Abstract: Animal cells are cultured while embedded in a collagen gel. The gel containing cells is formed by dispersing animal cells in a collagen solution, placing a drop (or drops) of the cell-containing collagen solution on a support surface and allowing the drop to gel to fix on the surface as a globular collagen gel having a convex surface. The cells are cultured by contacting the gel with a culture medium that may be serum-free or contain dextran sulfate. The drop preferably contains about 3 to about 300 microliters of the collagen solution and is about 2 mm or less in height. The cells may be precultured on a support surface having a collagen layer, released from the collagen layer by treatment with collagenase and dispersed in the collagen solution. The cells can be evaluated after culturing by staining such as with neutral red, or with fluorescein diacetate and irradiating, or by photographing cells in the collagen gel.

Abstract: The present invention relates to a method of testing the sensitivity of cancer drugs with cancer cells cultured in vitro. Cancer cells are cultured in a collagen gel substrate. A wide variety of human cancer cell types readily proliferate in the collagen gel substrate, however, fibroblast cells proliferate as well. The measurement of the growth of the cancer cells is hindered by the presence of the fibroblast cells. The present invention solves this problem by counting the number of colonies with an image processor which selectively extracts the image signals of cancer cells and their colonies. In a second embodiment, the growth of cancer cells is determined by measuring the volume of colonies with the image signals of cancer cells and their colonies selectively extracted. The results can be obtained effectively within a short period of time.

Abstract: A good tissue-affinity and lack of antigenicity are required for the collagen used as the carrier of BMP. Conventional collagens have these properties only insufficiently. When the tyrosine content is below 2 residues/1000 residues, then the above properties of such collagens are good. Moreover, collagens excelling in the above properties can be readily obtained by using proteolytic enzymes.