Thymosin beta-4

An actin sequestering protein present in most human cells that promotes cell migration and tissue repair in animal models, and the source of the fragment sold as TB-500.

What it is

Thymosin beta-4 is a 43 amino acid protein found in almost every human cell and in wound fluid. Its main job is to bind actin monomers, which controls how quickly a cell can rebuild its internal scaffolding and move.

That matters in repair, because migration is the first thing cells do at an injury site. In animal models the protein has accelerated healing in skin, cornea and heart tissue, and reduced scarring in some settings.

TB-500 is not the same thing

TB-500 is a short synthetic fragment containing the actin binding region, not the full protein. It is easier and cheaper to make, which is why it dominates the market, but the two are not interchangeable and most of the published biology was done with the full length protein.

Thymosin beta-4 has been through early clinical trials for pressure ulcers, venous stasis ulcers and dry eye. It has not been approved for any indication, and human trials of TB-500 specifically are essentially absent.

Practical notes

It appears on the World Anti-Doping Agency prohibited list, so it is disqualifying for tested athletes at all times.

Baseline catalogs a compounded BPC-157 and TB-500 blend as part of a physician-guided plan, and the therapy page states plainly how thin the human evidence is for both peptides.

Baseline offers a compounded BPC-157 and TB-500 blend through a physician-guided program. A consult with a Baseline consultant comes first, and an independent licensed provider decides whether it is appropriate.

References

  1. Goldstein AL, et al. Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005.
  2. Philp D, Kleinman HK. Animal studies with thymosin beta 4, a multifunctional tissue repair and regeneration peptide. Ann N Y Acad Sci. 2010.
  3. World Anti-Doping Agency. Prohibited list, section S2: peptide hormones, growth factors and related substances.