Date of Award
Master of Science in Biomedical Engineering
Committee Member 1
Committee Member 2
Prosthetic solutions currently available range from simple devices intended for aesthetics purposes to complex systems attempting to restore lost function and sensation; of these methods, none show more promise in restoration of normal function and life satisfaction than neural prosthetics. These devices directly interface with the nervous system in order to restore realistic function and feeling to the patient, potentially returning them to how their life once was. While in some cases patients requiring prosthetics can utilize peripheral nerves, those who suffer from injuries or disease which cause damage to the central nervous system can necessitate the usage of devices implanted directly into the brain or spinal cord. Research has shown that these implants lose efficacy over time due to the immunological reaction of the brain to injury, mirroring the foreign body response occurring in the rest of the body; these devices become encapsulated by scar tissue and local cells die or migrate over time. Outside of the response of cells like microglia and astrocytes to the injury, there is another factor influencing how the brain responds to injury: the vascular response. Previous experiments have shown the presence of visible vasospasms during and after implantation, as well as potential vasoconstriction in chronically implanted animals. As the vascular response can influence the survival of nearby cells as well as portions of the immunological response, as evidenced by stroke, Reversible cerebral vasoconstriction syndrome (RVCS), and other disorders which occur due to vascular abnormalities, understanding how local vasculature responds to chronic implantation is an important step in developing methods to maintain function for chronically implanted devices. ^ In order to quantify this response, we implanted shank electrodes into 12 animals and then sacrificed them at separate time points that already have a well characterized immunological response. The brains extracted from these animals were then sliced in order to capture the implant intact and stained to allow for confocal imaging. These images were then cleaned and post-processed to extract information on the blood vessels present, allowing for the quantification of vascular segment diameter and length. Our resulting data shows that local vasodilation occurs almost immediately following the initial implantation, and is still occurring at 7 days afterward. Furthermore, our data suggests that there is a degree of systemic vasodilation, as over the course of 7 days we find an increase in the vascular diameter present in the opposite hemisphere where no injury has occurred.
Ready, Andrew L., "The effects of chronic neural implantation on localized vasculature" (2014). Open Access Theses. 674.