TB-500

Dosing from the Literature

Published for tendon repair: nothing on TB-500 in people; one rat study gave 60 µg/kg a day into the abdomen for 30 days after Achilles tendon repair, using a vendor product the authors call synthetic thymosin β4 (Biçer et al., 2026). Not published: any human dose of the fragment.

The systemic (SubQ / IM) doses below are what online guides and a telehealth clinic describe. No study has tested a dose of the fragment in people (FDA’s 2026 review), and the horse studies were doping tests of a single 10 mg dose (Ho et al., 2012; Kwok et al., 2013). The ophthalmic and IV rows are the parent protein’s trial doses, listed for comparison; they are not TB-500 doses.

What It Is

TB-500 is a synthetic seven-amino-acid peptide, Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ, 889 Da): residues 17–23 of thymosin β4 with an acetyl group added at the front, a form not known to occur in the body. When doping-control labs analysed TB-500 in 2012, a customs-seized vial and a veterinary product given to racehorses, this fragment was the only active substance they found. FDA’s 2026 review defines TB-500 the same way, and says it plainly: “thymosin beta-4 and TB-500 are not the same substance.”

The parent, thymosin β4 (Tβ4; proposed INN timbetasin), is a naturally occurring 43-amino-acid protein (4,963 Da) sequenced from bovine thymus by Allan Goldstein’s group in 1981. It is present in virtually every mammalian cell and is released by platelets at sites of injury. TB-500 is its central actin-binding stretch. Vials don’t always match the name: one large US vendor listed full-length Tβ4 as “TB-500”, a survey of 2010–13 black-market products found Tβ4 itself, and a 2023 analysis reported TB-500 products whose content didn’t match their descriptions. No survey says how often a vial holds the fragment, the full protein or something else.

Functionally, full-length Tβ4 is the most abundant G-actin sequestering protein in mammalian cells. It binds monomeric (globular) G-actin 1:1 and holds it in a pool available for rapid polymerization into filamentous F-actin when needed for cell migration, wound contraction, angiogenesis (new blood vessel growth), and cytoskeletal remodeling. Whether the seven-amino-acid fragment does the same on its own is unproven: FDA’s 2026 review calls it a hypothesis.

The human trials quoted for TB-500 all used full-length Tβ4, developed by RegeneRx Biopharmaceuticals (now affiliated with HLB Therapeutics) as RGN-259 eye drops (dry eye, neurotrophic keratopathy), RGN-137 skin gel (chronic wounds, epidermolysis bullosa) and RGN-352 for IV use (a Phase 1 in healthy volunteers; its heart-attack trial was withdrawn before enrolling anyone). No study has given the fragment to people. That is the gap this page is about: a parent protein with real, mixed trial data, and a fragment, sold under the parent’s reputation, with none.

Mechanism of Action

Everything in this section was shown for full-length thymosin β4, the parent protein, unless it says otherwise. TB-500 is the parent’s actin-binding stretch; FDA’s 2026 review treats its actin binding on its own as a hypothesis, and no study has traced these effects to the fragment.

• G-actin sequestration — Tβ4 binds monomeric G-actin in a 1:1 complex, which keeps it from polymerizing into filaments (Safer et al., 1991); this makes it an actin buffer, holding a pool of monomers until the cell needs filaments (Huff et al., 2001). TB-500 carries the LKKTET actin-binding motif; whether the fragment alone holds actin as the whole protein does is a hypothesis (FDA’s 2026 review). After injury, platelets, macrophages and other cells release Tβ4, which promotes cell migration (Goldstein et al., 2012).
• Cell migration — Tβ4 promoted the migration of endothelial cells in lab tests (Philp et al., 2003), of heart cells in embryonic and postnatal heart tissue (Bock-Marquette et al., 2004) and of skin cells in the wounds of aged mice (Philp et al., 2003).
• Angiogenesis (vessel formation) — In lab tests Tβ4 promoted endothelial cell migration, tube formation and vessel sprouting (Philp et al., 2003), and in mice it was essential for coronary vessel development (Smart et al., 2007).
• Anti-inflammatory modulation — Tβ4 reduced inflammation in dermal wound tests (Philp et al., 2003), and a 2010 review lists the modulation of cytokines and chemokines among its activities (Crockford et al., 2010).
• Apoptosis (programmed cell death) reduction — In cultured heart-muscle cells Tβ4 formed a complex with PINCH and integrin-linked kinase (ILK) that activated the survival kinase Akt and improved cell survival; after coronary artery ligation in mice it improved early heart-muscle survival and heart function (Bock-Marquette et al., 2004).
• Progenitor cell activation — In adult mice, priming with Tβ4 before a heart attack reactivated epicardial progenitor cells, which gave rise to new heart-muscle cells after it (Smart et al., 2011); given after the heart attack, Tβ4 did not reprogram them (Zhou et al., 2012).
• Hair growth — Tβ4 promoted hair growth in normal and aged rodents (Philp et al., 2004). That work used full-length Tβ4; no hair study of the fragment has been published.
• Corneal epithelial repair — The rationale for RGN-259 eye drops (full-length Tβ4): in animal models of eye injury, Tβ4 healed the cornea faster and more completely than saline or the prescription drugs doxycycline and cyclosporine (Sosne & Kleinman, 2015).
• The fragment itself — In lab dishes the actin-binding motif alone matched full Tβ4 in endothelial cell migration at about 50 nM, and non-acetylated LKKTETQ helped wound repair in aged mice (Philp 2003). The acetylated molecule sold as TB-500 has been tested once: in a 2024 fibroblast scratch assay it showed no wound-healing effect, while one of its breakdown products, Ac-LKKTE, did (Rahaman 2024).
• Anti-fibrotic signal — A 2012 review reports that Tβ4 lowers the number of myofibroblasts, the cells that lay down scar, in wounds, with less scarring and fibrosis (Goldstein et al., 2012).

What the Research Shows

Nearly all of this research is on full-length thymosin β4. The few studies of TB-500 itself come first.

• What is in TB-500 (Esposito 2012; Ho 2012; Kwok 2013) — Doping-control labs identified Ac-LKKTETQ as the only active substance in a customs-seized TB-500 vial and in a veterinary TB-500 given to horses (10 mg); no full-length Tβ4. In horses it was gone from blood within 6–10 hours, broken down from its tail end (Ac-LKKTET, Ac-LKKTE … Ac-LK).
• TB-500 itself in a wound assay (Rahaman 2024) — The first study of Ac-LKKTETQ as such: its metabolite Ac-LKKTE sped fibroblast wound closure; TB-500 did not. In rats Ac-LK was the main metabolite, and Ac-LKK was measurable for 72 hours.
• Non-acetylated LKKTETQ (Philp 2003) — Applied to punch wounds in 26-month-old mice, the free heptapeptide helped repair about as well as full Tβ4.
• Discovery and characterization of the parent (Goldstein group, 1981–1999) — Original isolation of Tβ4 from thymus. Over the following two decades, characterization as the dominant G-actin sequestering protein, tissue distribution mapping, and early wound-healing evidence in rodent dermal models.
• Cardiac regeneration (Bock-Marquette et al., Nature 2004) — In a mouse myocardial infarction model, Tβ4 administered after infarction reduced myocyte loss, promoted cell migration in the injured heart, and improved cardiac function. This launched the cardiac development program.
• Cardiac progenitor reactivation (Smart et al., Nature 2011) — In adult mice primed with Tβ4 before a heart attack, epicardial progenitor cells made new heart-muscle cells; given after the heart attack, Tβ4 did not reprogram them (Zhou et al., 2012).
• Corneal wound healing (Sosne et al., 2002; Sosne et al., 2022) — In mice with alkali-burned corneas, Tβ4 drops sped re-epithelialization and reduced inflammation (Sosne et al., 2002). In the one published Phase 3, in people with neurotrophic keratopathy, 6 of 10 on the drops and 1 of 8 on placebo healed completely at 4 weeks (p = 0.0656), missing the main endpoint (Sosne et al., 2022); a Cochrane review rated this low-certainty evidence that the drops may not increase healing (Kruoch et al., 2025).
• Dry eye Phase 2 (two trials, 2015) — In 9 patients with severe dry eye, 0.1% Tβ4 drops improved signs and symptoms at day 56 (Sosne, Cornea 2015). In 72 patients in the controlled-adverse-environment model, neither primary endpoint differed from placebo, though some secondary ones did (Sosne & Ousler, Clin Ophthalmol 2015).
• Neurotrophic keratopathy Phase 3 (Sosne et al., Int J Mol Sci 2022) — 0.1% RGN-259 (timbetasin acetate) ophthalmic solution, 5x daily, in patients with stage 2–3 neurotrophic keratopathy. The trial stopped after 18 patients. Complete healing at 4 weeks: 6/10 RGN-259 vs 1/8 placebo (p = 0.0656), with healing and comfort improvements reported at later visits and no recurrent defects at day 43.
• Dry eye Phase 3 (ARISE-2, ARISE-3) — Two Phase 3 dry-eye trials of RGN-259 (601 and 700 patients) missed their main endpoints (RegeneRx 10-K, 2023), and their posted results show similar main-endpoint scores on the drops and on placebo (NCT02974907; NCT03937882); neither is published in a journal.
• Wound healing (Philp et al.) — Dermal wound healing, hair follicle migration, and epidermal stem cell mobilization data in rodent models.
• Skin wounds (RGN-137 gel) — In venous stasis ulcers (73 patients) the authors wrote that the 0.03% gel “may have the potential to accelerate wound healing” (Guarnera et al., 2010), but healing, a secondary endpoint, was no more common on gel than on placebo (12 of 55 vs 4 of 17; NCT00832091); Phase 2 trials in epidermolysis bullosa were terminated.
• Horses — The racing-lab papers (Ho 2012; Kwok 2013) measured TB-500 in horses to catch doping. We found no published study of TB-500 for tendon or soft-tissue repair in horses.
• Neurological and CNS data — Preclinical work in traumatic brain injury, stroke, and multiple sclerosis models showing reduced neuroinflammation and improved functional recovery.
• Platelet and hemostatic biology — Tβ4 is released from platelet α-granules on activation, placing it at the vascular injury site immediately after hemorrhage — a physiological signal that underpins the "first responder" framing of its repair role.

Human Data

No study has given TB-500, the fragment, to people; FDA’s 2026 review found no human exposure data for it. Everything below is full-length thymosin β4.

• Phase 1 safety (RGN-352, IV) — 40 healthy volunteers, single doses of 42–1,260 mg and 14 days of daily dosing; no dose-limiting toxicity (Ruff 2010).
• Heart attack (STEMI) — RGN-352’s Phase 2 (NCT01311518) was withdrawn before enrolling anyone. A recombinant Tβ4 was later tested in 96 STEMI patients: infarct size did not differ overall (Zhang 2025).
• Dry eye Phase 2 (NCT01393132; NCT01387347) — 0.1% drops: improvement in 9 patients with severe dry eye; in 72 patients neither primary endpoint beat placebo.
• Dry eye: ARISE-1 (Phase 2/3), ARISE-2 and ARISE-3 (Phase 3) — 317, 601 and 700 patients (NCT02597803; NCT02974907; NCT03937882). All three missed their main endpoints, by the developer’s account (RegeneRx 10-K, 2023), and ARISE-2 and ARISE-3 post similar main-endpoint scores on the drops and on placebo (NCT02974907; NCT03937882); none is published in a journal. (The SEER trials are in neurotrophic keratopathy, not dry eye.)
• Neurotrophic keratopathy Phase 3 (SEER-1; Sosne 2022) — Stopped after 18 patients; complete healing at 4 weeks in 6 of 10 on RGN-259 vs 1 of 8 on placebo (p = 0.0656), with healing and comfort improvements reported at later visits. SEER-2 is still listed as recruiting, but HLB Therapeutics reported its last patient visit in August 2026 and plans to report topline results in November 2026 (NCT05555589; Edaily, August 26, 2026).
• Epidermolysis bullosa (RGN-137) — Phase 2 trials terminated (30 and 4 patients).
• Venous stasis and pressure ulcers (RGN-137) — Phase 2s of 73 and 72 patients whose registered main endpoint was safety; healing, a secondary endpoint, was no more common on gel than on placebo (12 of 55 vs 4 of 17, and 8 of 54 vs 3 of 18; NCT00832091; NCT00382174), though the venous-ulcer authors wrote that the 0.03% gel “may have the potential to accelerate wound healing” (Guarnera et al., 2010).
• Safety across the parent’s trials — No program-stopping class of serious adverse events has been reported. None of that safety data is on the fragment.

What’s missing: any human study of TB-500 itself, and any randomized trial of injected Tβ4 or its fragment for tendon, joint or muscle injury. The case for that use rests on the parent protein’s mechanism and animal data. It is rationale, not proven clinical efficacy.

Reconstitution & Storage

Sellers list TB-500 as a freeze-dried powder in 2, 3, 5, 10 and 15 mg vials, labeled for research use only (FDA’s 2026 review).

• Reconstitution — Online guides describe adding the BAC water slowly down the inside wall of the vial, then swirling gently rather than shaking.
• Storage — Listings disagree. For the unmixed powder, supplier documents quoted in FDA’s 2026 review range from 2–8°C to frozen (below −15°C; a year at −20°C, two years at −80°C), and online guides from room temperature for short periods to −20°C long-term. For the mixed solution, guides and a telehealth clinic list 2–8°C and use within 2–4 weeks; a reagent data sheet quoted by FDA lists a month at −20°C.
• Injection sites — Online guides and seller pages describe injecting under the skin of the abdomen, thigh or upper arm, and some describe injecting into the muscle near an injury. Whether the site matters is unknown: where the fragment goes after an injection in people has never been studied (FDA’s 2026 review).
• Inspection — An online guide describes discarding a solution that turns cloudy, changes color or shows particles.

→ Calculator — vial-to-syringe math

Side Effects & Risks

Full-length Tβ4 was well tolerated in its eye-drop and IV trials (Sosne et al., 2015; Ruff et al., 2010). For the fragment there are only FDA’s adverse-event records. FDA’s 2026 TB-500 review found no reports for TB-500 through March 2025, and two reports in its food and supplement complaint system about blended TB-500 and BPC-157, with no safety assessment. Its BPC-157 review describes one report of skin and gum darkening in a woman injecting a BPC-157 and TB-500 blend twice a day; it came back when she used it again, and FDA judged the product the likely cause but could not say which peptide.

• Cancer / proliferative concerns — Because Tβ4 promotes cell migration and new blood vessel growth in lab and animal studies (Philp et al., 2003), and higher β-thymosin levels may promote metastasis by making cells more mobile (Huff et al., 2001), there is a theoretical concern about speeding the growth of an existing cancer. Several of the parent protein’s trial protocols excluded anyone with a current or past cancer (NCT00311766; NCT01387347; NCT01311518), so they say nothing about that risk.
• Hair growth — Full-length Tβ4 promoted hair growth in normal and aged rodents (Philp et al., 2004); no study has looked at hair in people taking the fragment.
• Skin pigmentation changes — FDA’s 2026 review of BPC-157 cites one report of diffuse skin and gum darkening, recurring on re-use, in someone injecting a BPC-157 and TB-500 blend.
• Drug interactions — Unstudied: no study has given TB-500 to people (FDA’s 2026 review).
• WADA banned substance — Prohibited at all times under S2.3 of the WADA List (“Thymosin-β4 and its derivatives e.g. TB-500”), named explicitly since the 2018 List. Doping labs detect the fragment and its metabolites in urine and plasma (Esposito et al., 2012; Ho et al., 2012).
• Purity and identity — A vial sold as TB-500 may hold the fragment, full-length Tβ4 or something else; products have been found not to match their descriptions (Delcourt 2023). FDA flags a risk of immune reactions from aggregation and peptide-related impurities.
• No human safety data for the fragment — FDA: it “lacks important information regarding any safety issues raised by this drug, including whether it would cause harm if administered to humans.”

Quick Compare — TB-500 vs BPC-157 vs Thymosin β4 vs GHK-Cu

The most clinically relevant comparators for TB-500 are the other tissue-repair peptides commonly used alongside or instead of it. BPC-157 is the single most-compared peer. Full-length thymosin β4 is TB-500’s parent and the molecule behind the human trials. GHK-Cu is a copper-binding tripeptide used for connective tissue and skin.

Practical interpretation:

• Systemic vs local intent — TB-500 is sold as a systemic repair peptide on the strength of full-length Tβ4, which circulates after IV dosing; where the fragment goes after an injection in people is unknown. Clinic protocols describe injecting BPC-157 near the target tissue.
• Dosing schedule — The once- or twice-weekly TB-500 schedule that guides describe assumes a long half-life that no published measurement of the fragment supports; in horses it was gone from blood within 6–10 hours (Ho et al., 2012). Clinic protocols describe BPC-157 once or twice a day.
• Oral route — BPC-157 is also sold as capsules (FDA’s 2026 BPC-157 review); TB-500 is sold for injection (FDA’s 2026 review).
• Fragment vs full-length — TB-500 is the fragment. Full-length Tβ4 is also sold, sometimes under the TB-500 name; the two differ in mass (889 vs 4,963 Da), which a mass-spec COA shows. The human trial data belong to the full-length protein.
• GHK-Cu — Different mechanism entirely (copper-delivery, gene expression, MMP regulation). GHK-Cu is topical-dominant for skin / hair / scar applications.
• Combinations — BPC-157 + TB-500 is sold as the Wolverine Stack, including as one vial holding both; adding GHK-Cu gives the GLOW Stack, and adding KPV as well gives KLOW, sold as one vial.

→ See full BPC-157 profile  •  → See GHK-Cu profile

Practical User Notes

• Loading, then maintenance — Online guides and a telehealth clinic describe 2–2.5 mg twice a week for 4–6 weeks, then about 2 mg once a week for 4–12 weeks. The long half-life used to justify weekly dosing has never been measured for the fragment; in horses it was gone from blood within 6–10 hours (Ho et al., 2012).
• Injection site — Whether location matters is unknown. Guides and seller pages describe injecting under the skin of the abdomen or thigh; some describe injecting into the muscle near an injury, which no study has tested.
• Needle and technique — A seller’s guide describes 28–31-gauge, half-inch insulin syringes for injections under the skin, and a week before re-using a site.
• Which molecule — A mass-spec report shows which molecule a vial holds: 889 Da is the fragment (FDA’s 2026 review), 4,963 Da is full-length Tβ4.
• After stopping — In horses the fragment was gone from blood within 6–10 hours (Ho et al., 2012); how long it lasts in people is unknown.

Bloodwork & Monitoring

No trial, label or guideline sets monitoring for TB-500, and no study has given it to people (FDA’s 2026 review). The intravenous Phase 1 of full-length Tβ4 tracked adverse events, safety evaluations and drug levels in 40 healthy volunteers (Ruff et al., 2010).

Commonly Stacked With

Stacking this? Read the receipt →

→ Calculator — vial-to-syringe math

Legal Status

Related Compounds

People researching TB-500 often also look at these:

Next Steps

References

1. Goldstein AL, Slater FD, White A. Preparation, assay, and partial purification of a thymic lymphocytopoietic factor (thymosin). Proc Natl Acad Sci U S A. 1966;56(3):1010-1017. PMID: 5230175. (Original thymosin concept.)
2. Low TL, Hu SK, Goldstein AL. Complete amino acid sequence of bovine thymosin beta 4: a thymic hormone that induces terminal deoxynucleotidyl transferase activity in thymocyte populations. Proc Natl Acad Sci U S A. 1981;78(2):1162-1166. PMID: 6940133. (Discovery publication.)
3. Safer D, Elzinga M, Nachmias VT. Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable. J Biol Chem. 1991;266(7):4029-4032. PMID: 1999398. (Actin-sequestering mechanism confirmed.)
4. Huff T, Müller CS, Otto AM, Netzker R, Hannappel E. beta-Thymosins, small acidic peptides with multiple functions. Int J Biochem Cell Biol. 2001;33(3):205-220. PMID: 11311852.
5. Bock-Marquette I, Saxena A, White MD, Dimaio JM, Srivastava D. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. PMID: 15565145. (Landmark cardiac regeneration paper.)
6. Smart N, Risebro CA, Melville AA, Moses K, Schwartz RJ, Chien KR, Riley PR. Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature. 2007;445(7124):177-182. PMID: 17108969.
7. Smart N, Bollini S, Dubé KN, Vieira JM, Zhou B, Davidson S, Yellon D, Riegler J, Price AN, Lythgoe MF, Pu WT, Riley PR. De novo cardiomyocytes from within the activated adult heart after injury. Nature. 2011;474(7353):640-644. PMID: 21654746.
8. Sosne G, Qiu P, Goldstein AL, Wheater M. Biological activities of thymosin beta4 defined by active sites in short peptide sequences. FASEB J. 2010;24(7):2144-2151. PMID: 20179146.
9. Sosne G, Kleinman HK. Primary Mechanisms of Thymosin β4 Repair Activity in Dry Eye Disorders and Other Tissue Injuries. Invest Ophthalmol Vis Sci. 2015;56(9):5110-5117. PMID: 26241398.
10. Sosne G, Dunn SP, Kim C. Thymosin β4 significantly improves signs and symptoms of severe dry eye in a Phase 2 randomized trial. Cornea. 2015;34(5):491-496. PMID: 25826322.
11. Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. 0.1% RGN-259 (Thymosin β4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical Trial. Int J Mol Sci. 2022;24(1):554. PMID: 36613994. DOI: 10.3390/ijms24010554.
12. Philp D, Huff T, Gho YS, Hannappel E, Kleinman HK. The actin binding site on thymosin beta4 promotes angiogenesis. FASEB J. 2003;17(14):2103-2105. PMID: 14500546.
13. Philp D, Goldstein AL, Kleinman HK. Thymosin beta4 promotes angiogenesis, wound healing, and hair follicle development. Mech Ageing Dev. 2004;125(2):113-115. PMID: 15037013.
14. Crockford D, Turjman N, Allan C, Angel J. Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications. Ann N Y Acad Sci. 2010;1194:179-189. PMID: 20536467.
15. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. PMID: 22074294.
16. Ruff D, Crockford D, Girardi G, Zhang Y. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. PMID: 20536472.
17. Hinkel R, El-Aouni C, Olson T, Horstkotte J, Mayer S, Müller S, Willhauck M, Spitzweg C, Gildehaus FJ, Münzing W, Hannappel E, Bock-Marquette I, DiMaio JM, Hatzopoulos AK, Boekstegers P, Kupatt C. Thymosin beta4 is an essential paracrine factor of embryonic endothelial progenitor cell-mediated cardioprotection. Circulation. 2008;117(17):2232-2240. PMID: 18427126.
18. WADA. 2026 Prohibited List. S2.3 — Growth factors and growth factor modulators: “Thymosin-ß4 and its derivatives e.g. TB-500”. World Anti-Doping Agency. TB-500 named explicitly since the 2018 List.
19. ClinicalTrials.gov. A Phase 2 Study on Effect of Thymosin Beta 4 on Wound Healing. NCT00311766.
20. FDA. Evaluation of TB-500-related bulk drug substances. Pharmacy Compounding Advisory Committee briefing document, July 23–24, 2026. fda.gov/media/193349. (Defines TB-500 as N-acetyl-LKKTETQ; found no human data.)
21. Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012;4(9):733-738. PMID: 22962027.
22. Ho EN, Kwok WH, Lau MY, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β₄, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012;1265:57-69. PMID: 23084823.
23. Kwok WH, Ho EN, Lau MY, et al. Doping control analysis of seven bioactive peptides in horse plasma by liquid chromatography-mass spectrometry. Anal Bioanal Chem. 2013;405(8):2595-2606. PMID: 23318763.
24. Rahaman KA, Muresan AR, Min H, et al. Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro. J Chromatogr B Analyt Technol Biomed Life Sci. 2024;1235:124033. PMID: 38382158.
25. Philp D, Badamchian M, Scheremeta B, et al. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice. Wound Repair Regen. 2003;11(1):19-24. PMID: 12581423.
26. Delcourt V, Garcia P, Chabot B, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023;15(4):458-464. PMID: 36482504.
27. Sosne G, Ousler GW. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) model. Clin Ophthalmol. 2015;9:877-884. PMID: 26056426.
28. Zhang Y, Dong Q, Bian X, et al. Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction. Cardiovasc Res. 2025;121(17):2747-2758. PMID: 41229390.
29. FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (503A categories list), versions updated April 15, April 22 and May 14, 2026. fda.gov/media/94155/download. Read October 3, 2026. (Notice that 12 peptides would leave Category 2 because their nominations were withdrawn; their removal; GHK-Cu, except injectable, back in Category 1.)
30. Biçer O, Adanir O, Güleryüz Y, Balci EC, Dinçel YM, Yenigün MY, et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg. 2026;37(3):822-837. PMID: 42542926.
31. RegeneRx Biopharmaceuticals, Inc. Annual report (Form 10-K) for the fiscal year ended December 31, 2022, filed April 11, 2023. sec.gov/Archives/edgar/data/707511/000141057823000628/rgrx-20221231x10k.htm. Read October 4, 2026.
32. ClinicalTrials.gov. Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-1. NCT02597803.
33. ClinicalTrials.gov. Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-2. NCT02974907. (Results posted.)
34. ClinicalTrials.gov. Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-3. NCT03937882. (Results posted.)
35. ClinicalTrials.gov. Assessment of the Safety and Efficacy of 0.1% RGN-259 Ophthalmic Solution for the Treatment of NK: SEER-2. NCT05555589.
36. Edaily (English edition). HLB Therapeutics Completes Global Phase 3 Clinical Trial for ‘RGN-259’… Topline Results to Be Announced in November. August 26, 2026. en.edaily.co.kr/news/eda202608265430. Read October 4, 2026.
37. Sosne G, Szliter EA, Barrett R, Kernacki KA, Kleinman H, Hazlett LD. Thymosin beta 4 promotes corneal wound healing and decreases inflammation in vivo following alkali injury. Exp Eye Res. 2002;74(2):293-299. PMID: 11950239. DOI: 10.1006/exer.2001.1125.
38. Kruoch Z, Choo AY, Kemp A, Gonzales M, et al. Medical and surgical interventions for neurotrophic keratopathy. Cochrane Database Syst Rev. 2025;12(12):CD015723. PMID: 41347649. DOI: 10.1002/14651858.CD015723.pub2.
39. Guarnera G, DeRosa A, Camerini R. The effect of thymosin treatment of venous ulcers. Ann N Y Acad Sci. 2010;1194:207-212. PMID: 20536470. DOI: 10.1111/j.1749-6632.2010.05490.x.
40. ClinicalTrials.gov. Study of Thymosin Beta 4 in Patients With Venous Stasis Ulcers. NCT00832091. (Results posted.)
41. ClinicalTrials.gov. Study of Thymosin Beta 4 in Patients With Pressure Ulcers. NCT00382174. (Results posted.)
42. Zhou B, Honor LB, Ma Q, Oh JH, et al. Thymosin beta 4 treatment after myocardial infarction does not reprogram epicardial cells into cardiomyocytes. J Mol Cell Cardiol. 2012;52(1):43-47. PMID: 21907210. DOI: 10.1016/j.yjmcc.2011.08.020.

Related Research

• BPC-157Tissue Repair & Cytoprotection
• BPC-157 FragmentTissue Repair (Derivative of BPC-157)
• ARA-290Innate Repair Receptor Agonist (EPO-derived)
• Glow StackBPC-157 · GHK-Cu · TB-500 — skin & tissue repair protocol
• KLOW StackBPC-157 · GHK-Cu · KPV · TB-500 — gut healing protocol
• Wolverine StackBPC-157 · TB-500 — accelerated recovery protocol
• FDA TrackerTB-500 was removed from Category 2 on April 22, 2026 (FDA notice April 15, 2026). PCAC recommended it on July 23–24, 2026. Rulemaking pending — not legal to compound today.
• Pentadeca Arginate (PDA)Sold as BPC-157’s replacement; paired with TB-500 as a “Wolverine Stack,” per one med spa