KLOW Peptide Blend: Research Guide, Identity and COA (USA)

Researched & reviewed by the Purity Collective Quality Team · Last reviewed October 1, 2026

Compound guide · KLOW

KLOW is Purity Collective’s four-component research blend: BPC-157, TB-500, GHK-Cu and KPV in one 80mg vial or pen. This guide collects what the peer-reviewed literature says about each component, the chemical identity of all four, what the evidence does not show, and what Purity’s own lot report measured.

For laboratory research only. Not for human or animal use. This guide gives no dosing, reconstitution, administration or therapeutic advice.

How to choose a KLOW listing

Purity Collective lists KLOW in two formats, and they share one lot report. The vial is the lyophilized 80mg blend; the pen is the same formulation supplied in a pre-filled cartridge device. Pick by how your laboratory stores and dispenses material, not by documentation, because the certificate is the same.

Where do the KLOW components come from?

BPC-157 is a 15-amino-acid fragment (GEPPPGKPADDAGLV, MW 1419) described by Sikirić and colleagues as a stable gastric pentadecapeptide; its early literature is almost entirely rat work from one group in Zagreb, and it was once in clinical trials for inflammatory bowel disease under the codes PL 14736 and PLD-116^[14554208]. TB-500 is the synthetic peptide marketed under that name and corresponds to the N-terminal acetylated 17-43 fragment, or in Purity’s listing the full-length sequence, of thymosin beta-4 (Tβ4), a 43-residue actin-sequestering protein found in most mammalian cells; the analytical literature on TB-500 comes from doping-control laboratories that had to characterize it^[22962027]. GHK (glycyl-L-histidyl-L-lysine) was isolated from human plasma as a growth-modulating factor and shown in 1980 to co-isolate with copper and to enhance copper uptake into cultured cells^[7453802]; the copper(II) complex is what the catalog sells. KPV (Lys-Pro-Val) is residues 11-13 of alpha-melanocyte-stimulating hormone, studied as a small anti-inflammatory tripeptide transported by the intestinal di/tripeptide carrier PepT1^[18061177].

Chemical identity

What has been studied in the laboratory?

BPC-157: tendon, vessel and nitric-oxide models (rat; cells in vitro)

In rats with a transected Achilles tendon, BPC-157 given systemically or locally improved the biomechanical, functional and histological markers of healing compared with saline, and the same paper reported that the peptide stimulated tendon-explant outgrowth in vitro^[14554208]. Follow-up work in rat tendon fibroblasts tied the effect to the VEGFR2 pathway and to angiogenic signaling^[27847966], and the Zagreb group has summarized a long series of rat experiments in which BPC-157 interacted with the nitric-oxide system, counteracting both NO-synthase blockade and NO over-stimulation^[23755725]. A 2026 rat study compared BPC-157, TB-500 and the two together in Achilles tendon repair: the TB-500 group reached statistical significance on load-to-failure and histology scores, the BPC-157 group showed numerically better scores without reaching significance, and the combination did not outperform TB-500 alone^[42542926].

TB-500 / thymosin beta-4: wound closure and cardiac-repair signaling (mouse, rat; one human phase I trial)

Thymosin beta-4 accelerated dermal wound healing in rats and in aged mice, increasing re-epithelialization, collagen deposition and angiogenesis^[10469335]; in mouse heart it activated integrin-linked kinase signaling and promoted cardiomyocyte survival after coronary ligation^[15565145]. The one human dataset in the reference list is a phase I study of recombinant thymosin beta-4 in healthy Chinese volunteers, which reported dose-proportional exposure and no accumulation and was designed only to assess safety and pharmacokinetics^[34346165]. Doping-control chemists have characterized synthetic TB-500 by LC-MS, which is why identity confirmation by mass spectrometry is meaningful for this component^[22962027].

GHK-Cu: collagen, wound and gene-expression models (cells, rat, mouse; one human trial)

GHK-Cu stimulated collagen synthesis in cultured fibroblasts at nanomolar concentrations without changing cell number^[3169264], and increased connective-tissue accumulation in rat wound chambers in vivo^[8227353]. The human evidence is cautionary: a randomized, evaluator-blinded trial of two candidate wound agents in venous ulcers did not show a healing benefit^[1495150]. A 2018 review reinterpreted the older data through gene-expression profiling, proposing that GHK resets a large set of genes toward a regenerative pattern, a hypothesis rather than a clinical finding^[29986520].

KPV: intestinal inflammation models (cells, mouse)

Nanomolar KPV inhibited NF-κB and MAP-kinase inflammatory signaling in human intestinal epithelial and T-cell lines, and oral KPV reduced the severity of DSS- and TNBS-induced colitis in mice; uptake depended on the PepT1 transporter^[18061177]. A second group reported earlier recovery and less histological inflammation in two mouse colitis models, with effects at least partly independent of the melanocortin-1 receptor^[18092346]. KPV and related alpha-MSH fragments have also shown antimicrobial activity against Staphylococcus aureus and Candida albicans in vitro^[10670585].

Study summary

What the evidence does not show

• No published study has tested the KLOW combination, or any four-component blend of these peptides, in any model. Component findings cannot be added together.
• There is no clinical efficacy evidence for BPC-157: a 2025 systematic review found 35 preclinical studies and a single retrospective case series, and no clinical safety data^[40756949].
• The only human GHK-Cu trial in this list was negative for venous ulcer healing^[1495150]; the human thymosin beta-4 study measured safety and pharmacokinetics, not efficacy^[34346165].
• The 2026 rat study found that combining BPC-157 with TB-500 did not beat TB-500 alone^[42542926], which argues against assuming synergy.
• Nothing here supports any use in people or animals. Every component is a research reference material.

Batch documentation

Purity Collective’s lot PCCL-7964352 was analyzed by Horizon Analytical on 29 March 2026 by UPLC/MS. The certificate gives each component its own quantity and purity result rather than a single blend-wide number; the endotoxin certificate for the matching lot (PCCL-7964352-E, 3 April 2026) reads <0.05 EU/mL. Both PDFs are in the COA library and linked from the vial and pen pages.

Reading it: the four quantity results sit within about 3% of specification, the purity results are all above the 98% specification, and the identity for each component is confirmed by mass spectrometry. One detail to know: the certificate prints a PubChem CID beside each component, and the CID beside KPV does not correspond to Lys-Pro-Val in PubChem; the mass result is what confirms identity, and the correct record is listed in the identity table above.

Handling and storage in the laboratory

The vial is lyophilized powder and should be kept cold, dry and away from light until use; once in solution, peptides of this size are best kept refrigerated and used within the window your protocol defines. The pen is supplied as a liquid cartridge and should be refrigerated per the product page. Document the lot number with your records so a result can be traced back to the certificate. For general handling guidance read how to read a peptide COA and the KPV, BPC-157, TB-500 and GHK-Cu records in the research library.

Frequently asked questions

References

1. Staresinic M, Sebecic B, Patrlj L et al. Gastric pentadecapeptide BPC 157 accelerates healing of transected rat Achilles tendon and in vitro stimulates tendocytes growth. J Orthop Res. 2003;21:976-83. PMID 14554208 · doi:10.1016/S0736-0266(03)00110-4
2. Hsieh MJ, Liu HT, Wang CN et al. Therapeutic potential of pro-angiogenic BPC157 is associated with VEGFR2 activation and up-regulation. J Mol Med (Berl). 2017;95:323-333. PMID 27847966 · doi:10.1007/s00109-016-1488-y
3. Sikiric P, Seiwerth S, Rucman R et al. Stable gastric pentadecapeptide BPC 157-NO-system relation. Curr Pharm Des. 2014;20:1126-35. PMID 23755725 · doi:10.2174/13816128113190990411
4. Vasireddi N, Hahamyan H, Salata MJ et al. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review. HSS J. 2025;21:485-495. PMID 40756949 · doi:10.1177/15563316251355551
5. Biçer O, Adanir O, Güleryüz Y et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg. 2026;37:822-837. PMID 42542926 · doi:10.52312/jdrs.2026.2951
6. Malinda KM, Sidhu GS, Mani H et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113:364-8. PMID 10469335 · doi:10.1046/j.1523-1747.1999.00708.x
7. Esposito S, Deventer K, Goeman J et al. 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 Test Anal. 2012;4:733-8. PMID 22962027 · doi:10.1002/dta.1402
8. Wang X, Liu L, Qi L et al. A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers. J Cell Mol Med. 2021;25:8222-8228. PMID 34346165 · doi:10.1111/jcmm.16693
9. Bock-Marquette I, Saxena A, White MD et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432:466-72. PMID 15565145 · doi:10.1038/nature03000
10. Pickart L, Freedman JH, Loker WJ et al. Growth-modulating plasma tripeptide may function by facilitating copper uptake into cells. Nature. 1980;288:715-7. PMID 7453802 · doi:10.1038/288715a0
11. Maquart FX, Pickart L, Laurent M et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988;238:343-6. PMID 3169264 · doi:10.1016/0014-5793(88)80509-x
12. Maquart FX, Bellon G, Chaqour B et al. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. J Clin Invest. 1993;92:2368-76. PMID 8227353 · doi:10.1172/JCI116842
13. Bishop JB, Phillips LG, Mustoe TA et al. A prospective randomized evaluator-blinded trial of two potential wound healing agents for the treatment of venous stasis ulcers. J Vasc Surg. 1992;16:251-7. PMID 1495150 · doi:10.1067/mva.1992.37086
14. Pickart L, Margolina A Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 2018;19. PMID 29986520 · doi:10.3390/ijms19071987
15. Dalmasso G, Charrier-Hisamuddin L, Nguyen HT et al. PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation. Gastroenterology. 2008;134:166-78. PMID 18061177 · doi:10.1053/j.gastro.2007.10.026
16. Kannengiesser K, Maaser C, Heidemann J et al. Melanocortin-derived tripeptide KPV has anti-inflammatory potential in murine models of inflammatory bowel disease. Inflamm Bowel Dis. 2008;14:324-31. PMID 18092346 · doi:10.1002/ibd.20334
17. Cutuli M, Cristiani S, Lipton JM et al. Antimicrobial effects of alpha-MSH peptides. J Leukoc Biol. 2000;67:233-9. PMID 10670585 · doi:10.1002/jlb.67.2.233

Related reading

• Buy research peptides online in the USA
• How to compare US peptide suppliers
• COA library
• KLOW 80mg Blend (vial)
• KLOW 80 mg (Pen)
• GLOW 70mg blend
• BPC-157 + TB-500 10mg
• GHK-Cu 50mg
• KPV 10mg