Periodic Reporting for period 1 - CAR-OAC (Carotid-artery-on-a-chip device to model thromboembolisms induced by vascular lesions and perform drug screenings)
Reporting period: 2020-02-17 to 2022-02-16
Stroke remains the second leading cause of mortality, the third leading reason for disability, and a top contributor to dementia and depression globally with insufficient preventative measures existing. Microfluidic arterial models of developing atherosclerosis can provide a platform for investigating pharmaceutical interventions without ethically questionable sacrifice of laboratory animals or human trials.
The main objective of the project was to produce a representative carotid artery model and to determine the compatibility and sustainability of the interactions between synthetic and biological materials. Following the establishment of the model, the biological cues released by endothelial and blood cells within the device were to be analysed. The results would have been compared to published data from control human carotid arteries to determine whether the constructed model gives comparable results and is therefore capable to reproduce the natural environment of the cells. As a further step in the development of the model, smooth muscle cells and fibroblasts would have been added to the wall surface and lipid-filled lipocytes would have been included to mimic an atherosclerotic lesion within the system.
The main objective of the project was to produce a representative carotid artery model and to determine the compatibility and sustainability of the interactions between synthetic and biological materials. Following the establishment of the model, the biological cues released by endothelial and blood cells within the device were to be analysed. The results would have been compared to published data from control human carotid arteries to determine whether the constructed model gives comparable results and is therefore capable to reproduce the natural environment of the cells. As a further step in the development of the model, smooth muscle cells and fibroblasts would have been added to the wall surface and lipid-filled lipocytes would have been included to mimic an atherosclerotic lesion within the system.
Initially, the microfluidic chip that would accommodate the human cell lines was to be fabricated in Polydimethylsiloxane (PDMS), classically used in chip fabrication, within a polycarbonate envelope incorporating the more flexible material Flexdym within the structure where flexibility was needed. However, this design was later evaluated as being too complex and a simpler version was designed. Flexdym by itself was found to be sufficient to serve as the sole material for the carotid model. Using Flexdym, circular channels could be produced in the microfluidic chip, something that had not been demonstrated before. The fabrication was reproducible and the devices were characterized using a simple image analysis software. The devices were tested in cell culture and found to be suitable for the culture of human embryonic kidney 293 cells. The results were published on the company website in the form of a short review covering the specifics of circular channel fabrication in microfluidic devices. In addition, a review on microfluidic approaches to detect and diagnose COVID-19 infections was published on the company website, in accordance to the topics’ actuality.
The use of the thermoplastic Flexdym by hot embossing is an innovative method for designing a channel with a smooth and continuous circular cross-section with inlets and outlets that can be used to connect a microfluidic flow control system to the chip. This method requires little infrastructure and is very adaptable for fabrication in simple academic laboratories. Cells were subsequently successfully seeded and attached in the microfluidic channel. Cell culture was sustained for up to 3 days within the channel. If the project were to continue, further elements could have been developed, adding higher complexity to the system. If the project would have continued, the microfluidic chip mimicking the human artery would have been connected to an Elveflow© microfluidic set-up and be tested in controlled and reproducible conditions, suitable for use in research facilities and the pharmaceutical sector.