Calcific Aortic Valve Disease (CAVD) affects 2.5 million Americans and is characterized by fibrocalcific remodeling of the aortic valve extracellular matrix (ECM). Thickened diseased aortic valve ECM hinders adequate oxygen diffusion to the aortic valve interstitial cells (VICs), creating hypoxic conditions. Currently, there is limited research on the role hypoxia plays in CAVD progression or the possibility of contributing to biological sex differences seen in CAVD. Thus, we created gelatin-based scaffolds with embedded aortic valve interstitial cells (VICs) that are 0.6 mm, 1.4 mm, or 2.4 mm thick in order to mimic native valvular thickening and achieve a range of oxygen gradients. To evaluate hypoxia in our scaffolds, we measured levels of angiogenic factors, expression of genes that are transcriptionally regulated by hypoxia, and expression of prolyl hydroxylases, which are regulators of the hypoxia response. We found that VEGF secretion increased with hydrogel thickness. Also, male VICs secreted more VEGF than females. CCN2 is transcriptionally silenced in hypoxia and we found decreased expression of CCN2 in VICs seeded in hydrogels compared to VICs seeded using traditional, 2-dimensional cell culture techniques. GLUT1 is transcriptionally activated by hypoxia, and we found increased expression of GLUT1 in VICs seeded in hydrogels. Prolyl hydroxylase expression was decreased in VICs seeded in hydrogels. These combined data indicate that scaffolds with varied thickness were effective in creating hypoxic conditions. Further, male VICs experience more hypoxia than females, which may contribute to CAVD sex differences.

Peripheral nerve loss is serious and can lead to a loss of function in parts of limbs or a limb all together. Recent studies have shown that electrical stimulation via conductive polymer nerve guides helps human neural progenitor cells differentiate and regenerate new nerves. The conductive polymer that will be inspected in this study is a mixture of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), Polyvinyl Alcohol (PVA), and deionized (DI) water. The goal of this study is to successfully 3D print structurally stable hollow cylinders by changing how the solution is made or the dimensions of the structure. The solution is made by mixing 4 mL of DI water, 18-24 percent concentration of PVA, and 100 uL PEDOT:PSS for every mL of DI water for 2-6 hours at 95C. Then the solution is put in a freezer at -20C for 1-24 hours. After the solution is done freezing it can be 3D printed using a CELLINK INKREDIBLE into a cylinder that can either have filament or no filament in the middle. After a successful structure has been 3D printed the structure undergoes one or multiple freeze thaw cycles. The data collection is based on the structural integrity of the 3D structures that are successfully printed after the freeze-thaw cycles. It has been found that PVA concentrations above 24 percent do not fully mix together and leaves clumps of PVA which clogs the 3D printer.

Neural prosthetics have the potential to benefit individuals with conditions such as locked-in syndrome and paralysis. Currently, many brain-computer interfaces require connectors that pass through the scalp, which limits their potential for daily use at home and is a significant source for infection. The Wyss Center's ABILITY system offers a promising solution in that it’s fully subcutaneous, using a wireless system to pass the information from below the scalp to a receiver above the scalp. This system was designed to be compatible with human skulls and has successfully undergone testing on sheep. Before it can be tested in humans the device must undergo validation in non-human primates, who have smaller and rounder skulls than humans or sheep. To accomplish this, the team at UC Davis has decided to create a platform that will be fitted to each individual monkey’s skull and accommodate the size of the ABILITY system. I assisted the team in developing this implantable mounting platform. Specifically, I translated the CT and MRI images into 3D CAD files and worked to customize the platform CAD model to fit each individual skull. Finalization of this platform will enable testing and validation of the ABILITY system in rhesus macaques at the California National Primate Research Center, which will represent an important step toward the realization of fully implantable neural prosthetics for patients.