Human pancreatic β cells contain high levels of heparan sulfate (HS) polysaccharide that is lost in type 1 diabetes (T1D) patients. Heparanase is the only human enzyme that degrades HS. During T1D and diabetic nephropathy, the immune system produces heparanase that destroys HS within β cells and causes their death. We synthesized two carbohydrate molecules by incorporating multiple sugar units or highly tunable sulfation patterns, Glycopolymer GPM and Trisaccharide 1α. GPM and Trisaccharide 1α efficiently mimic the properties of naturally existing HS, and thus act as specific inhibitors of heparanase. We treated mouse pancreatic β cell line MIN-6 and human pancreas islets with GPM or Trisaccharide 1 in the presence of heparanase, and then evaluated β cell or islets morphology, function, and survival. The results showed that GPM of nenomole (nM) doses or Trisaccharide 1α of micromole (µM) doses can effectively preserve cellular HS contents, prevent mitochondrial ROS damage, and help survival of human or mouse pancreas β cells under heparanase challenge. Protein affinity and toxicity analyses suggested that GPM and Trisaccharide 1α possess highly specific binding activities to heparanse but low affinity to many HS-binding proteins responsible for adverse effects.
In summary, we engineered and characterized glycopolymers as a new class of non-toxic, specific heparanase inhibitors to preserve pancreatic β cell function and survival, thus positioning these molecules as potential therapeutics for diabetes and its complications.
K. Zhang: None. H.M. Nguyen: None.
National Institutes of Health (GM098285, DK090313)