Abstract
Introduction
This presentation will focus on the lab-on-a-chip microsystems for different applications, ranging from cytotoxicity tests to the evaluation of the effectiveness of selected anticancer therapies. When in vitro tests are performed with the use of microsystems, manual activities that are required when seeding cells or administering solutions of tested compounds are eliminated. It allows for greater reproducibility and eliminates some limitations of studies conducted in the macroscale. Moreover, in microsystems it is possible to better reflect in vivo conditions and obtain a homogeneous (same size) population of multicellular spheroids (3D cell model) relatively easily [1]. This way, the results obtained in microfluidic systems can allow to better predict the response of an organism to the tested compounds/nanomaterials or applied anticancer treatment.
Microsystems for in vitro studies
The first stage in the development of a microsystems for in vitro studies is usually based on a selection of appropriate materials for their fabrication. Because non-toxic materials must be applied for this aim, glass and chosen polymers are among the most often used ones. In addition, the application of transparent materials enables observation of cell cultures during testing. The introduction of cells to microchambers, obtaining specific models of cell culture (monolayer or spheroids culture) as well as nutrient delivery to the cells is achieved thanks to the appropriate geometry of the microchannels and microchambers. In the framework of presented studies, microsystems u obtained by bonding several layers of PDMS or glass and PDMS will be discussed.
Methods
The cytotoxicity of selected nanomaterials (such as quantum dots or gold nanoparticles) was evaluated with the use of microsystems [2,3]. The research was carried out on two cell culture models (monolayer and spheroids) and the examination of cell viability was based on the fluorescence staining of live and dead cells or Alamar blue test. Additionally, the change in cell morphology during the conducted research was observed.
Two types of therapeutic procedures were performed with the use of microsystems. These were photothermal therapy (PTT) [4] and electrochemotherapy (ECT). In the case of PTT, after 24 hours from the introduction of cells, a photoactive agent was introduced into the microsystem (gold nanoparticle solutions were used) and incubated for another 24 hours. After this time, the cell medium was passed through the microsystem to wash away the excess of nanoparticles that did not penetrate or bind to the cell membranes, then a laser irradiation was applied. The ECT procedure was carried out in a microsystem equipped with specially designed electrodes. The electrodes were arranged parallelly to each other and tangent to the culture microcells. After introducing the cytostatic compound into the microsystem, the cells were subjected to electric impulse. In this way, drugs were actively introduced into the cells.
Results and Conclusions
The conducted experiments allowed to evaluate the cytotoxicity of quantum dots for normal and tumor cell lines. As the tests were carried out for both 2D and 3D models, the obtained results were compared. The effectiveness of the PTT procedure carried out in a microsystem with the use of aptamer-modified nanoparticles was assessed. The procedure was found to be more effective in the case of breast cancer cells than for lung cancer cells. A microsystem for ECT was developed and the effectiveness of this method was compared to chemotherapy, which was also carried out in the microsystem. For drugs that poorly penetrate the membranes by endocytosis, the use of electrical impulses increases the amount of drug introduced into the cells.
References
[1] Cui P., Wang S., "Application of microfluidic chip technology in pharmaceutical analysis: A review", Journal of Pharmaceutical Analysis, 2019, 9, 238-247.
[2] Grabowska-Jadach I., Haczyk M., Drozd M., Fischer A., Pietrzak M., Malinowska E., Brzózka Z., "Evaluation of biological activity of quantum dots in a microsystem", Electrophoresis, 2016, 35, 165-177.
[3] Grabowska-Jadach I., Zuchowska A., Olesik M., Drozd M., Pietrzak M., Malinowska E., Brzózka Z., "Cytotoxicity studies of selected cadmium-based quantum dots on 2D: Vs. 3D cell cultures", New Journal of Chemistry, 2018, 42, 12787-12795.
[4] Kalinowska D., Grabowska-Jadach I., Liwinska M., Drozd M., Pietrzak M., Dybko A., Brzozka Z., "Studies on effectiveness of PTT on 3D tumor model under microfluidic conditions using aptamer-modified nanoshells", Biosensors and Bioelectronics, 2019, 126, 214-221.