TB-500

TB-500 (also known as Tβ4, Thymosin β4 fragment, Thymosin B4) is a recovery research peptide. A synthetic fragment of Thymosin Beta-4, a ubiquitous actin-sequestering protein. Research focuses on promoting tissue repair, reducing inflammation, and supporting angiogenesis in cardiac and skeletal muscle models.

TB-500 corresponds to the actin-binding domain of Thymosin Beta-4 (Tβ4), a highly conserved 43-amino acid protein expressed in virtually all human cells. Tβ4 is one of the most abundant proteins in mammalian cytoplasm. TB-500 shares the core LKKTET motif responsible for G-actin sequestration. Research demonstrates promotion of endothelial cell migration and angiogenesis, keratinocyte migration for wound closure, cardiac progenitor cell activation, and anti-inflammatory activity. Cardiac repair studies in rodents show improved post-infarct recovery with Tβ4 administration.

1 Mechanism of action

Sequesters G-actin via LKKTET motif, regulating cytoskeletal dynamics and cell migration. Promotes endothelial progenitor mobilization from bone marrow, upregulates MMP-2, reduces inflammatory cytokines.

Primary targets: G-actin (direct binding) · integrin-linked kinase

2 Reported effects

Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.

2.1 Reported benefits

• Promotes endothelial cell migration and angiogenesis
• Accelerated wound closure and keratinocyte migration
• Cardiac protection post-infarction in animal models
• Anti-inflammatory effects via cytokine modulation

2.2 Side effects

• Injection site discomfort and erythema
• Mild fatigue reported in some protocols
• Potential for excessive angiogenesis (theoretical)
• Headache in a subset of subjects

3 Chemical and physical properties

3.1 Amino acid sequence

4 Research dosages

2.0–5.0 mg SC twice weekly in preclinical wound models; human-equivalent dose not established.

5 Research studies (8)

1. Thymosin Beta-4 Promotes Cardiac Repair in Myocardial Infarction
   Nature (2004) · Preclinical · N=96 (mice)
   Tβ4 treatment after MI stimulated epicardial progenitor cell migration and differentiation; improved cardiac function in mouse models.
   Key finding: Tβ4 mobilized epicardial progenitors to form new cardiomyocytes post-MI — identified a cardiac regeneration pathway.
2. Thymosin Beta-4 and Wound Healing
   Annals of the New York Academy of Sciences (2010) · Review · N/A (review)
   Review of Tβ4 mechanisms in wound healing: corneal, dermal, and cardiac. Covers clinical potential and LKKTET motif biology.
   Key finding: Tβ4 promotes keratinocyte migration and dermal wound closure 40–50% faster than controls in animal models.
3. Thymosin beta 4: An emerging therapeutic candidate for kidney diseases
   Peptides (2026) · Review
   Key challenges moving forward include validating efficacy in additional clinically relevant models, overcoming peptide instability and completing comprehensive safety assessments.
4. Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion
   Cardiovascular research (2025) · RCT
   These findings underscore the crucial role of rhTB4 in mitigating cardiac dysfunction in an ErbB2-dependent manner.
5. Thymosin Beta-4 Modulates Cardiac Remodeling by Regulating ROCK1 Expression in Adult Mammals
   International journal of molecular sciences (2025) · Preclinical
   Given the beneficial effects of ROCK1 inhibition in various cardiac pathologies, we propose a potential utilization for TB4 as a ROCK1 inhibitor in the future.
6. Inhaled exogenous thymosin beta 4 suppresses bleomycin-induced pulmonary fibrosis in mice via TGF-β1 signalling pathway
   The Journal of pharmacy and pharmacology (2025) · Preclinical
   This study suggests that nebulized rhTβ4 is a potential treatment for IPF.
7. Activation of pro-resolving pathways mediate the therapeutic effects of thymosin beta-4 during Pseudomonas aeruginosa-induced keratitis
   Frontiers in immunology (2024) · Preclinical
   Collectively, these findings suggest that the therapeutic effect of Tβ4 resolves inflammation through the activation of SPM pathways, thereby enhancing host defense and tissue repair.
8. In Vitro Study of Thymosin Beta 4 Promoting Transplanted Fat Survival by Regulating Adipose-Derived Stem Cells
   Aesthetic plastic surgery (2024) · Review
   Tβ4 enhances adipose viability in AFG via facilitating ADSC proliferation and reducing apoptosis, and acts as a crucial positive regulator of ADSC-associated angiogenesis.

6 Safety and risk profile

6.1 Regulatory status

TB-500 is currently classified as Phase 2 clinical trials. It has no approved human indication in the United States; availability elsewhere does not imply demonstrated safety or efficacy.

Safety score: 48/100 — moderate concern. Derived from clinical data volume, known risks and regulatory status.

6.2 Contraindications

Conditions and populations in which use is contraindicated:

• Active cancer or history of malignancy (angiogenesis concern)
• Diabetic retinopathy (neovascularization risk)
• Concurrent use with anti-angiogenic agents
• Pregnancy (teratogenicity unknown)

6.3 Drug interactions

6.4 Long-term risks

• Theoretical promotion of tumor angiogenesis with prolonged use
• Potential for pathological fibrosis in healing tissues
• Immunogenicity from chronic administration of exogenous Tβ4
• Unknown effects on cardiac remodeling in healthy hearts

6.5 Research best practices

• Store lyophilized at −20 °C; reconstituted at 2–8 °C
• Use within 21 days of reconstitution
• Research protocols typically dose 2x weekly (Mon/Thu) due to long half-life
• Avoid light exposure; amber vials recommended

7 Frequently asked questions

How does TB-500 differ from BPC-157 for tissue repair?

While both promote healing, TB-500 works primarily through actin cytoskeleton regulation and cell migration, whereas BPC-157 acts more broadly through angiogenesis and growth factor sensitization. TB-500 has a longer half-life (~3–7 days vs ~4 hours), making dosing less frequent in research protocols.

What does the cardiac repair research show?

Landmark Nature studies show Tβ4 can activate dormant epicardial progenitor cells in the heart, causing them to migrate and form new cardiomyocytes after a heart attack in mice — a finding with significant implications for cardiac regeneration research.

8 References

1. Thymosin beta 4: An emerging therapeutic candidate for kidney diseases PubMed (2026). Di H, et al.. View source
2. Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion PubMed (2025). Zhang Y, et al.. View source
3. Thymosin Beta-4 Modulates Cardiac Remodeling by Regulating ROCK1 Expression in Adult Mammals PubMed (2025). Maar K, et al.. View source
4. Inhaled exogenous thymosin beta 4 suppresses bleomycin-induced pulmonary fibrosis in mice via TGF-β1 signalling pathway PubMed (2025). Yu R, et al.. View source

9 See also

• Peptide encyclopedia index
• Peptide reconstitution calculator
• Glossary of peptide research terms