Recreating the hematon: microfabrication of artificial haematopoietic stem cell microniches in vitro using dielectrophoresis

The hematon is a three-dimensional aggregate of cells which is able to produce all blood types. To be able to do this, it must be able to create within the cell aggregate a microenvironment which enables haematopoietic stem cell maintenance, renewal and differentiation. A first step was taken towards the creation of artificial hematopoietic stem cell microniches in vitro by the creation with dielectrophoresis of hemispherical cell aggregates of a height of 50-100 mu m with a defined internal architecture similar to that of a putative hematon. It is shown that, after their dielectrophoretic manipulation, the cells remain viable and active. Cells within the aggregate are in direct contact with each other, potentially allowing direct cell-cell communication within the cell construct. Some cell immobilisation methods are explored for further stabilising the 3-D organisation of the cell aggregate after its formation. The introduction of traceable individual cells into the artificial microniche is demonstrated.