Comparison of neurosphere cells with cumulus cells after fusion with embryonic stem cells: reprogramming potential

Embryonic stem cells (ESCs) are the pluripotent cells that also have the capacity to induce the genomic reprogramming of differentiated somatic cells. The progressively restricted genomic potential of somatic cells observed during embryonic development can be reverted to a pluripotent state by the formation of cell hybrids with ESCs. To assess the reprogramming potential of ESCs, we investigated the reprogramming of one of two different somatic cell populations, neurosphere cells (NSCs) and cumulus cells (CCs), after fusion with ESCs. Specifically, hybrid cells were produced by cell fusion of E14 ESCs with either NSCs or CCs containing the neo/lacZ and Oct4-GFP transgenes. The first reprogramming event, observed by the presence of Oct4-GFP in the hybrid cells, could be identified on Day 2, at approximately 45 h after fusion in both ESC-NSC and ESC-CC hybrids. In addition, the two ESC-somatic cell hybrids exhibit a similar reprogramming rate and share characteristics with the E14 ESC line: (1) expression of pluripotent markers (Oct4, Rex-1 and nanog); (2) inactivation of differentiated tissue-specific gene expression; and (3) the capacity to differentiate into all three germ layers. Taken together, our results suggest that the ESC-somatic cell hybrids have fully acquired ESC characteristics and that somatic cells of different tissue origin have the same potential to be reprogrammed after fusion with ESCs.