Researchers have identified cell surface markers specific for the very earliest stem cells in the human embryo.
These cells are thought to possess great potential for replacing damaged tissue but until now have been difficult to distinguish from classical embryonic stem cells.
Fredrik Lanner’s research team at Karolinska Institutet and their colleagues in Peter Rugg-Gunn’s team at Cambridge’s Babraham Institute in the UK have developed a tool for separating the two stem cell states. They have screened combinations of antibodies that bind to specific proteins on the surface of the immature and mature stem cells and that can be used for flow cytometry, a common laboratory technique for sorting cells.
“We’ve not had cell surface markers for the different stem cell states before, which has made it hard to study them,” says Fredrik Lanner, Assistant Professor at Karolinska Institutet’s Department of Clinical Science, Intervention and Technology. “We now have a simple tool for identifying and sorting the cells, which benefits future stem cell research and basic research on early embryonic development.”
Mature embryonic stem cells cultivated in the laboratory can, under the right conditions, be backed up in their development to the more immature stem cell type. The researchers tested their technique on such cultivated stem cells of both a mature and immature type, and on donated human embryos left over from IVF treatments . As expected, only the immature stem cell type was identified in such pre-implanted embryos, which indicates that the antibodies are highly specific.
“It is at the point of implantation that the stem cells go through this change and ‘mature’, which is also a highly critical time for the embryo,” says Dr Lanner. “These cells are therefore also of interest to infertility research.”
Image showing: Immunofluorescence microscopy reveals the different protein profiles of immature stem cells (coloured pink) and mature stem cells (coloured green). Photographer: Sarita Panula