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Kite Pharma’s Single Cell Cloning Process Improved

The satisfaction that comes from seeing a carefully designed experiment unfold and coalesce into a clue, an answer, or a new tool is what makes research and development so gratifying. But every scientist knows that this process is not always seamless. When the goal is big, like Kite Pharma’s ultimate goal of curing cancer, there are bound to be obstacles.

Kite Pharma, a Gilead Company, develops genetically engineered, autologous CAR T cell therapies for the treatment of cancer. Kite’s mission statement emphasizes how these therapies can be used:

“At Kite, our singular focus is cell therapy to treat and potentially cure cancer. Our goal is to bring the promise of cell therapy to as many eligible patients as possible who may benefit. We believe cell therapy has the ability to change the way cancer is treated. Our industry-leading cell therapy technology uses the power of a patient’s own immune system (their white blood cells) to target and attack their cancer cells.”

At the heart of this mission is the ability to engineer cell lines for target discovery and disease modeling. At Kite, the Flow Cytometry and Cell Engineering Core uses Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) gene editing to develop cell lines for research. Even with expertise and advanced instrumentation at their disposal, the team at Kite found that relying on single cell cloning for cell engineering was causing a bottleneck that was a barrier to efficiency and progress.

customer kite3The Core at Kite Pharma had been using various techniques for single cell cloning, including manual limiting dilution, high-speed cell sorting, or combinations of bulk sorting and single cell dispensing. They often encountered poor or variable cell outgrowth after isolation of single cells into 96-well plates, resulting in timelines that were not amenable to their fast-paced goals. To alleviate these pain points and accelerate their cell line development pipeline, they leveraged the CellRaft AIR® System from Cell Microsystems.

To compare the efficiency of several methods for cell line generation, Kite created CRISPR knockout Raji cells, which are lymphoblast-like, suspension cells derived from B-lymphocytes commonly used to test anti-tumor activity for therapeutic approaches related to B cell malignancies. Kite analyzed various single cell clone generation workflows using the CellRaft AIR System as well as traditional cell sorters like the BD FACS Aria Fusion, the SONY SH800 Sorter, and ThermoFisher BigFoot Spectral Cell Sorter.

Concisely stated, cells were transfected with CD19 sgRNAs (Fig. 1), then either sorted directly into 96-well plates using the traditional cell sorters, or bulk sorted to enrich for the CD19PE+ cells and applied to a CellRaft® Array (Fig. 2).

Figure 1. sgRNA and Primer Design

 

Kite poster fig 1 1

• Stars on figure represent sgRNA edit sites. EX, exon; FWD, forward; REV, reverse; sgR A, single‑guide ribonucleic acid.
• Single-guide ribonucleic acides (sgRNAs) and primer sets were designed for the gene of interest.

 

Figure 2. Timeline for Generating Engineered Cell Lines

 

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Steps 2 and 3 are shown in greater detail to illustrate the workflow design phase. A,B. Unstained and stained Raji parental cells. C. Transfected cells with loss of CD19 expression nearly in 50% of the cell population; D‑F. Methods to generate clones, either by sorting into multiple plates, or bulk plate sorting cells onto CytoSort® Arrays.
• The biggest bottleneck in the timeline was generating clones from transfected or bulk sorted cell lines.
• To shorten the timelines and make the process more efficient, we tested many cell sorters as well as a new product from Cell Microsystems, the CellRaft AIR.

 

Table 2. These platforms and workflows were compared based on various parameters, including the clone-forming efficiency and the ease-of-use.

 

Kite poster table 2 1

We compared the conventional sorters, BDFACSAria, SONY SH8000, and Thermofisher Bigfoot, with an imaging and single‑cell isolation system, Cell Microsystems’ CellRaft AIR, using several parameters, including ease of use, and start‑up and shut-down processing times

 

Using the CellRaft AIR to image the CellRaft Array over the course of culture, the system captured an image-based record of single cells as they divide into clonal colonies of cells (Fig. 3A-H). The images shown in Fig. 3A-H are representative of individual CellRafts, with Fig. 3A-D and Fig. 3E-H showing the same CellRaft over the course of 4 and 5 days, respectively. After isolation, Kite found that colonies isolated from the CellRaft Array grew out in over 60% of wells, compared to only 30% growth from single cells dispensed into 96-well plates using cell sorters.

Figure 3. Images from the CellRaft AIR System

 

Kite Poster cells Fig 3

A‑D. Doubling of the Raji cell line. E‑H. Doubling of the Nalm6 cell line. I. Illustration of the collection wand selecting desired raft as specified by the user. J. A small square‑shaped raft with 16 cells grown into a colony in one of the 96 wells.
• Images from Cell Microsytems’ CellRaft AIR show doubling of Raji cell line (Figures 3A‑D) versus Nalm6 cell line (Figures 3E‑J), with sequential growth from single cell to ~16 cell stage
• The CellRaft AIR also has fluorescent imaging capability (not shown here) that can help identify specific population based on fluorescent parameters
– Kite Pharma: Our lab is still working on using this capability to move directly from transfection to CellRaft AIR without the need for cell sorting.

Ultimately, the team at Kite Pharma implemented CellRaft Technology in their Core because it provides a greater number of clones due to superior cell growth and expansion, enabling them to shorten their timeline to cell line generation and improve their efficiency.  Combined with the ease-of-use, confirmation of monoclonality, and software-driven clone selection, CellRaft Technology enables a more researcher-friendly workflow that helps companies achieve their overarching goals.

 

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Megan Harrison
Megan Harrison, Ph.D.
Field Application Scientist at  | mharrison@cellmicrosystems.com

Dr. Megan Harrison is responsible for demonstrating the power of the CellRaft® AIR System to the scientific community, training new users on CellRaft® Technology, and supporting current users by helping them to develop new workflows and to optimize existing processes. Dr. Harrison has experience as a researcher and leader in industry and academic settings. Most recently, as Principal Scientist for Frequency Therapeutics, she developed and characterized 3D culture models, such as primary tissue-derived organoids and spheroids, which were used for small molecule drug discovery in the regenerative medicine space. Dr. Harrison received post-doctoral training at Yale School of Medicine in the Cell Biology department, where her research focused on endosomal trafficking. She earned her Ph.D. in Pathobiology from The Pennsylvania State University, where her research focused on Paramyxovirus budding. Dr. Harrison holds a B.S. in Pre-Veterinary Medicine and Animal Biotechnology from the University of Delaware, where she first learned to conduct research in avian virology. 

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Single Cells: Lab Tune Sung to the Rhythm of "Jingle Bells"
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By Jessica Hartman, Ph.D.

Toiling in the lab

With a deadline on its way

To the scope I go

On a Saturday

I don’t see a clone

I’ve looked for one that’s right

What misery these data bring,

I’ll have to look all night,

Oh! Single cells, single cells, dilutions aren’t the way

Oh, I wish I had an AIR to pick a clone, to-da-ay!

Single cells, single cells, I need a better way

Use a Raft to grow a clone or be sad this holiday!

Use a Raft to grow a clone or be sad this holiday!

Now it’s getting late

My spirits are so low

My PI will hate

If my cells don’t grow

My eyesight’s getting dim

A clone I cannot see

My chances are so slim

I need CellRaft Cytometry

Oh! Single cells, single cells, sorters aren’t the way

Oh, I wish I had an AIR to pick a clone, to-da-ay!

Single cells, single cells, I need a better way

Use a Raft to grow a clone or be sad this holiday!

Use a Raft to grow a clone or be sad this holiday!

Oh! Single cells, single cells, dispensers aren’t the way

Oh, I wish I had an AIR to pick a clone, to-da-ay!

Single cells, single cells, I need a better way

Use a Raft to grow a clone or be sad this holiday!

Use a Raft to grow a clone or be sad this holiday!

 

 

 

 “Single Cell” vocalist: Virginia Laurie

Jessica Hartman, Ph.D.Senior Director of Product Applications | jessica.hartman@cellmicrosystems.comDr. Jessica Hartman has a B.S in Biology from the University…