Microfluidic Generation of Thin-Shelled Polyethylene Glycol-Tyramine Microgels for Non-Invasive Delivery of Immunoprotected beta -Cells

Transplantation of microencapsulated pancreatic cells is emerging as a promising therapy to replenish beta -cell mass lost from auto-immune nature of type I diabetes mellitus (T1DM). This strategy intends to use micrometer-sized microgels to provide immunoprotection to transplanted cells to avoid chronic application of immunosuppression. Clinical application of encapsulation has remained elusive due to often limited production throughputs and body's immunological reactions to implanted materials. This article presents a high-throughput fabrication of monodisperse, non-immunogenic, non-degradable, immunoprotective, semi-permeable, enzymatically-crosslinkable polyethylene glycol-tyramine (PEG-TA) microgels for beta -cell microencapsulation. Monodisperse beta -cell laden microgels of approximate to 120 mu m, with a shell thickness of 20 mu m are produced using an outside-in crosslinking strategy. Microencapsulated beta -cells rapidly self-assemble into islet-sized spheroids. Immunoprotection of the microencapsulated is demonstrated by inability of FITC-IgG antibodies to diffuse into cell-laden microgels and NK-cell inability to kill microencapsulated.. -cells. Multiplexed ELISA analysis on live blood immune reactivity confirms limited immunogenicity. Microencapsulated MIN6 beta 1 spheroids remain glucose responsive for 28 days in vitro, and able to restore normoglycemia 5 days post-implantation in diabetic mice without notable amounts of cell death. In short, PEG-TA microgels effectively protect implanted cells from the host's immune system while being viable and functional, validating this strategy for the treatment of T1DM.