What happened in wound tests
TB-500 is a short protein piece studied for wound repair.
You will see findings from skin and eye wounds. Most good results came from full thymosin beta-4 in animals or cells. People did not receive the short piece.
Rat wounds closed faster with the full protein
The main TB-500 repair claim rests on a rat test of the full thymosin protein. Scientists treated wounds that went through the skin with thymosin beta-4. They put it on the wound or used a belly injection. New skin cover rose by 42% at 4 days and up to 61% at 7 days, against salt water. Wound closing rose at least 11% by day 7. The rats also formed more collagen and small blood vessels [3]. Collagen is the firm protein that gives skin support.
In a lab dish, just 10 picograms made skin cells travel two to three times their usual distance [3]. A picogram measures a speck of weight. Those moving skin cells could help cover an open spot, which gave scientists a clear reason to study thymosin beta-4 for wounds.
The tests used rats and single cells, not people. They used full thymosin beta-4 rather than the seven-part TB-500 chain. You can't take a human benefit from them. The TB-500 study page puts this result beside the other work.
Skin and eye surfaces grew back faster in some tests
The best-known finding was faster growth of new cells across a wound [5]. Those surface cells must move into the open spot and grow. Actin helps them move, and thymosin beta-4 holds actin until it is needed [1].
The cornea, the clear front of your eye, has also been studied. Eye drops called RGN-259 used full thymosin beta-4 in finished dry-eye trials [7]. In 2025, scientists linked two small thymosin pieces. Eye-surface wounds then closed better than after the usual single piece [16]. That test didn't show the short piece healing a person's eye.
The full protein changed scars and blood-vessel growth
Wound tests suggest that full thymosin beta-4 changes the way a sore place closes. The protein lowered the count of cells that tighten a scar. It also grew small blood vessels inside healing tissue [5]. That could leave a softer scar and bring more blood to the injured area.
New blood vessels also raise a cancer concern. A cut needs them for repair, while a tumor might take the same blood supply for growth. The TB-500 side effects and safety page explains the concern [5]. Scientists have not found cancer caused by the fragment in people.
Work from 2024–2026 focused on carrying and finding peptides
Recent work asks how the full protein can stay beside a wound. A 2025 team packed thymosin beta-4 into tiny sacs made by cells, then put them in a gel. The gel slowed bleeding, fought germs, and helped wounded tissue form blood vessels [12]. Another 2025 test paired thymosin beta-4 with selenium, and diabetic sores healed better [13].
A 2024 lab test measured TB-500 along with what remained after it broke apart. The work used lab-grown cells and rats [15]. It was made for sports drug checks. Researchers measured the short piece but did not treat people. The finding tells you nothing about healing.
Human wounds have not been shown to heal with TB-500
Full thymosin beta-4 helped skin and eye surfaces close in animal and surface tests. It raised collagen, helped blood vessels grow, and moved skin cells at just 10 picograms [3]. Newer work put the protein in cell-made sacs inside gels [12]. Other work linked two small protein pieces [16]. No human wound trial has proved that TB-500 works [5].