Hematopoietic Stem Cell

Hox genes are clearly implicated in leukemia; however, neither the specificity of the leukemogenic potential among Hox genes of different paralog groups nor the role of the homeodomain is clear. We tested the leukemogenic potential of various NUP98-Hox fusion genes alone and with MEIS1. All genes tested had a significant overlapping effect in bone marrow cells in vitro. However, not all formed strong leukemogenic NUP98 fusion genes; but together with overexpression of MEIS1, all induced myeloid leukemia. This phenomenon was also seen with NUP98 fusions containing only the homeodomain of the corresponding Hox protein. We then exploited the strong transforming potential of NUP98-HOXD13 and NUP98-HOXA10 to establish preleukemic myeloid lines composed of early myeloid progenitors with extensive in vitro self-renewal capacity, short-term myeloid repopulating activity, and low propensity for spontaneous leukemic conversion. We also showed that MEIS1 can efficiently induce their conversion to leukemic stem cells, thus providing a novel model for the study of leukemic progression. In contrast to the leukemogenic effect of most of the Hox genes tested, HOXB4 has the ability to increase the self-renewal of hematopoietic stem cells without disrupting normal differentiation. On the basis of the discovery that the leukemogenic gene HOXA9 can also expand hematopoietic stem cells, we compared the ability of NUP98-Hox fusions to that of HOXB4 to trigger HSC expansion in vitro. Our preliminary results indicate that the expanding potential of HOXB4 is retained and even augmented by fusion to NUP98. Moreover, even greater expansion may be possible using Abd-B-like Hox fusions genes.

To evaluate safety and feasibility of autologous bone marrow-enriched CD34+ hematopoietic stem cell Tx through the hepatic artery in patients with decompensated cirrhosis. Four patients with decompensated cirrhosis were included. Approximately 200 mL of the bone marrow of the patients was aspirated, and CD34+ stem cells were selected. Between 3 to 10 million CD34+ cells were isolated. The cells were slowly infused through the hepatic artery of the patients. Patient 1 showed marginal improvement in serum albumin and no significant changes in other test results. In patient 2 prothrombin time was decreased; however, her total bilirubin, serum creatinine, and Model of End-Stage Liver Disease (MELD) score worsened at the end of follow up. In patient 3 there was improvement in serum albumin, porthrombin time (PT), and MELD score. Patient 4 developed radiocontrast nephropathy after the procedure, and progressed to type 1 hepatorenal syndrome and died of liver failure a few days later. Beca...

Hematopoietic stem cells (HSCs) have the capacity to self‐renew and the potential to differentiate into all of the mature blood cell types. The ability to prospectively identify and isolate HSCs has been the subject of extensive investigation since the first transplantation studies implying their existence almost 50 years ago. Despite significant advances in enrichment protocols, the continuous in vitro propagation of human HSCs has not yet been achieved. This chapter describes current procedures used to phenotypically and functionally characterize candidate human HSCs and initial efforts to derive permanent human HSC lines.

OBJECTIVES:One of the major challenges in the post-transplant period is nutrition. In this prospective, non-randomized study, total parenteral nutrition (TPN) was given to 31 patients and partial parenteral nutrition (PPN) was given to 30 patients undergoing autologous hematopoietic stem cell transplantation for solid tumors or hematologic malignancies to compare the effects of these parenteral nutrition modalities on post-transplant hematological engraftment, blood chemistry, and supportive therapy requirements.METHODS:All patients in the TPN group and 17 patients in the PPN group received growth factor in the post-transplant period. Both groups did not differ with respect to sex, age, and reinfused CD34+ cell numbers.RESULTS:After transplantation body mass index and body weight decreased significantly in both groups (P < 0.001). Whereas serum albumin concentrations did not decrease significantly in the TPN group, it fell markedly in the PPN group at the end of parenteral nutrition (P = 0.019). After parenteral nutrition, blood chemistry was also remarkable for serum urea and glucose levels, which were elevated significantly in the TPN group (P < 0.001 and P = 0.03, respectively). Patients receiving TPN had a higher incidence of positive microbial cultures and clinical infection than did patients receiving PPN (64.5% versus 40%, P = 0.05). The most striking result was a delay in platelet engraftment for the TPN group compared with the PPN group (15.54 and 12.93 d, respectively; P = 0.014). This difference was also noted in patients using growth factor in the PPN group (P = 0.017). Parallel to these results, platelet transfusion requirement increased in the TPN group compared with the PPN group (1.93 versus 1.16 U, P = 0.004). Both groups were unremarkable for leukocyte recovery and red blood cell transfusion requirement.CONCLUSIONS:Consequently, TPN has some pitfalls of hyperglycemia, infection tendency, delayed platelet engraftment, and increased platelet transfusion requirement. Therefore, it should not be used as a standard nutrition support for patients undergoing autotransplantation.

Given the generally poor outcome of advanced B cell chronic lymphocytic leukemia, experimental approaches are warranted, especially for younger patients in whom classical treatments have failed. We therefore conducted a prospective single-center study, using polychemotherapy (ESHAP) to prepare patients for hematopoietic stem cell collection and autologous stem cell transplantation as consolidation therapy. Twenty patients entered the study. An adequate response

DNA methylation is a dynamic epigenetic mark that undergoes extensive changes during differentiation of self-renewing stem cells. However, whether these changes are the cause or consequence of stem cell fate remains unknown. Here, we show that alternative functional programs of hematopoietic stem cells (HSCs) are governed by gradual differences in methylation levels. Constitutive methylation is essential for HSC self-renewal but dispensable for homing, cell cycle control and suppression of apoptosis. Notably, HSCs from mice with reduced DNA methyltransferase 1 activity cannot suppress key myeloerythroid regulators and thus can differentiate into myeloerythroid, but not lymphoid, progeny. A similar methylation dosage effect controls stem cell function in leukemia. These data identify DNA methylation as an essential epigenetic mechanism to protect stem cells from premature activation of predominant differentiation programs and suggest that methylation dynamics determine stem cell functions in tissue homeostasis and cancer.

Wnt molecules play a key role in growth, proliferation and development of some embryonic and adult organs as well as hematopoietic stem cells. Wnt signaling pathways are aberrantly activated in many tumor types, including solid tumors and hematologic malignancies. To investigate the expression profile of a large number of Wnt genes in leukemic cells from Iranian patients with acute myeloblastic leukemia. RT-PCR method was used to determine the Wnt genes expression in bone marrow (BM) and/or peripheral blood (PB) samples from 16 patients with AML and PB samples of 36 normal subjects. Among 14 Wnt molecules included in this study, Wnt-7A and Wnt-10A were significantly down-regulated (p = 0.002 and p &lt; 0.0001, respectively) and Wnt-3 was significantly over-expressed (p &lt; 0.02) in AML patients compared to normal subjects. No significant association was found between Wnt expression and FAB classification of the patients. Our results demonstrated for the first time aberrant expressi...