ODP305 Differentiation Potential of Marginal Layer-Derived Adult Pituitary Stem/Progenitor Cells into Vascular Endothelial Cells and Pericytes in Mice

The anterior lobe (AL) of the pituitary gland consists five types of hormone-producing cells and fenestrated sinusoids (i. e., vascular endothelial cells and pericytes) that cooperate to maintain the physiological function of the gland. In addition, the population of cells located in pituitary stem/ progenitor cell niche, the marginal layer, which faces the residual lumen of the Rathke's pouch, serve to renew pituitary cells throughout life. We recently established a protocol for isolating marginal layer-derived adult pituitary stem/progenitor cells (MPSCs) by using differences in cell adhesion (1), and then showed differentiation potential into hormone-producing cells by subjecting MPSCs to three-dimensional culture. However, it is unclear whether MPSCs are capable of differentiating into all types of cells that constitute the pituitary gland. In this study, we performed DNA microarray analysis in MPSCs, which were proliferated by two-dimensional (2D) culture, for studying comprehensively gene expression profiles. Next, we investigated what kind of cells MPSCs would differentiate into. Comparing gene expression profiles of the AL and MPSCs, in MPSCs, 1776 genes were increased more than 4-fold and 1715 genes were decreased 4-fold compared to the AL (p<0. 05, respectively). The upregulated genes included pituitary stem/progenitor cell markers (ex. Sox2, Sox9, Klf4, Prrx1), niche markers (ex. Cdh1, Krt8), and cell surface antigens (ex. Cd9, Cd34, Cd44). On the other hand, most of the downregulated genes were differentiation markers (ex. Pou1f1, Gata2, Tbx19, Kdr). Next, immunofluorescent analysis revealed that most of the MPSCs were positive for CD34, the hematopoietic stem cell marker. After further 2D culture of MPSCs for 5-7days, vascular endothelial marker PECAM1-positive cells were detected by immunofluorescent analysis, but pericyte marker CSPG4-positive cell not. When TGFβ was applied to 2D culture of MPSCs, CSPG4-positive cells were detected instead of PECAM1-positive cells. Expression levels of Pecam1and Cspg4 were also examined by qPCR analysis, which corresponded to the results of immunofluorescent analysis. On the other hand, expression levels of anterior hormone genes were almost unchanged. These results have demonstrated that MPSCs could differentiate into vascular endothelial cells and pericytes. The present study suggests that pituitary stem/progenitor cells, which derived from the marginal layer, are a source of not only hormone-producing cells but also cells that constitute blood vessels. Reference: (1) Shintani and Higuchi, Stem Cell Res. 2021 Feb 2;52: 102223. Presentation: No date and time listed