Nagy et al. have indicated that hydrogel plus heparin could treat autoimmune type 1 diabetes by inducing the sustained release of IL-2 (cytokine), which leads to an increase of T cells proliferation and provoking the expression of forkhead box P3-positive (FOXP3+) Tregs, but soluble IL-2 could not (Nagy et al., 2020). Here, FOXP3 is linked to autoimmune type 1 diabetes.