Next Generation Organ-on-Chip - 3D cell culture of heterogeneous tumors with full on-line control using electrochemical on-chip sensing
Abstract
Personalized chemotherapy comes within reach: This further development of an organ-on-chip system enables the online control of culture conditions as well as the in situ analysis of the intercellular communication of a three-dimensional, heterogeneous cell culture.
Background
In the field of tumor therapeutics, the percentage of patients who do not respond at all or do not respond in the desired way to current treatments and procedures (so-called non-responders) is particularly high. It is therefore hardly surprising that, in this area in particular, a great deal of development work has been invested in individually tailored drugs, so-called personalized chemotherapy, for some years now. The analysis of pharmacological components and their interactions with tumor replicas grown from the patient’s own stem cells offers an enormous opportunity - but also new challenges for technology and users.
Problem
The integration of microsensors into 3D cell culture systems is challenging. Matrix-based cultures must be reliably embedded and connected via microfluidics. In addition to optical inspection by microscopy or cell staining, electrochemical sensors are particularly suitable for accurate and continuous monitoring of metabolic parameters. However, there is currently no way to observe metabolism within a matrix-based 3D cell culture in its details in micromolar concentration ranges and a temporal resolution in the range of seconds.
Solution
Researchers at the Department of Microsystems Engineering at the University of Freiburg, in cooperation with the University Hospital of RWTH Aachen, have developed an optimized monitoring system for 3D cell culture - gas-tight and equipped with electrochemical microsensors - with the support of the Baden-Württemberg Stiftung gGmbH as part of the MEMONO project. With this system, continuous monitoring of the metabolic parameters oxygen, glucose and lactate is provided. Individual patient-derived stem cells are loaded into at least two miniaturized compartments, where they then grow into tumor organoids embedded in a gel matrix. The compartments are located on a glass sensor chip, onto which a microfluidic unit is placed. Special barrier structures confine the compartments, control filling, and allow diffusion-based communication between the organoids. Via microchannels, the compartments can be selectively supplied with nutrients, or concentration gradients can be adjusted. Electrochemical microsensors embedded in the bottom of the chip continuously record relevant parameters, allowing cell metabolism and culture conditions to be monitored online and analyzed in real time. In addition to the option of removing the cells for further analysis after the process, sampling via the microchannels is also possible while the process is running. In initial laboratory samples of the system, breast cancer stem cells and tumor-induced fibroblasts have already been successfully cultured, and their interaction has been studied.
![Fig. 1 Schematic of the chip. The organoids in the compartments are being supplied via microchannels. These are equipped with sensors for monitoring cell metabolism. [Fig.: Dr. A. Weltin, Professorship for Sensors, University of Freiburg]](/fileadmin/user_upload/img/Technologieangebote/20_013_Abb1_SchemaOCS.PNG "Fig. 1: Schematic of the chip. The organoids in the compartments are being supplied via microchannels. These are equipped with sensors for monitoring cell metabolism. [Fig.: Dr. A. Weltin, Professorship for Sensors, University of Freiburg]")
Fig. 1: Schematic of the chip. The organoids in the compartments are being supplied via microchannels. These are equipped with sensors for monitoring cell metabolism. [Fig.: Dr. A. Weltin, Professorship for Sensors, University of Freiburg]
![Fig.2 Photos of the sensor chip prototype with fluidic structures and microelectrodes, electrical connection and cell compartment filled with tumor organoids. [Fig.: Dr. A. Weltin, Professorship for Sensors, University of Freiburg]](/fileadmin/user_upload/img/Technologieangebote/20_013_Abb2FotosOCS.PNG "Fig.2: Photos of the sensor chip prototype with fluidic structures and microelectrodes, electrical connection and cell compartment filled with tumor organoids. [Fig.: Dr. A. Weltin, Professorship for Sensors, University of Freiburg]")
Advantages
- Continuous in-situ measurement of culture conditions and metabolic parameters in heterogeneous 3D culture
- Specific nutrient and active ingredient supply
- Selective communication inhibition is possible
- Selective state changes for simulation of e.g. hypoxia
- Suitable for microscopy and for optical measurement methods
- Sampling online as well as for external analysis
- Robust filling routine with commercially available laboratory pipettes
Fields of application
The standardization of 3D cell culture can be advanced with this. In addition to the analysis of breast, ovarian, liver or brain tumors, virtually any matrix-based 3D cell culture can be modeled with this 3D organoid system. Pathological and physiological states of organs can be mapped as well as cytotoxic or systemic toxicity investigations. The system is particularly suitable for drug analysis in personalized medicine and especially for individualized tumor treatment.
Publications and references
Dornhof, Johannes; Kieninger, Jochen; Muralidharan, Harshini; Maurer, Jochen; Urban, Gerald A.; Weltin, Andreas (2022). Microfluidic organ-on-chip system for multi-analyte monitoring of metabolites in 3D cell cultures. Lab on a Chip, vol. 22, pp. 225-239.
DOI: 10.1039/d1lc00689d.