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
The in vivo PK profiles of the anti-cancer drug BYL719 were re-generated in the chip and its effect on tumor spheroids was evaluated. The results revealed that while spheroids that 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, under constant drug concentration, cell density increased, while it oscillated in a concentration-dependent manner under PK profile.
DigesTable of the paper Lohasz, C., et al., A Microphysiological cell-culturing system for pharmacokinetic drug exposure and high-resolution imaging of arrays of 3D microtissues. Frontiers in pharmacology, 2021. 12: p. 3798.This paper is reproduced under https://creativecommons.org/licenses/by/4.0/. The image of the chip was edited for better clarity, data in the table and text were compiled and interpreted by AZAR Innovations.
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: Micromachining for modification
Sterilization: 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/refreshing: 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.
