The effect of human SCD1 heterologous expression on cellular fatty acid synthesis was investigated in the current study. The SCD1 gene expression cassette and PGK-neomycin-selectable marker cassette were co-introduced into HEK 293 cells by electroporation, and subsequently, SCD1 expression was evaluated by fatty acid analysis. RT-PCR analysis indicated that the foreign SCD1 gene could be expressed in transformed cell lines. Total lipid analysis of the transformed cells fed with vaccenic acid (t11-18:1) as a substrate showed that SCD1 expression resulted in an increase in c9t11-CLA from 0.73-1.03% to 2.69-2.86% (p < 0.05) and that the conversion efficiency was elevated from 5.11-6.88% to 16.49-20.06% (p < 0.05). Surprisingly, the concentration of t10c12-CLA was also increased, from 0.10-0.41% to 1.35-1.69% in SCD1 cells (p < 0.05). SCD1 expression also resulted in a significant (p < 0.05) increase in palmitoleic acid (16:1 n-7) from 1.56-2.26% to 3.47-4.04% and cis-vaccenic acid (18:1 n-7) from 2.42-3.97% to 6.20-7.22%, and the corresponding conversion ratio of n-7 fatty acid was elevated from 12.01-16.70% to 22.62-24.13% (p < 0.05). This study demonstrates that the foreign SCD1 gene was expressed with high efficiency and induced elevated c9t11-CLA, t10c12-CLA, and n-7 fatty acid levels in mammalian cells. (C) 2010 Elsevier Inc. All rights reserved.