ARA-290 (Cibinetide): Helix-B Mimetic Design, Receptor Logic and Research Use

ARA-290 — known in clinical papers as cibinetide — is an 11-amino-acid peptide modelled on the outward-facing side of helix B in erythropoietin. It was designed to engage the tissue-protective form of the erythropoietin receptor while leaving red-cell production untouched. That design goal is why a molecule derived from a blood-forming hormone turns up mainly in neuroprotection, neuropathic pain and inflammation research rather than in haematology. This guide covers what ARA-290 is, how its sequence was chosen, the receptor hypothesis behind it, the published findings, and how research material is specified and handled in the lab.

We supply ARA-290 as freeze-dried powder, strictly for laboratory research.

Reading a peptide off a protein surface: origin and structure

Erythropoietin is a glycoprotein of about 165 residues arranged as a bundle of four helices. It drives red-cell production by bringing two erythropoietin receptors together as a homodimer, using contact residues on specific faces of helices A and D. From the mid-2000s onward, researchers argued that the hormone also has a separate, structurally distinct tissue-protective activity. This second activity is thought to run through a heteromeric receptor: the erythropoietin receptor partnered with the beta-common chain, the signal-transducing subunit also used by the GM-CSF, IL-3 and IL-5 receptors. Papers generally refer to this complex as the innate repair receptor.

ARA-290 was made by reproducing, as a short linear peptide, the solvent-facing surface of helix B — a region that plays no part in classical receptor binding. The sequence is pyroglutamate-Glu-Gln-Leu-Glu-Arg-Ala-Leu-Asn-Ser-Ser. The leading pyroglutamate is a cyclised glutamine; by closing off the free N-terminus it protects the peptide from aminopeptidases, a stabilisation approach common in short synthetic sequences.

The purpose of that design defines the molecule. If you study tissue protection using full-length erythropoietin, you cannot separate the protective signal from increased red-cell production, a rising haematocrit and the associated vascular side effects. ARA-290 was built to remove that confounding variable. It is, in effect, a tool made for one experimental job, which is why it serves as the reference agonist for the innate repair receptor.

The proposed mechanism

Published work describes ARA-290 as binding selectively to the EPOR/beta-common complex. Reported downstream effects include activation of survival and inflammation-resolving pathways such as JAK2/STAT and PI3K/Akt, and reduced release of pro-inflammatory mediators by immune cells. The beta-common chain is expressed on macrophages, neurons, endothelial cells and other tissues outside the erythroid lineage, so where the proposed receptor occurs lines up with where the peptide has been studied.

A separate line of work concerns small-fibre nerve biology and the TRPV1 ion channel (transient receptor potential vanilloid 1); in model systems, ARA-290 has been reported to change how nociceptors behave and to affect intraepidermal nerve fibre density. These explanations fit together rather than competing, but none is established. They are hypotheses that researchers have proposed and tested in cells and animals.

Unusually for a research peptide, a negative result is among the best-documented facts about it. Studies repeatedly find no meaningful effect on red-cell production — and for a research tool, an activity that is reliably missing is as informative as one that is reliably present.

Fields of published research

Small nerve fibre and neuropathic pain models

This is where most of the ARA-290 literature sits, and it is what the peptide is best known for. It has been studied in rodent models of neuropathic pain, and under the name cibinetide in phase 2 trials in people, including sarcoidosis-related small-fibre neuropathy and neuropathy in type 2 diabetes mellitus. Endpoints included corneal nerve fibre measurements and symptom scores reported by participants. Those trials concern the investigational drug candidate, not research-grade substance sold for lab use, and the compound has never been granted marketing authorisation.

Inflammation and immune modulation

Cell and rodent work has examined macrophage polarisation, cytokine secretion and markers that inflammation is resolving. That places ARA-290 in broadly similar research territory to peptides such as KPV, but by an entirely different route: ARA-290 acts on a cell-surface receptor complex, whereas KPV works on NF-kappa B signalling inside the cell.

Ischaemia, organ protection and metabolic models

In line with the tissue-protection idea behind its design, preclinical groups have tested the peptide in ischaemia–reperfusion injury in several organs and in islet and transplant models. All of these data come from rodent and in-vitro work.

Immune and repair comparisons

When labs survey immunomodulatory peptides, ARA-290 is often compared with thymosin alpha-1 — which acts through toll-like receptors and T-cell maturation — or with BPC-157 in repair models. Such comparisons are informative precisely because the mechanisms do not overlap at all.

Available presentations

ARA-290 is available freeze-dried in sealed, crimp-capped vials: 10 mg (USD 100) and 20 mg (USD 180). At 1259.34 g/mol, 10 mg corresponds to roughly 7.9 micromoles — more moles than a vial of full-length protein, fewer than a tripeptide vial. Related products are listed under anti-inflammatory peptides, and, for immunology projects, under immune peptides.

Reconstitution and storage at the bench

The reconstitution maths is straightforward. Add 2 mL of bacteriostatic water to a 10 mg vial and you have 5 mg/mL (5,000 mcg/mL); 0.1 mL, the 10-unit mark on a U-100 syringe, then holds 500 mcg. In molar terms, 5 mg/mL of a 1259.34 g/mol peptide is about 3.97 mM — the number you actually need when diluting down to nanomolar or micromolar concentrations for cell assays.

The peptide goes into aqueous buffer without difficulty. Run the diluent slowly down the vial wall instead of squirting it onto the cake, and swirl rather than shake, because mechanical agitation encourages aggregation at air-liquid interfaces. Keep lyophilized vials at −20 °C out of the light; refrigerate reconstituted solution and split it into aliquots so that nothing is warmed repeatedly. The reconstitution guide gives the method step by step, and the storage guide covers temperature and stability in detail.

Purity, the COA and how to read it

Each lot is purified to 99% or higher by reversed-phase HPLC, its mass is confirmed, and the certificate carries the same lot number as the vial. For an 11-mer starting with pyroglutamate, two things deserve a closer look. First, the measured mass should be 1259.34 g/mol: if the N-terminal glutamine had not cyclised, the mass would be 17 Da heavier, so the MS result is direct evidence that the ring closed. Second, the sequence includes asparagine and serine, which can deamidate or break down under unsuitable storage conditions; any such damage shows up as shoulders next to the main HPLC peak. Look at the trace, not only the purity figure. Our COA reading guide works through real chromatograms and explains how net peptide content relates to the gross weight in the vial.

Regulatory position

Although cibinetide has been through clinical trials, it has no marketing authorisation in the European Union or the United States. ARA-290 is not an approved medicine, not a food supplement and not a routinely available compounded product. The published human data describe the investigational candidate studied under controlled conditions; they do not transfer to research-grade material, and we make no therapeutic claim for it.

Related peptides and further reading

Our healing and recovery research overview gives the wider context on repair-oriented peptides and how researchers choose between mechanisms. Elsewhere in the catalogue, KPV, VIP and thymosin alpha-1 provide three other, mechanistically unrelated entry points into inflammation biology. Of all of them, ARA-290 alone was engineered specifically to split a receptor complex's activity away from the main function of the hormone it came from.

Matching catalogue section: Anti-Inflammatory Peptides