Human Natural Killer Cell Expansion Using Corning® NK Expansion Kit

作者:admin 来源: 发布时间: 2017-07-06 21:08  浏览次数:


This application note describes the protocol for rapid expansion of NK cells using the Corning NK Expansion kit, as well as tests that validate the use of the kit. The results support the use of the Corning NK Expansion kit by researchers who need high expan- sion capacity, high viability, and high cytotoxicity of NK cells. The Corning NK Expansion kit contains a pre-coated T-75 flask, KBM NK Primary medium, KBM NK Primary supplement, and KBM NK Expansion medium. The first three components are specifically designed for NK cell activation, while the KBM NK Expansion

medium is utilized for NK cell expansion. Both the KBM NK Primary medium and KBM NK Expansion medium are manufactured using high quality reagents and GMP-grade raw materials. The only pro- teins present in the media are injectable levels of serum albumin and recombinant human insulin.



Natural killer (NK) cells are crucial immune cells that can recognize and kill tumors and virus infection. It is difficult to obtain the large numbers of NK cells ex vivo that are necessary for adoptive immu- notherapy. Several methods of NK activation/expansion have been reported that use expansion medium plus various cytokines (e.g., IL-2, IL-7, and IL-15). However, these require further optimization by researchers.

The Corning NK Expansion kit provides a complete set of materials and a standard operating procedure to expand NK cells with high expansion capacity, high viability, and high cytotoxicity. Researchers have no need to further optimize it, and the procedure has mini- mal consumables cost. In this application note, we provide com- petitive data, including cell yields, cell viability, and positive NK ratio and cytotoxicity capability in vitro, that compares the Corning NK expansion kit with other commercially available expansion media.


Materials and Methods

Peripheral blood mononuclear cells (PBMCs) were isolated from healthy donor whole blood using lymphocyte separation  medium

(Corning Cat. No. 25-072-CI) according to the manufacturer’s instructions. The wash buffer was PBS (Corning Cat. No. 21-040-CV), and the culture vessel was a gas-permeable cell culture media bag (Corning Cat. No. 88-610-20). Interleukin 2 (IL-2, Corning Cat. No. 354043) was used as an in vitro cytokine for NK cell activation and expansion.

NK Cell Activation and Expansion

◗◗ On Day 0, the auto-plasma was inactivated by heating at 56°C for 30 min. and centrifuged at 800 xg for 20 min. to remove the precipitates. The supernatant was collected and stored at 4°C for further use.

◗◗ The PBMCs were washed once with at least 5-fold PBS buffer, and the sample was centrifuged at 500 xg for 10 min. at room temperature. The density of PBMCs was adjusted to 1 x 106 cells/ mL using KBM NK Primary medium containing 1.8 mL KBM NK Primary supplement and 10% auto-plasma.

◗◗ The pre-coated T-75 flask was washed carefully twice with PBS just before use. Thirty milliliters of the suspension of PBMCs  were seeded into the pre-coated T-75 flask and incubated at 37°C in a humidified atmosphere of 5% CO2 in air.

Note: Before Day 6 when the medium turned yellow and the cell density was above 2 x 106 cells/mL, fresh KBM NK

Primary medium plus 10% auto-plasma were added to the cell suspension to ensure that cell density stayed within the range of

2.5 x 105 to 2.0 x 106 cells/mL.

◗◗ On Day 6, all cells were centrifuged and re-suspended with an appropriate volume of KBM NK Expansion  medium  containing 1,000 IU/mL  IL-2 and 10% auto-plasma and then transferred to a     new  T-225  flask  or  gas-permeable  culture bag.

◗◗ In the following days, KBM NK Expansion medium containing 1,000 IU/mL IL-2 was added every 2 to 3 days based on the cell proliferation status to ensure that cell density stayed within

2.5 x 105 to 2.0 x 106 cells/mL.

◗◗ The cells were harvested for CCK8 cytotoxic and immuno- phenotyping testing when the total cell number exceeded 2 x 109.

Note: The cells were gently dissociated, and the culture vessels were tapped softly to avoid cell damage and maintain cell viability throughout the entire experimental process.


The CD3-CD56+ ratio is used to evaluate the surface marker expression level of the harvested cells. Briefly, 1 x 106 cells were added into 100 μL PBS and then stained with CD3 FITC antibody (BD Cat. No. 349201) and/or CD56 PE antibody (BD Cat. No.

340363) for 20 min. at room temperature, avoiding light exposure during the entire stain process. After incubation, cells were briefly washed with PBS buffer and then resuspended with 200 μL PBS for subsequent flow cytometry analysis using the BD Accuri™ C6 flow cytometer (BD Biosciences). Ten thousand events were collected for each sample and analyzed by the histogram overlay subtraction method using BD Accuri C6 software.

CCK-8 Cytotoxicity Test

1 x 105 cells/mL of the target K-562 cells were co-cultured with 5 x 105 cells/mL effector cells (96-well microplate in triplicate for each sample with a final volume of 200 μL/well) at 37°C in a humidified atmosphere overnight. Before analysis, 20 μL Cell

Counting Kit-8 solution (CCK8, Sigma Cat. No. 96992) was added into each well and incubated for 1 hour at 37°C in a humidified atmosphere of 5% CO2. The data was read by SpectraMax® M4 (Molecular Devices) multifunction microplate reader.


Figure 1. A and B compare the cell growth curve and proliferation capacity using different manufacturers’ NK Expansion kits, respectively. The Corning NK Expansion kit  shows a very competitive expansion capacity (~8.6 x 109 cells, 290-fold proliferation on Day 19) compared with Competitors B and C.


Figure 2. CCK-8-based cytotoxicity activity detection. The Corning NK Expansion kit shows a more potent cytotoxicity capacity (77.9%) compared to Competitor B (54.1%) and Competitor C (57.6%) when the cells were co-cultured with K-562 for 16 hours (effector cells: target cells = 5:1) in triplicate for each kit.


Figure 3. Surface marker expression determined by flow cytometry. The CD3-CD56+ ratio is used to evaluate the surface marker expression level to measure the percentage of NK cells in the harvested cells. The Corning NK Expansion kit shows a result of 83.0%, which is higher than Competitor B (67.6%) and Competitor C (6.4%).


◗◗ The Corning® NK Expansion kit  supports the rapid expansion of    NK cells with high yields (~8.6 billion, 290-fold proliferation) and   potent  cytotoxicity activity (77.9% with an ET ratio of 5:1) which     is very competitive compared with Competitors B and C.



◗◗ The Corning NK Expansion kit provides a complete set of materials and a standard operation procedure. There are minimal consumables costs and no need for further optimization.







Corning NK Expansion Kit

Competitor B NK Kit

Competitor C NK media

Seeding vessels

Pre-coated T-75 flask

Coated by researchers using coating agent

No flask or coating agents


Pre-coated T-75 flask;

50 mL NK Primary medium

+ 1.8 mL primary supplements; 1L NK Expansion medium; permeable cell culture bag.

1 mL coating agent;

80 mL Activation medium; 2L Expansion medium + 1 mL supplements.

500 mL medium/bottle

Operator friendliness

Easy operation with clear protocol

No finalized protocol, NK culture process must be further optimized by researcher

No protocol

Anticoagulant  compatibility

Heparin, sodium citrate


Heparin, sodium citrate

Cell yields (14 days, 30 mL blood samples)

~3 billion

~0.64 billion

~4.2 billion

Expansion fold




Phenotype (CD3-CD56+) NK cell (Day 14)




Number of effective NK cells

~2.5 billion

~0.4 billion

~0.3 billion

Cytotoxicity (ET = 5:1, target cell: K562)




Media volume





14 days

14 days

14 days

Warranty/Disclaimer: Unless otherwise specified, all products are for research use only. Not intended for use in diagnostic or therapeutic procedures. Not for use in humans. Corning Life Sciences makes no claims regarding the performance of these products in clinical or diagnostic applications.











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