TB-500 explained: what the thymosin beta-4 research really shows

• What it is: TB-500 is the name used for a lab-made version of thymosin beta-4 (Tβ4), a 43-amino-acid protein found throughout the body's tissues [1].
• The headline results: in rats, new skin covered 42% more of a wound by day 4 and up to 61% more by day 7 [3]. In mice after a heart attack, it improved heart function [4].
• A 2026 tendon study: rats given TB-500 had significantly stronger repaired Achilles tendons at four weeks [9].
• The name trap: “TB-500” is sold as two different molecules. The lab report tells you which one is in the vial.

Start with thymosin beta-4. It's a 43-amino-acid protein with a molecular weight of about 4,963, and the most abundant member of its family in mammal tissue [1]. Its day job is holding on to actin, the protein cells use as scaffolding and as “legs” when they move [1]. When tissue gets hurt, platelets and immune cells release it right at the injury [2].

TB-500 is the trade name for a lab-made version. Here's the part most sites skip: the name is used for two different molecules.

• Full-length thymosin beta-4: all 43 amino acids, molecular weight about 4,963.
• The short fragment: just seven amino acids (Ac-LKKTETQ), molecular weight about 889. It copies the stretch of Tβ4 that grabs actin [10].

They're related, but they're not the same thing — one is more than five times heavier than the other. That's why every TB-500 lot we release gets its identity checked by mass spectrometry, and the certificate shows which molecule the lab found.

Think of actin as scaffolding that cells build and tear down all the time. Tβ4 keeps actin “bricks” in reserve, so a cell can rebuild its frame fast and crawl where it's needed [1]. In studies, Tβ4 also:

• helped new blood vessels sprout [1][5],
• helped heart-muscle cells survive by switching on a survival enzyme called Akt [4],
• and lowered the number of scar-forming cells in wounds, pointing to less scarring [2].

A 2003 study found that the seven-amino-acid actin-binding stretch does much of the work. In blood-vessel tests it matched the full protein's activity, while fragments missing any part of it did nothing [1].

• Skin wounds (rats, 1999). New skin covered 42% more of the wound by day 4 and up to 61% more by day 7. Wounds also shrank at least 11% more, with more collagen and new blood vessels [3].
• Hearts (mice, 2004 and 2007). After a blocked heart artery, Tβ4 improved heart-cell survival and heart function [4]. A 2007 study found it woke up dormant cells from the heart's outer layer, which then turned into blood-vessel-building cells [5].
• Hair (rats and mice, 2004). It made hair grow faster by activating hair-follicle stem cells [6].
• Tendons (rats, 2026). In 32 rats with repaired Achilles tendons, the TB-500 group's tendons held significantly more load before failing at four weeks, with better-organized tissue. BPC-157 trended the same way, and combining the two added nothing extra in this study [9].
• Eyes (people, 2015). In a Phase 2 trial with 72 people with dry eye, Tβ4 eye drops missed both main goals. But discomfort in a dry-air challenge was 27% lower than placebo at day 28, corneal staining improved, and no adverse events were reported [7]. By 2023, dry-eye trials had reached Phase 3 [8].

• Most of the big results are for full-length Tβ4, not the short fragment. In 2024, researchers noted that the biological effects of the fragment itself hadn't been documented, and that its wound-healing activity may come from a breakdown product, Ac-LKKTE [10].
• Human data are limited to eye drops so far [7][8]. A 2026 sports-medicine review notes that rigorous human safety data for Tβ4 and TB-500 are scarce [12].
• It isn't approved anywhere for use in people. We supply it for laboratory research only.

With TB-500, the label alone doesn't tell you much. A 2023 lab analysis of products sold online as “TB500” and “TB1000” found their contents didn't consistently match their descriptions [11].

So before any batch goes on sale, an outside lab tests it:

• Identity by mass spectrometry. The certificate names the molecule the lab found and shows the mass spectrum behind it.
• Purity by HPLC. The exact figure for that lot, to two decimals. Never “99%+.”

Every TB-500 batch we've released is on the TB-500 lab-reports page, with its signed certificate. If a vial doesn't match its report, test it at any lab you like and we'll refund it in full.

Thymosin beta-4 is one of the body's own repair proteins, and the animal research on wounds, hearts and hair is genuinely striking. The evidence for the short fragment is thinner, and human data are limited to eye drops. Whatever you study, check the certificate for the molecule, not just the name.