PDF) Effects of GHK Cu on MMP and TIMP Expression, Collagen and Elastin Production, and Facial Wrinkle Parameters By age 30, your skin produces about 25% less collagen. By 40, that number can reach 40%. This decline affects more than just how your skin looks. It changes how it heals, Does GHK Cu Really Work? 40 Years of Research Reviewed Human Growth Hormone Therapy HRT HealthGAINS Protective effects of GHK Cu in bleomycin induced pulmonary fibrosis via anti oxidative stress and anti inflammation pathways ScienceDirect Electrophoretic deposition of GHK Cu loaded MSN chitosan coatings with pH responsive release of copper and its bioactivity ScienceDirect