MicroTesla Enabled 3D Printing Microfluidic Co-culturing of Adipocytes and Beta Cells for Diabetes on a Chip

Abstract

Diabetes has become a serious life-threatening pandemic disease: 1.5 million people perish as a direct result of diabetes each year worldwide. Due to the lack of methods for diabetes prevention and treatments, there is an urgent need to explore the mechanisms in diabetes and its related health disorders, such as obesity; excessive arterial stiffness; hypertension; cerebral microvascular complications, among others. In particular, diabetic patients with comorbidities like cancer, kidney dysfunction, and cardiovascular conditions have more complications and lower survival rates than those without diabetes. To better understand the mechanisms and pervasive effects of diabetes throughout the body, researchers are actively developing in vitro and in vivo models. One promising technique is microfluidics—where cellular and tissue microenvironments are precisely controlled to mimic pathophysiological conditions, within devices we call disease-on-a-chip. By combining the advantages of cell and tissue engineering, materials engineering, and on-chip biosensing, microfluidics has become a powerful tool for biomedical and disease research. This dissertation reports the approaches and results in microfluidic device fabrication, microfluidics oxygen gradient generating; cells stimulation; biosensing; hydrogel-based biosensors fabrication; and integrated on-chip disease model building. From the outcome points of view, this dissertation provided a comprehensive method to fabricate flow-source integrated microfluidics in fast and cost-efficient ways, examined the beta cells dysfunction under oxygen and glucose stimulations, and in combination, realized an on-chip co-culture model to study the relationship between obesity and diabetes. Following the microfluidics development, the dissertation was divided into four main parts: i) beta cells stimulation and sensing under oxygen gradient, ii) μTesla pump design and fabrication, iii) 3D printed microfluidic device, and iv) co-culture of adipocytes and islet beta cells. The oxygen microfluidics were fabricated using traditional SU8/PDMS softlithography. The prototype μTesla pump was fabricated using Stereolithography (SLP) 3D printing. The pump integrated co-culture device was fabricated via Fused Deposition Modeling 3D (FDM) printing. These fabrication methods showed a progressive advancement of our device techniques. Moreover, oxygen gradients was generated by the oxygen diffusion and nitrogen conviction inside the microfluidic channels. The integrated device was enabled co-culturing of adipocytes and beta cells. The cells were then stimulated by oxygen and glucose, with the insulin secretion from beta cells and IL-6 secretion from adipocytes detected using hydrogel enhanced biosensors. Membrane Znt8 level were measured under microscopy using fluorescent probes. With the integrated device, we demonstrated the in situ detection of insulin, IL-6, and Znt8 during the co-culture of adipocytes and beta cells in response to oxygen and glucose stimulation. This demonstrated the power of our 3D printed co-culture platform for on-chip diabetes research. In future applications, this platform can also be functionalized to many other disease models for biomedical studies.