Preservation of ultrastructure of cells cultured on protein-hydroxyethylmethacrylate hydrogels

A method for studying the ultrastructure of cells grown on hydroxyethylmethacrylate (HEMA) hydrogels is described. Under normal conditions, HEMA hydrogels tend to swell when placed in hypotonic solutions and to shrink during alcohol dehydration. To overcome this severe swelling and/or shrinking, all solutions used during the fixation procedure are made in Puck's saline G, and dehydration is accomplished with a graded series of ethanol solutions prepared with Puck's saline G and polyethylene glycol. Infiltration of the sample with embedding material is achieved with the aid of a vacuum oven. Our findings suggest that the cells cultured on collagen hydrogels are ultrastructurally indistinguishable from those cultured on tissue-culture plastic. In addition, the unusual crater-like topography of the hydrogel can be utilized as an experimental aid in the study of cell attachment and spreading.