|University of British Columbia
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For the treatment of type 1 diabetes, islet transplantation has the potential to control blood glucose levels more effectively than daily insulin injections. However, its widespread application is hindered by the limited supply of transplantable human islets and the side effects of life-long immunosuppression. Microencapsulation of islets in alginate can contribute to overcoming these barriers by facilitating the use of alternative sources of islets, such as neonatal porcine islets (NPI), and by reducing the need for immunosuppressive therapy. This work describes a process for immobilization of NPI in 5% alginate capsules by an emulsification and internal gelation approach utilizing droplet generators fabricated via soft lithography or stereolithography. Alginate capsules produced with microfluidic devices fabricated in PDMS had mean diameters between 300 and 600 µm. Capsules generated with 3D-printed droplet generators fabricated via stereolithography were capable of producing more than 30-times the number of capsules per minute than a microfluidic devices, but with approximately 2-fold greater mean bead diameters. These results suggest that 3D-printed droplet generators are better suited for encapsulating NPI for transplantation applications (e.g., future in vivo studies). Furthermore, encapsulation in 3D-printed droplet generators did not alter cell viability after processing unlike the microfluidic devices where the viability decreased 20%. After encapsulation, three different imaging techniques were explored to aid in the quantification of partially encapsulated islets. Overall, the results of this study should be useful for the improvement of immunoisolation approaches employing alginate immobilization.