Analysis of SSEA1(+) vs. SSEA1(-) fractions of bulk-cultured XENP cell lines

Abstract

Previously isolated rat extraembryonic endoderm precursor (XENP) cell lines had been characterized after clonal density plating. The arising colonies had consisted of peripheral XENP cells expressing the surface antigen SSEA1 and the transcription factor Oct4, and inner XENP-derived extraembryonic endoderm cells that were nearly negative for SSEA I and Oct4. We now sorted bulk-cultured XENP cell lines from two rat strains by FACS into SSEA1(+) and SSEA1(-) populations and compared their expression profiles by microarray and RT-PCR. In the bulk cultures, the SSEA1(+) fraction was only slightly enriched for Oct4, and also slightly enriched for the visceral endoderm markers, Dab2 and Ihh. Both fractions expressed vascular-associated mesodermal markers (VE-cadherin, Flk 1). Thus, in regular-density XENP cell cultures, SSEA1 is not suitable as a stem cell marker, and the XENP cells appear to undergo partial somatic differentiation.