Title : Parallelized precision medicine applications with a microprocessor-controlled, 3D-printed Mini-Bioreactor
The reduction and replacement of animal experiments requires novel strategies for 3D cell culture that better reflect the complex 3D interaction of different cell types in living tissue. Compared to static 3D methods e.g. hanging drops, v-bottom plates or magnetic levitation in vitro cultivation using agitation-mediating devices significantly improves many physiological parameters such as oxygen supply and nutrient uptake. Devices such as orbital shakers or stirrer-tank bioreactors do not support parallelization and occupy significant incubator space, so only minimal condition testing is possible. To overcome these limitations we developed a microprocessor-controlled, fully 3D-printed mini-bioreactor system that allows stirred agitation of human cell spheroids and tissue aggregates in 12 or 24 well plates in a highly parallelized manner – i.e. simultaneous cultivation of up to 384 (16x 24 well plates) wells per bioreactor. The system is successfully used for growing brain-organoids and tumor cell / fibroblast spheroids. With these mini-bioreactors we now also developed a protocol to culture and expand tumor spheroids isolated from the ascites of ovarian cancer patients, which allows us parallel testing of multiple anti-cancer drugs. These free-floating tumor spheroids might be responsible for the spreading of ovarian cancer throughout the abdomen and the poor prognosis of patients with this malignancy. Interestingly, tumor-spheroids frequently show significant resistance to standard drugs used for ovarian cancer therapy (e.g. cisplatin), suggesting that these spheroids either represent a drug-resistant subpopulation of cancer cells that is shed off from the primary tumor or that these spheroids have an entirely different metabolism making them resistant to therapeutic drugs, which in both cases is detrimental for the patient. Parallelized testing with the mini-bioreactor system now provides an option to identify those chemotherapeutics that eradicate also ascites-derived tumor-spheroids and to study the underlying drug resistance mechanism. We believe that the depletion of freely-floating, metastasis-inducing tumor spheroids in the ascites of ovarian cancer patients is critical to improve the long term survival of these cancer patients and the use of mini-bioreactors for parallelized drug screening provides an option to identify effective chemotherapeutic drugs.