14
Nov

Automatic pharmacokinetic drug exposure in tumor spheroid on a chip

Normally, you would have to wash your cells many times before and after drug exposure, especially if you want to create pharmacokinetic (PK) exposure profile in your system. Here is the thing: what if you had an automatic perfusion system that can do this automatically? This is possible with organ on a chip, for example look at this beautiful paper from Lohasz and hierleman et al. at the university of ETH Zürich. The authors modified the spheroid on a chip from Insphero and perfused it to be able to
i. generate pharmacokinetic (PK) profiles, and
ii. image spheroids with high resolution microscopy

Results
Firstly, the in vivo PK profiles of the anti-cancer drug BYL719 were re-generated in the chip using drug surrogate fluorescein and BYL719 mass-spectrometric analysis. Then, the effect of BYL719 exposure was evaluated by applying both constant concentration and the 24 h-cycles of PK profile on tumor spheroids. The results revealed that while spheroids were exposed to constant drug concentration experienced a steady size decrease, PK drug dosing caused spheroid size sequential regression and regrowth. However, the overall size decrease in both scenarios were similar. Moreover, after assessing the cell density in the core and shell region of the spheroids, the authors reported that while cell density increased in both regions under constant drug concentration, it manifested an increasing and decreasing pattern for drug PK profile in the core and shell region, respectively.

organ on a chip, microphysiological systems, microfluidics, tissue chips, tumor spheroids, breast cancer, perfusion, pharmacokinetics, drug testing, high resolution imaging, insphero, eth Zurich, azar innovations
Figure 1 – Digestible of the organ on a chip assay; schematic of the technology and a summary of the important points in the paper. Adapted from Lohasz C, Loretan J, Sterker D, Görlach E, Renggli K, Argast P, Frey O, Wiesmann M, Wartmann M, Rausch M and Hierlemann A (2021) A Microphysiological Cell-Culturing System for Pharmacokinetic Drug Exposure and High-Resolution Imaging of Arrays of 3D Microtissues. Front. Pharmacol. 12:785851. doi: 10.3389/fphar.2021.785851; Images were changed for clarity; This article was reproduced under Creative Commons Attribution License (CC BY).

Method
The authors used the microfluidic chip from Insphero, cells (breast cancer cell line T-47D) were labelled and seeded in non-adherent AkuraTM 96 plate, drug treatment (constant concentration and PK profile) with a PI3K inhibitor (BL719 drug)
Fabrication method: Micromachining for modification
Sterilization method: Sterilization of the chip with UV for 30 min, sterilization of tubing and connections with 70% ethanol
Spheroid incorporation: Spheroids were added to the chip from the top then the chip was closed
Perfusion method: Enough medium/drug for 3 days in inlet reservoirs, pressure pumps and flow rate sensors that enabled the perfusion
On-chip read-outs: Real-time microscopy (with 2-photon microscope)

Strong points:
+ Automatic drug exposure for up to 72 hours
+ Continuous-flow immersion system for high resolution 2-photon microscopy (single cell level imaging)
+ Automatic switching between normal medium and drug-containing medium

Improvement points:
– The system is very advanced, but still needs quite some manual handling for assembling, this can be seen by the number of the chip experiments (2).
– Connecting tubing to the system always decreases the yield of the experiments, and decreases the “user-friendliness” of the system

-More Fluorescent-based characterization of the tumor spheroids would have been insightful.

Conclusion and outlook
A beautiful work emphasizing the importance of drug exposure profile on spheroid response. Since the system is so flexible and provides the same experimental conditions for up to 10 spheroids, it can be used for drug efficacy studies.

Do you have questions about the system in this paper or similar technologies? Or do you want to start with organ on a chip. Feel free to contact us!

Link to paper: https://www.frontiersin.org/articles/10.3389/fbioe.2022.855777/full;
Citation: Lohasz C, Loretan J, Sterker D, Görlach E, Renggli K, Argast P, Frey O, Wiesmann M, Wartmann M, Rausch M and Hierlemann A (2021) A Microphysiological Cell-Culturing System for Pharmacokinetic Drug Exposure and High-Resolution Imaging of Arrays of 3D Microtissues. Front. Pharmacol. 12:785851. doi: 10.3389/fphar.2021.785851;
This article was reproduced under Creative Commons Attribution License (CC BY).