Is GHK Cu enough to tighten loose skin after major fat loss? : r Peptidesource Biostetix Not everything that stimulates collagen is automatically beneficial in excess. GHK Cu is a powerful regenerative peptide but like many Instagram Nanoengineered Self Assembling Peptides with Increased Proteolytic Stability Promote Wound Healing ACS Applied Materials & Interfaces GHK Cu Peptide Regenerative & Cosmetic Research