For example, Zeng et al. used PLGA nanoparticles to deliver Interleukin-12 (IL-12), a cytokine that can diminish the levels of matrix metalloproteinase-9 (MMP-9) and VEGF-A, both of which are known to affect the severity of diabetic retinopathy [85]. This evidence concerns the gene VEGFA and diabetic retinopathy.