The process of tissue engineering often involves the mixing of cells with polymers that may elevate the level of endogenous free radicals and thus cause genetic damage to the cell. In order to assure that such composite materials are free of genetic damage, our laboratory is responding to the need for test methods used to assess the safety and performance of tissue-engineered materials. Specifically, we are identifying cellular biomarkers that could be used to ensure that the cells of tissue-engineered materials have not undergone any oxidative DNA damage from the production of free radicals by oxidative stress during the development, storage or shipment of the product. Using the technique of gas chromatography/mass spectrometry, we have screened for the xidatively modified DNA base 8-hydroxyguanine in tissue-engineered skin and compared the levels to those in control cells, neonatal fibroblasts and neonatal keratinocytes. No significant level of damage was detected compared to control cells. The technique of liquid chromatography/mass spectrometry was also used in the validation of this biomarker by measuring its nucleoside form. The results obtained with this technique were nearly identical to those obtained with gas chromatography/mass spectrometry. Biomarker programs such as this can provide the basis for an international reference standard of cellular biomarkers that can aid in the development and safety of tissue-engineered medical products.