Purple cell, NK-Xpander, and wavy background


Natural killer (NK) cells are innate lymphocytes that kill virally infected or malignant cells. Unlike T cells, NK cells function in an antigen independent manner, responding to anything they perceive as "non-self", including malignant cells. NK cells are an attractive allogeneic immune modulator, as they have a well-known safety profile and lack the potential to cause graft-vs-host disease, a risk associated with CAR-T cell immunotherapy. This makes them an attractive cell type for development of off-the-shelf immunotherapies (Front Immunol 13:1869 (2018)).

Pre-clinical and clinical studies have demonstrated safety and efficacy of allogeneic NK cells against various malignancies—both hematological and solid tumors, without the need for strict HLA-matching. Several clinical trials are currently ongoing which use NK or CAR NK cells as off-the-shelf allogeneic therapeutics. However, many NK cells are needed in order to infiltrate solid tumors effectively. Generation of sufficient cell numbers for off-the-shelf allogeneic translational, cancer immunotherapy requires efficient scale-up culture conditions.

At Thermo Fisher Scientific, we have developed Gibco Cell Therapy Systems (CTS) products across the cell therapy workflow to facilitate the transition from discovery to commercial manufacturing. CTS reagents are manufactured in conformity with GMP for medical devices, 21 CFR Part 820, and follow USP<1043> and Ph Eur 5.2.12.  They are available at commercial scale with a high degree of qualification, traceability, and regulatory documentation, to help you transition your cell therapy to the clinic with confidence.

Cell isolation

Human peripheral blood mononuclear cells (PBMCs) are a rich source of many immune cell types, including NK cells. Often, PBMCs are isolated from whole peripheral blood or leukapheresis preparation via density gradient separation, but this requires a lengthy, manual process, which can be prone to error and contamination.

Alternatively, the CTS Rotea Counterflow Centrifugation System offers a closed, semi-automated solution to PBMC isolation.

NK cells can be isolated from the purified PBMC preparation using immunomagnetic beads such as the Invitrogen Dynabeads Untouched Human NK Cells Kit.

Gibco CTS Rotea Counterflow Centrifugation System

Gibco CTS Rotea Counterflow Centrifugation System

A compact, flexible closed cell processing system, designed to streamline and expedite your cell therapy development, that enables:

  • Process flexibility—user-programmable software enables you to create and optimize a broad range of protocols for cell separation, washing, and concentration
  • High cell recovery and viability—gentle processing enables >95% cell recovery while maintaining cell viability
  • Low output volumes—proprietary technology can deliver as little as 5 mL of concentrate
  • Research through commercial manufacturing—the closed single-use kit enables sterile processing, and an OPC-UA interface enables connectivity to a 21 CFR Part 11-compliant system

Learn more    Request a demo    Request a quote

Gibco CTS Xenon Electroporation System


A closed, scalable electroporation system for GMP-compliant cell therapy manufacturing

  • High speed and large volume—transfect up to 2.5 x 109 T cells/25 mL in less than 25 minutes
  • Scalable, proven performance and viability—up to 90% gene knockout with CTS TrueCut Cas9 Protein and 80% cell viability
  • Process flexibility—user-programmable system enables you to create and optimize electroporation protocols for various cell types and payloads, from process development through commercial manufacturing
  • Efficient nonviral transfection—can be used to deliver DNA, RNA, and protein payloads
  • Closed-system processing—Xenon MultiShot Electroporation Cartridge helps enable sterile welding to PVC or C-Flex™ tubing

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Cell expansion

Feeder-free NK cell expansion systems are the desirable choice for clinical applications due to their reduced safety risks. However, the historically lower expansion rates of feeder-free culture systems present a challenge to widespread clinical adoption and are a key reason why feeder-based expansion systems are frequently used today, despite the safety and regulatory risks they pose.

A 2 L bag of NK-Xpander media, showing supplement and tubing appropriate for closed large scale applications
A 500 mL bottle of NK-Xpander media with supplement for benchtop applications

CTS NK-Xpander Medium is available in 5 L bags and 500 mL bottles.

Gibco CTS NK-Xpander Medium was designed to proliferate a high yield of functional human NK cells to address the needs of translational and clinical cell therapy researchers with or without the use of feeder cells.

  • Best-in-class performance—capable of expanding a high yield of human NK cells without the need for feeder cells; cells maintain CD56+ and CD16+ expression and demonstrate cytolytic capabilities
  • Reduction of regulatory risks—designed to help meet regulatory compliance requirements for ancillary materials used in cell and gene therapy manufacturing; manufactured AOF (human AB serum supplementation is recommended for best results); offers Drug Master File, Certificate of Origin, Certificate of Analysis, and Safety Data Sheet
  • Closed-system compatible format available off-the-shelf—available in 500 mL bottles and 5 L bag kit formats for convenient process development and closed-system manufacturing scale-up
NK cells grown in CTS NK-Xpander Medium grow to approximately twice as many cells after 14 days than the leading alternative medium

CTS NK-Xpander Medium offers significantly higher fold expansion than all other media systems tested, including a specialty NK culture medium (Supplier 1) (p<0.0001) with average expansion greater than 1,500-fold after 14 days of small-scale culture (n = 20 donors).

Serum-free Expansion of NK Cells with K562- Based Feeder Systems for Clinical Applications

In this webinar, Dr. Dean Lee of Nationwide Children’s Hospital discusses his work with NK cells, including optimization of culture conditions.

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Genetic modification

Lentiviral methods

NK cells are often genetically modified to improve NK cell function, persistence, and trafficking to tumor sites. Lentiviral vectors can be used to make genetic modifications such as insertion of chimeric antigen receptors. The Gibco CTS LV-MAX Lentiviral Production System offers a scalable and high-yield lentiviral vector production platform that is based on a suspension culture of HEK 293-derived Viral Production Cells adapted to a special chemically defined, serum-free, and protein-free CTS LV-MAX Production Medium.

The CTS LV-MAX Lentiviral Production System offers:

  • High titer—greater than 1 x 108 TU/mL (unconcentrated LVVs-GFP)
  • Scalable suspension system—from 96 deep-well plate to 2 L bioreactor
  • Serum-free—eliminating animal-origin components and associated risks
  • Easy, robust culture and transfection protocols—fits into current transient production workflows

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Non-viral methods

As you move your genome editing research from basic research to clinical settings, high-quality cell therapy ancillary materials and documentation are critical. We now offer our Gibco CTS TrueCut Cas9 Protein for clinical research that requires Cas9 nuclease that is manufactured with stringent specifications.

  • Exceptional performance—consistently high performance in all tested cell lines, including >90% editing in iPSCs
  • Higher stringency manufacturing—manufactured in compliance for Ancillary Materials for Cell, Gene and Tissue-Based Products
  • Extensive safety testing—including sterility, endotoxin, mycoplasma, residual host nucleic acids, and proteins

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Wash and concentration

NK cell therapy culture volumes can often reach final volumes of 10-20 L, which must be concentrated and undergo buffer exchange prior to final product formulation. The Gibco CTS Rotea Counterflow Centrifugation System is a closed, semi-automated alternative to commonly used manual centrifugation processes and offers exceptional flexibility in cell therapy development and manufacturing to enable scaling from research through commercial manufacturing.

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NK cells are traditionally identified by the presence of CD56 and absence of CD3 on their cell surface via flow cytometry. In addition to CD56, NK cells can be further characterized into a variety of subsets through many different cell surface markers including CD16 and the KIR family of receptors. Check out our tools that can be used for NK cell analysis including flow cytometry, functional assays, and immunoassays, and for additional characterization information, visit our NK cell overview page.

For the most advanced cell analysis, the Attune CytPix Flow Cytometer combines acoustic focusing fluidics for high sensitivity and high throughput with a high-speed camera.


NK cell therapies typically require a cryopreservation step to ensure that the cellular product is preserved without compromising viability and efficacy. Thermo Scientific CryoMed Controlled-Rate Freezers (CRF) offer precise, repeatable freezing results that protect precious samples from intracellular freezing and are equipped with enhanced data traceability features to support audit requirements and offers customizable freezing profiles while supporting 21 CFR part 11 and GMP needs.