What tests found in animals and people
TB-500 is a lab copy of one section of thymosin beta-4, a protein in your cells.
You'll learn which tests used that section, which used the whole protein, and what each test found.
What might TB-500 do near an injury?
TB-500 copies a section of the thymosin beta-4 protein. This page tracks the short form and full thymosin beta-4 through the research. Actin grips the copied section and gives cells their form and motion [5]. That's an early clue, not proof that your injury will heal.
An X-ray image showed one full thymosin beta-4 protein gripping one actin protein in a 1:1 match [1]. The image used 1 helper protein and showed a width of 2 parts in ten billion of a meter. Another 1:1 image confirmed where the proteins met [1]. I'd ask whether your clinic's claim came from the short form or the complete protein.
In injured animals, cells reached damaged areas, more blood vessels formed, and fewer cells died after full thymosin beta-4 [5]. A review tied those findings to repair with less scar tissue [9]. No good human comparison shows that the short form does all of that [5]. Full thymosin beta-4 findings can't predict what your injury will do.
How much of thymosin beta-4 does TB-500 contain?
Thymosin beta-4 is the whole protein, with forty-three joined parts found throughout your body [5]. The thymosin beta-4 protein has a listed lab weight of about 4963 daltons. TB-500 copies only a seven-part section of thymosin beta-4 [5]. Those lab weights separate the forms, but they can't guide your care.
Sellers use TB-500 for the small form weighing 889 daltons. Most repair studies instead used the whole thymosin beta-4 protein, which weighs 4963 daltons [7]. Those studies can't promise the same effects from TB-500 in you [5][7]. The full thymosin beta-4 protein can shed another small part; TB-500 can't produce it because the copy comes from elsewhere [5].
What closed faster in TB-500 and thymosin beta-4 wound research?
The clearest wound result came from rats, not people. With full thymosin beta-4, rat skin closed by 42% at 4 days and 61% at 7 days; salt-water wounds shrank at least 11% by day 7. In a dish, skin cells crossed a wound-like gap two to three times farther after 10 trillionths of a gram [3]. That movement may help close a gap, but it can't forecast your skin result.
Other thymosin beta-4 animal tests covered muscle, heart, brain, and hair repair [5]. One review found cells filling damaged areas, less scar tissue, and more small blood vessels [5]. Platelets, which help blood clot, released the protein near an injury; immune cells did the same. Another skin review reported like results with thymosin beta-4 [10].
Nearly all those tests used the whole thymosin beta-4 protein. They didn't show TB-500 healing people in the same way. No finished human comparison has confirmed those gains for the small form [6]. Keep that limit handy when a clinic sounds certain about your skin or another injury.
Has TB-500 ever been compared with BPC-157?
BPC-157 is another lab-made protein piece discussed for injuries. No human study has put it against TB-500. A 2026 sports-medicine review found repair signs in animals, not people [13]. It warned that little is known about human harm, so saying either one works better for your injury would be guesswork.
The two pieces may affect cells in different ways. TB-500 copies a thymosin beta-4 section that grips actin, which may let cells fill a damaged area [1][5]. BPC-157 animal work centers on new blood vessels and keeping cells alive. Neither animal record proves a benefit for you, and the TB-500 pharmacy law page explains a separate concern.
What happened in the heart, stroke, and hair tests?
After researchers blocked one artery, full thymosin beta-4 helped mouse heart cells survive and reach the damaged area [2]. The mice then had better heart function. That doesn't tell us what your heart would do. A pig test of thymosin beta-4 found no benefit after blood flow was cut off, then restored.
Starting 24 hours after a stroke, rats got 2, 12, or 18 milligrams for every kilogram the rat weighed, followed by four more treatments every three days. The 2 and 12 groups improved from day 14 through day 56. The 18 group didn't improve [4]. The uneven results mean that more wasn't always better in this rat test [4].
Hair grew more in rats and mice given very small amounts of thymosin beta-4 [11]. Stem cells are starter cells that can make new tissue near a hair root. Thymosin beta-4 made those cells more active in the animals, and another thymosin beta-4 mouse test found more hair. Neither test shows what the small form would do to your hair.