Standardized mini-spheroids Manufacturing and Dispensing for HTP Testing

Introduction

Spheroids offer several advantages over traditional 2D cultures, including better mimicking the in vivo environment of tissues. In recent years, it has become evident that spheroids are indispensable tools for both research and industry.

While structurally simple, high-throughput (HTP) production of spheroids for drug screening can be a challenge. Indeed, the commonly used processes can be labour-intensive and often lead to spheroids heterogeneous in size. This, along with the difficulty of seeding a single spheroid per well, hinders robust drug screening.

Thanks to LiveDrop’sOneFlow™ microfluidics instrument and the SEED Biosciences Dispen3D dispenser, highly homogeneous spheroids of desired size can easily be manufactured at high-speed, then be precisely seeded down to one spheroid per well.

Materials and Methods

Compact and homogeneous spheroids suitable for HTP drug screening were successfully produced with the OneFlow™instrument. Approximately 150 cells of MCF7 (mCherry, red) or of a mixed culture (1:10 of GFP labelled cells, green with neg cells) were encapsulated in 3 nL droplets of complete media at a rate of > 2,000spheroids/min.Following an overnight incubation of the droplets, spheroids were recovered and resuspended at 150-300 per mL.Spheroids were < 200 µm in diameter and remained compact and undamaged during the recovery process.

Subsequently, collected spheroids were loaded in the Dispen3D dispenser, an impedance-based pipetting robot that allows gentle and traceable single-spheroid dispensing. Spheroids were seeded at one (GFP) or two spheroids (GFP/mCherry) per well. Images were taken after 24h of incubation at 37°C with a 4x objective.

‍Discussion and Conclusions

This collaborative work introduces a robust approach to efficiently produce homogeneous miniaturised spheroids,(20,000 spheroids in just 10 minutes) which could then be seeded in wells in less than 7 minutes.

The incubation of cells in nanolitre-scale droplets promotes cell contact, facilitating cell aggregation and accelerating homogeneous spheroid formation. The automated peak analyser of the Dispen3D ensures a controlled seeding of the spheroids with > 90% of reliability demonstrating the robustness of the instrument. The Dispen3D software reports provide the time per plate, the number of elements seeded per plate and the plate-filling rate.

Thanks to its robustness and simplicity, this unique workflow holds potential for reliable exploration of new therapeutics and personalised medicine applications.

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Discussion and Conclusions

This collaborative work introduces a robust approach to efficiently produce homogeneous miniaturised spheroids,(20,000 spheroids in just 10 minutes) which could then be seeded in wells in less than 7 minutes.

The incubation of cells in nanolitre-scale droplets promotes cell contact, facilitating cell aggregation and accelerating homogeneous spheroid formation. The automated peak analyser of the Dispen3D ensures a controlled seeding of the spheroids with > 90% of reliability demonstrating the robustness of the instrument. The Dispen3D software reports provide the time per plate, the number of elements seeded per plate and the plate-filling rate.

Thanks to its robustness and simplicity, this unique workflow holds potential for reliable exploration of new therapeutics and personalised medicine applications.

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Quentin Graillet¹, Natacha Coppieters1, Charlotte Broennimann², Yacine Bounab¹, Georges Muller², Stéphanie van Loo¹ and Christine Gilles³.

¹ LiveDrop SA , Belgium, ² SEED Biosciences, Switzerland, ³ GIGA Cancer - Tumour and development biology, ULiège – Belgium.

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