ARA-290 (Cibinetide) Peptide: Innate Repair Receptor Agonism and Preclinical Evidence

ARA-290 (cibinetide) is a linear eleven-residue peptide, pyroglutamate helix B surface peptide, engineered from the aqueous face of helix B of erythropoietin, and ARA-290 research centres on selective activation of the innate repair receptor, an EPO receptor and beta common receptor heterocomplex, without any erythropoietic activity. Its defining pharmacological feature is a disconnect between exposure and effect: the plasma half-life is roughly two minutes, yet single treatment courses produce anti-allodynic effects measurable for twenty weeks in rodents. The compound has been carried through phase 2 trials in sarcoidosis-associated small nerve fibre loss and in type 2 diabetes with painful neuropathy. ARA-290 is a reference compound discussed here for its pharmacology; it is not an item in the Maple Research Labs catalogue.

Disclaimer: For research purposes only. Not for human consumption. Not for diagnostic or therapeutic use. The information presented here is drawn from published scientific literature and is intended solely for educational reference.

What ARA-290 Actually Is

The compound is an eleven-residue peptide with the sequence QEQLERALNSS in which the N-terminal glutamine has cyclised to pyroglutamate, which is why the literature name is pyroglutamate helix B surface peptide, abbreviated pHBSP. The molecular formula is C51H84N16O21 and the average molecular mass is approximately 1257.3 Da. Two properties of that formula matter for anyone handling the material analytically. There is no sulfur in it, so the peptide contains no cysteine and cannot form a disulfide bond, and an earlier version of this page stated that ARA-290 is cyclised through a disulfide between positions 1 and 9, which is not chemically possible for this sequence. The only ring in the molecule is the five-membered lactam of the N-terminal pyroglutamate residue.

The peptide traces back to a specific structural argument. Brines and colleagues established first that erythropoietin protects tissue through a receptor distinct from the erythropoietic one. In Brines 2004 (PNAS 101:14907-14912, PMID 15456912), EPO receptor was recovered from rat brain, heart, liver and kidney membranes in covalent complex with the common beta receptor, the signalling subunit shared by the GM-CSF, IL-3 and IL-5 receptors, and neither EPO nor carbamylated EPO protected cardiomyocytes or spinal cord in the beta common receptor knockout mouse. Carbamylated EPO itself, described in Leist 2004 (Science 305:239-242, PMID 15247477), was the proof of principle that tissue protection and erythropoiesis are separable.

Brines 2008 (PNAS 105:10925-10930, PMID 18676614) then narrowed the protective activity to a peptide. Helix B of EPO, residues 58 to 82, faces the aqueous medium when EPO is bound to the receptor homodimer, and an eleven-residue peptide composed of the adjacent amino acids forming that aqueous face reproduced tissue protection in models of ischaemic stroke and renal ischaemia-reperfusion, accelerated wound healing and improved cognitive performance in rodents, while showing no erythropoietic activity in vitro or in vivo. The peptide is not a contiguous fragment of the EPO primary sequence. It is a surface mimetic, which is the reason the design generalises poorly from sequence alignment alone.

The Pharmacokinetic Paradox

The most useful thing to know about ARA-290 as a research tool is that its exposure profile does not predict its effect duration. Collino, Thiemermann and Cerami reviewed the pharmacokinetic and pharmacodynamic data in Pharmacology and Therapeutics (2015, 151:32-40, PMID 25728128) and reported a plasma half-life of approximately two minutes. An earlier version of this page gave four to six hours, which is wrong by more than two orders of magnitude and, more importantly, obscures the actual phenomenon. The review frames it as a molecular switch: a short-lived ligand engages a receptor that is itself transient, and the downstream transcriptional and cellular consequences outlast both by weeks. Any experimental design that assumes sustained plasma exposure is required for effect will produce misleading dose-ranging data for this compound.

The receptor’s expression pattern follows the same logic. The innate repair receptor is largely absent from healthy tissue and is induced by injury, hypoxia or metabolic stress, a point made explicitly in the wound-healing work discussed below. That is a meaningful difference from a constitutively expressed target, and it means vehicle-treated and injured-untreated controls are not interchangeable in receptor-occupancy experiments.

Neuropathic Pain and Nerve Injury Models

The best-characterised preclinical dataset for ARA-290 is in neuropathic pain, and it is also where the receptor dependence was demonstrated most cleanly. Swartjes and colleagues (Anesthesiology 2011, 115:1084-1092, PMID 21873879) used the spared nerve injury model in rats and in beta common receptor knockout mice. Rats received five intraperitoneal injections of 30 micrograms per kilogram at two-day intervals beginning twenty-four hours after injury, followed by weekly dosing, with eight animals per group, and a separate group received only the five doses given during the first two weeks. Both paradigms produced relief of tactile and cold allodynia lasting as long as fifteen weeks (P less than 0.001 against vehicle). ARA-290 was active in wild-type mice and produced no effect at all in the beta common receptor knockout, which is the experiment that ties the behavioural readout to the intended receptor rather than to a generic anti-inflammatory action.

The follow-up study (Swartjes 2014, Molecular Pain 10:13, PMID 24529189) established the dose-response relationship and a plausible cellular correlate. Rats with spared nerve injury received 3, 10, 30 or 60 micrograms per kilogram on days 1, 3, 6, 8 and 10. Mechanical allodynia was significantly reduced out to twenty weeks, and cold allodynia was significantly reduced at every dose tested over the same interval. Spinal cord immunohistochemistry at two and twenty weeks showed that animals given 30 micrograms per kilogram did not develop the microglial reactivity, measured as iba-1 immunoreactivity, seen in vehicle-treated animals, while the 10 microgram per kilogram group showed the increase at twenty weeks. Astrocyte reactivity measured by GFAP did not differ between groups. The dissociation between the microglial and astrocytic response is the informative part, since it narrows the candidate mechanism to the microglial compartment.

More recent work has addressed the Schwann cell side of peripheral nerve injury. In a rat sciatic nerve crush model (European Journal of Pharmacology 2025, PMID 40216181), both EPO and ARA-290 suppressed early inflammatory signalling and improved functional recovery, and the mechanism reported is inhibition of NLRP3 inflammasome activation in Schwann cells through reduced NF-kB phosphorylation and lower reactive oxygen species production.

Clinical Translation

ARA-290 is unusual among peptides discussed in a research context in that it has generated controlled human data, which is worth knowing because it constrains what the preclinical literature can be claimed to predict. In a blinded placebo-controlled trial in patients with sarcoidosis-associated small nerve fibre loss (Heij and colleagues, Molecular Medicine 2013, 19:334-345, PMID 24136731), twenty-eight days of daily subcutaneous administration significantly improved neuropathic symptom scores and was associated with an increase in corneal small nerve fibre density, changes in cutaneous temperature sensitivity and increased six-minute walk distance. Culver and colleagues (Investigative Ophthalmology and Visual Science 2017, 58:BIO52-BIO60, PMID 28475703) reported the corneal nerve fibre findings in more detail, and Brines and colleagues (Scientific Reports 2018, 8:4734, PMID 29549285) added corneal nerve fibre size as a measure that improves on density alone for detecting change.

A separate phase 2 study in type 2 diabetes with painful neuropathy (Brines and colleagues, Molecular Medicine 2015, 20:658-666, PMID 25387363) ran twenty-eight days of daily subcutaneous treatment with a further month of follow-up off treatment. The reported outcomes were improvement in HbA1c and lipid profile sustained across the fifty-six day observation period, significant improvement in PainDetect neuropathic symptom scores, and an increase in corneal nerve fibre density restricted to the subgroup whose baseline density was more than one standard deviation below normal. Van Velzen and colleagues (Expert Opinion on Investigational Drugs 2014, 23:541-550, PMID 24555851) reviewed the two sarcoidosis trials together. These are small phase 2 datasets, and the appropriate reading is that the innate repair receptor is a tractable target in humans, not that efficacy is established.

An earlier version of this page attributed a streptozotocin-induced diabetic neuropathy rat study to Rolan and colleagues in 2013, with a twenty-eight day dosing schedule, intraepidermal nerve fibre density figures and von Frey statistics. No such study could be located. The diabetic neuropathy data for this compound is the human phase 2 work above, and the rodent neuropathy data is the spared nerve injury work of Swartjes.

Islet, Wound and Cardiac Models

Pancreatic islet protection has been examined in human tissue rather than only in rodents. Cibinetide was tested on isolated human islets cultured for eighteen hours with pro-inflammatory cytokines (Cell Transplantation 2021, PMID 34498509), where it maintained islet ATP content, reduced caspase 3/7 activity and improved insulin secretory capacity on dynamic glucose perfusion. In a polyvinyl chloride loop system with ABO-compatible blood, used to model the instant blood mediated inflammatory reaction that destroys islets during intraportal transplantation, cibinetide reduced platelet consumption. Human islets transplanted into athymic mouse liver with perioperative cibinetide yielded higher hepatic human insulin, higher serum human C-peptide and less CD11b-positive cell infiltration around the grafts. An earlier version of this page reported murine islet TUNEL percentages, a glucose stimulation index and pancreatic insulin content figures that are not traceable to any located study; they have been removed.

Wound healing in genetically diabetic mice (Biochimica et Biophysica Acta, Molecular Basis of Disease 2018, 1864:632-639, PMID 29223734) is the clearest demonstration that the receptor is injury-induced rather than constitutive. Daily cibinetide at 30 micrograms per kilogram subcutaneously in db/db mice, with animals examined at three, seven and fourteen days, raised wound VEGF, phospho-Akt, phospho-eNOS and nitrite/nitrate content and lowered malondialdehyde, with corresponding improvement in re-epithelialisation, angiogenesis, wound breaking strength and time to closure.

The cardiac ageing dataset is the largest in the ARA-290 literature by animal numbers. A fifteen-month randomised controlled study in Fischer 344 by Brown Norway rats beginning at eighteen months of age (Frontiers in Cardiovascular Medicine 2022, PMID 36741836) combined a longitudinal arm of forty-eight animals with a cross-sectional arm of one hundred and forty-four. Chronic treatment reduced the age-related rise in the cardiac non-myocyte to myocyte ratio, infiltrating leukocytes and monocytes, pro-inflammatory cytokines and total and phosphorylated NF-kB, enhanced cardiomyocyte autophagic flux, reduced lipofuscin accumulation, desensitised the mitochondrial permeability transition pore response to oxidant stress, blunted the age-associated rise in blood pressure and preserved left ventricular ejection fraction.

A model-dependence result worth carrying forward comes from the Alzheimer’s literature (Brain, Behavior and Immunity 2022, PMID 34343617). Early systemic ARA-290 in young APP/PS1 mice slowed amyloid-beta pathology and improved cognitive performance, and the mechanism was an increase in Ly6C-low patrolling monocytes, since the benefit disappeared in chimeric mice in which that subset was selectively depleted. In aged APP/PS1 mice with established pathology the same treatment failed to reduce amyloid burden or raise circulating monocytes. The compound acts on a repair response that has to still be available.

One caution for anyone building on the renal literature: the widely cited 2012 Molecular Medicine report on delayed pHBSP administration in acute kidney injury (PMID 22415011) was retracted in 2026 (retraction note PMID 41749083). Claims about renal ischaemia-reperfusion should be sourced to Brines 2008 or to work that does not depend on that paper.

Comparison With Other Neuroprotective Research Peptides

ARA-290 occupies a distinct receptor niche. Humanin, a mitochondria-derived peptide with overlapping anti-apoptotic and neuroprotective activity, signals through a gp130-containing complex rather than the EPO receptor family, and the humanin research profile sets out that mechanism. PACAP acts through PAC1 and VPAC receptors and cAMP/PKA, covered in the PACAP receptor research summary. Researchers comparing tissue-repair mechanisms across unrelated receptor families may also find the BPC-157 and TB-500 research comparison useful, since those two compounds address repair through pathways with no relationship to the innate repair receptor.

What ARA-290 uniquely allows is interrogation of the EPO tissue-protective pathway in isolation. Recombinant EPO activates the erythropoietic homodimer and the protective heterocomplex at once, so rising haematocrit and altered blood viscosity confound any in vivo protective readout. A ligand that engages only the heterocomplex removes that confound, which is why the beta common receptor knockout comparison in Swartjes 2011 is the reference experiment for the whole class.

Analytical Considerations for ARA-290 Material

The identity check that matters for this peptide is the N-terminal pyroglutamate, not a disulfide. Cyclisation of an N-terminal glutamine to pyroglutamate involves loss of ammonia, so the pyroglutamate form is 17 Da lighter than the corresponding free-glutamine linear peptide. A mass spectrum showing approximately 1257 Da for the neutral peptide is consistent with the pyroglutamate form, while a species 17 Da heavier indicates unconverted HBSP, which is a different compound with its own literature. Because pyroglutamate formation can also occur spontaneously during storage of the glutamine-terminal peptide, the ratio of the two species is a stability-indicating measurement rather than a simple pass or fail.

Beyond identity, the usual chromatographic questions apply: purity by integrated UV area at a stated wavelength, with the wavelength named, and resolution of deletion and truncation sequences from the target peak. The general methodology is covered in the discussion of HPLC testing for peptide purity and in the treatment of mass spectrometry for identity confirmation.

Where a batch of a compound in our catalogue has been tested, the independent laboratory report is published on the certificates of analysis page, which also lists the compounds still awaiting a report. ARA-290 is not a catalogue compound. The research peptide catalogue and the documentation section cover the compounds that are.

Citations in this article were checked against the indexed PubMed record on 20 September 2026. Corrections made in this revision: the structure is linear with no disulfide bond, confirmed against the molecular formula C51H84N16O21, which contains no sulfur; the plasma half-life is approximately two minutes rather than four to six hours; a 2013 streptozotocin rat study attributed to Rolan, a receptor binding constant of approximately 20 nM, stroke infarct volumes, paclitaxel fibre-density figures, carrageenan hyperalgesia figures, murine islet apoptosis and insulin content figures, dendritic cell and mixed lymphocyte reaction figures, plasma stability data and CNS penetration percentages were removed as untraceable to any located source.

For research purposes only. Not for human consumption. Not for diagnostic or therapeutic use.