TB-500 (Thymosin Beta-4) — Research Reference
TB-500 is a synthetic peptide corresponding to the actin-binding domain of Thymosin Beta-4, a protein found throughout the body and concentrated in platelets, wound fluid, and immune cells. The full Thymosin Beta-4 protein consists of 43 amino acids; TB-500 is the fragment most commonly used in research contexts and is sometimes referred to interchangeably with the full protein.
Quick Reference
| Parameter | Reported Value |
|---|---|
| Full name | Thymosin Beta-4 (TB-500 active fragment) |
| Amino acids | 43 (full protein) |
| Half-life | ~3–4 days (reported) |
| Common reported doses | 2–5 mg per week |
| Administration routes | Subcutaneous, intramuscular |
| Storage (lyophilized) | Refrigerator preferred; room temperature stable short-term |
| Storage (reconstituted) | Refrigerated; use within 4–6 weeks |
Overview
Thymosin Beta-4 (Tβ4) is an endogenous protein encoded by the TMSB4X gene and is among the most abundant intracellular proteins in mammalian tissue. Its primary characterised function involves the sequestration of actin monomers, which regulates actin polymerisation — a process central to cell motility, migration, and wound healing.
Research has investigated TB-500 for its potential role in:
- Promoting keratinocyte and endothelial cell migration during tissue repair
- Stimulating angiogenesis (the formation of new blood vessels)
- Reducing inflammatory signalling in damaged tissue
- Protecting cardiac tissue following ischaemic events in rodent models
A small number of human trials have examined Thymosin Beta-4 for dry eye syndrome (as an eye drop formulation), representing one of the few direct human investigations. The majority of the supporting research base consists of rodent models.
TB-500 is not approved for human therapeutic use in any major jurisdiction and is classified as a research chemical in most countries. It appears on the World Anti-Doping Agency (WADA) Prohibited List and is prohibited in competitive sport.
Reported Protocols
The following information represents commonly reported research ranges drawn from anecdotal accounts and available research literature. These are not medical recommendations.
Subcutaneous Protocol
Subcutaneous injection is the most commonly reported administration route. Commonly reported doses range from 2 mg to 5 mg per week, administered in one or two injections.
- Loading phase: Anecdotal research accounts frequently describe a loading period of 2–2.5 mg twice per week for 4–6 weeks to establish elevated tissue levels
- Maintenance phase: Commonly reported as 2–2.5 mg once per week or once every two weeks following the loading phase
- Duration: Commonly reported cycles range from 6 to 12 weeks total
Intramuscular Protocol
Intramuscular injection is reported, particularly in protocols targeting specific musculoskeletal tissues. Reported doses are similar to the subcutaneous protocol.
Combination with BPC-157
TB-500 and BPC-157 are frequently discussed together in healing-focused research contexts. Anecdotal reports suggest complementary mechanisms — BPC-157 is reported to act more locally at the site of injury, while TB-500 is reported to produce more systemic upregulation of repair processes. Both compounds are typically used at their standard individual doses when combined.
Reported Effects
The following effects have been reported in preclinical research and anecdotal accounts. This list reflects the research landscape, not confirmed clinical outcomes.
Tissue Repair & Healing
Animal studies have investigated TB-500 for potential effects on:
- Tendon and ligament repair
- Skeletal muscle regeneration following injury
- Wound healing (dermal and surgical wounds)
- Corneal and ocular surface repair
Research has focused particularly on Thymosin Beta-4’s role in promoting cell migration — a rate-limiting step in wound closure — and its reported ability to stimulate the differentiation of stem cells and progenitor cells into tissue-specific cell types.
Cardiac Protection
A notable research area has examined Thymosin Beta-4’s potential in cardiac tissue protection and repair. Studies in rodent models of myocardial infarction have reported reduced infarct size and improved cardiac function following Tβ4 administration, with researchers proposing activation of cardiac stem cell migration as a potential mechanism.
Angiogenesis
Research has investigated TB-500 for its potential role in stimulating the formation of new blood vessels. Angiogenesis is considered a critical component of effective tissue repair, as the restoration of blood supply is necessary for sustained healing.
Anti-inflammatory
Anecdotal reports and preclinical data suggest anti-inflammatory activity. Some research has proposed interaction with actin-mediated immune cell signalling as a contributing mechanism, though the precise pathway remains under investigation.
Reported Side Effects
Reported side effects in research and anecdotal accounts include the following. This list does not constitute a comprehensive safety profile and should not be interpreted as predictive of individual outcomes.
| Side Effect | Frequency Reported |
|---|---|
| Injection site redness or mild pain | Common (any SubQ/IM injection) |
| Mild fatigue | Occasionally reported during initial loading phase |
| Headache | Occasionally reported |
| Nausea | Rare |
| Dizziness | Rare |
Theoretical concern: TB-500 is reported to be pro-angiogenic. Researchers have noted the theoretical question of whether pro-angiogenic compounds could influence tumour vascularity in subjects with pre-existing neoplastic disease. This has not been demonstrated in short-term research studies, but is considered relevant to disclose for completeness.
The compound has not undergone comprehensive human safety trials.
Storage & Handling
Lyophilized Powder (Unreconstituted)
- Room temperature: Reported stable for up to 3 months when kept away from light and moisture
- Refrigerator (2–8°C): Preferred for extended storage; commonly reported stable for 12 months or more
- Freezer: Acceptable for long-term storage; avoid repeated freeze-thaw cycles of the dry powder
- Light sensitivity: Store in an opaque or amber vial; avoid direct light exposure
Reconstituted Solution
- Refrigerator (2–8°C): Use within 4–6 weeks of reconstitution
- Do not freeze a reconstituted solution — freezing may degrade the peptide and cause aggregation
- Bacteriostatic water (BAC water) is the standard diluent for multi-use vials; the benzyl alcohol preservative extends refrigerated shelf life compared to sterile water
- Discard if the solution becomes cloudy, discoloured, or shows particulate matter
Reconstitution
Add bacteriostatic water slowly to the lyophilized vial, directing liquid along the inside wall rather than directly onto the peptide powder. Swirl gently — do not shake. Allow a few minutes for complete dissolution. See the Reconstitution Guide for step-by-step instructions.
Frequently Asked Questions
What is the difference between TB-500 and BPC-157? TB-500 and BPC-157 are distinct peptides with different mechanisms and origins. TB-500 is derived from the Thymosin Beta-4 protein and is reported to promote cell migration and angiogenesis systemically. BPC-157 is derived from a gastric protein and is reported to act more locally on tissue repair and gut healing. Both are commonly discussed in healing-focused research, and anecdotal accounts frequently describe their use in combination.
Is TB-500 prohibited in sport? Yes. Thymosin Beta-4 and its peptide fragments, including TB-500, appear on the World Anti-Doping Agency (WADA) Prohibited List under the category of Peptide Hormones, Growth Factors, Related Substances and Mimetics. Use in competitive sport governed by WADA rules is prohibited.
How long does a TB-500 cycle typically run? Commonly reported research protocols describe cycles of 6–12 weeks, frequently beginning with a loading phase (higher frequency for the first 4–6 weeks) followed by a maintenance phase. Individual anecdotal accounts vary considerably.
Is there a difference between TB-500 and Thymosin Beta-4? TB-500 is a synthetic peptide corresponding to the actin-binding domain of the full Thymosin Beta-4 protein. Research products labelled TB-500 may contain either the full protein sequence or the active fragment. In most commercial research contexts, TB-500 refers to the fragment.
Related Pages
Goals: Recovery & Healing · Inflammation · Performance · Immune Support
Class: Thymosin Peptides
Comparisons: BPC-157 vs TB-500
Stacks: Wolverine · GLOW · KLOW
References & Further Reading
- Goldstein AL, Hannappel E, Kleinman HK. (2005). Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine, 11(9), 421–429. PubMed →
- Bock-Marquette I, et al. (2004). Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature, 432(7016), 466–472. PubMed →
- Malinda KM, et al. (1999). Thymosin beta4 stimulates directional migration of human umbilical vein endothelial cells. FASEB Journal, 13(2), 227–231. PubMed →