GHK Cu (copper peptide) used topically is one of the most well studied skin repair peptides. Here's how it helps the skin, in practical terms: 1. Boosts collagen & elastin GHK Cu signals your skin GHK Cu Peptide Therapy Connecticut Skin Rejuvenation Benefits GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? Cu Peptide Before and After: What to Expect for Skin and Hair