Encapsulation of Astragaloside with Matrix Metalloproteinase-2-Responsive Hyaluronic Acid End-Conjugated Polyamidoamine Dendrimers Improves Wound Healing in Diabetes.

Impaired wound healing that occurs in diabetics can result in many life-threatening complications associated with excessive expression of matrix metalloproteinases (MMPs), which mediate the proteolysis of major matrix constituents. In this study, the dendrimer polyamidoamine (PAMAM) and the polysaccharide hyaluronic acid (HA) were connected through the substrate polypeptide (Gly-PLGLAG-Cys) of MMP-2 to obtain the MMP-2-responsive nanocarrier HA-pep-PAMAM. Insoluble astragaloside (ASI) was encapsulated in this nanocarrier to achieve controlled release at the site of intractable wounds. The HA-pep-PAMAM-ASI was successfully prepared with an average diameter of 142.3 ± 28.9 nm. Immunohistochemical staining of the skin revealed that the hard-to-heal wounds of diabetic mice showed stronger expression of MMP-2 than the wounds of normal mice. HA-pep-PAMAM-ASI achieved 73.9% release in the presence of MMP-2, but only 13.5% in PBS. A dose-dependent effect of H₂O₂ on the proliferation of BJ and HaCaT cells was observed, and HA-pep-PAMAM-ASI treatment had the best antioxidant capacity with MMP-2 pretreatment. HA-pep-PAMAM-ASI significantly increased GSH levels and reduced reactive oxygen species (ROS) levels to achieve antioxidant effects. The MMP-2-pretreated HA-pep-PAMAM-ASI group showed more improved cell proliferation and migration abilities. Compared with ASI group, the expression of all wound-repair-related genes in the group of HA-pep-PAMAM-ASI was significantly increased, and HA-pep-PAMAM-ASI showed a pronounced in vivo therapeutic effect. Therefore, our results revealed that enzyme-responsive MMP-2-loaded PAMAM nanoparticles could promote wound healing in diabetes and may be a promising biomaterial for treatment.