Klow 80
Klow 80 is not a single molecule. It is a mixture of four separately studied research peptides: BPC-157, a synthetic 15-residue peptide (GEPPPGKPADDAGLV); thymosin beta-4, the 43-residue actin-sequestering peptide sold under the name TB-500; KPV, the C-terminal tripeptide Lys-Pro-Val of alpha-melanocyte-stimulating hormone; and GHK-Cu, the copper(II) complex of the plasma tripeptide glycyl-L-histidyl-L-lysine that was identified as a growth-modulating serum tripeptide in 1977 and shown by potentiometric titration and absorption spectrophotometry to form multiple Cu(II) species in solution, including ternary complexes with L-histidine. No study of this four-component combination exists in the indexed literature, so everything below is evidence about one constituent at a time and none of it is evidence about the mixture. The naming is itself unsettled: analytical work on commercial TB-500 identified the material as the N-terminal acetylated 17-23 fragment Ac-LKKTETQ rather than the full-length peptide, so results obtained with thymosin beta-4 do not automatically transfer to a product carrying that label. None of the four is an approved drug, and a 2026 sports-medicine review places BPC-157, GHK-Cu, thymosin beta-4 and TB-500 within a parallel market of unapproved compounds sold direct to patients outside regulatory oversight.
Information on this page is provided for laboratory research reference. The compound is not a drug, supplement, or medical product, and is not for human or veterinary use, ingestion, or consumption.
No reviewed report has been published for this product family yet. The molecular values opposite are public reference data, not results measured on a CRX sample.
Browse published reports →The four constituents act through unrelated mechanisms, and the combination has no proposed mechanism of its own. Thymosin beta-4 is the best characterised: it is the principal G-actin-sequestering peptide of mammalian cells, holding most of the monomeric actin pool in resting human neutrophils, and in mouse cardiac work it was reported to form a functional complex with PINCH and integrin-linked kinase, resulting in activation of Akt. KPV enters cells through the di/tripeptide transporter PepT1, and its anti-inflammatory effect in cultured human intestinal epithelial and T cells was PepT1-dependent and involved suppression of NF-kappaB and MAP-kinase signalling; in human keratinocytes both KPV and its parent hormone raised intracellular calcium with no detectable rise in cyclic AMP, so the canonical cAMP account of melanocortin signalling did not hold for this tripeptide. GHK-Cu is understood as a copper carrier rather than a receptor agonist, competing with albumin for Cu(II) and raising collagen and matrix-metalloproteinase expression in fibroblast culture, though copper ions alone reproduced the MMP-2 effect while the uncomplexed tripeptide did not. BPC-157 is the least resolved of the four: no receptor has been identified, the most reproduced observation is upregulation and internalisation of VEGFR2 in cultured endothelial cells, and formal ADME work in rats and beagle dogs found an elimination half-life of the prototype under 30 minutes with rapid metabolism into small peptide fragments and single amino acids, which is difficult to reconcile with the multi-day effects reported in the efficacy literature.2,3,6,7,8,9,10,11
Sequesters monomeric actin; measured to be the major G-actin-sequestering peptide in resting human polymorphonuclear leukocytes, at a cytoplasmic concentration of roughly 149 microM3
Reported to form a functional complex with PINCH and integrin-linked kinase with resulting activation of Akt in embryonic and postnatal mouse cardiomyocytes, and upregulation of ILK and Akt activity in mouse heart after coronary artery ligation; proposed basis for the migration and survival effects6
Transporter that carries KPV into intestinal epithelial and immune cells; in the AOM/DSS mouse model of colitis-associated cancer, KPV's inhibitory effect on tumorigenesis seen in wild-type mice was absent in PepT1-knockout mice7,12
Inhibited at nanomolar concentrations in cultured human intestinal epithelial cells (Caco2-BBE, HT29-Cl.19A) and Jurkat T cells, with reduced pro-inflammatory cytokine secretion7
Raised intracellular calcium in HaCaT keratinocytes (observed only in the presence of PIA, an adenosine agonist that inhibits the cyclic AMP pathway), in normal human keratinocytes and in MC-1R-transfected CHO cells, with no cyclic AMP elevation detected — so the canonical cAMP account of melanocortin signalling did not hold for this tripeptide8
Forms multiple Cu(II) complexes, and ternary complexes with L-histidine, whose stability is enhanced by the peptide's epsilon-amino group; in equilibrium dialysis it competed with albumin for Cu(II), binding about 42% of the Cu(II) at equimolar albumin and peptide, though only about 6% of Cu(II) sat on low-molecular-weight components at physiologically relevant concentrations. Proposed on that basis to participate in copper transport from blood to tissues2
Increased collagen synthesis and raised MMP-2 alongside its inhibitors TIMP-1 and TIMP-2 in dermal fibroblast culture; copper ions alone reproduced the MMP-2 effect while the uncomplexed tripeptide GHK did not9,13
Reported upregulation and receptor internalisation in cultured human vascular endothelial cells, with VEGFR2-Akt-eNOS activation, and enhanced vascular VEGFR2 expression in rat ischaemic hind-limb muscle. VEGF-A expression was not increased, and no receptor for BPC-157 itself has been identified10
Tissue repair
In a multicentre randomised evaluator-blinded placebo-controlled trial in patients with diabetic neuropathic plantar ulcers, all of whom received sharp debridement at entry and pressure-relieving footwear, topical GHK-Cu gel produced 98.5% median percentage area closure versus 60.8% for vehicle (p < 0.05). Among ulcers treated immediately after the initial debridement, infection occurred in 7% of GHK-Cu-treated ulcers versus 34% of vehicle-treated ulcers (p < 0.05).14
In a prospective randomised evaluator-blinded trial in 86 evaluable patients with venous stasis ulcers, a 0.4% tripeptide copper complex cream did not differ from inert vehicle placebo in ulcer size reduction, while 1% silver sulfadiazine cream was statistically superior to both.15
A 2025 Cochrane review of neurotrophic keratopathy interventions, which included seven parallel-group randomised trials totalling 494 participants, appraised the 18-participant trial of 0.1% thymosin beta-4 (RGN-259) ophthalmic solution as low-certainty evidence, with a risk ratio of 9.00 for corneal re-epithelialisation but a confidence interval spanning 0.57 to 141.88, and concluded that 0.1% RGN-259 may not increase the proportion of participants who re-epithelialise.16
In a rat full-thickness skin wound model, thymosin beta-4 applied topically or intraperitoneally increased re-epithelialisation by 42% over saline controls at day 4 and by as much as 61% at day 7, with treated wounds contracting at least 11% more than controls by day 7 alongside increased collagen deposition and angiogenesis.17
A 2025 systematic review of BPC-157 in orthopaedic sports medicine searched PubMed, Cochrane and Embase from database inception to 3 June 2024, identified 544 articles and included 36 studies, of which 35 were preclinical and one was clinical. The authors characterised the body of evidence as level IV and level V studies and recorded that no clinical safety data were found.18
In rats whose right Achilles tendon was surgically transected, BPC-157-treated animals showed increased load to failure and Young's modulus, significantly higher Achilles functional index scores and smaller, shallower macroscopic tendon defects than saline-treated controls across assessments through day 14.19
Inflammation & immune
In cultured human intestinal epithelial cells (Caco2-BBE, HT29-Cl.19A) and Jurkat T cells stimulated with pro-inflammatory cytokines, nanomolar KPV inhibited NF-kappaB and MAP-kinase signalling and reduced pro-inflammatory cytokine secretion. In mice with DSS- or TNBS-induced colitis, KPV added to drinking water reduced colitis incidence and pro-inflammatory cytokine expression; uptake experiments identified PepT1 as the transporter carrying KPV into these cells.7
In colony-formation and viability assays, alpha-MSH and its C-terminal tripeptide KPV inhibited Staphylococcus aureus colony formation and reduced viability and germ-tube formation of Candida albicans across a broad concentration range including the physiological picomolar range; the killing activity was partly reversed by the adenylyl cyclase inhibitor dideoxyadenosine, and the peptides enhanced rather than reduced killing of both organisms by human neutrophils.20
In antimicrobial assays run under a variety of conditions, an independent chemistry group testing Ac-KPV-NH2 alongside alpha- and epsilon-glycoalkylated analogues found no antimicrobial activity for any of them, so the antimicrobial property attributed to this tripeptide has not been uniformly reproduced.21
What investigators recorded alongside the results above, at the rates their papers state.
No safety data exist for this four-component combination. No study administering BPC-157, thymosin beta-4, KPV and GHK-Cu together could be located in the indexed literature, so nothing is known about interaction, additive toxicity or the effect of combining a copper-loaded peptide with three others. A 2026 sports-medicine review covering BPC-157, GHK-Cu, thymosin beta-4 and TB-500 concluded that rigorous human safety data for the unapproved peptides in this class are scarce and that there is potential for serious harm to patients.5
no data
Adverse events were mild to moderate with no dose-limiting toxicities and no serious adverse events in a first-in-human randomised double-blind phase 1 study of recombinant human thymosin beta-4 (NL005), which also monitored anti-drug antibodies; 54 subjects across seven cohorts received single ascending intravenous doses and 30 subjects across three cohorts received daily dosing for 10 days, each observed for 28 days. This is the largest single human safety dataset located for any constituent of this blend.22
mild to moderate; 0 serious adverse events, as reported
Ulcer infection during topical treatment of diabetic neuropathic plantar ulcers occurred in 7% of GHK-Cu-treated ulcers versus 34% of vehicle-treated ulcers among those treated immediately after debridement. The separate 13-patient trial of a GHK-Cu regimen on CO2 laser-resurfaced facial skin reports no adverse-event data at all: its published account describes only erythema, wrinkle and skin-quality endpoints, so it should not be read as a null safety result.14,23
7% versus 34% vehicle in the diabetic ulcer trial; not reported in the laser-resurfacing trial
In a keratinocyte-based in vitro irritation model, GHK-Cu was not cytotoxic and did not significantly change expression of skin-irritation biomarkers (IL-1alpha, IL-8, HSPA1A, FOSL1), whereas copper chloride and copper acetate at 58 and 580 micromolar significantly upregulated them without inhibiting cell viability; the authors concluded that GHK-Cu has low potential to induce skin irritation. This is a cell-based assay, not clinical safety data, and no systemic copper-exposure safety dataset for GHK-Cu could be located.24
no data for systemic exposure
The published human safety record for BPC-157 consists of an uncontrolled, unblinded two-person intravenous pilot at a private clinic — both participants had received intravenous BPC-157 before the study — in which no side effects were reported and no measurable change was found in cardiac, hepatic, renal, thyroid or blood-glucose biomarkers. The 2025 systematic review of the musculoskeletal literature recorded that no clinical safety data were found, while noting that preclinical safety studies showed no adverse effects across several organ systems; the review also flags unregulated manufacturing and contamination as sources of possible harm.18,25
0 of 2 participants, as reported; otherwise no clinical data
No human study of KPV of any kind could be located in the indexed literature. The published record cited here for this constituent is cell culture and rodent or rabbit work, so there is no human safety, tolerability or pharmacokinetic dataset for it — an absence that is not resolved by the human evidence for the other three constituents.7,12,26
no data
- 1.Growth-modulating serum tripeptide is glycyl-histidyl-lysine. · Experientia · 1977 · PMID 858356
- 2.The interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma. · The Biochemical Journal · 1981 · PMID 7340824
- 3.Thymosin beta 4 sequesters the majority of G-actin in resting human polymorphonuclear leukocytes. · The Journal of Cell Biology · 1992 · PMID 1447300
- 4.Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. · Drug Testing and Analysis · 2012 · PMID 22962027
- 5.Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. · Sports Medicine · 2026 · PMID 41966639
- 6.Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. · Nature · 2004 · PMID 15565145
- 7.PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation. · Gastroenterology · 2008 · PMID 18061177
- 8.alpha-Melanocyte-stimulating hormone, MSH 11-13 KPV and adrenocorticotropic hormone signalling in human keratinocyte cells. · The Journal of Investigative Dermatology · 2004 · PMID 15102092
- 9.The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. · Life Sciences · 2000 · PMID 11045606
- 10.Therapeutic potential of pro-angiogenic BPC157 is associated with VEGFR2 activation and up-regulation. · Journal of Molecular Medicine · 2017 · PMID 27847966
- 11.Pharmacokinetics, distribution, metabolism, and excretion of body-protective compound 157, a potential drug for treating various wounds, in rats and dogs. · Frontiers in Pharmacology · 2022 · PMID 36588717
- 12.Critical role of PepT1 in promoting colitis-associated cancer and therapeutic benefits of the anti-inflammatory PepT1-mediated tripeptide KPV in a murine model. · Cellular and Molecular Gastroenterology and Hepatology · 2016 · PMID 27458604
- 13.Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. · FEBS Letters · 1988 · PMID 3169264
- 14.Enhanced healing of ulcers in patients with diabetes by topical treatment with glycyl-l-histidyl-l-lysine copper. · Wound Repair and Regeneration · 1994 · PMID 17147644
- 15.A prospective randomized evaluator-blinded trial of two potential wound healing agents for the treatment of venous stasis ulcers. · Journal of Vascular Surgery · 1992 · PMID 1495150
- 16.Medical and surgical interventions for neurotrophic keratopathy. · Cochrane Database of Systematic Reviews · 2025 · PMID 41347649
- 17.Thymosin beta4 accelerates wound healing. · The Journal of Investigative Dermatology · 1999 · PMID 10469335
- 18.Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review. · HSS Journal · 2025 · PMID 40756949
- 19.Gastric pentadecapeptide BPC 157 accelerates healing of transected rat Achilles tendon and in vitro stimulates tendocytes growth. · Journal of Orthopaedic Research · 2003 · PMID 14554208
- 20.Antimicrobial effects of alpha-MSH peptides. · Journal of Leukocyte Biology · 2000 · PMID 10670585
- 21.Structural modification of the tripeptide KPV by reductive "glycoalkylation" of the lysine residue. · PLoS One · 2018 · PMID 29953505
- 22.A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers. · Journal of Cellular and Molecular Medicine · 2021 · PMID 34346165
- 23.Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. · Archives of Facial Plastic Surgery · 2006 · PMID 16847171
- 24.Selected Biomarkers Revealed Potential Skin Toxicity Caused by Certain Copper Compounds. · Scientific Reports · 2016 · PMID 27892491
- 25.Safety of Intravenous Infusion of BPC157 in Humans: A Pilot Study. · Alternative Therapies in Health and Medicine · 2025 · PMID 40131143
- 26.Effects of the COOH-terminal tripeptide alpha-MSH(11-13) on corneal epithelial wound healing: role of nitric oxide. · Experimental Eye Research · 2006 · PMID 16965771
- 27.Intra-Articular Injection of BPC 157 for Multiple Types of Knee Pain. · Alternative Therapies in Health and Medicine · 2021 · PMID 34324435
- 28.Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro. · Journal of Chromatography B · 2024 · PMID 38382158