Healing & Recovery
TB-500 and Thymosin Beta-4: What Has Actually Been Studied?
The short answer
Eighteen human trials of thymosin beta-4 have ever been registered on ClinicalTrials.gov, but they studied heart attacks, dry eye, corneal wounds, pressure ulcers, and a rare skin disease — not tendons. Only one of those 18 was registered specifically as 'TB-500,' the fragment version sold online; it opened in 2026 to study cardiovascular biomarkers, not soft-tissue injury. The tendon-healing claim behind TB-500's popularity comes from a single 2026 rat study comparing it to BPC-157 in a surgically cut Achilles tendon. No human trial has ever tested thymosin beta-4 or TB-500 on a tendon, ligament, or muscle injury.
Quick answers
- What is it?
- TB-500 is marketed as a fragment of thymosin beta-4, a naturally occurring protein involved in cell movement and tissue repair, sold online as a recovery peptide.
- Why are people interested in it?
- TB-500 is popular among athletes for tendon and injury recovery, so buyers want to know whether any real human trial supports that specific use.
- What has actually been studied?
- A full ClinicalTrials.gov search of 18 registered thymosin beta-4 human trials (cardiac repair, dry eye, chronic skin ulcers), verification of a template TB-500 registry record, and the single published rat study testing TB-500 on a surgically cut Achilles tendon.
- How strong is the evidence?
- Essentially no human evidence for tendon use: none of the 18 real registered human trials tested tendon, ligament, or muscle injury, the one record specifically named "TB-500" is a self-declared fictional template, and the only tendon-healing data is a single 32-rat study.
- What don't we know yet?
- Whether TB-500 or thymosin beta-4 helps a human tendon heal, whether the rat biomechanical result replicates, what a safe human dose would be, and whether TB-500 and full-length thymosin beta-4 behave the same way.
- Where can I read the original research?
- Sources at the bottom of this page: Biçer O, Adanir O, Güleryüz Y, et al., Joint Diseases and Related Surgery, 2026; and ClinicalTrials.gov, NCT00382174, RegeneRx Biopharmaceuticals.
The short answer: TB-500 is marketed as a fragment of thymosin beta-4, a naturally occurring protein studied in various forms for three decades. According to ClinicalTrials.gov, thymosin beta-4 has been tested in 18 registered human trials — for heart attacks, dry eye disease, corneal wounds, pressure ulcers, venous ulcers, and a rare inherited skin disorder. None studied a tendon, ligament, or muscle injury. Only one of those 18 trials is registered under the specific "TB-500" name, and it opened in 2026 to study cardiovascular biomarkers. The tendon-healing claim that drives TB-500's popularity as a recovery supplement traces to a single 2026 rat study.
What the research shows
Thymosin beta-4 has a real, if narrow, human trial record
Thymosin beta-4 (Tβ4) is a naturally occurring 43-amino-acid protein involved in cell movement and tissue repair signaling. "TB-500" as sold online is typically a shorter synthetic fragment or analog marketed under that name. Searching ClinicalTrials.gov for "thymosin beta-4," "TB-500," and "TB500" together returns 18 registered interventional human trials. They cluster into a few groups, according to ClinicalTrials.gov:
- Cardiac repair. Several completed and ongoing Phase 2 trials of injectable recombinant human Tβ4 (branded NL005) in patients with acute myocardial infarction, sponsored by Beijing Northland Biotech, ranging from 62 to 189 participants.
- Corneal and ocular disease. A cluster of trials — including three Phase 3 "ARISE" studies with up to 700 participants each — testing a Tβ4-based eye drop (RGN-259) for dry eye syndrome and neurotrophic keratopathy, sponsored by ReGenTree.
- Chronic wounds and rare skin disease. Completed Phase 2 trials testing injectable Tβ4 in patients with pressure ulcers (72 participants) and venous stasis ulcers (72 participants), plus a terminated trial in epidermolysis bullosa, a genetic blistering skin disorder.
- Healthy-volunteer pharmacokinetics. Several Phase 1 dose-escalation studies in China assessing safety and tolerability of recombinant Tβ4 in healthy adults.
Not one of these 18 trials tested tendon, ligament, or muscle injury. The closest any of them come to musculoskeletal or soft-tissue repair is chronic skin ulceration.
The name "TB-500" belongs to exactly one trial
One registry record names "TB-500" specifically rather than full-length thymosin beta-4 — NCT07487363 — and it is not a real trial. Its own brief summary reads: "This fictional study is an example of a ClinicalTrials.gov-style record." It is one of three template records sharing a single sponsor (Hudson Biotech), site, investigator contact, and an identical primary-completion date.
So the accurate count is zero. No human trial has ever tested TB-500. The seventeen genuine registered trials all studied full-length thymosin beta-4, a longer and different molecule from the 17-23 fragment sold under the TB-500 name, and none of them studied tendon or muscle recovery.
The tendon-healing evidence is one rat study
The single piece of research connecting TB-500 or thymosin beta-4 to tendon repair is a 2026 study published in the Joint Diseases and Related Surgery journal. Researchers surgically transected the Achilles tendon in 32 Sprague-Dawley rats and randomized them into four groups: untreated control, BPC-157, TB-500 (dosed as "synthetic thymosin beta-4" at 60 µg/kg/day), and a combination of both peptides, given by daily intraperitoneal injection for four weeks. At four weeks, the TB-500 group showed a statistically significant increase in maximum load to failure compared to controls (P<0.05) — a biomechanical advantage the BPC-157-only group did not reach on its own. The TB-500 group also had significantly better histopathology scores (Bonar score, P=0.016; Movin score, P=0.017) indicating improved tendon architecture and collagen organization. Combining both peptides produced no additional benefit over TB-500 alone, which the authors suggested may reflect the two compounds converging on the same repair pathways. According to PubMed, the study's own authors described this as an "exploratory" and "preliminary" finding requiring "dose-optimization and longer-term studies" before any translational claim could be made. DOI
That is the entire published evidence base, in any species, connecting TB-500 specifically to tendon repair: one rat study, 32 animals, four weeks of follow-up.
What we don't know yet
Whether TB-500 or thymosin beta-4 helps a human tendon heal. No human trial — registered, recruiting, completed, or otherwise — has ever tested this question directly.
Whether the rat biomechanical result replicates. A single 32-animal study with a four-week endpoint is not confirmed by any independent replication, in rats or any other species.
What a safe human dose would be. There is no dose-finding data for TB-500 in humans at all — the one registry record naming it is a template example, not a study.
Whether TB-500 (the fragment) and full-length thymosin beta-4 behave the same way. Most of the 18 registered human trials tested full-length recombinant Tβ4, not the shorter fragment marketed as TB-500; whether findings from one apply to the other has not been established in a published human trial.
Long-term safety with the injection regimens used by recreational and athletic users. Every completed human trial used tightly controlled, short-duration dosing under medical supervision for a specific disease — not the repeated, self-administered use pattern common among people taking TB-500 for recovery.
Sources
- Biçer O, Adanir O, Güleryüz Y, et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Joint Diseases and Related Surgery, 2026;37(3):822-837. DOI
- ClinicalTrials.gov. NCT07487363 — a template record that self-identifies as fictional; cited here only as an example of what appears in the registry. Retrieved August 2026.
- ClinicalTrials.gov. NCT00382174 — Thymosin Beta 4 in the Treatment of Patients With Pressure Ulcers. Sponsor: RegeneRx Biopharmaceuticals. Retrieved August 2026.
- ClinicalTrials.gov. NCT03937882 — RGN-259 Ophthalmic Solution for Dry Eye (ARISE-3). Sponsor: ReGenTree, LLC. Retrieved August 2026.
- ClinicalTrials.gov. Full search of 18 registered thymosin beta-4 / TB-500 human trials. Retrieved August 2026.
Article records maintained via PubMed. Peptide Proof reports what studies found. It does not provide medical advice, dosing guidance, or treatment recommendations.
Topic: Recovery & Tissue Research | Evidence Index: tb-500
Sources
- Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study
- Joint Diseases and Related Surgery, 2026 · n=32 · DOI
- A Phase 1/2, Randomized, Double-Blind, Placebo-Controlled, Sequential Dose-Escalation Study of TB-500 in Adults With Stable Atherosclerotic Cardiovascular Disease
- ClinicalTrials.gov, 2026 · n=80
- A Randomized, Double-Blind, Placebo-Controlled, Dose-Response Study of the Safety and Efficacy of Thymosin Beta 4 in the Treatment of Patients With Pressure Ulcers
- ClinicalTrials.gov, 2006 · n=72
- A Multi-Center, Randomized, Double Masked, Placebo Controlled Clinical Study to Assess the Safety and Efficacy of RGN-259 Ophthalmic Solutions for the Treatment of Dry Eye (ARISE-3)
- ClinicalTrials.gov, 2019 · n=700
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