TB-500 20 mg PEN

One-Peptides TB-500 20 mg PEN – Thymosin Beta-4 fragment in a pre-dissolved pen

TB-500 20 mg PEN is a research reagent (Research Use Only) in the form of a pre-dissolved pen. The pen is the physical format of the reagent; TB-500 is not a registered medicine in any jurisdiction. Label: “For research use only. Not for human use”. TB-500 (Thymosin Beta-4) is listed on the WADA Prohibited List year-round (S2) – athletes subject to anti-doping control must not use TB-500 at any time.

In the literature on regenerative peptides, the Thymosin Beta-4 fragment occupies a special place. Full-length Tbeta4 was isolated from calf thymus in 1981 by Allan Goldstein and Ewald Hannappel; since then, it has remained one of the best-described regulators of the actin cytoskeleton in cell biology. TB-500 in RUO reagent trade typically refers to the synthetic heptapeptide LKKTETQ (positions 17-23 of full Tbeta4), containing the actin-binding motif responsible for G-actin sequestration. Some suppliers also use the name “TB-500” for full-length Thymosin Beta-4 (43 amino acids); a professional supplier clearly states the sequence in the COA. A full literature overview is available in the article on tissue repair and Thymosin Beta-4.

The pre-dissolved pen format containing 20 mg of peptide is an operational solution for laboratories that want to skip the lyophilizate reconstitution step. The pen contains a solution ready for microliter sampling: no bacteriostatic water measurement, no solvent-error risk, and one batch number for the entire material. The broader mechanistic background of regenerative peptides is discussed in the guide to regenerative peptides.

What is TB-500 20 mg PEN – sequence and class

In a research reagent catalogue, TB-500 refers to a synthetic N-terminal fragment of Thymosin Beta-4 (Tbeta4) with the sequence Leu-Lys-Lys-Thr-Glu-Thr-Gln (LKKTETQ) – positions 17-23 of the full protein and the biochemical core of Tbeta4 activity. Full-length Thymosin Beta-4 is a 43-amino-acid cytoplasmic protein of approximately 4961 Da from the beta-thymosin class, naturally present in humans with the highest expression in platelets, macrophages and lymphocytes.

In commerce, the name “TB-500” is used in two ways: most often for the LKKTETQ fragment, while some manufacturers use the label for full-length Tbeta4. The sequence stated in the COA is the only binding reference point; MS mass identification (approximately 880 Da for the fragment vs approximately 4961 Da for full Tbeta4) confirms the structural identity of the batch.

Chemical characteristics of TB-500 20 mg PEN

Mechanism of action in research

All reported effects of Tbeta4 and the LKKTETQ fragment originate from one biochemical mechanism: sequestration of monomeric G-actin in a 1:1 ratio, which regulates actin availability for polymerization into F-actin. This single mechanism gives rise to a cascade of secondary effects.

• Modulation of cell migration. G-actin sequestration affects F-actin polymerization in the lamellipodium and modifies the ability of endothelial cells, fibroblasts and myocytes to move within the damaged area (Malinda et al., 1999).
• Stimulation of angiogenesis. Formation of capillary-like structures through endothelial migration and secondary VEGF-expression effects.
• Anti-inflammatory profile. Modulation of macrophage function supports a shift from the M1 phenotype toward M2.
• Anti-apoptotic profile. Cytoskeletal stabilization under ischemic and hypoxic conditions limits cardiomyocyte death (Bock-Marquette et al., 2004).
• Activation of progenitor cells. Smart et al. (2007) described reactivation of epicardial progenitor cells in cardiac muscle regeneration.

All these effects are reported in preclinical studies. Clinical translation remains limited: three RegeneRx programs using Tbeta4 fragments (RGN-259, RGN-137, RGN-352) did not result in drug registration. A deeper comparison of TB-500 and BPC-157 mechanisms is available in the article comparing two regenerative peptides.

RUO pen vs pharmaceutical pen – the fundamental difference

The visual similarity between an RUO pen and pharmaceutical pens (Ozempic, Wegovy, Mounjaro) can create confusion. The difference is not in the applicator itself, but in the substance, documentation and legal purpose.

Applications in scientific research

TB-500 PEN is research material for areas well documented in the tissue-regeneration literature.

• Cardiac muscle injury – the best documented area for Tbeta4 (Bock-Marquette 2004, Smart 2007). RegeneRx clinical program RGN-352.
• Corneal and ocular epithelial injury – RegeneRx RGN-259 reached phase III in dry-eye syndrome and corneal wounds.
• Skin wound healing – Malinda et al. (1999); RegeneRx RGN-137 program in epidermolysis bullosa.
• CNS ischemic stroke – regeneration after cerebral ischemia, neuronal protection and induction of neurogenesis.
• Muscular dystrophy – skeletal muscle regeneration in genetic models (mdx).
• Reactivation of progenitor cells – modulation of precursor pools in the heart, muscle and neural tissue.

One Peptides quality specification

The TB-500 pen follows the standard analytical control process for research material, with additional documentation that clearly identifies the peptide sequence in the batch.

• HPLC >=98% – chromatographic purity confirmed in the HPLC spectrum for each batch; a dominant main peak and no significant impurities.
• MS confirmation – the measured mass matches the theoretical mass of the sequence (~880 Da for the LKKTETQ fragment or ~4961 Da for full Tbeta4).
• COA per batch – a public certificate of analysis with peptide sequence, theoretical and measured mass, salt form, HPLC chromatogram, MS spectrum, solution concentration, synthesis date and batch number.
• Cold chain 2-8°C – cold-chain handling from synthesis to delivery. TB-500 in solution is less stable than BPC-157, which requires strict refrigerated handling.
• Batch traceability – batch number shown in three places: pen label, invoice and COA.

Details of the QA process, example COAs and a description of each of the five control stages are available under quality testing and certificates.

Working with a pre-dissolved pen in a laboratory protocol

The following description refers to general work with a pre-dissolved pen in the context of a laboratory research reagent. It is not an instruction for administration to humans or animals.

No reconstitution step. The pen contains a ready-made peptide solution – no bacteriostatic water, no mixing and no waiting for lyophilizate dissolution. A full step-by-step guide for lyophilizates is available in the article how to dissolve peptides – the pen bypasses this stage.

Concentration in the pen. 20 mg of peptide in a typical pen solution volume of around ~2 mL (exact volume specified in the batch COA); the resulting concentration of approximately ~10 mg/mL falls within the higher range of practical peptide concentrations.

Sampling the solution. Typically with an insulin syringe or microliter applicator, according to the laboratory protocol. Each sample retains the starting concentration.

Stability after first opening. Conservatively 14-28 days at 2-8°C. TB-500 in solution is less stable than BPC-157 and requires strict refrigerated handling. Freeze-thaw cycles should be strictly avoided. Protect from light and temperatures above 25°C.

Sampling hygiene. Sterile technique, clean tools and disinfection of the pen membrane with isopropyl alcohol before each sampling.

The peptide calculator helps calculate the sampling volume for a planned peptide mass.

Regulatory status and WADA

TB-500 PEN in the One Peptides catalogue is a chemical reagent intended exclusively for laboratory research (Research Use Only). Under EU pharmaceutical law it is not a medicinal product or dietary supplement, and it has no EMA, FDA or national regulatory authorization.

WADA status – prohibited year-round for athletes subject to anti-doping control.

TB-500 (Thymosin Beta-4 and its fragments) is included on the World Anti-Doping Agency Prohibited List in category S2 (peptide hormones, growth factors, related substances and mimetics). The prohibition applies in-competition and out-of-competition – without exception, throughout the calendar year. Athletes subject to anti-doping control must not use TB-500 at any time, regardless of form (lyophilizate, solution, pen) and regardless of whether the batch contains the LKKTETQ fragment or full Tbeta4.

Verification of current status in the applicable WADA list rests with the researcher and athlete.

Frequently asked questions

How does TB-500 PEN differ from lyophilized TB-500 in a vial?

The pen is pre-dissolved, so there is no reconstitution step. A lyophilized vial (5 mg, 10 mg) requires solvent addition before sampling. The pen contains 20 mg of peptide in a ready-made solution. A lyophilizate offers greater flexibility in selecting the starting concentration, while the pen eliminates reconstitution and reduces solvent-error risk.

Is TB-500 PEN a medicine?

No. Despite visual similarity to pharmaceutical pens (Ozempic, Wegovy, Mounjaro), TB-500 PEN is an RUO research reagent. It has no EMA or FDA authorization, no patient leaflet, no registered indications and no dietary supplement status. The label clearly states: “For research use only. Not for human use”.

Can an amateur athlete use TB-500?

No, if they are subject to anti-doping control, regardless of level (amateur, masters, veteran). TB-500 is on the WADA Prohibited List in category S2, with no exception year-round. Federations that follow the World Anti-Doping Code apply the same list as WADA; detection of TB-500 in a sample constitutes an anti-doping rule violation.

How long does the pen retain activity after first opening?

At 2-8°C, conservatively 14-28 days. TB-500 in solution is less stable than BPC-157 and requires strict refrigerated handling. The pen is not intended to be frozen or thawed. Protect from light and temperatures above 25°C.

Does TB-500 PEN require reconstitution?

No. The pen contains a solution ready for microliter sampling from the moment the package is opened. No reconstitution means less solvent-error risk and no need to measure water.

How does TB-500 20 mg PEN differ from BPC-157?

They differ mechanistically. TB-500 acts mainly through G-actin sequestration (cell migration, angiogenesis, cytoskeletal protection). BPC-157 acts more broadly through NO/cGMP, VEGF/VEGFR2 and growth factors. The second difference: TB-500 is on the WADA Prohibited List (S2), while BPC-157 is on the monitoring list.

Parent category: Peptides for Regeneration organize RUO reagents associated with recovery-related research contexts.

References

1. Goldstein AL et al. (2012). Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications
2. Bock-Marquette I et al. (2004). Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair
3. Smart N et al. (2007). Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization
4. Malinda KM et al. (1999). Thymosin beta4 Accelerates Wound Healing
5. Sosne G et al. (2018). Thymosin beta 4 and the eye: the journey from bench to bedside
6. World Anti-Doping Agency. The Prohibited List

Chemical reagent intended exclusively for laboratory research (Research Use Only). TB-500 PEN in the One Peptides catalogue is not a medicinal product, dietary supplement or food product, regardless of applicator format. All information in this description is educational and scientific, referring to findings reported in experimental literature; it is not medical advice and does not suggest clinical use. The WADA status of TB-500 (S2 Prohibited List, year-round) excludes pen use by athletes subject to anti-doping control at any time of the calendar year.