Inertia Microfluidics

The Optimising Me Manufacturing System (OMMS) project was focused on developing a healthcare microfactory that provides on-the-body manufacturing of therapeutics1. The project focused on producing Chimeric Antigen Receptor (CAR) T-Cells for specific cancer treatment for acute lymphoid leukaemia (ALL)2 in a continuous fashion. My objective was to produce a microfluidic device for whole blood separation of T-Cells as well as supporting the microfluidic transfection project at the University of Kent.

When the project was conducted, CAR T-Cell therapy required a minimum of 21 days to extract patient T-Cells, transfer cryo-preserved T-Cells to a facility for CAR T-Cell production which expanded, activated, modified and cryo-preserved, returned to the patient’s hospital for expansion before re-entering the patient’s body3. Many of these steps could be replaced with continuous or local processing of cells at the point of care similar to chemotherapy treatments. The difficulty at the time was automating the growth and modification of CAR T-Cells reliably due to the adverse risks associated with CAR T-Cell therapy4.

Inertia microfluidic focuses on manipulating flow without any external forces or stimuli5. The applications explored here focused on cell separation without any external stimulus. More can be read here. Inertia microfluidics was investigated due to the lack of solution foul important for continuous operation of the device as well as low power requirements important for portable devices. Ideally, whole blood would be returned to the body and T-cell are enriched, activated and modified, before returning to the patient’s whole blood. The separation of whole blood would likely have to occur continuously due to the low levels of circulating T-Cells, around 0.0145% of whole blood6.

The project focused on producing a spiral microfluidic device for the separation of T-Cells. Initial studies focused in simulation testing different geometries and flow speeds in the formation of Dean Drag forces7, figure 1. The strength of the Dean Drag forces, secondary flow velocity, affects the forces lifting and dragging on particles. The differences in the size and density of cells as well as the predictable flow in microfluidics allows for controlled separation.

Figure 1: Dean Drag forces forming within a curved microchannel. The velocity of secondary flow is indicated blue, 7.1e-8 to red, 1.9e-5.

The initial wet laboratory studies focused on JURKAT T-Cells8 in Gibco RPMI 1640 Gluta-MAX media suspension9 before testing with horse whole blood10. Additionally surface modifications such as poloxamer F12711 were added due to the hydrophobic nature of Polydimethylsiloxane (PDMS) which adsorbed cells12.

The early implementation of spiral separation microfluidic devices was a master’s project in 2019 by George Tushingham where I was the main supervisor with Dr. Robert Barker as principal investigator at the University of Kent. The work co-created by George Tushingham and myself was taken further and supported using Binary ElectRohydrodyNAmIc SolvEr (BERNAISE), a computational fluid dynamics (CFD) software13 I helped develop. These were two of my primary objectives as a post-doctoral research associate (PDRA) at the University of Kent under Optimising Me Manufacturing Systems (OMMS) project funded by EPSRC EP/R022534/11.

Check out my Science Communication video setting up Inertia Microfluidic Separation computational fluid dynamic (CFD) problem using Binary ElectRohydrodyNAmIc SolvEr (BERNAISE) a CFD software I helped develop.

References

  1. EPSRC (2021) New Industrial Systems: Optimising Me Manufacturing Systems. EPSRC Reference: EP/R022534/1. [Accessed 08/10/21] https://gow.epsrc.ukri.org/NGBOViewGrant.aspx?GrantRef=EP/R022534/1
  2. National Institude of Health (US) (2021) CAR T Cells: Engineering Patients’ Immune Cells to Treat Their Cancers. [Accessed 08/10/21] https://www.cancer.gov/about-cancer/treatment/research/car-t-cells
  3. Fesnak, A., & O’Doherty, U. (2017). Clinical development and manufacture of chimeric antigen receptor T cells and the role of leukapheresis. In European Oncology and Haematology (Vol. 13, Issue 1, pp. 28–34). Touch Briefings. https://doi.org/10.17925/eoh.2017.13.01.28
  4. America Cancer Society (2021) CAR T-cell Therapy and Its Side Effects. [Accessed 08/10/21] https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/car-t-cell1.html
  5. Zhang, J., Yan, S., Yuan, D., Alici, G., Nguyen, N. T., Ebrahimi Warkiani, M., & Li, W. (2016). Fundamentals and applications of inertial microfluidics: A review. In Lab on a Chip (Vol. 16, Issue 1, pp. 10–34). The Royal Society of Chemistry. https://doi.org/10.1039/c5lc01159k
  6. Miltenyi Biotec (2021) Blood. [Accessed 08/10/21] https://www.miltenyibiotec.com/GB-en/resources/macs-handbook/human-cells-and-organs/human-cell-sources/blood-human.html
  7. Ying, Y., & Lin, Y. (2019). Inertial Focusing and Separation of Particles in Similar Curved Channels. Scientific Reports, 9(1), 1–12. https://doi.org/10.1038/s41598-019-52983-z
  8. ATCC (2021) JURKAT T-Cells. [Accessed 08/10/21] https://www.atcc.org/products/tib-152
  9. Gibco (2021) RPMI 1640 Medium, GlutaMAX™ Supplement. [Accessed 08/10/21] https://www.thermofisher.com/order/catalog/product/61870036#/61870036
  10. tcs Biosciences (2021) Horse Blood Defibrinated. [Accessed 08/10/21] https://www.tcsbiosciences.co.uk/catalog/product_detail.php?CI_ID=6
  11. Merck. (2021) Pluronic F-127 powder. [Accessed 06/10/2021] https://www.sigmaaldrich.com/GB/en/product/sigma/p2443
  12. Qiu, W., Sun, X., Wu, C., Hjort, K., & Wu, Z. (2014). A Contact angle study of the interaction between embedded amphiphilic molecules and the PDMS matrix in an aqueous environment. Micromachines, 5(3), 515–527. https://doi.org/10.3390/mi5030515
  13. Hockley, M., Bolet, A., Linga, G., & Mathiesen, J. (2021) BERNAISE (Binary ElectRohydrodyNAmIc SolvEr). GitHub [Accessed 09/10/21] https://github.com/MattH688/BERNAISE
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