Conditionally immortalized retinal capillary endothelial cell lines (TR-iBRB) expressing differentiated endothelial cell functions derived from a transgenic rat

The objective of this study was to establish and characterize a retinal capillary endothelial cell line (TR-iBRB) from a newly developed transgenic rat harboring the temperature-sensitive simian virus 40 (SV 40) large T-antigen gene (Tg rat). Retinal capillary endothelial cells were isolated from a Tg rat and cultured in collagen-coated dishes at 37 degreesC for a period of 48 hr. Cells were subsequently cultured at 33 degreesC to activate the large T-antigen, At the third passage, cells were cloned by colony formation and isolated from other cells. Nine immortalized cell lines of retinal capillary endothelial cells (TR-iBRB1 similar to 9) were obtained from a Tg rat. These cell lines had a spindle-fiber shape morphology, expressed the typical endothelial marker, von Willebrand factor, and internalized acetylated-low density lipoprotein. Moreover, vascular endothelial growth factor (VEGF) receptor-2 was expressed in TR-iBRBs. TR-iBRBs expressed a large T-antigen and grew well at 33 degreesC with a doubling time of 19-21 hr. In contrast, cells did not grow at 37 and 39 degreesC due to the reduced expression of large T-antigen, supporting temperature-dependent cell growth. TR-iBRBs expressed GLUT1 and exhibited 3-O-methyl-D-glucose (3-OMG) uptake activity This 3-OMG uptake was saturable with a Michaelis-Menten constant of 5.56 +/- 0.51 mM and a maximum uptake rate of 45.3 +/- 2.6 nmol min(-1) mg protein(-1). P-Glycoprotein, with a molecular weight of similar to 180 KDa, was expressed in TR-iBRBs. In addition, mdr 1a, mdr 1b and mdr 2 were detected in TR-iBRB2 using RT-PCR. In conclusion, conditionally immortalized retinal capillary endothelial cell lines were established from a transgenic rat harboring the temperature-sensitive SV 40 large T-antigen gene and these lines were shown to exhibit the properties of retinal capillary endothelial cells. (C) 2001 Academic Press.