Schofield K P, Humphries M J, de Wynter E, Testa N, Gallagher J T
Departments of Medical Oncology and Experimental Haematology, Paterson Institute for Cancer Research, Manchester, UK.
Blood. 1998 May 1;91(9):3230-8.
Highly regulated interactions between adhesion receptors on progenitor cells and their extracellular matrix ligands are essential for the control of hematopoiesis in bone marrow stroma. We have examined the relationship between alpha4beta1-integrin-mediated adhesion and growth of CD34(+) cells by assessing their adhesive and migratory patterns of proliferation in a mixture of hematopoietic growth factors in the presence of different recombinant fragments of the HepII/IIICS region of fibronectin. CD34(+) cells were isolated from cord blood and placed in culture wells containing serum-free medium and growth factors. Wells were precoated with either the H120 fragment of fibronectin, which contains three alpha4beta1-integrin binding sites, or the H0 fragment, which lacks the two highest affinity alpha4beta1 binding sequences. Proliferation of single cells of CD34(+)38(+)DR+ and CD34(+)38(-)DR+ phenotypes occurred in contact with the H120 substrate and was associated with migration. Larger numbers of cells were used to quantitate proliferative responses. Cells growing in wells coated with H120 formed attachments to the base of the wells throughout the culture period. Higher total cell counts were consistently found in wells coated with H120 compared with H0 and bovine serum albumin controls. The difference was first apparent at day 8 of culture and reached a maximum at days 11 through 13, when expansion with H120 was a mean of 1.8-fold higher than that seen with H0 (P</= .0001). The greatest expansion (2.25-fold) with H120 compared with H0 was seen when the growth factor concentrations were reduced to 1/16 of the standard levels (P </= .001). The increase in total cell numbers was not at the expense of CD34(+) cells as numbers of these were similar in H120 and control cultures. These results provide evidence for synergy between growth factors and integrins that may be relevant to understanding hematopoiesis in marrow stroma.
祖细胞上的黏附受体与其细胞外基质配体之间高度有序的相互作用对于控制骨髓基质中的造血作用至关重要。我们通过评估CD34(+)细胞在纤连蛋白HepII/IIICS区域不同重组片段存在的情况下，在造血生长因子混合物中的黏附及增殖迁移模式，研究了α4β1整合素介导的黏附与CD34(+)细胞生长之间的关系。从脐血中分离出CD34(+)细胞，并将其置于含有无血清培养基和生长因子的培养孔中。培养孔预先包被纤连蛋白的H120片段（含有三个α4β1整合素结合位点）或H0片段（缺乏两个最高亲和力的α4β1结合序列）。CD34(+)38(+)DR+和CD34(+)38(-)DR+表型的单细胞与H120底物接触时发生增殖，并伴有迁移。使用更多数量的细胞来定量增殖反应。在整个培养期间，生长在包被有H120的孔中的细胞与孔底部形成附着。与H0和牛血清白蛋白对照相比，包被有H120的孔中始终发现更高的总细胞数。这种差异在培养第8天首次明显，在第11至13天达到最大值，此时H120诱导的扩增比H0高1.8倍（P≤0.0001）。当生长因子浓度降至标准水平的1/16时，与H0相比，H120诱导的扩增最大（2.25倍）（P≤0.001）。总细胞数的增加并非以CD34(+)细胞数量减少为代价，因为这些细胞在H120和对照培养物中的数量相似。这些结果为生长因子与整合素之间的协同作用提供了证据，这可能与理解骨髓基质中的造血作用相关。
