by Kamil W. Nowicki, MD, PhD; Bradley Gross, MD; and Robert M. Friedlander, MD
Cerebral aneurysms form due to complex interactions between hemodynamic shear stress and inflammation. Almost 1 in 20 people harbor an aneurysm and their rupture can result in catastrophic consequences. Our existing knowledge of how these lesions form limits the available medical therapies. Current in vivo models are costly and time consuming, while described in vitro models lack the complexity of in vivo systems. We set out to develop an advanced, multi-lumen flow chamber bioreactor that would allow for inflammatory, endothelial, and smooth muscle cell interactions to study cerebral aneurysm formation under flow conditions. Rapid prototyping is an efficient method in development of a next generation bioreactor as it allows quick turn- around of subsequent iterations of the device as flaws are discovered and corrected.
First, we used a previously published flow chamber device as a starting point. Specifically, we used a flow field that was described and studied using both in silico and in vitro methods. A 3D model was then designed in SketchUp software (Trimble, Inc., Sunnyvale, CA). MakerBot Replicator 3D printer (MakerBot, New York, NY) loaded with polylactic acid (PLA) filament was used to create initial phantoms to optimize design and characteristics. We previously showed that human endothelial cells and smooth muscle cells can be successfully studied on semi-permeable membrane and exposed to pulsatile flow at wall shear stress of 10 dynes/cm2 (unpublished data). For this project, we used rapid 3D printing to design a multi-lumen flow chamber bioreactor. The components were then manufactured in polycarbonate and overall fit was validated. For this design, we decided to incorporate a semi-permeable membrane, which allows for separation of endothelial and smooth muscle cell populations, while allowing for cell-to-cell communication.
Once cells of interest grown on slides or membranes are locked inside the bioreactor, the device is exposed to pulsatile flow under sterile conditions in a typical laboratory incubator at 37°C and 5% CO2. After the experimental period, the device is broken down, samples are collected, and components can be reused. In summary, we used rapid prototyping and 3D printing to manufacture an advanced multi-lumen flow chamber bioreactor for study of inflammatory interactions in cerebral aneurysm formation. This device allows for sampling of individual cell populations and high-throughput discovery of inflammatory factors. Future studies will focus on using the device as a platform for biomarker discovery.