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Art of Cell Culture

In 2024, MarinBio successfully passed the FDA inspection with no 483s and no observations and in 2025 passed the EU inspection

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Cell-Based Assay Solutions for Drug Development

The Art of Cell Culture​

Cell culture is an in vitro method to grow or maintain cells in the laboratory to mimic an in vivoprocess or for a specialized function. Cells display a remarkable range of characteristics depending on their growth stage—whether they’re just thawed from a frozen ampoule, actively dividing during the log phase, or settling into the stationary phase. Each cell type demands carefully tailored conditions and methods to thrive. Without robust, healthy cultures, the reliability and reproducibility of any cell-based assay or bioassay are compromised. 

Cell-based assays are a cornerstone of modern drug discovery, offering a wide range of applications that help identify, validate, and optimize potential drug candidates.

Our expertise is the development of robust cell-based methods for drug discovery, we pay careful attention to all of the critical elements to make an assay ideal to ensure progression of therapeutics to the clinic.

MarinBio scientist performing advanced cell culture techniques
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1000 TRIALS ALREADY COMPLETED

Our practices require that we monitor the health of our cells all the time. We have performed 1000s of studies on the variables of cell culture.  Because of our extensive experience in The Art of Cell Culture we take into consideration the critical elements for optimal assay development.

  • Cell Type Selection: Primary Cells vs Cell Lines
  • Cell Density and Growth
  • Cell Culture Observation and Morphology
  • Cell Culture Conditions: Medium Selection
  • Fetal Bovine Serum: Batch Screening
  • Cryopreservation

•        Routine Cell Line Mycoplasma and Genomic Testing

Questions about Our Cell Based Assay Services?​

Contact us to discuss the specifics of your project. Our team of experienced scientists is ready to assist you with tailored solutions to meet your unique needs. Whether you need help with assay development, FDA IND, stability study,  lot release approval, or other scientific endeavors, we are here to support you.
Contact us to learn more about our cell based assay services

We will initiate your project as soon as the proposal is approved and signed by you. Our streamlined process ensures a quick start, minimizing delays and maximizing efficiency. Fill out the form below to email us or click our live chat option to speak with a MarinBio Scientist and get your project underway.

Yes, we have over 30 years of expertise in developing and validating cell based assays for FDA IND, lot release or stability study approval. Our team can also liaise directly with the FDA on your behalf, ensuring a smooth and compliant process. Please contact us to learn more about how we can assist you with your assay development and FDA approval needs.

MarinBio scientists are experienced and creative in designing, developing, validating assays. Some of the assays we perform are listed below, but there are many more that we created, developed and validated. Give us call so that we may help you.

MarinBio scientists conducting targeted protein degradation assays in advanced laboratory

Need help or have questions on cell based assays?

Give us a call at 415-883-8000

Six Ways to Make Your Assay Out-Perform

(1) Cell Type Selection

Selecting the optimal cell type for in vitro drug discovery assays requires practical experimental considerations to ensure assay accuracy and reproducibility.

a) Primary Cells vs Cell Lines

  • Primary cells are derived directly from tissues and may offer more complex and accurate physiological responses. However, primary cells have limitations including restricted passage numbers, availability, cost, lifespan, and donor variability.
  • Cell lines are easy to use, cost-effective, highly reproducible, scalable for high-throughput screening, and can be expanded and stored.
  • Researchers often use a combination of both models to balance physiological relevance and experimental feasibility in drug discovery workflows. It is preferable to align both primary cells and cell lines with the disease being studied.

b) Assay Compatibility

Contemporary drug development includes multiple molecular and cellular formats, targets, and mechanisms of action. The selected cell line must have the intracellular and extracellular machinery required to develop an assay to test a drug of interest. Different drug modalities include:

  • Small Molecules
  • Monoclonal Antibodies
  • Cell Therapies (e.g., CAR-T Cells, Stem Cells)
  • Gene Therapies (DNA, RNA)
  • Antibody-Drug Conjugates
  • PROTACS
  • Multi-Specific Antibodies (e.g., BiTEs)
  • Other drugs

(2) Cell Density and Growth

a) Cell Density

Consistent cell density ensures reliable sensitivity.

  • Overcrowding can cause adherent cells to become unattached or undergo cell death, increasing background signals.
  • Sparse cultures may skew detection.
  • To obtain reproducible density, perform cell seeding experiments to determine the best cell number and time in culture for the assay.

b) Cell Growth and Viability

It is critical to establish a reliable standard growth curve and identify the optimal seeding density for your specific cell type and assay.

  • Perform growth curve experiments to determine the optimal time in culture for an assay and ensure reproducibility.
  • Each cell line has different growth characteristics. Therefore, documenting and keeping records is a time-saving and valuable practice for future reference.

(3) Cell Culture Observation and Morphology

  • Monitoring cell morphology throughout the culture is essential for achieving optimal assay results.
  • Changes in cell morphology can indicate shifts in metabolism, which may impact assay outcomes.
  • It is best practice to add your drug to cultures when the cells appear normal—without blebs or granules and in the logarithmic growth phase.
Female scientist wearing protective gear and using a microscope in a modern laboratory for research.
Scientist examining cell culture flask in laboratory

(4) Cell Culture Conditions: Medium Selection

Differences in nutrient composition, buffering systems, and cell type specificity are critical for selecting the optimal medium for in vitro drug development experiments.

Here are four common tissue culture media used for in vitro drug development, along with what distinguishes each from the others:

  • DMEM: High amino acids/vitamins, basal medium. Used for many mammalian cell lines and fast-growing cells.
  • RPMI 1640: Designed for suspension/immune cells. Hematopoietic cells, lymphocytes, hybridomas.
  • IMDM: Highly enriched with extra buffering. Designed for high-density, immune/hematopoietic cells.
  • Serum Free: Multiple versions commercially available tailored to specific cell types. Widely used in both research and industrial settings.

(5) Serum

  • The single most undefined tissue culture reagent is serum. Fetal bovine serum, as an example, varies from batch to batch and vendor to vendor.
  • To overcome this variability and eliminate it as a risk for future experiments, we acquire volumes of pre-tested lots to last for months or even years’ worth of experiments.

(6) Assay Conditions

  • Substrate development timing is critical for any assay that uses color/fluorescence/luminescence detection.
  • When developing a 4-parameter drug concentration curve, we anchor each plateau far from the inflection point, which prevents the curve from moving day-to-day. We use concentrations that describe the two inflection points, and the linear portion results in a precise EC50 determination.

These are just a few tidbits that our experience has led us to improve performance. Hope this helps you in your assay development

Quick Reads

Assay – Custom Development

When you need an assay to test your drug and there is no commercial kit available, one solution is the development of a custom assay. Our extensive expertise will quickly and methodically develop your assay to prepare it for validation.

Assay – Kits

We are firm believers in kits. The analytical portion of the assay itself is only a single component of what it takes to perform a successful experiment. It is all the other skills, experience and GLP/GMP conditions that we do day in and day out that will save you time getting to the results you actually want.

Assay Qualification

Many companies planning an IND submission or in Phase I/II may only require a well-qualified assay rather than a fully validated assay. You may or may not need GLP/GMP stringency and auditability yet. Our scientific team works with your scientists to qualify your assay for reproducibility, appropriate precision and accuracy.

Assay Validation

To validate an assay is to measure precision, linearity, accuracy, robustness, system suitability and repeatability. To achieve these results, we conduct multiple experiments in a pre-validation phase with the assay. This phase is a series of experiments that specifically examines these capabilities and allows the assignment of acceptance criteria. Once we have advanced an assay, we re-test it for at least 3 identical repeats, for a minimal statistical analysis. At that point, your assay meets the FDA GLP or GMP requirements.  For more late phase assays, phase III or commercial, many more tests are conducted.

Sample Analysis, Clinical Testing, Toxicology Studies

Whether patient samples or drug product samples, MarinBio will map out a timeline and follow through with sample receipts, meeting your regulatory needs at all points. We perform your assay as developed, qualified or validated, and promptly communicate the results and/or Certificate of Testing for any or all of your preclinical or clinical phases.

Lot Release Testing

Knowing the importance to the FDA of lot release potency testing, the MarinBio scientific team tests every manufacturing lot with your assay providing Certificates of Testing in a timely manner, under GMP Conditions.

Stability Testing

In order to determine shelf life for a particular drug substance, stability tests are performed at pre-determined calendar intervals. MarinBio project coordinators communicate closely with you to anticipate the arrival of samples so as to have our staff and resources available for timely analysis and submittal of data and Certificates of Testing.

Contact Us About Our Art of Cell Culture Services

For More Information about our Art of Cell Culture services, please use the following informational form