An article for culturing cells includes a substrate on which cells can be cultured. The substrate has a base surface. An array of projections extends from the base surface. The projections have a height of about 1 micrometer to about 100 micrometers, and have a gap distance along the major surface from center to center between neighboring projections of about 10 micrometers to 80 micrometers. A plurality of arrays of projections may extend from the surface with gaps in the base surface between the arrays. Hepatocytes cultures on such microprojection array substrates maintained in vivo like morphology and membrane polarity. Hepatocytes co-cultured with helper cells on such substrates tended to grow in the area of the arrays, while the helper cells tended to grow in the areas between the arrays.