TB 500

Thymosin Beta-4 Fragment · TB4-FRAG

Rank#999
Tissue RepairCategory 2Phase IIResearchSubQIM

Popular for:Tissue repair, wound healing, muscle recovery

14

Total Studies

11

Human Studies

Phase II

Evidence Level

Category 2

FDA Status

Overview

TB-500 (Thymosin Beta-4 fragment, also called fequesetide) is a synthetic 7-amino-acid peptide derived from the active region of Thymosin Beta-4 (TB4), a naturally occurring 43-amino-acid peptide found in nearly all human cells. TB-500 is one of the most popular peptides for injury recovery and tissue repair.

**Originally developed for: **Wound healing and tissue repair research. TB4 was initially studied for its role in cardiac repair after myocardial infarction, corneal wound healing, and dermal wound repair. TB-500 was developed as a more stable, bioavailable synthetic fragment of the active region.

Mechanism of Action

TB-500 is an actin-binding peptide that promotes cell migration, proliferation, and differentiation. It sequesters G-actin monomers, enabling cytoskeletal reorganization necessary for cell movement to injury sites. It upregulates cell-surface receptors for extracellular matrix proteins, promotes angiogenesis (new blood vessel formation), and reduces inflammation by downregulating pro-inflammatory cytokines. It also promotes stem cell maturation and differentiation for tissue regeneration.

Key Research Benefits

Primary Benefits:

Accelerated wound healing — TB4 in solution/gel form promoted wound healing in healthy, diabetic, and aged mice (Malinda et al., 2003)
Cardiac repair — Promotes cardiomyocyte survival and repair after myocardial infarction; promotes new blood vessel formation in damaged cardiac tissue (Bock-Marquette et al., 2004)
Anti-inflammatory — Reduces inflammatory cytokines; effective in models of arthritis and tissue inflammation
Soft tissue repair — Promotes tendon, ligament, and muscle healing through enhanced cell migration and extracellular matrix remodeling

Secondary/Emerging Benefits:

Hair growth — Stimulates hair follicle stem cells; community reports of improved hair thickness
Corneal healing — Promotes corneal wound repair; studied for dry eye and corneal injuries
Neuroprotection — Potential benefits for nerve regeneration and brain injury recovery
Liver protection — Hepatoprotective effects in animal models of fibrosis

Clinical Evidence Summary

Research Pipeline

Preclinical
Animal
Phase I
Phase II
Phase III
Approved

14

Total Studies

11

Human Studies

- Malinda et al. (2003) — TB4 promoted accelerated wound healing in healthy, diabetic, and aged mice; the 7-amino-acid active fragment (TB-500) was identified as responsible for cell migration effects.

- Bock-Marquette et al. (2004) — TB4 promoted cardiomyocyte survival post-MI via activation of integrin-linked kinase (ILK); published in Nature.

- Goldstein et al. (2011) — Comprehensive review of TB4 as a multi-functional regenerative peptide, summarizing clinical applications.

- RegeneRx Biopharmaceuticals conducted Phase 2 clinical trials for TB4 eye drops (RGN-259) for dry eye syndrome with positive results.

> Clinical trial status: TB4 (the full peptide) has had some human trials, particularly for ophthalmic applications. TB-500 (the synthetic fragment) has very limited human trial data. Most evidence remains preclinical.

Key Studies / PubMed References

Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.

Review

Rahman OF, Lee SJ, Seeds WA · Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews · 2026

PMID: 41490200

Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.

Review

Mayfield CK, Bolia IK, Feingold CL, et al. · The American journal of sports medicine · 2026

PMID: 41476424

Comparative effects of dietary sodium butyrate and tributyrin on broiler chickens' performance, gene expression, intestinal histomorphometry, blood indices, and litter.

Review

Ismael E, Kamel S, Elleithy EMM, et al. · Scientific reports · 2025

PMID: 40681595

Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro.

In Vitro

Rahaman KA, Muresan AR, Min H, et al. · Journal of chromatography. B, Analytical technologies in the biomedical and life sciences · 2024

PMID: 38382158

Adsorption effects of the doping relevant peptides Insulin Lispro, Synachten, TB-500 and GHRP 5.

Review

Judák P, Van Eenoo P, Deventer K · Analytical biochemistry · 2017

PMID: 28887173

Side Effects & Safety

Common Side Effects:

Injection site redness/irritation
Mild headache
Temporary lethargy/fatigue
Head rush/lightheadedness shortly after injection

Rare but Serious Risks:

Same angiogenesis concern as BPC-157 — theoretical risk of promoting tumor growth in individuals with existing cancer
Some early research suggested possible association with cancer progression, though more recent studies have challenged this; TB4 levels may be a marker rather than a cause

> Contraindications: Avoid in individuals with active cancer or history of cancer. Not recommended during pregnancy or breastfeeding. Use caution when combining with anticoagulants as TB-500 may affect platelet function.

Known Interactions

No curated interaction entry is live for TB 500 yet.

Until the interaction table is fully populated, use the interaction checker and related peptides below to explore adjacent compounds and likely research pairings.

Frequently Asked Questions

Research Disclaimer

This page is for research and educational purposes only. The information presented is based on published scientific literature and does not constitute medical advice, diagnosis, or treatment recommendations. TB 500 is not approved by the FDA for human therapeutic use. Always consult a qualified healthcare professional before making any health-related decisions. The studies referenced are linked to their original PubMed sources for verification.