TB-500 | Peptide Research Hub

At a Glance

TB-500 is a synthetic peptide representing the active region (amino acids 17-23) of thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide found in most human cells. Tβ4 is involved in actin regulation, cell migration, and tissue repair.

TB-500 has been studied primarily in animal models for wound healing, muscle repair, and cardiac protection. It has gained attention in veterinary medicine (particularly horse racing) and is banned by WADA.

⚠️ Research Status: TB-500 is not approved for human use by any regulatory agency. Human clinical data is extremely limited. Most evidence comes from animal studies.

Mechanism of Action

TB-500’s proposed mechanisms are based primarily on in vitro and animal studies:

Actin Sequestration

Binds G-actin and promotes actin polymerization
Enhances cell migration and motility
Critical for wound healing processes

Angiogenesis Promotion

Upregulates vascular endothelial growth factor (VEGF)
Promotes new blood vessel formation
May enhance tissue perfusion during repair

Anti-inflammatory Effects

Modulates inflammatory cytokine production
May reduce tissue inflammation during injury
Potential immunomodulatory properties

Cell Migration & Proliferation

Promotes keratinocyte and endothelial cell migration
Enhances stem/progenitor cell recruitment to injury sites

Evidence Summary

Cardiac Repair (Animal Studies)

Low Confidence Animal Study 3-10 Years

Rodent studies have shown:

Reduced infarct size when administered after myocardial ischemia
Improved cardiac function markers
Enhanced angiogenesis in infarcted tissue

Limitations: Small sample sizes; rodent-to-human translation unclear; no published human cardiac trials.

Wound Healing (Animal Studies)

Low Confidence Animal Study 3-10 Years

Accelerated wound closure in dermal wound models
Enhanced corneal epithelial healing (led to clinical development of RGN-259)
Improved tendon and ligament repair in some models

Dry Eye (Human Trial - RGN-259)

Moderate Confidence RCT 3-10 Years

RegeneRx developed RGN-259 (Tβ4 eye drops) for dry eye syndrome:

Phase 2 trials showed improvements in ocular surface disease
Demonstrated safety in human ophthalmic use
Development status uncertain

Safety & Unknowns

Known Considerations

Cancer concern: Tβ4 is overexpressed in some tumors; theoretical concern about promoting tumor angiogenesis (not proven)
No systemic human safety data: Oral/injectable TB-500 has not completed human safety trials
Quality control: Research-grade peptides vary in purity and composition

Adverse Events (Limited Data)

Injection site reactions (anecdotal)
Headache, fatigue (reported in online communities; unverified)
No systematic adverse event data in humans

Regulatory Status

Region	Status
FDA	Not approved
EMA	Not approved
WADA	Prohibited (S0 – Non-Approved Substances)
Veterinary	Used off-label in horses; banned in racing

Key Studies

Year	Type	Finding
2004	Animal	Cardiac repair after MI in mice
2010	Animal	Accelerated dermal wound healing in rats
2017	Phase 2	RGN-259 showed efficacy in dry eye

BPC-157: Another tissue-repair peptide (gastric origin)
GHK-Cu: Copper peptide with wound healing properties
Thymosin Alpha-1: Immunomodulatory peptide (different mechanism)

Changelog

Date	Change
2026-01-21	Initial dossier created