HEMATOPOIETIC RECONSTITUTION USING ISOLATED PROGENITOR CELL SUBPOPULATIONS

本项目研究的目的是确定狒狒体内骨髓源祖细胞的特定亚群重建淋巴造血的能力。到目前为止，我们已经获得了以下重要结果：(1)CD34抗原通过骨髓细胞表达，在致命辐照狒狒移植后重建稳定的长期淋巴系统和骨髓系统。用纯化的同种异体CD34+骨髓细胞（不含成熟和未成熟的T淋巴细胞和B淋巴细胞）移植的三只动物在移植后1100、1020和640天内作为稳定的造血嵌合体存活和健康。(2)这些纯化的CD34+细胞在HLA匹配的动物之间移植未产生可检测到的移植物抗宿主病。(3)表达最高水平的II类抗原HLA-DR的CD34+骨髓细胞比表达低水平或检测不到的HLA-DR的CD34+骨髓细胞亚群更快地移植致死性辐照动物。(4) CD34+骨髓细胞的谱系阳性亚群和谱系阴性亚群都可以移植到辐照致死的狒狒体内，谱系阴性亚群可以重建淋巴造血功能。(5)谱系阴性、HLA-DR阴性、CD34+的骨髓细胞在移植后可以向髓系和淋巴系贡献后代，这与干细胞可能的功能一致；然而，它们本身不足以拯救受致命辐射的动物。进一步明确CD34+骨髓和外周血细胞亚群在移植后骨髓重建中的具体作用的研究正在进行中。同样，将克隆标记物引入骨髓再生CD34+干细胞亚群的研究正在进行中，以便在体内建立单个细胞对淋巴造血干细胞的能力。

The goal of the studies in this project is to determine the ability of specific subsets of marrow-derived progenitor cells to reconstitute lymphohemaotpoiesis in vivo in baboons. To date we have obtained the following important results (1) The CD34 antigen is expressed by marrow cells that reconstitute stable long-term lymphopoiesis and myelopoiesis after transplantation of lethally irradiated baboons. Three animals that were transplanted with purified allogeneic CD34+ marrow cells devoid of mature and immature T and B lymphocytes remain alive and healthy as stable hematopoietic chimeras more than 1100, 1020, and 640 days after transplantation. (2) Transplantation of these purified CD34+ cells between HLA matched animals has produced no detectable graft vs. host disease. (3) CD34+ marrow cells expressing the highest levels of the class II antigen HLA-DR engraft lethally irradiated animals more rapidly than does the subset of CD34+ marrow cells expressing low or undetectable levels of HLA-DR. (4) Both the Lineage positive and Lineage negative subpopulations of CD34+ marrow cells can engraft lethally irradiated baboons, and the Lineage negative subpopulation can reconstitute lymphohematopoiesis. (5) The Lineage negative, HLA-DR negative, CD34+ marrow cells can contribute progeny to both the myeloid and lymphoid lineages following transplantation, consistent with possible stem cell function; however, by themselves they are insufficient for rescuing lethally irradiated animals. Studies to further define the specific role of subsets of CD34+ marrow and peripheral blood cells in marrow reconstitution after transplantation are in progress. Likewise, studies are under way to introduce clonal markers into subpopulations of marrow repopulating CD34+ stem cells, in order to establish the capacity of individual cells to lymphohematopoietic stem cells in vivo.