# Skin & Aesthetics research peptides — Peptide Renewal Serum > Peptide Renewal Serum is an independent digest on Skin & Aesthetics research peptides — GHK-Cu, GLOW, and Melanotan II — with citations, mechanism, and safety cautions. No products, no dosing advice. The peptides behind renewal-serum research, read straight from the literature. Copper-peptide matrix biology, a three-peptide repair blend, and a melanocortin agonist. Citations only. No products. ## The short version Peptide Renewal Serum is a research digest. Three peptides sit on this desk: GHK-Cu, GLOW, and Melanotan II. Each is studied for a different piece of skin, hair, or pigment biology. **GHK-Cu** is a copper peptide — a short chain of three amino acids (small building blocks that link into proteins) bound to a copper atom. It occurs naturally in human skin and blood, and levels fall with age. Studies tie it to collagen, the protein that keeps skin firm. **GLOW** is not one peptide. It is a mix of three: GHK-Cu plus two tissue-repair peptides, BPC-157 and TB-500. **Melanotan II** is different again. It drives pigment production — the process that darkens skin and hair — through a receptor pathway in skin and brain. This page reads the published research on all three. It states what the studies found, and where the evidence stops. No doses. No advice. No products. ## The peptides behind renewal-serum research These three compounds share a frame: skin remodeling, hair, pigmentation, and the biology behind anti-aging research. GHK-Cu is the lead. It has the deepest human evidence of the three — small controlled trials in skin and hair [1][3][4] plus decades of mechanistic work on collagen, elastin, and wound repair [5][6][7]. GLOW builds on GHK-Cu's matrix-remodeling profile and pairs it with two peptides studied for tissue repair: BPC-157, pro-angiogenic and cytoprotective, and TB-500, a cell-migration peptide. The combination rationale is mechanistic, not tested — no trial has run the three-peptide blend against its parts, or against placebo [8][9]. Melanotan II sits apart. It is a melanocortin receptor agonist, developed for tanning and studied clinically for erectile dysfunction [14][15]. It reached small controlled human trials decades ago and stalled there — no approval followed, and case reports since have documented serious harms [11][12][13]. Read together, the three trace a line from a well-characterized cosmetic ingredient (GHK-Cu) through an unregulated combination product (GLOW) to an unapproved systemic agonist (Melanotan II). Evidence quality drops at each step. This desk states that plainly on every page. ## What are research peptides? Peptides are short chains of amino acids — smaller than proteins, built from the same twenty building blocks. The three compounds here are structurally unrelated to each other. GHK-Cu is a tripeptide (three amino acids) bound to copper. BPC-157 and TB-500, the other two components of GLOW, are longer peptide fragments derived from a gastric-protection protein and a cell-structural protein. Melanotan II is a cyclic peptide analog of a natural pituitary hormone, alpha-MSH. Topical Copper Tripeptide-1 — GHK-Cu applied to skin — is a legal cosmetic ingredient in the US, EU, and UK. Injectable GHK-Cu, GLOW, and Melanotan II are not approved medicines anywhere. They are sold as research chemicals: labeled for laboratory use, not human consumption. This desk reports what published studies found in cell cultures, animals, and small human trials. It never reports a human dose as a recommendation — only as the number a specific cited study used. ## How this desk reads the evidence The three compounds sit at different points on the evidence scale, and this desk names the difference rather than blurring it. GHK-Cu has the most human data: two small controlled trials [3][4] plus a large mechanistic literature, much of it from one research group [2][6]. GLOW has zero blend-level trials — every claim traces back to a single-compound study, never the combination [8][9][10]. Melanotan II has the oldest human trial data [15] and the most serious documented harms: renal infarction, rhabdomyolysis, priapism, and melanoma have each appeared in the published case-report record [11][12][13]. Findings are attributed to the species and model that produced them — human, mouse, or cell culture — never generalized past that. Community-reported effects are labeled anecdotal on the pages where they appear, and are never presented as clinical findings. --- A citation-anchored digest on renewal-serum peptides. Not a serum. Not a clinic. Not advice.