Cell-Based Assay Services

How Boster Runs a Project

Cell-based work varies by nature, so each project starts with a written plan that fixes the design before any plates are run.

• Assay design: we start from your biological question and agree on the cell model, endpoint, readout and dose range.
• Pilot first: a small feasibility run confirms the signal window and model fit before a full study.
• Controls: positive, negative and vehicle controls on every plate, plus a reference standard for potency work.
• Replicates: the number per condition is set in the study plan and confirmed at quote.
• Reporting: raw data, analysis methods, relevant plots and summary results, and any deviations. Concentration–response studies include EC50/IC50 estimates and fit statistics where supported by the data.
• Timeline and price: quoted per project once the design is agreed.

What Cell-Based Assays Measure

A cell-based assay measures a biological response in intact, living cells rather than in an isolated protein or receptor.

Biochemical assays measure target binding or biochemical activity, such as enzyme inhibition, in a defined system. Cell-based assays complement these measurements by assessing responses within a cellular context, where membrane permeability, signaling, metabolism and gene expression can influence the result. A compound can bind a receptor tightly and still fail to trigger the downstream biology a program needs.

Each assay reads one or more functional endpoints: cell number or viability, reporter or pathway activation, cytokine secretion, migration or differentiation. Results are usually reported as a dose-response relationship rather than a single yes/no answer.

Custom Assay Development

When a target or pathway has no established assay, Boster builds one in five stages.

1. Feasibility review. Check the literature, target biology and available reagents to decide whether a functional readout is achievable, and in which cell background.
2. Model selection. Choose a cell line or primary cell that expresses the target in the right context. For target validation, a custom knockout cell line can serve as the matched negative control.
3. Optimization. Titrate cell density, incubation time, reagent concentrations and readout to widen the signal window and cut noise.
4. Qualification. Confirm reproducibility, specificity and acceptance criteria across independent runs and cell lots.
5. Protocol handoff. Document the final protocol, controls and analysis method so results stay interpretable across studies, or so your team can run it in-house.

Toxicity & Cytotoxicity Assessment

Cytotoxicity testing shows early whether a compound harms cells at concentrations close to those needed for activity.

What Is Cell Viability?

Cell viability describes the proportion or relative abundance of living cells, assessed through indicators such as membrane integrity or metabolic activity. Viability is a prerequisite for cell division, while proliferation assays measure whether and how much cells divide. Depending on the method, results may be reported as the percentage of viable cells or as a signal relative to an untreated or vehicle control:

• Membrane integrity dyes (e.g., trypan blue exclusion), which stain only cells with compromised membranes.
• Metabolic activity assays (e.g., MTT, MTS or resazurin reduction), which use cellular reducing activity as a proxy for viable cell abundance. Changes in metabolism or compound interference can also affect the signal.
• ATP-based luminescence, which quantifies intracellular ATP as a marker of metabolically active cells.
• Fluorescent live/dead staining, paired with imaging or flow cytometry to assess cell viability. Additional apoptosis-associated markers and complementary measurements can help distinguish cell-death populations.

A parallel viability readout helps determine whether a drop in a functional signal reflects biological modulation, reduced viable cell numbers, or both. Without this assessment, proliferation and signaling results can be misinterpreted.

Beyond Viability: Cytotoxicity Endpoints

Finding a cytotoxicity problem at the hit stage, in cells, costs far less than finding it later in an animal study.

Screening & Drug Discovery Applications

The assay format and cell model change with the question at each stage of a discovery program.

Primary screening of compound libraries runs through Boster's compound screening services; cell-based assays then confirm and rank the hits.

Automation & Scalable Screening

Automated liquid handling and 384-well formats help when a study needs more compounds, conditions or replicates than manual pipetting handles reliably. Smaller volumes are more sensitive to evaporation, edge effects and pipetting error, so an assay moved to a smaller format needs extra optimization first.

Automated and miniaturized formats are available on request. For larger screening campaigns, explore our high-throughput screening (HTS) services. Small or exploratory panels are often faster to set up and troubleshoot by hand.

Frequently Asked Questions