Hematopoietic Progenitor Cells - Cord Blood

描述（由申请人提供）：脐带血（CB）越来越多地用于恢复缺乏兄弟姐妹或无关供体的移植患者的造血。CB移植（CBT）的主要缺点是低细胞剂量，导致中性粒细胞和血小板植入延迟，以及植入失败率高。这项资助的一个主要假设是，离体扩增的CB祖细胞将提供更快的造血重建和更少的植入失败比未经处理的CB。在上一个RO 1资助期进行的两项临床CB扩增试验中，分离了CD 133+祖细胞，并在液体培养系统中离体培养，靶向定向或更原始的造血祖细胞。在这些连续试验中，观察到植入时间更快的趋势，但发生了CD 34+祖细胞的显著损失。为了避免阳性选择的需要，这会导致CD 34+细胞的大量损失，我们已经开发了一种替代方法，该方法涉及CB单核细胞（MNC）与骨髓来源的间充质干细胞（MSC）的离体共培养。我们假设，MSC，作为一个替代造血“利基”，将提供一个更合适的微环境的扩展谱系承诺CB造血祖细胞比目前的液体悬浮培养系统。随着当前CB扩增试验的累积接近完成，该竞争性更新申请将重点关注MSC共培养中CB扩增的临床评价，长期目标是改善CBT患者的中性粒细胞和血小板植入。虽然低细胞剂量显然是CBT的主要限制，但许多研究人员也报告了CB细胞向骨髓归巢的缺陷。因此，可以想象的是，即使具有最佳的离体扩增，不充分的归巢也可能限制植入的快速性，这是该提议的目标。归巢缺陷归因于负责与骨髓微血管系统表达的P-和/或E-选择素结合的细胞表面分子的低水平岩藻糖基化。这种相互作用是造血祖细胞向骨髓募集的关键组成部分。我们假设CB细胞表面岩藻糖基化水平的增加将改善与选择素的相互作用，从而改善归巢和植入。目的3将评估用岩藻糖基转移酶修饰未经操作和扩增的CB祖细胞，作为促进其向骨髓募集的手段。

DESCRIPTION (provided by applicant): Umbilical cord blood (CB) is used increasingly to restore hematopoiesis in transplant patients lacking sibling, or unrelated donors. A major disadvantage of CB transplantation (CBT) is the low cell dose with resultant delays in neutrophil and platelet engraftment, as well as a high rate of engraftment failure. A major hypothesis of this grant is that ex vivo-expanded CB progenitors will provide more rapid hematopoietic reconstitution and less engraftment failure than unmanipulated CB. In the two clinical CB expansion trials conducted during the last RO1 funding period, CD133+ progenitors were isolated and cultured ex vivo in a liquid culture system targeting committed, or more primitive hematopoietic progenitors. In those sequential trials, trends in faster time to engraftment were seen, but significant losses of CD34+ progenitors occurred. To avoid the need for positive selection, which results in a substantial loss of CD34+ cells, we have developed an alternative approach that involves the ex vivo co-culture of CB mononuclear cells (MNC) with bone marrow-derived mesenchymal stem cells (MSC). We hypothesize that MSC, by functioning as a surrogate hematopoietic 'niche', will provide a more suitable microenvironment for the expansion of lineage-committed CB hematopoietic progenitors than afforded by current liquid suspension culture systems. As accrual to the current CB expansion trials nears completion, this competitive renewal application will focus on the clinical evaluation of CB expansion in MSC co-cultures, with the long-term goal of improving neutrophil and platelet engraftment in CBT patients. Although a low cell dose is clearly the chief limitation of CBT, a number of investigators have also reported a deficit in the homing of CB cells to the marrow. Thus, it is conceivable that even with optimal ex vivo expansion, inadequate homing may limit the rapidity of engraftment which is the goal of this proposal. The homing defect has been attributed to low levels of fucosylation of cell surface molecules responsible for binding to P- and/or E-selectins expressed by the marrow microvasculature. This interaction is a key component of the recruitment of hematopoietic progenitors to the marrow. We hypothesize that increasing the level of CB cell surface fucosylation will improve interactions with selectins, thereby improving homing and engraftment. Aim 3 will evaluate the modification of unmanipulated and expanded CB progenitor cells with a fucosyltransferase, as a means to facilitate their recruitment to the marrow.