技术资料

Human hematopoietic stem cells are defined by their ability to repopulate multiple hematopoietic lineages in the bone marrow of transplanted recipients and therefore are functionally distinct from hematopoietic progenitors detected in vitro. Although factors capable of regulating progenitors are well established,in vivo regulators of hematopoietic repopulating function are unknown. By using a member of the vertebrate Wnt family,Wnt-5A,the proliferation and differentiation of progenitors cocultured on stromal cells transduced with Wnt-5A or treated with Wnt-5A conditioned medium (CM) was unaffected. However,i.p. injection of Wnt-5A CM into mice engrafted with human repopulating cells increased multilineage reconstitution by textgreater3-fold compared with controls. Furthermore,in vivo treatment of human repopulating cells with Wnt-5A CM produced a greater proportion of phenotypically primitive hematopoietic progeny that could be isolated and shown to possess enhanced progenitor function independent of continued Wnt-5A treatment. Our study demonstrates that Wnt-5A augments primitive hematopoietic development in vivo and represents an in vivo regulator of hematopoietic stem cell function in the human. Based on these findings,we suggest a potential role for activation of Wnt signaling in managing patients exhibiting poor hematopoietic recovery shortly after stem cell transplantation. View Publication

The mechanisms that regulate hematopoietic stem cell (HSC) fate decisions between proliferation and multilineage differentiation are unclear. Members of the Wnt family of ligands that activate the canonical Wnt signaling pathway,which utilizes beta-catenin to relay the signal,have been demonstrated to regulate HSC function. In this study,we examined the role of noncanonical Wnt signaling in regulating HSC fate. We observed that noncanonical Wnt5a inhibited Wnt3a-mediated canonical Wnt signaling in HSCs and suppressed Wnt3a-mediated alterations in gene expression associated with HSC differentiation,such as increased expression of myc. Wnt5a increased short- and long-term HSC repopulation by maintaining HSCs in a quiescent G(0) state. From these data,we propose that Wnt5a regulates hematopoiesis by the antagonism of the canonical Wnt pathway,resulting in a pool of quiescent HSCs. View Publication

OBJECTIVE: To explore the effects of anti-CD44 monoclonal antibody-IM7 on the in vitro adhesion and migration of chronic myeloid leukemia stem cell (CML-LSC) and its mechanism. METHODS: CD34(+)CD38(-)CD123(+) leukemic stem cells (LSC) from 20 newly-diagnosed chronic myeloid leukemia (CML) patients BM cells and CD34(+)CD38(-) hematopoietic stem cells (HSC) from 20 full-term newborn cord blood cells were isolated with EasySep(TM) magnet beads. The CD44 expression of the LSC and HSC was detected by flow cytometry (FCM),and the adhesion and migration ability of the LSC and HSC pre- and post-incubated with IM7 in vitro by MTT assay and transendothelial migration assay,respectively. RESULTS: (1) After incubated with IM7,the LSC and HSC CD44 expression rates were (86.60 ± 2.10)% vs. (25.40 ± 1.70)% (P textless 0.05),respectively. (2) The adhesive ability of the LSC to endothelial cells was decreased markedly after incubated with IM7,the OD value (A(570)) changing from pre-incubation of (0.62 ± 0.11) to post-incubation of (0.34 ± 0.07),while there was little change of A(570) in the HSC group. (3) The migration ability of the LSC group was inhibited evidently after incubated with IM7,the inhibition rate being 46% ∼ 63%,while little change of that in HSC group was detected. (4) The adhesive ability of the LSC group to marrow stromal cells was decreased markedly after incubated with IM7,while little change was found in that of HSC group. CONCLUSION: The anti-CD44 monoclonal antibody-IM7 can effectively inhibit the adhesion and migration abilities of the LSC in vitro,which might provide a theoretical evidence for targeting therapy. View Publication