Possible mechanism of hematopietic stem cells homing to the bone marrow microenvironment

我们发现基质细胞衍生因子-1/前B细胞生长刺激因子(SDF1/PBSF)受体CXCR4在人CD34+骨髓(BM)细胞上表达。FACS分选的CD34~+CXCR4~+BM细胞完全缺乏髓系、红系、巨核细胞和混合集落形成能力(髓系祖细胞)，但能产生B和T淋巴祖细胞，而CD34~+CXCR4^-BM细胞可以产生髓系祖细胞形成的集落，也可以发育成这些淋巴祖细胞。因此，在CD34^+BM细胞上表达CXCR4可以区分淋巴祖细胞和髓系祖细胞。由于CD34^+CXCR4^+细胞是从CD34^+CXCR4^-细胞分化而来的，位于骨髓中的多潜能祖细胞可能不表达CXCR4。CXCR4似乎早于白细胞介素7受体和末端脱氧核苷酸转移酶在早期淋巴造血中表达。这些结果提示CD34^+BM细胞上CXCR4的表达是致病淋巴祖细胞的表型改变之一。

We found that the stromal cell derived factor-1/pre-B cell growth stimulating factor (SDF1/PBSF) receptor, CXCR4, is expressed on human CD34^+ bone marrow (BM) cells. Stringently FACS-sorted CD34^+CXCR4^+ BM cells completely lack myeloid, erythroid, megakaryocytic, and mixed colony forming potential (myeloid progenitors), but give rise to B and T lymphoid progenitors, whereas CD34^+CXCR4^- BM cells can generate colonies formed by myeloid progenitors and can also develop into these lymphoid progenitors. Therefore, expression of CXCR4 on CD34^+ BM cells can allow lymphoid progenitors to be discriminated from myeloid progenitors. Since CD34^+CXCR4^+ cells are differentiated from CD34^+CXCR4^- cells, multipotential progenitors located in the BM are likely to be negative for CXCR4 expression. CXCR4 seems to be expressed earlier than the interleukin-7 receptor and terminal deoxynucleotidyl transferase during early lymphohemopoiesis. These results suggest that the expression of CXCR4 on CD34^+ BM cells is one of the phenotypic alterations for committed lymphoid progenitors.