Start from the readout time. Work backward to decide when cells should be seeded, when treatment should start, and what confluence range is acceptable at each stage.
2. Calculate seeding density
Use a recent count and viability value. If cells were counted long before plating or the suspension settled, re-mix or recount before trusting the number.
3. Assign controls
Include untreated, vehicle, positive control, and any technical controls required by the assay. Controls should be distributed in a way that does not make location effects look like treatment effects.
4. Build the plate layout
Avoid ambiguous labels. Keep replicate names consistent and record empty wells. If edge effects matter, avoid placing all critical wells at the edge.
5. Record deviations
Treatment timing, cell morphology, passage number, and media changes should be recorded with the final plate map. These details often explain variation later.
Review checklist
- Target confluence defined.
- Viability checked.
- Controls assigned.
- Plate map saved.
- Treatment timing documented.