HPSE and diabetic retinopathy: Since both apoE and heparanase use the same LRP-1 receptor present on the cell surface ECM, we rationalized (Figure 5) that competitive inhibition between precursor heparanase and apoEdp (derived from the LRP receptor binding region of apoE) would prevent active heparanase formation needed for ECM degradation and hence can alleviate or even prevent diabetic retinopathy.