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Abstract：
Cell surface marker expression is one of the criteria for defining human mesenchymal stem or stromal cells (MSC) in vitro. However, it is unclear if expression of markers including CD73 and CD90 reflects the in vivo origin of cultured cells. We evaluated expression of 15 putative MSC markers in primary cultured cells from periosteum and cartilage to determine whether expression of these markers reflects either the differentiation state of cultured cells or the self-renewal of in vivo populations. Cultured cells had universal and consistent expression of various putative stem cell markers including > 95% expression CD73, CD90 and PDPN in both periosteal and cartilage cultures. Altering the culture surface with extracellular matrix coatings had minimal effect on cell surface marker expression. Osteogenic differentiation led to loss of CD106 and CD146 expression, however CD73 and CD90 were retained in > 90% of cells. We sorted freshly isolated periosteal populations capable of CFU-F formation on the basis of CD90 expression in combination with CD34, CD73 and CD26. All primary cultures universally expressed CD73 and CD90 and lacked CD34, irrespective of the expression of these markers ex vivo indicating phenotypic convergence in vitro. We conclude that markers including CD73 and CD90 are acquired in vitro in most \'mesenchymal\' cells capable of expansion. Overall, we demonstrate that in vitro expression of many cell surface markers in plastic-adherent cultures is unrelated to their expression prior to culture.
摘要：
细胞表面标志物表达是体外定义人间充质干细胞或基质细胞(MSC)的标准之一。然而,目前尚不清楚CD73和CD90等标志物的表达是否反映了培养细胞的体内起源。我们评估了来自骨膜和软骨的原代培养细胞中15种推定的MSC标志物的表达，以确定这些标志物的表达是否反映了培养细胞的分化状态或体内群体的自我更新。培养的细胞在骨膜和软骨培养中均具有各种推定的干细胞标志物的普遍且一致的表达,包括>95%表达CD73、CD90和PDPN。用细胞外基质涂层改变培养表面对细胞表面标记表达的影响最小。成骨分化导致CD106和CD146表达缺失，然而CD73和CD90保留在>90%的细胞中。我们基于CD90与CD34，CD73和CD26的组合表达，对能够形成CFU-F的新鲜分离的骨膜种群进行了分类。所有原代培养物普遍表达CD73和CD90并且缺乏CD34,而与这些标记物的离体表达无关,表明体外表型趋同。我们得出的结论是，在大多数能够扩增的间充质细胞中，包括CD73和CD90在内的标志物都是在体外获得的。总的来说,我们证明，在塑料贴壁培养物中许多细胞表面标志物的体外表达与培养前的表达无关。
