Methods of measuring cell viability in tissue engineered products

A method of measuring the cytotoxicity of a treatment to cells in a tissue-engineered product maintained in a cell culture medium comprising:

• (a) applying the treatment to the tissue engineered product;
• (b) detecting a cell death-stable enzyme activity in a portion of a cell culture conditioned medium not containing cells of the tissue-engineered product;
• (c) detecting a cell death-stable enzyme activity in the cells and conditioned medium of a portion of the cell culture medium containing cells of the tissue-engineered product;
• and
• (d) comparing the level of cell death-stable enzyme activity in the portion of the cell culture medium containing cells of the tissue-engineered product to the level of cell death-stable enzyme activity in the portion of the cell culture conditioned medium not containing cells of the tissue-engineered product,
• wherein the cytotoxicity of the treatment is proportional to the difference in the fraction of viable cells in the treated tissue engineered product to an untreated tissue engineered product, and wherein the fraction of viable cells in the tissue-engineered product is directly proportional to the difference between the level of cell death-stable enzyme activity in the portion of the cell culture medium containing cells of the tissue-engineered product and the level of cell death-stable enzyme activity in the portion of the cell culture conditioned medium not containing cells of the tissue-engineered product.