Human blood-mobilized hematopoietic precursors differentiate into osteoclasts in the absence of stromal cells.

Osteoclastogenesis is a complex process that is facilitated by bone marrow stromal cells (SCs). To determine if SCs are an absolute requirement for the differentiation of human hematopoietic precursors into fully mature, osteoclasts (OCs), CD34+ cells were mobilized into the peripheral circulation with granulocyte colony-stimulating factor, harvested by leukapheresis, and purified by magnetic-activated cell sorting. This procedure yields a population of CD34+ cells that does not contain SC precursors, as assessed by the lack of expression of the SC antigen Stro-1, and that differentiates only into hematopoietic cells. We found that CD34+, Stro-1- cells cultured with a combination of granulocyte/macrophage colony-stimulating factor, interleukin 1, and interleukin 3 generated cells that fulfill current criteria for the characterization of OCs, including multinucleation, presence of tartrate-resistant acid phosphatase, and expression of the calcitonin and vitronectin receptors and of pp60c-src tyrosine kinase. These OCs also expressed mRNA for the noninserted isoform of the calcitonin receptor and excavated characteristic resorption pits in devitalized bone slices. These data demonstrate that accessory SCs are not essential for human osteoclastogenesis and that granulocyte colony-stimulating factor treatment mobilizes OC precursors into the peripheral circulation. IMAGES:

破骨细胞生成（Osteoclastogenesis）是一类由骨髓基质细胞（bone marrow stromal cells, SCs）介导的复杂生物学过程。为明确骨髓基质细胞是否为人类造血前体细胞分化为完全成熟的破骨细胞（OCs）所必需的绝对条件，研究人员通过粒细胞集落刺激因子（granulocyte colony-stimulating factor）将CD34+细胞动员至外周循环，经白细胞分离术采集并通过磁激活细胞分选（magnetic-activated cell sorting）纯化。经检测，该纯化得到的CD34+细胞群不包含骨髓基质细胞前体，表现为不表达骨髓基质细胞抗原Stro-1，且仅能分化为造血细胞。研究发现，经粒细胞-巨噬细胞集落刺激因子（granulocyte/macrophage colony-stimulating factor）、白细胞介素1和白细胞介素3联合培养的CD34+、Stro-1-细胞生成了符合当前破骨细胞鉴定标准的细胞，包括多核化、抗酒石酸酸性磷酸酶（tartrate-resistant acid phosphatase）阳性、表达降钙素受体、玻连蛋白受体及pp60c-src酪氨酸激酶（pp60c-src tyrosine kinase）。这些破骨细胞还表达降钙素受体非插入型同工型的信使核糖核酸（mRNA），并在脱活骨切片（devitalized bone slices）中形成特征性的骨吸收陷窝。本研究数据表明，辅助性骨髓基质细胞并非人类破骨细胞生成所必需，且粒细胞集落刺激因子治疗可将破骨细胞前体细胞动员至外周循环。IMAGES: