TB-500 (Thymosin Beta-4) Preclinical

What It Is

TB-500 is the marketing name used in the research-peptide community for synthetic Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide first isolated from bovine thymus by Allan Goldstein and colleagues at George Washington University in 1981. Thymosin Beta-4 is the most abundant member of the thymosin β-family, present at high concentrations in virtually every mammalian cell and in particularly high concentrations in platelets — which is why it is released at sites of tissue injury within seconds of vascular disruption.

Strictly speaking, "TB-500" is not identical to Tβ4 as marketed. In the original Regina Biopharma / RegeneRx / research-use patents, "TB-500" was used as a product code for full-length synthetic Tβ4 (the 43-amino-acid molecule). In practice, gray-market "TB-500" vials on the research-peptide market are nearly always full-length 43-aa Tβ4. There is also a much shorter "TB-500 Fragment 17-23" (7-aa Ac-LKKTETQ, the core actin-binding domain), which is a distinct compound with overlapping but narrower mechanistic activity and is covered in its own profile.

Functionally, 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, and cytoskeletal remodeling. That mechanism — rather than a receptor-mediated signaling cascade — is the core of why Tβ4 acts across so many tissue types and appears in such a wide range of repair contexts.

Clinical development has been led primarily by RegeneRx Biopharmaceuticals (now affiliated with HLB Therapeutics), which has pursued three product formulations: RGN-259 (topical ophthalmic, for dry eye and neurotrophic keratopathy), RGN-137 (topical dermal, for epidermolysis bullosa and pressure ulcers), and RGN-352 (systemic IV, for acute myocardial infarction). As of 2023, RGN-259 (0.1% timbetasin ophthalmic solution) has positive Phase 3 data for neurotrophic keratopathy published in the International Journal of Molecular Sciences. The systemic cardiac program (RGN-352) completed Phase 1 and advanced into exploratory studies before the program slowed. TB-500 / Tβ4 is one of the few "research peptides" with genuine multi-phase human clinical data across multiple indications — which is what separates it from most of the community-only peptides in its category.

Mechanism of Action

Tβ4's mechanism is mechanistic-physical as much as it is receptor-mediated. The core biological action is actin-binding; the downstream effects cascade from there.

• G-actin sequestration (primary mechanism) — Tβ4 binds monomeric G-actin in a 1:1 complex via a well-defined actin-binding motif (particularly residues 17–23, LKKTETQ). This prevents spontaneous polymerization into F-actin filaments and maintains a large soluble G-actin pool — the reserve supply for rapid cytoskeletal remodeling. At sites of injury, local release of Tβ4 and concurrent release of actin-polymerizing factors allow the stored G-actin pool to be mobilized into directional F-actin filaments driving cell migration and wound contraction.
• Cell migration — The cytoskeletal consequence of regulated G-actin availability is accelerated directional migration of fibroblasts, endothelial cells, keratinocytes, and cardiomyocyte progenitors toward sites of injury. This is the single unifying effect across wound healing, corneal repair, and cardiac regeneration contexts.
• Angiogenesis (vessel formation) — Tβ4 drives endothelial cell migration and tube formation in vitro. It upregulates VEGF receptor signaling without itself being a growth factor, and cooperates with VEGF-A to produce the mature vascular sprouts needed for repair.
• Anti-inflammatory modulation — Reduces NF-κB activation, suppresses inflammatory cytokine release, and reduces neutrophil infiltration at injury sites. Unlike a simple anti-inflammatory (which blunts the entire response), Tβ4 modulates the inflammatory phase toward resolution rather than elimination.
• Apoptosis reduction — Binds and regulates levels of PINCH-1/ILK/alpha-parvin complexes in cardiomyocytes and endothelial cells, reducing hypoxia- or ischemia-driven apoptosis. Bock-Marquette et al. (Nature, 2004) demonstrated this in cardiac tissue after infarction in mice.
• Progenitor cell activation — Tβ4 appears to reactivate epicardial progenitor cells in adult mammalian hearts, recapitulating embryonic cardiac regeneration patterns after myocardial infarction (Smart et al., Nature 2011). This underpins the cardiac-regeneration indication.
• Hair follicle stem cell mobilization — Philp et al. demonstrated that Tβ4 promotes hair follicle growth and migration of hair follicle stem cells. This mechanism supports anecdotal reports of improved hair growth on TB-500.
• Corneal epithelial repair — RGN-259's Phase 3 efficacy in neurotrophic keratopathy is driven by Tβ4's ability to accelerate corneal epithelial cell migration and reduce inflammation in a damaged ocular surface — a classically complex wound environment.
• Anti-fibrotic signal — In chronic wounds and dermal fibrosis models, Tβ4 modulates TGF-β1 signaling to favor regenerative rather than fibrotic healing. This is why Tβ4-treated wounds in animal models show reduced scar formation.

What the Research Shows

Thymosin Beta-4 has one of the most mechanism-rich and indication-diverse research footprints of any tissue-repair peptide. Key findings by application:

• Discovery and characterization (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) — Tβ4 reactivated a population of epicardial progenitor cells in adult mouse hearts after priming, demonstrating potential for adult mammalian cardiac regeneration.
• Corneal wound healing (Sosne et al., multiple publications, 2010–2020) — Preclinical and clinical evidence that topical Tβ4 accelerates corneal epithelial cell migration, reduces inflammation, and promotes closure of corneal defects — the mechanistic basis for the RGN-259 program.
• Dry eye Phase 2 (Sosne et al., Cornea 2015) — Randomized, placebo-controlled Phase 2 trial in moderate-to-severe dry eye disease using the controlled adverse environment model. Topical 0.1% Tβ4 showed improvement in ocular discomfort signs and symptoms.
• Neurotrophic keratopathy Phase 3 (Sosne et al., Int J Mol Sci 2023) — 0.1% RGN-259 (timbetasin acetate) ophthalmic solution, 5x daily, in patients with stage 2–3 neurotrophic keratopathy. Complete healing at 4 weeks: 6/10 RGN-259 vs 1/8 placebo (p = 0.0656). Significant healing and comfort improvements with no recurrent defects at day 43. Positive safety profile.
• Ocular Phase 3 (SEER-3) — HLB Therapeutics announced that SEER-3 missed its primary endpoint in dry eye disease. Development for specific ocular indications is evolving as a result.
• Wound healing (Philp et al.) — Dermal wound healing, hair follicle migration, and epidermal stem cell mobilization data in rodent models.
• Epidermolysis bullosa (RGN-137) — RegeneRx's topical dermal Tβ4 entered clinical studies for EB; full Phase 3 not yet published.
• Equine tendon and soft tissue — Multiple veterinary studies showing accelerated tendon repair and soft-tissue recovery in horses — the original context from which "TB-500" became widely known in the performance/athletic community.
• 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

Human data for Tβ4 is concentrated in topical (ophthalmic, dermal) and IV (cardiac) formulations. The subcutaneous "TB-500" used recreationally is derived from these formulations but has not been studied in an identical context in humans.

• Phase 1 safety (multiple) — IV Tβ4 (RGN-352) studied in healthy volunteers and post-MI patients. Doses up to 42 mg IV were well-tolerated.
• Cardiac pilot (RGN-352) — Small pilot in acute STEMI patients documenting safety and proof-of-concept cardiac endpoints (Ruff et al., exploratory results).
• Dry eye Phase 2 (NCT00883935; Sosne 2015) — Topical 0.1% Tβ4 in dry eye; improvement in discomfort and ocular surface markers.
• Dry eye Phase 3 (SEER-1, SEER-2, SEER-3) — Multiple Phase 3 trials in dry eye. SEER-3 missed primary endpoint; other trials have published varying results. Dry-eye indication development continues to evolve.
• Neurotrophic keratopathy Phase 3 (Sosne et al., 2023) — Positive efficacy on healing and comfort in stage 2–3 NK patients, published in Int J Mol Sci 2023;24(1):554.
• Epidermolysis bullosa (RGN-137) — Topical dermal Tβ4 in Phase 2/3 for EB wound healing; commercialization decisions ongoing.
• Pressure ulcers / venous stasis ulcers — Earlier RGN-137 program in chronic dermal wounds; preliminary positive signals.
• Long-term safety database — Across all formulations, Tβ4 has accumulated a meaningful safety dataset; no classes of serious adverse events have emerged as program-stopping.

Notably absent from the formal human database: a randomized controlled trial of systemic (SubQ or IM) Tβ4 for musculoskeletal injury in humans. That is the gap between the recreational "TB-500 for tendon repair" use case and the formal evidence base. The rationale for the use case is sound (mechanism, equine data, safety pool), but it is rationale — not proven clinical efficacy.

Dosing from the Literature

For systemic (SubQ / IM) dosing, most protocols are practitioner-derived from equine studies and from the cardiac IV trials. Topical and ophthalmic dosing is derived from RGN-259 Phase 2/3 protocols.

Reconstitution & Storage

TB-500 is supplied as a lyophilized powder, typically in 2 mg, 5 mg, or 10 mg vials.

• Reconstitution — Inject BAC water slowly down the inside wall of the vial at a 45° angle. Swirl gently; do not shake. Tβ4 should dissolve into a clear, colorless solution within 30–60 seconds.
• Storage — Unreconstituted: 2–8°C long-term; room temp acceptable for several weeks short-term. Reconstituted: 2–8°C, use within 28 days. Do not freeze reconstituted solution — repeated freeze-thaw can denature peptides of this size.
• Injection sites — SubQ in abdomen (2" from navel), thigh, or upper arm for systemic protocols. IM into target muscle group is used by some practitioners for localized muscle/tendon injuries, though systemic circulation of Tβ4 is the expected distribution regardless of injection site.
• Inspection — Discard if the solution is cloudy, discolored, or has visible particulates.

→ Use the Kalios Peptide Calculator for exact syringe units

Side Effects & Risks

Across the aggregated Phase 1/2/3 human database (ophthalmic, cardiac, dermal) and extensive veterinary use, Tβ4 has a favorable safety profile. Caveats apply to systemic off-label use in humans.

• Injection site reactions — Mild local erythema, transient tenderness, occasional bruising. Usually self-limited within 24 hours.
• Fatigue / post-dose lethargy — Subjective reports of mild flu-like fatigue for 24–48 hours after the first 1–2 doses in some users. Not a characterized AE in formal trials.
• Head pressure / sinus congestion — Anecdotal reports within hours of dosing; not well-characterized.
• Cancer / proliferative concerns — Because Tβ4 promotes cell migration and angiogenesis, there is a theoretical concern about accelerating growth in pre-existing malignancies. No controlled human trials have shown tumor-promoting effect, but pre-existing malignancy is a standard contraindication in RegeneRx trial exclusion criteria.
• Hair growth — Not an adverse effect per se — Tβ4 has been studied for hair follicle mobilization — but users sometimes note accelerated hair growth as a surprise finding.
• Skin pigmentation changes — Very rare; occasional reports of focal hyperpigmentation at injection sites with chronic use.
• Drug interactions — Largely unstudied in humans. Theoretical interactions with anti-angiogenic cancer therapies (which would work against Tβ4's pro-angiogenic mechanism) and with high-dose corticosteroids (which may blunt the repair signal).
• WADA banned substance — Banned under S2 of the WADA Prohibited List since 2011. Detection methods (urinary metabolite panels, UHPLC-HRMS) are established. Athletes subject to anti-doping testing must not use Tβ4 in any formulation.
• Purity concerns — Gray-market 43-aa Tβ4 varies in purity across vendors. Because the molecule is comparatively large (43 aa) for solid-phase synthesis, truncated/deletion-sequence impurities are more common than in short peptides. Independent third-party HPLC + mass spec COAs are the practical floor for due diligence.
• No documented lethal dose in mammals — Long accumulated safety record in veterinary and human trial populations with no LD1 identified.

Supportive Nutrition & Supplements

Tissue repair on TB-500 is better when the structural and metabolic inputs for rebuilding are optimized. The following applies to any repair protocol, not just TB-500.

• Protein (1.6–2.2 g/kg/day) — Non-negotiable for repair. Distribute across 3–5 feedings. Leucine-rich sources (whey, eggs, lean meat) drive mTOR-mediated protein synthesis.
• Collagen peptides + vitamin C — 15 g hydrolyzed collagen with 50 mg vitamin C 1 hour before loading/rehab session (Shaw 2017). Supplies substrate during the collagen-synthesis window.
• Vitamin D (2,000–5,000 IU to 40–60 ng/mL) — Deficiency impairs tendon and bone repair independent of any peptide.
• Zinc (15–25 mg) — Cofactor for collagen cross-linking, matrix metalloproteinase regulation. Avoid chronic >40 mg (copper depletion).
• Magnesium (300–400 mg) — Broad cofactor for ATP generation and protein synthesis.
• Omega-3 (2–3 g EPA/DHA) — Resolves inflammation without blunting it. Preferred over chronic NSAIDs during acute tissue repair.
• Creatine monohydrate (3–5 g) — Supports training load during rehab. Emerging data on tendon benefits.
• Glycine (3–5 g at night) — Rate-limiting amino acid for collagen synthesis, often underconsumed in muscle-meat-dominant diets.
• Things to avoid — Chronic alcohol (impairs tendon healing), smoking/nicotine (vasoconstrictive; strongly antagonizes any repair), chronic NSAIDs during early inflammatory phase (impairs organized collagen deposition in animal models), and corticosteroid injections (directly antagonize repair signaling).

What to Expect — Timeline

Individual response varies. TB-500's multi-day half-life and systemic distribution produce a different experiential arc than short-half-life local peptides like BPC-157.

• Week 1 (loading) — Users typically describe minimal subjective change. Occasional mild flu-like fatigue 24–48 hours after the first few doses. Because of multi-day half-life, cumulative exposure builds across the first week.
• Week 2–3 — Earliest subjective reports of reduced chronic inflammation, improved post-exertion recovery, or subtle ROM gains in a target joint/tendon. Highly variable; selection bias is heavy in community reports.
• Week 4–6 — Typical response window for MSK applications. Users targeting tendinopathy, chronic soft-tissue injuries, or non-resolving inflammation often report their first clearer signal here. Hair and skin quality changes, if present, start to emerge.
• Week 6–8 — Practical endpoint of a loading cycle. Loading dose (typically 5 mg/week split) transitions to maintenance (2 mg/week).
• Week 8–12 (maintenance) — Remodeling-phase window. Objective imaging changes (MRI, ultrasound tendon structure) are sometimes documented in horses and anecdotally in practitioners' human cases; not formally studied.
• Post-cycle (4–8 weeks off) — Because plasma half-life is multi-day, active compound is cleared within 2–3 weeks. If benefit persists, it reflects actual tissue remodeling, not ongoing drug action.
• Non-responders — Estimated 20–30% of community users report no clear benefit. Common reasons: product quality/purity, injecting too far from (or irrelevant to) the target, structural damage beyond what any peptide will address without surgery, absence of loading/rehab component.
• If you feel worse — Stop. Purity, dose, storage, and reconstitution are first suspects. Persistent new-onset symptoms (any) on any unapproved compound warrant cessation first and evaluation second.

Quick Compare — TB-500 vs BPC-157 vs TB-500 Fragment 17-23 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. TB-500 Fragment 17-23 (Ac-LKKTETQ) is the 7-aa actin-binding domain of Tβ4 itself. GHK-Cu is a copper-binding tripeptide used for connective tissue and skin.

Practical interpretation:

• Systemic vs local intent — TB-500 circulates systemically; BPC-157 is typically used locally. TB-500 is the better choice when the repair target is systemic or diffuse (whole-body inflammation, multiple joints, cardiac concerns, hair). BPC-157 is the better choice when injection-site-adjacent target tissue matters.
• Dosing convenience — TB-500's multi-day half-life allows once or twice weekly injections. BPC-157 requires daily or twice-daily dosing because of its <30-minute plasma half-life.
• Oral route — BPC-157 is uniquely oral-viable. TB-500 and Fragment 17-23 must be injected.
• Fragment vs full-length — Fragment 17-23 captures the core actin-binding sequence of Tβ4 at roughly one-fifth the molecular weight and typically 20–30% of the cost per dose. What it gives up: the broader activity of full-length Tβ4 beyond the core actin-binding domain.
• GHK-Cu — Different mechanism entirely (copper-delivery, gene expression, MMP regulation). GHK-Cu is topical-dominant for skin / hair / scar applications; systemic use is less common but emerging in practitioner protocols.
• Combinations — BPC-157 + TB-500 (Wolverine Stack) is the most common tissue-repair pairing. Adding GHK-Cu yields the GLOW stack; adding KPV yields the KLOW stack. Fragment 17-23 + BPC-157 is a cost-reduced minimalist version of Wolverine.

→ See full BPC-157 profile  •  → See TB-500 Fragment 17-23 profile  •  → See GHK-Cu profile

Practical User Notes

• Loading cycle, then taper — Most common pattern: 5 mg/week total split into 2–3 doses for 4–6 weeks (loading), then 2 mg/week for 4–8 weeks (maintenance). There is no pharmacokinetic reason to split doses within a week given the 2–3-day half-life, but community practice persists.
• Injection site — Because Tβ4 distributes systemically, injection location doesn't matter much for most use cases. SubQ in abdomen or thigh is standard. IM directly into a targeted muscle group is used by some practitioners for proximity-to-tissue intuition rather than evidence.
• Needle and technique — 29G–31G half-inch insulin syringe, SubQ at 45°. Slow push, rotate sites weekly.
• Timing with training — Does not matter acutely — the multi-day half-life means you're always dosed. Anchor it to a fixed day of the week for adherence.
• Sourcing discipline — Full-length 43-aa Tβ4 is harder to synthesize cleanly than short peptides. Independent third-party HPLC + mass spec COAs (not just vendor-provided) are the practical floor. Truncated/deletion sequences are the most common impurity in cheap product.
• Storage discipline — 2–8°C refrigerated, reconstituted solution; ≤28 days after reconstitution. No freezing of reconstituted peptide.
• Don't skip the mechanical load — Tissue remodeling is driven by mechanical stress. Peptide support without structured rehab or training load is a common reason for "no effect" in tendon protocols.
• Combine thoughtfully — BPC-157 (local + oral), GHK-Cu (skin/scar), KPV (inflammation). Starting a single compound at a time for the first 2–4 weeks makes it easier to attribute any effect (or adverse effect).
• Cancer history / active malignancy — Absolute contraindication. Pro-angiogenic and pro-migratory mechanisms theoretically support tumor growth.
• Stop criteria — New-onset unexplained headache, persistent fatigue past week 2, any new lumps/skin changes, persistent fever, or any other unexpected symptom. Stop first, evaluate second.
• After cessation — Multi-day half-life means active compound is cleared within 2–3 weeks. If MSK benefit persists beyond that, it reflects actual tissue remodeling, not ongoing drug action.
• Honest expectations — Most responders report "subtle but real" benefit — faster recovery between sessions, less chronic ache, less post-travel joint stiffness. Dramatic transformations reported in some forums are outliers and often confounded with concurrent rehab, sleep, or other interventions.

Bloodwork & Monitoring

No specific monitoring protocol is formally required for systemic TB-500. Informed users and practitioners commonly track:

• Baseline CMP and CBC — Liver, kidney, hematology baseline; repeat at 8–12 weeks on a prolonged cycle.
• Inflammatory markers — CRP / ESR. Useful for tracking progress of a chronic inflammatory injury.
• Imaging for MSK applications — Baseline MRI or ultrasound of the target tissue is the objective way to confirm structural change rather than relying on subjective pain reports.
• Cancer screening — Age-appropriate screening (colonoscopy, mammography, PSA, dermatologic) before initiating prolonged TB-500 protocols. Not a research-mandated recommendation, but a rational precaution given the pro-angiogenic and pro-migratory mechanism.
• Injection-site photo log — Useful for tracking unusual local reactions across weeks.
• Symptom diary — Subjective pain, ROM, and functional status are the primary outcomes for musculoskeletal use. Weekly 0–10 pain scales + objective function markers (grip strength, ROM) help distinguish response from placebo.

Commonly Stacked With

→ Check compound compatibility in the Stack Builder

Regulatory Status

Related Compounds

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Next Steps

Key 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: 5230181. (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: 1999397. (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.
11. Sosne G, Kim C, Kleinman HK. 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. 2023;24(1):554.
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.
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: 20536465.
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.
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.
18. WADA. 2025 Prohibited List. Section S2 — Peptide hormones, growth factors, related substances and mimetics. World Anti-Doping Agency. Thymosin β4 and derivatives prohibited since 2011.
19. ClinicalTrials.gov. A Phase 2 Study on Effect of Thymosin Beta 4 on Wound Healing. NCT00311766.
20. FDA. Bulk Drug Substances That Raise Significant Safety Risks (Category 2) under Section 503A / 503B. FDA.gov. Updated 2025.