TB-500 (Thymosin Beta-4): reported timelines in the literature
TB-500 is a synthetic 17-23 fragment of thymosin beta-4. This page summarises the reported timelines in the published and registered literature, including which findings are animal-only or in vitro.
TB-500 is the common research name for a synthetic peptide corresponding to the 17-23 fragment of thymosin beta-4 (Tβ4), a naturally occurring actin-binding protein. Synonyms in the literature include thymosin beta-4 17-23 fragment, TB-4 fragment, and, in some commercial and review contexts, TB-500. It is a short synthetic peptide rather than the full-length parent protein, and it is handled in laboratory work as a research reagent. The evidence block used for this page does not supply a sequence, molecular formula, or molecular weight for the fragment, so none is stated here.
The work summarised below centres on actin sequestration and on the downstream cell-migration and tissue-repair signalling associated with the thymosin beta-4 family; the registered clinical records in the evidence block evaluate recombinant human thymosin beta-4 and related ophthalmic formulations rather than the 17-23 fragment itself, and that distinction is carried through the sections that follow.
Research Studies
TB-500 and tendon healing in a rat model
A histopathological and biomechanical study examined the effects of BPC-157, synthetic thymosin beta-4 (TB-500), and their combination on Achilles tendon healing in rats. The work used biomechanical, histopathological, histochemical, and immunohistochemical analyses in thirty-two male Sprague-Dawley animals [9]. This is an animal model, and the findings are reported for that model only; no human tendon-healing timeline is established by this study.
TB-500 and regenerative-medicine reviews of tissue repair
A narrative review of regenerative peptides relevant to chronic pain management summarised current evidence on collagen peptides, BPC-157, thymosin beta-4 (TB-4), TB-500, GHK-Cu, and growth-hormone-related peptides in the context of tissue repair [10]. A separate review of peptide supplements and their therapeutic applications in sports medicine described the rapid growth of the peptide supplement market and noted that these products are often perceived as low risk despite the absence of efficacy or safety data in the settings in which they are marketed [11]. Both are review-level sources; neither reports a primary timeline for the 17-23 fragment.
TB-500 and analytical detection in blood matrices
An analytical workflow study reported a fast, streamlined, harmonised method for detecting 54 prohibited substances, including peptidic and non-peptidic doping agents, in dried and liquid blood matrices [12]. This work concerns detection methodology rather than a biological effect or a healing timeline, and it is included here because it bears on how peptide exposure is measured in samples.
Thymosin beta-4 and cardiovascular biomarkers in stable ASCVD
A Phase 1/2 record describes a trial evaluating the safety and tolerability of TB-500, described as a 17-23 fragment of thymosin beta-4, versus placebo in adults with stable atherosclerotic cardiovascular disease (ASCVD). Exploratory endpoints assess vascular function and inflammation biomarkers [1]. The record is a registered trial description; it does not report completed outcome data or a timeline of observed effects.
Recombinant human thymosin beta-4 and acute myocardial infarction (NL005)
A Phase IIc record describes a trial of recombinant human thymosin beta-4 injection (NL005) in people who had experienced ST-segment elevation myocardial infarction (STEMI) and had been treated with emergency percutaneous coronary intervention (PCI). The stated aims were to determine whether NL005 lowers the size of permanent heart muscle damage measured by cardiac magnetic resonance (CMR) at 90 days after treatment, and to characterise the medical problems participants experienced [2]. The 90-day CMR timepoint is the timeline specified in the record; results are not reported in the evidence block.
Thymosin beta-4 and acute myocardial infarction: dose-ranging records
Several registered records describe randomised, double-blind, placebo-controlled designs in acute myocardial infarction, with observation at 90 days after PCI. The table below summarises the dose groups and administration schedules as stated in each record.
| Record | Population | Dose groups | Administration | Observation |
|---|---|---|---|---|
| NCT05984134 [4] | 90 participants, acute myocardial infarction | Placebo, 0.5 µg/kg, 1.0 µg/kg (1:1:1) | Intravenous within 12 hours and on days 2 to 7 after PCI | 90 days after PCI |
| NCT05485818 [5] | 60 participants, acute myocardial infarction | Low 0.25 µg/kg, medium 0.5 µg/kg, high 2.0 µg/kg, placebo (1:1:1:1) | Intravenous once daily on days 2 to 7, at 12 hours and 4 hours after PCI | 90 days after PCI |
| NCT01311518 [6] | Approximately 75 participants, acute myocardial infarction receiving PCI angioplasty with or without stent placement | RGN-352 1200 mg, RGN-352 450 mg, or placebo | Intravenous push daily for the first 3 consecutive days, then weekly for 4 more weeks | Not specified in the record excerpt |
These are registered trial descriptions. They set out planned dose levels, routes, and observation windows; they do not report whether any effect was observed.
Thymosin beta-4 and pharmacokinetics in healthy volunteers
A Phase 1b record describes a study to evaluate the safety, tolerance, pharmacokinetics, and potential immunological reaction of single intravenous recombinant human thymosin beta-4 (NL005) or placebo at 0.5, 2.0, and 5.0 µg/kg in Chinese healthy volunteers. Thirty volunteers were to be randomly assigned to one of three groups to receive either NL005 or placebo for 10 consecutive days [8]. This record concerns healthy volunteers and pharmacokinetic characterisation rather than a tissue-repair endpoint.
RGN-259 ophthalmic solution and neurotrophic keratopathy
The SEER-2 record describes a study comparing the safety and efficacy of 0.1% RGN-259 ophthalmic solution to placebo for the treatment of neurotrophic keratopathy (NK) [3]. This is an ocular formulation and a corneal indication, distinct from the systemic routes described in the cardiovascular records above.
RGN-259 ophthalmic solution and dry eye
The ARISE-3 record describes a study comparing the safety and efficacy of RGN-259 ophthalmic solutions to placebo for the treatment of the signs and symptoms of dry eye [7]. As with the NK record, this concerns a topical ocular formulation rather than the 17-23 fragment administered systemically.
What the timelines in this literature actually represent
Across the registered records in the evidence block, the recurring observation window is 90 days after PCI, with dosing concentrated in the first week and, in one record, weekly for four further weeks [2][4][5][6]. Those windows are protocol-defined follow-up periods, not measured onset times. The evidence block does not contain completed results for any of these records, so no statement can be made here about how quickly any effect appeared or whether one appeared at all.
For the 17-23 fragment specifically, the evidence block contains one registered record in stable ASCVD with exploratory vascular and inflammatory endpoints [1] and one animal study in Achilles tendon healing [9]. The tendon work is animal-only. The review-level sources describe the broader peptide field and its evidentiary limits rather than supplying timelines of their own [10][11]. The analytical workflow source addresses detection in blood matrices and does not bear on biological timing [12].
If you are reading this for personal health reasons
This material is sold for laboratory research use only. We do not provide dosing, administration, or medical guidance of any kind. Anyone considering a compound for themselves should speak to a licensed clinician.
Sources
- [1] TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD — https://clinicaltrials.gov/study/NCT07487363
- [2] Recombinant Human Thymosin Beta 4 for Injection (NL005) for Acute Myocardial Infarction — https://clinicaltrials.gov/study/NCT07586865
- [3] Assessment of the Safety and Efficacy of 0.1% RGN-259 Ophthalmic Solution for the Treatment of NK: SEER-2 — https://clinicaltrials.gov/study/NCT05555589
- [4] Efficacy and Safety Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction — https://clinicaltrials.gov/study/NCT05984134
- [5] Safety and Efficacy Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction — https://clinicaltrials.gov/study/NCT05485818
- [6] A Study of the Safety and Efficacy of Injectable Thymosin Beta 4 for Treating Acute Myocardial Infarction — https://clinicaltrials.gov/study/NCT01311518
- [7] Assessment of the Safety and Efficacy of RGN-259 Ophthalmic Solutions for Dry Eye Syndrome: ARISE-3 — https://clinicaltrials.gov/study/NCT03937882
- [8] A Phase 1b Study of Thymosin Beta 4 in Healthy Volunteers — https://clinicaltrials.gov/study/NCT04555850
- [9] Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study — https://pubmed.ncbi.nlm.nih.gov/42542926/
- [10] Peptides in Regenerative Medicine: A Comprehensive Review of Clinical Applications in Tissue Repair and Chronic Pain Management — https://pubmed.ncbi.nlm.nih.gov/42635865/
- [11] Peptide Supplements and Their Therapeutic Applications in Sports Medicine — https://pubmed.ncbi.nlm.nih.gov/42578445/
- [12] Rapid and harmonized analytical workflow for the determination of peptidic and non-peptidic doping agents in dried and liquid blood matrices — https://pubmed.ncbi.nlm.nih.gov/42328738/