Professor Winston joined forces with Dr Carol Readhead, a senior scientist from the California Institute of Technology, Pasadena. They currently supervise a group working between London and California focused on stem cells and the production of transgenics using male germ cells. This team, which offers opportunities for appropriate post-graduate students, includes Dr Ellen Poon and Dr Sheba Jarvis.

Dr Ellen Poon derives human and mouse embryonic stem cells. Embryonic stem cells seem capable of differentiating into cells of any one of the 220 different cell types in the human body. Consequently, they offer promise for transplantation. When disease causes destruction or dysfunction of a limited number of cell types, such as in Parkinson disease or diabetes, the replacement of relevant brain cells or insulin-producing cells types by appropriate stem cell-derivatives could be therapeutic. To derive these stem cells, donated human embryos, obtained after IVF, are cultured for five days. The inner cell mass, the part that will become the embryo, is placed on mouse embryonic fibroblasts in a culture system. This process is inefficient and the chance of getting normal stem cells is less than five, partly because most human embryos contain significant faults i.e. they are not viable, but there is no certain way of detecting this.

Ellen attempts to optimise conditions to produce stem cells. She is examining the expression of different stem cell markers during embryonic development using DNA analysis and cell staining techniques. Effect of culture conditions on embryo morphology, maturation and gene expression is being assessed. Ellen also derives stem cells from testicular germ cells, potentially a useful alternate source of stem cells. We know that stem cells obtained from newborn and adult mouse testes are able to develop into many different cell types under various conditions. Ellen has isolated different cell populations by cell sorting and, using gene expression profiling, has identified those with the ability to produce stem cells.

Dr Sheba Jarvis examines the development of male germ cells and the genes they express at different stages of differentiation. The markers she is identifying support the work of the rest of the group. Sheba uses three-dimensional confocal videomicroscopy to follow living fluorescent male germ cells during the peri-natal period in order to study germ cell behaviour.

This work gives insight into the fate of such cells in the seminiferous tubules. She is correlating the behavioural changes of the cells to changes of the cell surface, apoptosis and proliferation markers. She uses immunohistochemistry and assesses proliferation markers, proliferating cell nuclear antigen (PCNA) with mini chromosome maintenance protein-2 (MSM-2) and apoptosis markers, cleaved Caspase-3 and TUNEL labelling. If you wish to donate to this research please click here

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