Targeted Drug Delivery to Human β-Cells Using Novel Nanocapsule Delivery Vehicle for T1D Treatment

Introduction:: In type 1 diabetes (T1D), autoreactive immune cells destroy insulin secreting β-cells in pancreatic islets. Islet transplantation shows promise in restoring glucose homeostasis without exogenous insulin; however, long-term graft survival remains a critical barrier to the success of this treatment. Therapies aimed to protect or proliferate endogenous β-cells have off target affects and require targeted delivery to improve efficacy. We have developed a nanocapsule (NC) delivery system to specifically target and deliver cargo to human β-cells. We hypothesize NCs will selectively be taken up by human β-cells and deliver therapeutic cargo.


Materials and Methods:: NCs were synthesized with a water in oil emulsion evaporation technique. NCs were coated via ionic interactions with ectonucleoside triphosphate 3 (ENTPD3) antibody, a human β-cell specific marker or Exendin-4 conjugated to hyaluronic acid (HA-Ex4). NC size, size distribution, charge, stability and drug release profiles were determined. NCs loaded with pentamidine (PTM) or Cy5 were cultured for 24-168h with human iPSC-derived β-cells (sBC), human islets, or injected into the tail vein of non-obese diabetic immunodeficient (NOD-SCID) mice. Confocal microscopy confirmed delivery of cargo to β-cells and pancreatic islets, viability, and cytotoxicity.


Results, Conclusions, and Discussions:: NCs were 271 ± 7nm in size with excellent size homogeneity (polydispersity index 0.06 ± 0.03, n=3) and can have HA coating the outside of the NCs confirmed by zeta potential (3mV vs -35mV, n=3). NCs displayed a sustained release of cargo for >45 days (n=5). SEM images support NCs can be freeze-dried and reconstituted with a cryoprotectant without a significant change in NC size (n=3). In vitro, we observed no cytotoxicity of NCs up to 168h and a significant increase in β-cell death with PTM loaded ENTPD3 coated NCs compared to controls at 24 (p< 0.001, n=4) and 72h (p< 0.01, n=4). Human islets display similar trends as the sBCs. sBCs treated with PTM loaded ENTPD3 coated NCs had more insulin+ dead cells (88 ± 4%) than controls (p< 0.01, n=4). ENTPD3 or HA-Ex4 NCs were internalized into sBCs in vitro and pancreatic islets in vivo respectively. Our data shows long term stability and in vivo targeting of NCs to β-cells and supports use of our NCs for targeted delivery of therapeutics to human β-cells to treat T1D.


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