Airplug-assisted Biochip for Unbiased Multiplex Biosensing from Single T Cells

Immune T cells are specialized cells responsible for protecting our bodies against all types of infections, and well-known for dynamically secreting cytokines as part of their defense mechanisms. However, the immune status of patients changes with disease progression, therefore, making effective immunotherapies a great challenge. To address this, quantitative and cytokine profiling of T cells have been intensively researched during the past decade, which in turn helped in immunophenotyping studies.

To date, several methods for sorting T cells based on their characteristic surface marking have been developed. These methods are, however, not suitable for studying heterogeneity of T cells due to their limited ability to achieve single-cell resolution. Recently, the technology of microwell arrays, integrated with biosensing platforms, have been identified for effective cytokine profiling of single T cells. Opposite to circular and square microwells, rectangular microwells are highly desirable to accommodate several antibody barcodes for multiplexed cytokine profiling. However, direct loading of T cells onto rectangular microwells results in low isolation efficiency of single cell per microwell, and large variation in the cell positions within the microwells. This cause a bias in temporal sensing that originates from random (unpredicted) positions of isolated cells.

In a recent research paper published in the Advanced Therapeutics journal, researchers from the global campus of New York University in Abu Dhabi (NYUAD), led by Professor Mohammad A. Qasaimeh, have developed an innovative air plug-mediated approach for isolation and centralization of single T cells in a massive array of rectangular microwells. The NYUAD team included the first author Pavithra Sukumar, Dr. Muhammedin Deliorman, Ayoola T. Brimmo, and Roaa Alnemari, and the work was in collaboration with Dr. Deena Elsori from Abu Dhabi University and Dr. Weiqiang Chen from the New York campus of New York University. The study attempted to eliminate bias in temporal cytokine sensing by centralizing isolated cells within the microwells, via generating engineered air-plugs prior to cell loading. After cell isolation and centralization, air-plugs were released in a controlled manner, leaving isolated cell centralized and equally positioned in relative to the sensing elements.

The approach allowed for quick and precise profiling of cytokines released from individual T cells. In particular, the centralized T cells resulted in dynamic and unbiased cytokine sensing in real-time. For instance, a 20% efficiency in trapping single cell per microwell was reported especially where cells were localized within ±3% of the microwells center. The improved centralization efficiency was attributed to the pressure oscillations with the air plugs at the air-liquid interface. Furthermore, different strategies such as increasing the number of loading channels and microwells were highlighted as potential for achieving higher throughput and scaling up the device.

Overall, rectangular microwells are required in multiplexed biosensing where antibody barcodes are placed atop microwells. The presented approach offers robust and efficient isolation and precise centralization of a large number of single T cells within rectangular microwells. Therefore, Professor Mohammad A. Qasaimeh, the corresponding author, in a statement to Medicine Innovates, said their study can provide dynamic cytokine profiling in real time for accurate phenotyping and biotherapeutic applications. He added: The developed technology can be adopted to single cell secretomics applications, of various cell types, including circulating tumor cells.