Clinical Trials Healing & Recovery

Thymosin β4

also known as: Tβ4, TB4, TMSB4X, RGN-259, Lacripep

The natural 44-amino-acid parent of the TB-500 research peptide — in clinical trials (as RGN-259/Lacripep) for dry eye disease, corneal wounds, and dermal healing.

A highly conserved 44-amino-acid actin-sequestering peptide abundant in platelets and wound fluid, distinct from the shorter TB-500 fragment sold in the peptide community.

Mechanism of action

Binds G-actin and sequesters monomeric actin, regulating cytoskeletal dynamics. Effects include promotion of endothelial cell migration (angiogenesis), modulation of inflammation via downregulation of NF-κB signaling, inhibition of myofibroblast transition (anti-scarring), and activation of progenitor cell populations. The actin-binding motif LKKTETQ within Tβ4 is the active core shared with the TB-500 fragment.

Primary uses

Dry eye disease (Phase 3)
Neurotrophic keratopathy (clinical trials)
Corneal wound healing
Dermal wound healing research
Post-MI cardiac repair (preclinical)

Typical dosing

varies varies by formulation (ophthalmic (Lacripep); systemic research only)

No approved systemic dosing. Research injectable doses in the community overlap with TB-500 dosing despite being a longer peptide.

Regulatory status

Not approved. ReGenTree advanced RGN-259 (thymosin β4 ophthalmic) through Phase 3 for dry eye disease and neurotrophic keratopathy. Additional investigational use in dermal wound healing, corneal injury, and post-stroke recovery.

References

[pubmed] Goldstein AL, Hannappel E, Kleinman HK. "Thymosin β4: actin-sequestering protein moonlights to repair injured tissues." Trends Mol Med, 2005;11:421-429.
[clinical-trial] Dunn SP, et al. "Evaluation of RGN-259 ophthalmic solution (thymosin β4) for dry eye." ClinicalTrials.gov NCT03784768.
[review] Crockford D, et al. "Review of the clinical pharmacology of thymosin β4 and utility as a therapeutic." Ann N Y Acad Sci, 2010;1194:179-189.

Related peptides

TB-500

A synthetic fragment of thymosin β4 studied in animal models for actin-binding-mediated tissue repair, particularly in cardiac and soft-tissue injury.

BPC-157

A synthetic pentadecapeptide from gastric protein, widely studied in animal models for tendon, ligament, and gastrointestinal healing.

GHK-Cu

A naturally occurring human tripeptide-copper complex with extensive topical cosmetic evidence and strong in-vitro data on collagen synthesis, angiogenesis, and anti-inflammatory signaling.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.