Needs Statement: An affordable method to control as many shear generating cones as possible using a single motor within the space constraints of a standard 12 well plate.
In cardiovascular blood flow, shear stress applied to the walls of arteries can have many physiological effects that are important to the function of the system. A major cause of death in the world is due to atherosclerosis, where causes such as high cholesterol levels, smoking, and diabetes can have detrimental effects on cardiovascular function. As a result of the affected layers that are altered due to atherosclerosis, shear stress applied to the walls weakens (1). This affects the function and phenotype of endothelial cells, which are important in other biological processes. In terms of stenosis, where a blood vessel becomes narrower, an increase of shear stress on the outer walls is a result. In turn, these mechanical stimuli can activate platelets and trigger microparticle formation (2). This is especially true in severe atherosclerotic arteries.
We can model such events in the lab by observing the results the shear stress has on platelets and endothelial cells by using shearing cones and a motor to control the motion of these cones. The cones are then used on well plates, which contain cell culture or other types of material. For our senior design project, we are focusing on developing a more efficient method for allowing more well plates to be mechanically induced by these shearing cones by attaching more than one cone to a single motor. The problem with having one motor controlling only one cone is an immense loss of efficiency by way of cost and material. By using a single cone per motor as shown in the following figures, the space constraints of the current setup only allow the shearing of a 4 wells in a 6 well plate.
This results in the uneccessary loss of material; the less wells there are per plate, the larger the wells are, and therefore the more material they require. Connecting a single motor to more than one shearing cone would remove these space constraints, allowing the shearing of plates with more wells, and significantly cutting down on the amount of material required per sample.
Moreover, having one motor controlling multiple cones would decrease the amount of motors required for shearing multiple samples. A motor connected to 3 cones can shear 3 wells by itself, while the current setup would require 3 respective motors for each well, which would cost 3 times more. Our goal is to be able to develop a device that will be able to shear 12 well plates at a given time using the least number of motors possible. The following figures are images of our final design machined, which is used to shear 12 well plates as opposed to 4.
With a specific set of pulley configurations and a remodeling of the physical system we were able to develop a simple, efficient, and scalable design to induce shear on multiple wells.
(1) Malek, A., Alper, S., et al. (1999) Hemodynamic shear stress and its role in atherosclerosis. JAMA. 282(21): 2035-2042
(2) Holme, P., Orvim, U., et al. (1997) Shear-Induced Platelet Activation and Platelet Microparticle Formation at Blood Flow conditions as in Arteries With a Severe Stenosis
Arteriosclerosis, Thrombosis, and Vascular Biology. 17: 646-653