Hello Melonney Patrick,

If the treatment is diluted with complete medium, there will be non-specific binding of the candidate drug to proteins present in the serum. As a result the amount of drug available to the cells in culture during the treatment will be reduced.

So, to avoid non-specific binding of the drug to serum proteins, it is better to dilute the treatment with growth medium without FBS in order to maintain the intracellular concentration of the drug.

Best.

Dilution with Medium Without FBS & Pen/Strep

Dilution with Complete Medium (Including FBS & Pen/Strep)

Practical Considerations

• Short-term vs. Long-term Exposure:For short-term treatments (a few hours), using medium without FBS may be more feasible and less likely to impact cell viability. For longer treatments, consider a reduced-serum medium to balance cell health and experimental control.
• Cell Type Specificity:Some cells tolerate serum-free conditions well, while others do not. Perform preliminary tests to determine how your specific cell line responds to serum withdrawal.
• Experimental Goals:If your goal is to specifically understand the impact of your treatment on gene/protein expression, medium without FBS is often preferred. If maintaining cell health is critical and serum-free conditions significantly impact cell viability, using complete medium with careful controls might be necessary.

Recommendations

• Pre-treatment Acclimatization: Gradually acclimatize cells to reduced-serum conditions before the actual experiment to minimize stress.
• Controls: Include appropriate controls to differentiate the effects of serum withdrawal from the effects of your treatment.
• Optimization: Optimize the concentration and duration of your treatment in both conditions (with and without FBS) to determine the best approach for your specific study.