Taylor Pack; Caden Duffy; Rachel Glew, Brigham Young University
Objective: Type 1 Diabetes (T1D) is an autoimmune disease characterized by the destruction of pancreatic β-cells. No protocol has yet been established for a retrievable device that contains pancreatic β-cells differentiated from induced pluripotent stem cells (iPSCs) to treat T1D. We are investigating methods to increase the yield of pancreatic β-cells differentiated from iPSCs and researching the use of hydrophilized, expanded polytetrafluoroethylene (ePTFE) for use in an implantable, retrievable, and replaceable containment device that mitigates the effects of T1D. Methodology: Human iPSCs were generated from peripheral blood monocytes. Differentiation to the pancreatic progenitor stage was accomplished by using the STEMdiff Pancreatic Progenitor kit. Correctly differentiated cells were then tested by performing fluorescence-activated cell sorting (FACS), using a Becton, Dickinson FACSAria- Fusion system. FACS analysis was performed with FlowJo- software. The ePTFE membranes were treated with cross-linked polyvinyl alcohol to create a hydrophilic surface modification. Results and Significance: We successfully completed the STEMdiff Pancreatic Progenitor kit protocol and our analysis suggests that approximately 23% of differentiated cells expressed CXCR-4, a key definitive endoderm marker, compared to only 2% of the undifferentiated iPSCs. This demonstrated that iPSCs can be differentiated to an early pancreatic lineage with moderate yield. Improved yields are the focus of future work. After testing three different densities of ePTFE, we found that the highest porosity membranes of lowest density allowed for the best diffusion of D-glucose, greater than 96%. This demonstrated that glucose can diffuse through ePTFE. These results increase the feasibility of encapsulating differentiated pancreatic β-cells in an ePTFE containment device.