Reprogramming in Inter-Species Embryonal Carcinoma–Somatic Cell Hybrids Induces Expression of Pluripotency and Differentiation Markers

Abstract

Somatic cell reprogramming holds great promise for the development of novel cellular therapeutics. A number of sources of reprogramming potential have been identified, including oocytes, embryonic germ (EG) cells and embryonic stem (ES) cells. However, each of these sources of reprogramming factors is problematic, since they are either not freely available or have special growth requirements. Embryonal carcinoma (EC) cells are another source of pluripotent cells that, unlike ES and EG cells, do not usually require special growth conditions. Since they share many of the key characteristics of ES cells, such as pluripotency, EC cells may provide a readily amenable alternative source of reprogramming factors and could serve as a model for ES cells in this respect. Here we show that mouse EC cells can also function as donors of reprogramming factors. PEG-mediated fusion between murine EC cells (P19) and the cells of a human T-lymphoma cell line (CEM-GFP) resulted in inter-species hybrid colony formation. Colonies of hybrid cells displayed heterogeneity in cellular morphology as well as in their pattern of human gene expression. Expression of two human transcription factors characteristic of undifferentiated pluripotent stem cells, Oct-4 and Sox-2, was detected in the hybrid cells, demonstrating activation of endogenous human markers of pluripotency. Simultaneously, down-regulation of CD45, a marker present in lymphocytic cells, was observed in some hybrids. The detection of human specific markers of differentiation, such as nestin, lamininbeta1, and collagen IValpha1, indicates that fusion resulted in reprogramming of the human cells to reflect the differentiation potential of the murine EC partner.

H3K9 histone acetylation predicts pluripotency and reprogramming capacity of ES cells

“…7 In addition, embryonal carcinoma (EC) and embryonic germ (EG) cells have also been shown to contain reprogramming activities in fusion experiments. [13][14][15] Human fibroblasts have been successfully reprogrammed as well upon fusion with human ESC 8 or myeloid precursor cells. 16 The reprogramming activity of ESCs likely resides within the nuclear compartment because karyoplasts, but not cytoplasts, derived from these cells, can bring about reprogramming of somatic cells upon fusion.…”

Reprogrammed Pluripotent Stem Cells from Somatic Cells

“…Moreover, mouse pluripotent stem cells can reprogram nuclei of human somatic cells into pluripotent state. This result indicates that reprogramming factors can cross-act through another species (29). Hence, reprogrammed fusion hybrid cells have been used for study of reprogramming mechanism.…”

Kinetics of reprogramming in cell fusion hybrids

“…Following this initial study, many studies have shown that various somatic cells can be reprogrammed by fusing with pluripotent stem cell like ES, EG, or EC cells ( Fig. 1) (Cowan et al, 2005;Flasza et al, 2003;Matveeva et al, 1998;Shimazaki et al, 1993;Tada et al, 2003;Tada et al, 2001;Terada et al, 2002, Yu et al, 2006.…”

“…Since EC cells share many of the key pluripotent characteristics with ES and EC cells can provide a readily amenable alternative source for reprogramming (Do et al, 2009a;Flasza et al, 2003;Mise et al, 1996). Moreover, mouse EC cells can reprogram human somatic cells into pluripotent state, indicating that reprogramming factors can cross-act through another species (Flasza et al, 2003).…”