Methodological aspects of attempts to trans-differentiate adult stem cells into embryonic-like cells in vitro.

AIMS The aim of this research was to set up an in vitro system to trans-differentiate haematopoietic stem cells (HSCs) into embryo-like stem cells in order to de-differentiate them. In this more naive state they should be cultivated more easily in order to augment them for consecutive differentiation and autologous transplantation for use in clinical practice. METHODS Using the principle of the methodology of blastocyst injection, HSCs were co-cultivated with mouse embryonic stem cells (mES) with and without cell to cell contact. After co-cultivation HSCs were analyzed by flow-cytometry using haematopoietic markers (CD34, CD45, CD133) and embryonic stem cell markers (SSEA-4, Tra-1-60, Tra-1-81). RESULTS No ES cell markers were detected on the former HSCs. A decrease in HSC marker intensity was the only finding. This implies that no de-differentiation took place. CONCLUSIONS We hypothesize that the unnatural situation of a mixture of two cell types originating in different species may have led to this outcome. To achieve our goal of in vitro de-differentiation we need to use a purely human culture system without animal additives.