Exosome Cell Viability and Proliferation Assays
OverviewServicesSamplesAdvantagesApplicationsCase StudyFAQs
Overview
Before a microbial extracellular vesicle (mEV) preparation can advance to mechanistic studies, animal models, or product development, one question must be answered definitively: what does it do to target cells? Does it promote survival, inhibit growth, kill outright, or leave cells unaffected? The answer determines whether the vesicle is a therapeutic candidate, a safety concern, or biologically inert—and cell viability and proliferation assays are the fastest, most quantitative way to find out.
At Creative BioMart Microbe, we provide a complete cell viability and proliferation assay platform for bacterial and probiotic extracellular vesicles, integrating colorimetric viability assays (MTT, MTS, CCK-8), fluorescence-based live/dead discrimination, proliferation quantification (BrdU, Ki-67, CFSE), and cytotoxicity profiling (LDH release) into a single coordinated workflow. Our protocols span cancer cell lines, normal epithelial and fibroblast lines, primary immune cells, and organoid models, with vesicle doses normalized to both particle count and protein content for cross-study comparability.
Each project includes dose-response curves at a minimum of four concentrations, vehicle controls, positive cytotoxicity controls, and vesicle-depleted supernatant references. Results are delivered as normalized viability percentages, IC50 values where applicable, and statistical comparisons that directly support go/no-go decisions for downstream development. Contact us to discuss your mEV cell viability and proliferation testing needs.
Figure 1. End-to-end workflow for microbial exosome cell viability and proliferation assays, from vesicle preparation through multi-method quantification to dose-response analysis.
Services
Service Workflow
Our workflow is built around generating publication-quality dose-response data from a single vesicle preparation across multiple cell types and assay formats. The four-step process ensures that every result is normalized, controlled, and statistically interpretable.
Service Details
Cell Viability Assessment
We quantify cell viability using MTT, MTS, and CCK-8 colorimetric assays, complemented by Calcein-AM/EthD-1 fluorescence live/dead staining. Each method provides a distinct viability readout—metabolic activity, membrane integrity, and intracellular esterase function—ensuring robust cross-validation. Clients receive viability percentages normalized to vehicle controls at each dose level.
Cell Proliferation Quantification
We measure proliferation rates using BrdU incorporation (DNA synthesis), Ki-67 immunostaining (cell cycle active phase), and CFSE dilution (division tracking by flow cytometry). These complementary approaches distinguish between cytostatic effects (reduced division rate) and cytotoxic effects (cell death), a critical distinction for therapeutic candidate triage.
Cytotoxicity Profiling
We assess membrane-damaging cytotoxicity using LDH release assays and annexin V/PI double staining for apoptosis versus necrosis discrimination. This service is essential for safety assessment of OMV preparations that may carry pore-forming toxins or membrane-disrupting cargo, and for demonstrating selective cytotoxicity against cancer cells.
Dose-Response & IC50 Determination
We generate full dose-response curves across 5–8 vesicle concentrations and calculate IC50, EC50, or GI50 values using four-parameter logistic regression. Selectivity indices comparing cancer versus normal cell IC50 values provide a quantitative therapeutic window assessment for anti-cancer mEV candidates.
Assay Specifications & QC Standards
Cell Panel & Assay Format
| Cell Category |
Representative Lines |
Assay Formats |
| Cancer cell lines |
HCT116, A549, MCF-7, HeLa, B16F10 |
MTT, CCK-8, BrdU, LDH, Annexin V/PI |
| Normal epithelial |
Caco-2, HaCaT, HEK293 |
MTT, MTS, Live/Dead, Ki-67 |
| Fibroblast |
HDF, NIH-3T3, BJ-1 |
MTT, CCK-8, CFSE, LDH |
| Immune cells |
RAW264.7, THP-1, primary PBMCs |
MTT, CCK-8, Annexin V/PI, CFSE |
| Primary / organoid |
Client-provided or custom-sourced |
Method-dependent (consult) |
Typical Data Range
- Vesicle dose range: 107–1011 particles/mL across 5–8 concentrations.
- Viability assay dynamic range: 0–100% relative viability with LOD at 5% of control.
- IC50 range for cytotoxic OMVs: 109–1011 particles/mL (strain and cell type dependent).
- Probiotic EV viability preservation: ≥90% viability across tested doses for non-cytotoxic preparations.
- Selectivity index (cancer vs. normal IC50): 1.5–10× for anti-cancer vesicle candidates.
- Intra-assay CV ≤ 10%; inter-assay CV ≤ 15% for all viability readouts.
Turnaround Time
| Service Type |
Timeline |
| Single viability assay (one cell line, one preparation) |
1–2 weeks |
| Multi-method viability panel (MTT + Live/Dead + LDH) |
2–3 weeks |
| Dose-response & IC50 determination (one cell line) |
2–3 weeks |
| Multi-cell-line screening (3+ lines, one preparation) |
3–4 weeks |
| Comprehensive package (viability + proliferation + cytotoxicity + dose-response) |
4–6 weeks |
| Expedited timeline |
+50% fee, 40% time reduction |
Timeline may vary based on cell line growth rate, number of vesicle concentrations, and assay complexity.
Deliverables
- Viability data: Raw absorbance/fluorescence values, normalized viability percentages, and dose-response curves for each cell line.
- Proliferation data: BrdU incorporation rates, Ki-67 positivity percentages, or CFSE division profiles with proliferation indices.
- Cytotoxicity data: LDH release percentages, Annexin V/PI quadrant analysis, and apoptosis/necrosis classification.
- IC50/EC50 report: Calculated values with 95% confidence intervals, four-parameter logistic fit curves, and selectivity indices.
- Control data: Vehicle, positive cytotoxicity control (Triton X-100 or staurosporine), and vesicle-depleted supernatant for every assay.
Quality Control
- Vesicle dosing: NTA-verified particle concentration and BCA protein normalization before cell treatment.
- Endotoxin monitoring: LAL assay on every preparation; endotoxin levels reported alongside viability data.
- Cell line authentication: STR profiling and mycoplasma testing on all cell lines used in the assay.
- Positive controls: Triton X-100 (100% lysis), staurosporine (apoptosis inducer), and known cytotoxic OMV references where available.
- Negative control: Vesicle-depleted supernatant and vehicle-only treatment to establish baseline viability.
- Intra-assay CV ≤ 10%; inter-assay CV ≤ 15% for all viability readouts.
Sample Requirements
| Required Information |
Optional Information |
Not Accepted |
- Vesicle source organism (species and strain)
- Vesicle type (OMV, CMV, or mixed)
- Target cell line(s) or primary cell type
- Expected effect (cytotoxic, cytoprotective, or neutral)
- Vesicle particle concentration (NTA data preferred)
- Intended application (drug screening, safety, functional food)
|
- Specific viability assay method preference (MTT, CCK-8, etc.)
- Desired dose range and concentration points
- Reference compound for positive control
- Historical viability data on the cell line
- Client-provided cell lines (with authentication data)
- Selectivity comparison cell lines (cancer vs. normal)
|
- Vesicle preparations in cytotoxic buffers or detergents
- Contaminated or mixed vesicle populations
- Fixed or cross-linked vesicles
- Preparations without particle concentration data
- Samples with endotoxin >10 EU/mL without neutralization plan
- Samples shipped without cold-chain documentation
|
Recommended Sample Quantity by Assay Scope:
| Assay Scope |
Minimum |
Recommended |
| Single viability assay (one cell line) |
50 µL purified vesicles |
100–200 µL |
| Dose-response (5+ concentrations, one cell line) |
100 µL purified vesicles |
200–300 µL |
| Multi-cell-line screening (3+ lines) |
200 µL purified vesicles |
300–500 µL |
| Comprehensive package (all methods + dose-response) |
300 µL purified vesicles |
500 µL–1 mL |
Storage & Shipping: Ship purified vesicle suspensions on dry ice in sterile PBS. Include NTA data and endotoxin measurement. For client-provided cell lines, provide STR authentication and mycoplasma test certificates. Indicate preferred assay methods and dose range if known. Avoid freeze-thaw cycles; aliquot for multi-assay projects.
Our Advantages
- Multi-Method Cross-Validation — We combine MTT/CCK-8, LDH/Live-Dead, and BrdU/Ki-67 assays to eliminate false positives from single-method artifacts.
- Selectivity Index Calculation — We calculate cancer versus normal cell IC50 ratios to quantify therapeutic windows for anti-cancer mEV candidates.
- Dose-Response by Default — Standard protocols include 5–8 concentrations with logistic curve fitting for publication-grade IC50/EC50 values.
- Broad Cell Panel Coverage — Our panel spans cancer, epithelial, fibroblast, immune, and organoid models for comprehensive efficacy and safety data.
- Endotoxin-Aware Interpretation — Every batch is quantified by LAL assay with LPS-neutralized controls to exclude endotoxin confounding effects.
Applications
Anti-Cancer Vesicle Screening
Bacterial OMVs evaluated for selective cytotoxicity against cancer cell lines with selectivity index calculation.
Safety & Biocompatibility
Probiotic EVs and engineered vesicles tested for cytotoxicity on normal cell lines for preclinical safety assessment.
Probiotic EV Efficacy
Cytoprotective and proliferative effects of probiotic EVs on intestinal, skin, and immune cells under stress.
Wound Healing & Regeneration
Proliferation and migration stimulation by probiotic EVs on dermal fibroblasts and keratinocytes for skin repair.
Case Study
Case Study 1: Lactobacillus paracasei EVs Show Dose-Dependent Cytoprotection on Skin Cells
Researchers evaluated the cytotoxicity profile of extracellular vesicles derived from Lactobacillus paracasei (LpEVs) on human dermal fibroblasts (HDFs) using WST viability assays. Across most concentrations, LpEVs maintained cell viability above 80% of the untreated control, indicating minimal cytotoxicity. Notably, when HDFs were challenged with TNF-α to induce inflammatory stress and subsequently treated with LpEVs, the vesicles dose-dependently restored cell viability that had been reduced by cytokine exposure. LDH release assays under inflammatory conditions confirmed that LpEVs reduced membrane damage in a concentration-dependent manner. This study demonstrates the importance of testing vesicle effects across a full dose range and under both basal and stress conditions—a vesicle that appears inert under normal conditions may reveal significant cytoprotective activity when cells are challenged.
Figure 2. Cell viability after LpEV or LpEX treatment and recovery of cell viability after LpEV treatment in TNF-α-induced inflammatory conditions. (Lee, et al. 2023)
Case Study 2: Lactobacillus rhamnosus EVs Protect Fibroblasts from Oxidative Stress-Induced Cell Death
Investigators assessed the cytotoxicity and cytoprotective capacity of Lactobacillus rhamnosus-derived extracellular vesicles (EVs) and cell-derived vesicles (CDVs) on human dermal fibroblasts using MTT assays. Under baseline conditions, neither vesicle type showed significant cytotoxicity, confirming biocompatibility. When fibroblasts were pre-treated with EVs or CDVs and subsequently exposed to H₂O₂-induced oxidative stress, EVs dose-dependently restored cell viability to 121–128% of control, markedly outperforming CDVs which showed significantly lower protection. Intracellular ROS levels were assessed using the H₂DCFDA fluorescence assay at 2% concentration; EVs reduced ROS production by 62.9%, exceeding the positive control EGCG, while CDVs showed only 26.8% inhibition. This dual-readout approach—measuring both direct cytotoxicity and stress-protective benefit—illustrates how viability assays can reveal therapeutic potential that single-condition screening would miss.
Figure 3. Cytotoxicity and ROS-scavenging capacity of EVs and CDVs in HDF cells. (Wang, et al. 2025)
FAQs
Q: What is the difference between cell viability and cell proliferation assays?
A: Viability assays (MTT, CCK-8, Live/Dead) measure whether cells are alive at a given time point based on metabolic activity or membrane integrity. Proliferation assays (BrdU, Ki-67, CFSE) measure the rate at which cells are dividing over time. A vesicle can reduce proliferation without killing cells (cytostatic effect) or kill cells without affecting the proliferation rate of survivors—these are therapeutically distinct outcomes that require both assay types to distinguish.
Q: Why do you include vesicle-depleted supernatant as a control?
A: Vesicle-depleted supernatant contains all soluble factors from the culture medium except intact vesicles. If viability effects are seen with the supernatant control but not intact vesicles, the effect is due to free molecules rather than vesicle cargo. This control is essential for attributing biological activity to the vesicle itself, which is a common requirement for publication and regulatory review.
Q: Can you calculate IC50 values for cytotoxic vesicles?
A: Yes. For vesicle preparations showing dose-dependent cytotoxicity, we generate 5–8 concentration dose-response curves and calculate IC50 values using four-parameter logistic regression with 95% confidence intervals. We also calculate selectivity indices by comparing IC50 values against cancer and normal cell lines when both are tested.
Q: Which viability assay method should I choose?
A: MTT is the most widely cited and accepted for publications. CCK-8 offers higher sensitivity and non-destructive readout. Live/Dead fluorescence staining provides single-cell resolution and distinguishes viability mechanisms. For comprehensive studies, we recommend running at least two methods in parallel to cross-validate results and eliminate assay-specific artifacts.
Q: How do you handle endotoxin interference in viability assays?
A: Endotoxin (LPS) from Gram-negative OMV preparations can independently affect cell viability, particularly in immune cell lines. We quantify endotoxin by LAL assay on every preparation and include polymyxin B controls to neutralize free LPS. For immune cell assays, we recommend testing both intact and LPS-neutralized vesicle preparations to distinguish vesicle-specific effects from endotoxin contributions.
Q: Can you test vesicles on primary cells or organoids?
A: Yes. We can work with client-provided primary cells or source primary cells (PBMCs, dermal fibroblasts, intestinal epithelial cells) for viability and proliferation testing. Organoid models (intestinal, tumor) are available for advanced screening projects. Primary cell assays require additional setup time and may have higher donor variability, so we recommend multi-donor testing.
Q: Can viability data be used for batch release testing?
A: Yes. Viability assays on a standard cell line can serve as a potency bioassay for batch consistency in Food-Grade and Cosmetic-Grade vesicle manufacturing. We can establish acceptance criteria (e.g., viability within ±15% of reference batch) and provide CoA-compatible reports for regulatory submissions.
References:
- Lee, K.-S., Kim, Y., Lee, J. H., et al. (2023). Human Probiotic Lactobacillus paracasei-Derived Extracellular Vesicles Improve Tumor Necrosis Factor-α-Induced Inflammatory Phenotypes in Human Skin. Cells, 12(24), 2789.
- Wang, H., Sim, J., Jeong, A. H., et al. (2025). Functional and proteomic analysis of Lactobacillus rhamnosus-derived extracellular vesicles with antioxidant and anti-inflammatory activity. Scientific Reports, 15, 6070.
