RESEARCH PROFILE
TB-500
Synthetic Thymosin Beta-4 Fragment • Tissue Repair Research
TB-500 is a synthetic 7 amino acid peptide associated with a functional region of thymosin beta-4. Research interest centers on actin binding, cell migration, tissue remodeling, angiogenesis, and inflammatory signaling.
Most direct TB-500 fragment evidence remains preclinical. Human studies involving full-length thymosin beta-4 should not be treated as direct clinical evidence for TB-500.
INVESTIGATIONAL • NOT FDA APPROVED • DIRECT HUMAN EVIDENCE VERY LIMITED
TB-500 AT A GLANCE
Category
Tissue repair and regenerative research peptide
Compound Type
Synthetic 7 amino acid thymosin beta-4 fragment
Sequence
Ac-LKKTETQ
Primary Research Focus
Actin dynamics • Cell migration • Angiogenesis • Tissue remodeling
Evidence Base
Primarily preclinical for the TB-500 fragment
Regulatory Status
Not FDA approved
IMPORTANT DISTINCTION
TB-500 is not the same molecule as full-length thymosin beta-4.
Your Project profile identifies TB-500 as a 7 amino acid fragment, while endogenous thymosin beta-4 is a 43 amino acid peptide.
Much of the strongest published human evidence in this research area involves full-length thymosin beta-4, especially topical or ophthalmic pharmaceutical development.
Those results should not automatically be transferred to injectable TB-500.
WHAT IS TB-500?
TB-500 is a synthetic peptide fragment derived from a biologically active region associated with thymosin beta-4, a naturally occurring peptide found widely throughout the body.
The Project profile identifies the TB-500 sequence as:
Ac-LKKTETQ
The “Ac” refers to acetylation, a chemical modification at one end of the peptide.
Thymosin beta-4 is involved in regulation of actin, an important structural protein that helps cells maintain shape, migrate, divide, and participate in tissue repair.
TB-500 retains an actin-binding region associated with thymosin beta-4 but does not contain the entire parent peptide.
Research interest in TB-500 therefore focuses on whether this smaller fragment can influence some of the same processes associated with full-length thymosin beta-4.
However, fragment-level pharmacology and full-length thymosin beta-4 pharmacology should remain distinct.
MECHANISM OF ACTION
The proposed biology of TB-500 centers primarily on actin regulation and tissue-response pathways.
ACTIN BINDING
Actin is a major structural protein involved in:
Cell shape
Cell movement
Tissue organization
Wound response
Full-length thymosin beta-4 is a major regulator of the monomeric actin pool.
The TB-500 fragment retains an actin-binding region associated with this system.
CELL MIGRATION
Preclinical research involving thymosin beta-4 has demonstrated increased migration of several cell types involved in tissue repair, including:
Keratinocytes
Endothelial cells
Fibroblasts
Myoblasts
Corneal epithelial cells
Cell migration is important because injured tissue must recruit and reorganize cells during repair.
ANGIOGENESIS
Thymosin beta-4 research has also demonstrated angiogenic activity, or promotion of new blood vessel formation, in animal injury models.
This may contribute to tissue remodeling by improving local vascular supply.
INFLAMMATORY SIGNALING
Preclinical studies have reported effects on inflammatory mediators, including reduced inflammatory signaling in some injury models.
IMPORTANT MECHANISM LIMITATION
Most of these mechanisms are best documented for full-length thymosin beta-4.
Some activity may also be associated with TB-500 fragment biology, but the Project source explicitly warns against treating the full-length peptide and fragment as interchangeable.
WHAT THE RESEARCH SHOWS
DIRECT TB-500 HUMAN EVIDENCE
The most important evidence boundary is straightforward:
Your Project source identifies no published human randomized controlled trial of injectable TB-500 for any clinical indication.
Direct human evidence for the 7 amino acid fragment is essentially absent.
FULL-LENGTH THYMOSIN BETA-4 HUMAN RESEARCH
Full-length thymosin beta-4 has undergone considerably more human study.
These studies provide relevant biological context but do not establish efficacy for TB-500.
PHASE I HUMAN SAFETY RESEARCH
Your Project profile cites a Phase I study involving approximately 40 healthy volunteers who received full-length thymosin beta-4 intravenously.
Doses ranged from single IV exposures to repeated administration.
The study reported no serious dose-limiting toxicities.
This provides human safety information for full-length thymosin beta-4, not the shorter TB-500 fragment.
VENOUS ULCER RESEARCH
Full-length thymosin beta-4 was studied topically in chronic venous ulcers.
One Phase II trial reported acceptable tolerability and suggested improved wound closure in some treatment groups.
Again, this involved a topical full-length thymosin beta-4 formulation, not injectable TB-500.
PRESSURE ULCER RESEARCH
Your Project source also cites a Phase II study of topical thymosin beta-4 in pressure ulcers.
The research examined wound-healing outcomes, but the formulation and molecule differed from TB-500 fragment products.
OPHTHALMIC RESEARCH
Topical thymosin beta-4 ophthalmic formulations have also been evaluated in clinical studies involving corneal disease and neurotrophic keratopathy.
These trials contribute to the human evidence base for thymosin beta-4 but should not be represented as TB-500 trials.
TENDON & LIGAMENT PRECLINICAL RESEARCH
Animal studies involving thymosin beta-4 have reported:
Improved collagen organization
Changes in fibril diameter
Improved ligament-healing measures
Cell migration and tissue remodeling
These studies are frequently cited in discussions of TB-500.
However, the Project profile stresses that animal thymosin beta-4 research does not validate injectable TB-500 as a human tendon or ligament treatment.
CARDIAC RESEARCH
Preclinical research has also explored thymosin beta-4 in cardiac injury models, including effects on myocardial repair and vascular biology.
These findings remain separate from direct TB-500 human evidence.
IMPORTANT EVIDENCE LIMITATION
The widespread research-use claim that injectable TB-500 “heals tendons and ligaments” is not established by human randomized trials.
The strongest literature belongs to:
Full-length thymosin beta-4
Animal injury models
Topical wound research
Ophthalmic development
Those findings should not be presented as direct clinical validation of injectable TB-500.
SAFETY & RESEARCH CONSIDERATIONS
Direct human safety data for the TB-500 fragment are extremely limited.
The nearest human safety evidence comes largely from studies of full-length thymosin beta-4.
FULL-LENGTH THYMOSIN BETA-4 SAFETY
Your Project source cites a Phase I study in which healthy volunteers received IV full-length thymosin beta-4.
No serious or dose-limiting toxicities were reported in that study.
That safety signal is useful context but cannot automatically be transferred to TB-500 fragment products, different routes, repeated cycles, or research-supply formulations.
RESEARCH-COMMUNITY REPORTS
Your Project profile notes community reports involving:
Mild injection-site discomfort
Redness
Short-lived fatigue
Head-pressure sensations
These are anecdotal observations rather than a validated clinical adverse-event profile.
ANGIOGENESIS & CANCER CONCERN
Thymosin beta-4 participates in angiogenic signaling.
Because angiogenesis can also support tumor growth, the Project profile identifies active or prior cancer as a theoretical concern.
The human relevance of this concern specifically for TB-500 has not been established.
This does not mean TB-500 has been shown to cause cancer.
IMMUNE & INFLAMMATORY EFFECTS
Thymosin beta-4 participates in inflammatory and immune signaling.
The consequences of repeated long-term TB-500 exposure on immune function have not been adequately characterized in humans.
PREGNANCY & LACTATION
The Project profile identifies no human safety data establishing TB-500 safety during pregnancy or breastfeeding.
PRODUCT QUALITY
Research-use peptide quality is another independent risk.
Potential concerns include:
Incorrect peptide identity
Mislabeling
Incorrect concentration
Degradation
Contamination
Sterility failure
Lot-to-lot variability
A valid COA can characterize a specific tested sample but does not establish overall medical safety.
REGULATORY CONTEXT
TB-500 IS NOT FDA APPROVED
TB-500 is not an FDA-approved drug for any indication.
There is no FDA-approved branded TB-500 product.
FDA COMPOUNDING HISTORY
Your Project profile documents several regulatory developments during 2026.
TB-500 had previously appeared in FDA 503A Category 2.
In April 2026, FDA removed TB-500 from Category 2 after the original nomination was withdrawn.
The Project source explicitly notes that removal from Category 2 was not a positive FDA safety determination.
PHARMACY COMPOUNDING ADVISORY COMMITTEE
Your Project profile states that the FDA Pharmacy Compounding Advisory Committee considered TB-500-related substances in July 2026.
The committee discussed whether TB-500 should be included on the 503A Bulks List.
This regulatory process concerns compounding policy and does not constitute FDA approval.
FDA HUMAN EXPOSURE DATA
Your Project profile notes that FDA reported it had not identified direct human exposure data for drug products containing the TB-500 fragment.
Human safety data involving full-length thymosin beta-4 should therefore remain clearly separated.
ANTI-DOPING STATUS
TB-500 and thymosin beta-4 derivatives are prohibited under the World Anti-Doping Agency Prohibited List, including the non-approved substances category.
Competitive athletes should not assume research status makes TB-500 permissible.
INTERNATIONAL STATUS
Your Project profile notes that regulatory treatment varies internationally and that some jurisdictions classify TB-500 more restrictively.
IMPORTANT REGULATORY DISTINCTION
Removal from an FDA compounding category does not equal FDA approval.
A compounding advisory review does not establish clinical efficacy.
Human data for full-length thymosin beta-4 do not establish an approved TB-500 treatment.
ANALYTICAL DOCUMENTATION
Croix maintains available third party analytical documentation only for specific samples and lots that can be matched to corresponding laboratory reports.
TB-500 10 MG
Laboratory
Optiq Health Labs
Sample Name
tb500 10mg
Lot
kizn072426
Sample ID
1271.OPT.260910
Report Date
September 18, 2026
Sample Matrix
Lyophilized Peptide
Intended Use
Research Use Only
Reported Net Content
9.97 mg/vial
Reported Purity
99.6%
Laboratory Identity Label
Thymosin Beta-4
Identity Method
LC-MS confirmation
Endotoxin
Pass • LAL ≤ 0.05 EU/mg
Sterility
Pass • USP <71> • No Growth
IMPORTANT DOCUMENTATION NOTE
The laboratory report identifies the sample name as “tb500 10mg” but identifies the tested peptide as “THYMOSIN BETA-4.”
Your TB-500 Project profile, however, defines TB-500 as a 7 amino acid fragment of thymosin beta-4, not full-length thymosin beta-4.
Because those are not chemically identical molecules, this COA should be displayed exactly as reported rather than described as definitive analytical confirmation of the 7 amino acid TB-500 fragment.
That naming discrepancy should be resolved with the supplier or laboratory before making a stronger identity claim.
IMPORTANT COA LIMITATION
Analytical results apply only to the specific sample identified in the corresponding laboratory report.
A Certificate of Analysis for one sample does not establish the composition, purity, sterility, safety, efficacy, or characteristics of another sample, lot, batch, or product.
Croix requires the product, strength, lot or batch, sample ID, laboratory, and report date to be matched before analytical documentation is represented as supporting a product.
A passing COA does not establish FDA approval, clinical efficacy, medical suitability, or the characteristics of unrelated lots.
SELECTED RESEARCH & REFERENCES
Ruff D, Crockford D, Girardi M, Zhang Y.
A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta-4 in healthy volunteers.
Annals of the New York Academy of Sciences. 2010.
Human Phase I safety research involving full-length thymosin beta-4.
Guarnera G, DeRosa A, Camerini R.
Research examining thymosin treatment in venous ulcers.
Annals of the New York Academy of Sciences. 2010.
Clinical wound research involving full-length thymosin beta-4.
Malinda KM, Sidhu GS, Mani H, et al.
Thymosin beta-4 accelerates wound healing.
Journal of Investigative Dermatology. 1999.
Preclinical wound-healing research.
Bock-Marquette I, Saxena A, White MD, Dimaio JM, Srivastava D.
Thymosin beta-4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair.
Nature. 2004.
Preclinical cardiac and cell-migration research.
Kim S, Baek KY.
Research examining thymosin beta-4 and medial collateral ligament healing in animal models.
Preclinical ligament-healing evidence.
Sosne G, Dunn SP, Kim C.
Research examining thymosin beta-4 in severe dry-eye disease.
Clinical ophthalmic evidence involving the parent peptide.
Sosne G, Ousler GW, Kim K, et al.
Phase III ophthalmic research involving topical thymosin beta-4.
Goldstein AL, Hannappel E, Sosne G, Kleinman HK.
Thymosin beta-4: a multi-functional regenerative peptide.
Review of thymosin beta-4 biology and tissue-repair pathways.
Xu B, Robinson RC.
Review of thymosin beta-4 function and applications.
U.S. Food & Drug Administration
503A bulk drug substance and Pharmacy Compounding Advisory Committee materials concerning TB-500.
World Anti-Doping Agency
Prohibited List and TB-500-related anti-doping materials.
EVIDENCE NOTE
The distinction between TB-500 fragment research and full-length thymosin beta-4 research is essential.
Most of the human clinical literature concerns the full-length parent peptide, often delivered topically, ophthalmically, or intravenously.
Those findings should not be described as direct clinical evidence that injectable TB-500 improves tendon healing, ligament healing, muscle recovery, joint function, or other regenerative outcomes.
RESEARCH & EDUCATIONAL INFORMATION
This profile is provided for research and educational reference. It does not constitute individualized medical advice or establish TB-500 as safe or effective for personal use.
TB-500 is not FDA approved for any therapeutic indication.
Direct human evidence for the 7 amino acid TB-500 fragment is extremely limited. Much of the published human literature commonly associated with TB-500 actually concerns full-length thymosin beta-4, which is a different molecule.
Preclinical findings involving actin regulation, cell migration, angiogenesis, inflammation, tendon or ligament repair, wound healing, or cardiac biology should not be interpreted as established clinical benefits of TB-500 in humans.
Analytical documentation presented by Croix applies only to the specific samples and lots identified in corresponding laboratory reports.