Using cadherin expression to assess spontaneous differentiation of embryonic stem cells.

Embryonic stem cells (ESCs) are pluripotent cells derived from preimplantation embryos and can be maintained in an undifferentiated state over prolonged periods in vitro. In addition, ESCs can be induced to differentiate into cells representative of the three primary germ layers. As such, ESCs are a useful system for studying early developmental events in vitro and have the potential to provide a ubiquitous supply of somatic cells for use in regenerative medicine. However, significant differences in the expression pattern of various cell surface markers between murine and human ESCs, e.g. the SSEA series, necessitate the use of separate markers for determining the undifferentiated state of these cells. We have recently shown that an E- to N-cadherin switch occurs during spontaneous differentiation of both murine and human ESCs. Here we describe the use of E-cadherin and N-cadherin proteins and transcript expression for assessing the proportion of undifferentiated and spontaneously differentiated cells within ESC populations. In summary, loss of cell surface E-cadherin and/or gain of N-cadherin protein expression provides a useful nondestructive assay for the determination of the proportion of spontaneously differentiated cells within an ESC population. In addition, presence of N-cadherin transcripts in an ESC population is indicative of spontaneous differentiation of a proportion of the cells.