Schipper Laurus F, Brand Anneke, Reniers Nathalie, Melief Cees J J, Willemze Roel, Fibbe Willem E
Blood Bank Leiden-Haaglanden, Leiden, The Netherlands.
Exp Hematol. 2003 Apr;31(4):324-30. doi: 10.1016/s0301-472x(03)00004-3.
In comparison with stem cell transplantation using bone marrow or cytokine-mobilized peripheral blood, cord blood transplantation is characterized by delayed engraftment, in particular platelet recovery. The differences in the kinetics of engraftment may be related to quantitative differences in the numbers of stem cells and megakaryocyte progenitor cells and/or to qualitative differences between megakaryocyte progenitor cells in these grafts. We compared the hematopoietic composition of these grafts and determined the distribution of mature and immature megakaryocyte progenitor cells in cord blood and mobilized peripheral blood and their in vitro kinetic behavior.
Megakaryocyte progenitor cell subpopulations from cord blood (CB) and mobilized peripheral blood (PBSC) were expanded in vitro in the presence of mpl-ligand. The developmental differences during expansion of megakaryocyte progenitors were analyzed by flow cytometry and progenitor assays.
We found that the immature (CD34(+)/CD41(-)) subpopulation from CB contains more than 98% of all megakaryocyte progenitor cells, responsible for 99% of all megakaryocytic cells cultured during 2 weeks. The CB CD34(+)/CD41(+) subpopulation shows no contribution to megakaryocytic cell formation. In contrast, in PBSC the mature (CD34(+)/CD41(+)) subpopulation contains 7% of all megakaryocyte progenitor cells. Moreover, CD34(+) cells from CB and PBSC also showed distinct phenotypic differences during maturation in vitro. PBSC megakaryocyte progenitor cells transiently express both CD34 and CD41 during maturation in vitro, whereas CB progenitor cells transiently lack expression of both markers before differention into (CD34(-)/CD41(+)) megakaryocytic cells.
The in vitro data indicate the presence of different developmental stages of megakaryocyte progenitor cells in CB as compared to PBSC. These differences in composition and maturation between CB and PBSC may be related to the different kinetics of engraftment following transplantation of these stem cell sources.
与使用骨髓或细胞因子动员的外周血进行干细胞移植相比，脐血移植的特点是植入延迟，尤其是血小板恢复延迟。植入动力学的差异可能与干细胞和巨核细胞祖细胞数量的定量差异和/或这些移植物中巨核细胞祖细胞之间的定性差异有关。我们比较了这些移植物的造血组成，并确定了脐血和动员外周血中成熟和未成熟巨核细胞祖细胞的分布及其体外动力学行为。
在mpl配体存在的情况下，体外扩增脐血（CB）和动员外周血（PBSC）中的巨核细胞祖细胞亚群。通过流式细胞术和祖细胞测定分析巨核细胞祖细胞扩增过程中的发育差异。
我们发现，CB中未成熟（CD34(+)/CD41(-)）亚群包含所有巨核细胞祖细胞的98%以上，在2周培养期间负责所有培养的巨核细胞的99%。CB CD34(+)/CD41(+)亚群对巨核细胞形成没有贡献。相比之下，在PBSC中，成熟（CD34(+)/CD41(+)）亚群包含所有巨核细胞祖细胞的7%。此外，CB和PBSC的CD34(+)细胞在体外成熟过程中也表现出明显的表型差异。PBSC巨核细胞祖细胞在体外成熟过程中短暂表达CD34和CD41，而CB祖细胞在分化为（CD34(-)/CD41(+)）巨核细胞之前短暂缺乏这两种标志物的表达。
体外数据表明，与PBSC相比，CB中存在不同发育阶段的巨核细胞祖细胞。CB和PBSC在组成和成熟方面的这些差异可能与这些干细胞来源移植后不同的植入动力学有关。
