Nanoengineered Self Assembling Peptides with Increased Proteolytic Stability Promote Wound Healing ACS Applied Materials & Interfaces GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with The glycyl l histidyl l lysine Cu2+ tripeptide complex attenuates lung inflammation and fibrosis in silicosis by targeting peroxiredoxin 6 ScienceDirect Growth Hormone and Aging Endotext NCBI Bookshelf GHK Cu Peptide Therapy: The Definitive Clinical Guide to Gene Modulation, Protocols, and Efficacy