HOPE Fixation of Cytospin Preparations of Human Cells for In Situ Hybridization and Immunocytochemistry

In primary or cultured cells, in situ hybridization (ISH) or immunocytochemistry (ICC) is often performed on tissue that has been fixed by paraformaldehyde or Carnoy's. Recently we reported an optimized HOPE (HEPES–glutamic acid buffer-mediated organic solvent protection effect) fixation protocol for ISH targeting mRNA in lung tissues. We have now examined whether HOPE fixation could also be used on in vitro cultured cells for targeting mRNA by ISH or proteins by ICC on cytospin preparations. Using the myeloid stem cell line KG-1a as a model system, we showed that HOPE fixation can be applied for ISH and ICC on cultured cells. HOPE can be used with cells and tissues and with a broad spectrum of immunohistocytochemical and molecular techniques.