What it is
TB4-FRAG is a peptide made of 4 amino acids, known in research as Ac-SDKP. The body makes it naturally by cutting it off the front end of thymosin beta-4. It can also be made in a lab. It is a different piece of thymosin beta-4 than TB-500, and the two do not work the same way. ACE, the enzyme that common blood pressure drugs called ACE inhibitors block, is what breaks TB4-FRAG down. So people taking ACE inhibitors have higher levels of it. Other names: Ac-SDKP, Thymosin Beta-4 Fragment, Acetyl-N-Ser-Asp-Lys-Pro.
What researchers study it for
- Heart scarring in rats
- Scarring in kidney, lung, and liver in animals
- Blood-forming stem cells in bone marrow
- How ACE inhibitors protect the heart
What the studies found
1. It reversed heart scarring in rats with high blood pressure.
A 2003 study used rats that had high blood pressure and heart scarring for 8 weeks. They then got TB4-FRAG under the skin for another 8 weeks. Scar collagen in the heart's main pumping chamber dropped back, with a bigger drop at the higher dose. Two signals that drive scarring, TGF-beta and CTGF, went down. Blood pressure responses did not change, so the effect was not from blocking ACE. Rat data only.
2. A blood pressure drug raised its levels in people.
This 1996 study gave people an ACE inhibitor. TB4-FRAG levels in their blood rose sharply, because ACE is the main enzyme that breaks it down. The study describes TB4-FRAG as a natural signal that keeps blood-forming stem cells in bone marrow in a resting state. Human data, but it measured natural levels, not an injected dose.
3. A review found less inflammation and scarring across animal studies.
This 2018 review sums up animal studies of TB4-FRAG in the heart, kidney, and other organs. Fewer immune cells moved into damaged tissue, and less scar tissue formed. The authors suggest this may explain part of how ACE inhibitors protect organs beyond lowering blood pressure. Review of animal data.
How much research exists
Many animal studies on scarring and stem cells. No human trial of TB4-FRAG given as a treatment has been published. Human data comes only from studies of ACE inhibitors raising natural levels.
Facts
- Formula: C20H33N5O9
- Weight: 446.5 g/mol
- CAS number: 32795-96-3
- Sequence: Ac-Ser-Asp-Lys-Pro
- Time in the blood: minutes. ACE breaks it down quickly.
- Storage: freeze the dry powder. Keep mixed solution in the fridge.
Legal status
Not approved by the FDA or any other agency for human use.
For research use only. Not for human use. Nothing here is medical advice.