📄 cell biology

cloneXplorer: A high-throughput clone discovery platform based on conical microwell arrays

The paper introduces cloneXplorer, a high-throughput platform utilizing conical microwell arrays to monitor single-cell proliferation and cytokine secretion, enabling the efficient discovery, isolation, and expansion of rare antigen-specific T cells directly from peripheral blood.

Original authors: Stadler, G. K., Tkachenko, E., Neri, O., Zakharov, M., Zohar, O., Deng, D. X., Paraiso, K. D., Rajaei, H., Steele, S., Shen, X., Chenchik, A., Yellen, B. B.

Published 2026-01-20

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CC0 1.0

Original authors: Stadler, G. K., Tkachenko, E., Neri, O., Zakharov, M., Zohar, O., Deng, D. X., Paraiso, K. D., Rajaei, H., Steele, S., Shen, X., Chenchik, A., Yellen, B. B.

Original paper dedicated to the public domain under CC0 1.0 (https://creativecommons.org/publicdomain/zero/1.0/). ⚕️ This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer

Imagine trying to find a single, specific needle in a haystack of a million other needles. That is essentially what scientists face when they try to find specific immune cells (T cells) in a drop of blood that are capable of fighting a particular disease. Traditionally, finding these "needle" cells has been like trying to fish them out one by one with a tiny, slow hook—a tedious process called "limiting dilution" that takes a long time and often fails.

This paper introduces a new, high-tech tool called cloneXplorer that changes the game. Think of cloneXplorer as a massive, automated smart hotel with 100,000 tiny, cone-shaped rooms (microwells). Instead of fishing for cells, you invite your blood cells to check into this hotel, with each cell getting its own private room.

Here is how the system works, using simple analogies:

The Hotel Check-In: You mix your blood cells with "bait" (antigens) and put them into the hotel. Because the rooms are shaped like cones, the cells naturally settle into the bottom of their own individual rooms, ensuring no two cells get mixed up.
The 24/7 Surveillance Camera: Once the cells are settled, the cloneXplorer acts like a security system that never sleeps. It watches every single room simultaneously. It doesn't just look at the cells; it watches them grow (proliferate), listens to what they shout (cytokine secretion), and checks their ID badges (surface markers).
The "Secret Handshake" Test: To prove the system works, the researchers set up a test where they mixed cells that act like a "light-up" switch (Jurkat cells) with cells holding a library of different keys (antigens). When the right key turned the lock, the cell lit up. The cloneXplorer spotted this light instantly, proving it could identify the exact match among thousands of possibilities.
The "Screaming" Alarm: In another test, the system looked for cells that were "screaming" (releasing a chemical called Interferon-gamma) when they encountered a threat. The cloneXplorer could see exactly which specific room was screaming, even if that room was just one out of 100,000.

The Grand Finale:
The researchers combined all these features to find specific "soldier" cells (CD8+ T cells) in human blood that were ready to fight a specific enemy. They used the system to filter the crowd: first looking for cells that were "screaming" the alarm, and then checking if they had the right "ID badge." Once they found the winners, they pulled them out of their rooms and let them multiply. They confirmed these new clones were indeed the right fighters by checking them with a special "tetramer" stain (a high-tech ID scanner).

In short: The paper claims that cloneXplorer is a fast, automated platform that can watch 100,000 individual cell conversations at once. It successfully demonstrated that it can:

Create pure groups of identical cells from cell lines and human blood.
Find specific immune cells by seeing which ones react to specific antigens.
Isolate and grow these specific cells for further study.

The authors state this tool is useful for developing cell lines and for screening and validating how immune receptors interact with specific antigens. They do not claim it is currently a medical treatment or a diagnostic tool for patients, but rather a powerful research engine for understanding and isolating immune cells.

Technical Summary: cloneXplorer: A High-Throughput Clone Discovery Platform Based on Conical Microwell Arrays

Problem Statement
Antigen-specific T cell populations are critical for understanding immune recognition; however, generating these populations through traditional methods such as limiting dilution or standard cloning is described as tedious and inefficient. There is a need for a streamlined approach to isolate and expand rare, functionally defined T cells directly from peripheral blood without the bottlenecks of conventional techniques.

Methodology
The authors introduce cloneXplorer, a live-cell analysis and clone isolation platform designed to address these limitations. The core of the system utilizes conical microwell arrays capable of hosting up to 100,000 single-cell co-cultures. The platform operates through the following technical mechanisms:

Continuous Monitoring: It tracks cell proliferation, cytokine secretion, and surface marker expression in real-time within individual microwells.
Fluorescent Sandwich Assay: To detect immune activation, the system employs a fluorescent sandwich assay to monitor Interferon gamma (IFN- $\gamma$ ) secretion at the single-cell level.
Hierarchical Gating: The system uses specific markers (e.g., CD8 surface presence) and functional outputs (e.g., IFN- $\gamma$ secretion) as hierarchical gates to identify and isolate target cells.
Co-culture Systems: The methodology involves co-culturing T cells with antigen-presenting cells (APCs), such as K562 cells expressing peptide libraries, or using reporter cell lines like Jurkat cells expressing NFAT-GFP, CD8, and specific T cell receptors (TCRs).

Key Contributions and Results
The paper presents a series of demonstrations to benchmark the cloneXplorer platform:

Monoclonal Population Generation: The platform was shown to efficiently generate monoclonal cell populations from both established cell lines and primary human T cells.
Single-Cell Antigen Specificity: Using a co-culture of NFAT-GFP/CD8/TCR-expressing Jurkat cells and K562 APCs with a peptide library, the authors demonstrated the ability to identify antigen-specificity at single-cell resolution.
Primary Sample Monitoring: Time-lapse analysis successfully monitored immune activation in both mouse and human primary samples by detecting IFN- $\gamma$ secretion in individual microwell co-cultures.
Proof-of-Concept Isolation: In a comprehensive demonstration, the authors combined IFN- $\gamma$ secretion detection and CD8 surface marker analysis to isolate and expand antigen-specific T cells from human peripheral blood. The specificity of these expanded clones was subsequently verified using tetramer staining.

Significance
The paper claims that the cloneXplorer platform offers a significant advancement in cell line development and the screening and validation of immune receptor interactions with specific antigens. By enabling the recovery of rare, functionally defined T cells for clonal expansion or sequence analysis, the platform provides a streamlined alternative to traditional cloning methods. The results showcase its potential utility in high-throughput discovery workflows where identifying and isolating specific immune responses is required.

Technical Summary: cloneXplorer: A High-Throughput Clone Discovery Platform Based on Conical Microwell Arrays

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