single injection of 300 microg/kg pegfilgrastim in the hematological steady state is an efficient and well-tolerated method of HPC mobilization in children with solid malignancies.
Abstract: OBJECTIVE: This letter reports on the effect of enzyme replacement therapy with imiglucerase on bone healing and bone and blood abnormalities in a woman with previously untreated type 1 Gaucher disease (GD). METHODS: The 49-year-old patient had been diagnosed with GD at the age of 28 years and had previously undergone splenectomy. She presented with pseudarthrosis 14 months after sustaining a traumatic fracture of the tibia and fibula. Therapy was begun with imiglucerase 60 U/kg q2wk. The effects of treatment on bone healing were monitored radiographically, and effects on blood and bone marrow biology were monitored by hemograms, myelograms, and hematopoietic and mesenchymal clonogenic assays. RESULTS: Objective bone healing was observed starting in the third month of imiglucerase treatment. Blood abnormalities normalized and bone marrow parameters improved over the first 9 months, including a decrease in Gaucher cells, an increase in bone marrow CD34+ cell cloning efficiency, and the appearance of mesenchymal progenitors. CONCLUSION: This research letter reports the results of hematologic and bone evaluations during enzyme replacement therapy with imiglucerase in a woman with previously untreated type 1 GD who presented with a traumatic fracture.
Abstract: The predictive values of common biological criteria for the diagnosis of polycythemia vera were studied in a cohort of patients with high hematocrit. We found JAK2V617F and erythropoietin assays were the most relevant first tests. Classification of patients according to their JAK2V617F status and erythropoietin levels facilitated the choice of further diagnostic investigations.
Abstract: The scarcity of mesenchymal stem cells (MSC) in bone marrow (BM) has justified their ex vivo expansion before therapeutic use, but a method to evaluate the quality of initial mesenchymal content and track the modifications induced by graft processing has not yet been proposed. The aim of this study was to establish such a procedure. Flow cytometric and functional assay methods were modified to count CD45(-) CD14(-)/CD73(+) subsets containing all MSC and used them to study BM from spongy bone (SB) and iliac crest aspirate (ICA). These methods detected the target subsets in all BM suspensions derived from SB (n = 154) and ICA, (n = 44) with a satisfactory correlation between immuno-phenotyping and functional tests by low-density plating. We noted a higher overall MSC frequency in SB cell suspensions but a lower plating efficiency of CD45(-) CD14(-)/CD73(+) SB cells under standard culture conditions. We propose a cell quality control on un-manipulated BM cell suspensions to quantify the mesenchymal compartment with regard to varying donor factors, such as age and sampling site, that influence expansion and define a therapeutic threshold value. Furthermore, we were able to confirm differences in plating efficiency and proliferative capacity between two BM origins.
Abstract: We determined the allelic frequency of the JAK2-V617F mutation in DNA and assessed the expression levels of the mutant and wild-type JAK2 mRNA in granulocytes from 60 patients with essential thrombocythemia (ET) and 62 patients with polycythemia vera (PV) at the time of diagnosis. Using allele-specific quantitative polymerase chain reaction (qPCR), we detected JAK2-V617F in 75% of ET and 97% of PV at diagnosis. The total JAK2 mRNA levels were elevated in ET, PV, and secondary and idiopathic erythrocytosis, suggesting that hyperactive hematopoiesis alters JAK2 expression. The expression levels of JAK2-V617F mRNA were variable but strongly correlated with the allelic ratio of JAK2-V617F determined in DNA. Thus, differences in JAK2-V617F expression, markedly lower in ET than in PV, reflected different percentages of granulocytes carrying the mutation. Moreover, allelic ratios higher than 50% JAK2-V617F, indicating the presence of granulocytes homozygous for JAK2-V617F, were found in 70% of PV at diagnosis but never in ET.
Abstract: For most therapeutic strategies using MSC, the preliminary amplification is carried out in media containing fetal calf serum (FCS). The theoretical health risk of using a xenogenic serum, a recent practice for which we have limited data, cannot be underestimated, while amplification using human serum (HS) remains controversial. At present, the available information on multipotentiality, self-renewal, and transplantability does not permit the selection of FCS rather than HS. Cellular modifications observed during cell passage seem to indicate a gradual impairment of cells in relation to native MSC, suggesting the making of short cell cultures without necessarily trying to reinfuse a high number of MSC in patients. With this approach, the volume of HS required would remain limited. While clinical studies have already started, many problems remain, such as evaluating the quality of the initial mesenchymal compartment and the biological properties of the cell suspension with FCS compared to those with HS, and depending on culture time.
