TB-500 Frequently Asked Questions
Answers to the most common questions about TB-500, thymosin beta-4, reconstitution, dosing, storage, and research applications.
What Is TB-500?
What is TB-500?
TB-500 is a synthetic 7-amino acid peptide (Ac-LKKTETQ) corresponding to the actin-binding domain of thymosin beta-4, a 43-amino acid protein naturally abundant in mammalian cells. It is studied in preclinical research for tissue repair, anti-inflammatory, and angiogenic properties.
What is the difference between TB-500 and thymosin beta-4?
Thymosin beta-4 (Tβ4) is the full 43-amino acid endogenous protein (~4,900 Da). TB-500 is a synthetic fragment representing only the Ac-LKKTETQ active region (residues 17–23, ~2,100 Da) responsible for actin sequestration. TB-500 is smaller, easier to synthesize, and used as a functional proxy for full-length Tβ4 in most preclinical models.
How does TB-500 work?
TB-500 binds G-actin (monomeric actin), modulating the G-actin/F-actin equilibrium within cells. This facilitates lamellipodia formation and directed cell migration — the cellular basis for wound closure, satellite cell recruitment, and endothelial cell homing to injury sites. It also inhibits NF-κB signaling (anti-inflammatory) and activates ILK/Akt survival pathways (cardioprotective).
What is TB-500's molecular weight?
The Ac-LKKTETQ active fragment is approximately 2,100 Da (~2.1 kDa). Full-length thymosin beta-4 (43 AA) is approximately 4,900 Da (~4.9 kDa). The small size contributes to TB-500's rapid systemic distribution after injection.
Is TB-500 the same as RGN-259?
No. RGN-259 is a topical ophthalmic formulation of full-length thymosin beta-4 (not the TB-500 fragment), developed by RegeneRx Biopharmaceuticals for dry eye and neurotrophic keratitis. It progressed to Phase III clinical trials. TB-500 is a synthetic fragment of Tβ4 used in preclinical research and is not identical in sequence or formulation.
Research Applications
What is TB-500 used for in research?
Published preclinical research has studied TB-500 in: skeletal muscle injury, tendon and ligament repair, cardiac infarction models, wound healing, angiogenesis, anti-inflammatory applications, peripheral nerve regeneration, hair follicle cycling, and hepatic/cardiac fibrosis attenuation. Ophthalmological applications have progressed to human clinical trials under the name RGN-259.
What tissues does TB-500 research cover?
Published preclinical research spans: cardiac muscle, skeletal muscle, tendon and ligament, bone, cornea and ocular surface, peripheral nerve, skin/wound healing, liver (fibrosis attenuation), brain (neuroprotection), and vascular endothelium. The breadth reflects thymosin beta-4's near-universal cellular expression.
What are the key papers on TB-500?
Foundational references include: Smart et al. (2007) on Tβ4 cardiac progenitor activation (Nature); Bock-Marquette et al. (2004) on ILK/Akt cardiac survival signaling (Nature); Hannappel & Huff (2003) on Tβ4 actin sequestration; Philp et al. (2004, FASEB J) on TB-500 hair growth; and the RegeneRx Phase II/III ophthalmic trial publications. Search PubMed for "thymosin beta-4" plus your tissue of interest.
TB-500 vs BPC-157
What is the difference between TB-500 and BPC-157?
They are mechanistically distinct. TB-500 primarily works via actin sequestration and systemic cell migration facilitation, with strong cardiac, macrophage-polarizing, and anti-fibrotic effects. BPC-157 primarily upregulates VEGF locally and activates the eNOS/NO pathway, with strong GI-specific cytoprotective and local angiogenic effects. They are complementary, not redundant.
Can TB-500 and BPC-157 be used together in research?
Yes — combination studies are common because their mechanisms are complementary. BPC-157 drives local VEGF-mediated capillary budding; TB-500 facilitates endothelial cell migration to populate new vessels systemically. Current evidence suggests additive effects. They should be reconstituted in separate vials and administered at separate injection sites in subcutaneous protocols.
Reconstitution & Storage
How do you reconstitute TB-500?
Add bacteriostatic water slowly along the glass wall of the vial — not directly onto the lyophilized cake. For a 10mg vial, 5mL BAC water yields 2mg/mL (a practical working concentration). Swirl gently for 60–90 seconds; do not shake. Solution should be clear and colorless.
How much BAC water do I add to a 10mg TB-500 vial?
It depends on your target concentration. 2mL gives 5mg/mL; 5mL gives 2mg/mL; 10mL gives 1mg/mL. The 5mL preparation (2mg/mL) is most common in published research. Use the reconstitution calculator on this site for custom concentrations.
How long does reconstituted TB-500 last?
Reconstituted with bacteriostatic water and stored at 2–8°C, TB-500 maintains stability for approximately 4–8 weeks. Do not freeze reconstituted peptide — freeze-thaw cycles damage the peptide structure. Lyophilized TB-500 stored at –20°C is stable for 12+ months.
Does TB-500 need to be refrigerated?
Yes. Lyophilized TB-500 should be stored at 2–8°C (short-term) or –20°C (long-term). Once reconstituted, store at 2–8°C only — do not freeze. Protect from light. Room temperature exposure should be minimized to the duration of the reconstitution procedure.
Dosing & Protocols
What dose is used in TB-500 research?
Published rodent studies use a range of 25–150 µg/kg, most commonly 100 µg/kg, administered i.p. or s.c., once daily to twice weekly. The appropriate dose depends on the injury model, species, and research endpoint. Use the dosing calculator on this site to convert µg/kg doses to per-animal volumes.
What injection route is used for TB-500 in research?
Both intraperitoneal (i.p.) and subcutaneous (s.c.) routes are used in published literature. For combination studies with BPC-157 (often dosed i.p.), TB-500 is sometimes given s.c. at a separate site to avoid confounding local effects. Intravenous administration has been used in cardiac models.
What is TB-500's half-life?
The precise half-life of the Ac-LKKTETQ fragment has not been rigorously established. Estimates based on peptide size and distribution suggest a half-life of several hours. The weekly dosing frequency used in most research is empirically derived from observed biological effect duration rather than strict pharmacokinetic modeling.
What is TB-500's CAS number?
The CAS number most commonly assigned to TB-500 (thymosin beta-4 fragment, Ac-SDKP-containing) is 77591-33-4. Note: CAS numbering for peptide fragments can vary by registry and exact sequence specification.
Sourcing
Where can I source research-grade TB-500?
Research-grade TB-500 should come with HPLC purity verification and mass spectrometry confirmation of molecular identity, with an accessible Certificate of Analysis (COA). Apollo Peptide Sciences supplies TB-500 10mg lyophilized vials for laboratory research purposes, with documented purity and research-only intended use.
What should a TB-500 Certificate of Analysis include?
A thorough COA should include: HPLC purity (expressed as area %, target ≥98%), mass spectrometry confirmation of molecular weight, lot number, manufacture date, and storage recommendations. Endotoxin testing (LAL assay) is a premium quality signal. Request the COA before or with your order.
Ready to Research TB-500?
Research-grade TB-500 10mg from Apollo Peptide Sciences. >98% purity, COA available.