el Hafny B, Bourre J M, Roux F
INSERM U26, Unité de Neuro-Pharmaco-Nutrition, Hôpital F. Widal, Paris, France.
J Cell Physiol. 1996 Jun;167(3):451-60. doi: 10.1002/(SICI)1097-4652(199606)167:3<451::AID-JCP9>3.0.CO;2-O.
The immortalized rat brain microvessel endothelial cell line RBE4 was used to investigate the in vitro regulation of two blood-brain barrier specific enzymes, gamma-glutamyl transpeptidase (GTP) and alkaline phosphatase (ALP). The effects of bFGF, astroglial factors, and retinoic acid (a cell differentiation agent) on GTP and ALP activities were separately or simultaneously studied in order to define optimal culture conditions for induction of these two specific enzymes of the blood-brain barrier. In the present study, a phenotypically distinct subpopulation of endothelial cells has been shown to develop from confluent cobblestone monolayers of RBE4 immortalized cerebral endothelial cells. These distinct cells were present within multicellular aggregates and specifically exhibited GTP and ALP activities. Addition of bFGF, astroglial factors, or retinoic acid induced the formation of these three-dimensional structures and in consequence an increase in GTP and ALP activities. For retinoic acid and astroglial factors, this increase could also be explained by the stimulation of either GTP or ALP expression in the phenotypically distinct positive cells associated with aggregates. Simultaneous treatment with retinoic acid and astroglial factors had a synergistic effect on GTP and ALP expression and thus may allow these distinct cells to evolve toward a more differentiated state. Since such results were also obtained with physiological concentrations of retinoic acid, we suggest that addition of this agent might contribute to greater differentiation of cells in in vitro blood-brain barrier models where endothelial cells are cocultured with astrocytes.
永生化大鼠脑微血管内皮细胞系RBE4被用于研究血脑屏障特异性酶γ-谷氨酰转肽酶（GTP）和碱性磷酸酶（ALP）的体外调控。分别或同时研究了碱性成纤维细胞生长因子（bFGF）、星形胶质细胞因子和视黄酸（一种细胞分化剂）对GTP和ALP活性的影响，以确定诱导血脑屏障这两种特异性酶的最佳培养条件。在本研究中，已证明从RBE4永生化脑内皮细胞的汇合鹅卵石单层中可发育出一种表型不同的内皮细胞亚群。这些不同的细胞存在于多细胞聚集体中，并特异性地表现出GTP和ALP活性。添加bFGF、星形胶质细胞因子或视黄酸可诱导这些三维结构的形成，从而导致GTP和ALP活性增加。对于视黄酸和星形胶质细胞因子，这种增加也可以通过刺激与聚集体相关的表型不同的阳性细胞中GTP或ALP的表达来解释。视黄酸和星形胶质细胞因子同时处理对GTP和ALP表达具有协同作用，因此可能使这些不同的细胞向更分化的状态发展。由于在生理浓度的视黄酸下也获得了这样的结果，我们建议在体外血脑屏障模型中，当内皮细胞与星形胶质细胞共培养时，添加这种试剂可能有助于细胞的更大分化。
