Bioassay for follicle stimulating activity of equine gonadotropic hormone in mare serum using frozen/thawed transiently transfected reporter cells.

The research aims to create a cell-based assay for Follicle Stimulating Hormone (FSH) in horse serum. The experiment employs transiently transfected cells and the outcomes demonstrate high specificity for FSH without cross-reactivity with other hormones.

Transfection and Cultivation of Cells

• For this study, the researchers used a cell line known as HEK293. These cells were selected as they could be easily manipulated genetically and grown in a laboratory setting.
• The cells were subtly altered by undergoing ‘transient transfection’; they temporarily received genetic material (in this case, an FSH reporter expression plasmid and a cAMP-responsive β-galactosidase reporter plasmid), to enable the researchers to assess the activity of FSH in serum samples.
• After transfection, the cells were frozen and then thawed out when needed for assay tests. This process facilitated the efficient storage and usage of cells for different batches of the experiment.

Assay Specificity and Validity

• The assay demonstrated high levels of specificity for FSH, with no cross-reactivity with other biologically relevant molecules such as Luteinizing Hormone (LH) or an insulin-like growth factor-1.
• This specificity was confirmed through standard curves and serum samples from pregnant mares. These samples passed parallel line bioassay validity tests (linearity and parallelism), indicating the assay can specifically bind and measure FSH with minimal interference from other substances in the serum.

Correlation and Practicality of the Assay

• The results of the bioassay correlated highly with those from a related test, the Steelman-Pohley hCG augmentation assay, thereby adding confidence in the reliability and accuracy of this new method.
• The end colorimetric measurement, a simple color change indicating the presence of a specific substance, could be easily read and interpreted. This feature allowed this bioassay to serve as a rapid, non-animal-based screening tool for FSH.
• The reduced complexity and the non-requirement of elaborate cell culture facilities make this bioassay technique a highly effective and practical tool for large-scale assays in different research and veterinary contexts.