Cloning Hematopoietic Genes by MRNA Differential Display

Advances in the use of hematopoietic stem cells for transplantation and gene therapy haveincreased the urgency for a better knowledge of the molecular control of their development andproliferation. An understanding of the molecular processes involved in the earliest stages of stem celldevelopment, currently poorly understood, would provide very useful guide to the selection, expansionand ex-vivo manipulation of stem cells. Our long-term objective is to identify, clone and investigatethese genes. An in vitro assay is now available which allow totipotent murine embryonic stem (ES) cellsto develop into hematopoietic cells. This transition must involve the activatiOn of the earliest geneticprogram for initiating hematopoiesis. By comparison with mRNA species from ES cells that are notdifferentiating into hematopoietic cells, these mRNA may be detected and cloned. A new PCR-basedtechnique has made it possible to obtain "differential display" of mRNA species between two populationof cells. We will combine these two technological advances to identify and clone cDNAs of stem cellrelated genes which could include receptors, transcriptional factors, adhesion molecules and structuralprotein unique and specific to hematopoietic cells. Together they should have a wide range of potentialapplication technologically and commercially.