What is Thymosin Beta 4 (TB4)?
Thymosin beta 4 (TB4) is a naturally occurring peptide comprised of 43 amino acids that is best known for its ability to control the cell cytoskeleton, and consequently, cell migration (i.e. movement) and tissue repair.
What is the Cell Cytoskeleton?
Each cell is held together by a structural framework called the cytoskeleton, which is made up of three main parts: microtubules, intermediate filaments, and microfilaments (especially actin).
These parts work together to give the cell its shape and keep it stable. They also help the cell move — when these filaments interact with certain proteins, they can shift and rearrange, allowing the cell to change shape or move around. On top of that, the cytoskeleton acts as a network of highways inside the cell, helping transport nutrients and other materials where they need to go.
The integrity of the cytoskeleton, along with the proteins and peptides it interacts with, is essential for tissue repair, as cells need to be able to move, divide, and reorganize in order to heal damaged tissue.
How Does Thymosin Beta 4 (TB4) Work?
Thymosin beta 4 (TB4) is a naturally occurring peptide in the human body, encoded by a gene on the X chromosome. Because of this, males only inherit one copy of the gene from their mother, while females inherit one copy from each parent.
TB4 is found in nearly every cell in the body, and its primary role is to bind to actin, one of the key microfilaments in the cytoskeleton. By binding to actin, TB4 helps reorganize the cytoskeleton, which in turn affects how cells move.
Research has shown that TB4 plays an important role in tissue repair, helping cells migrate to the site of injury so they can rebuild and heal damaged tissue.
What is Thymosin Beta 4 (TB4) Used For?
- Investigational use for aiding in wound healing and tissue repair, especially muscles, tendons, ligaments
- Reducing inflammation
- Ocular (eye) surface healing, when applied topically
Side Effects of Thymosin Beta 4 (TB4)
Clinical trials have shown that thymosin beta 4 (TB4) is well-tolerated, with side effects mostly related to the injection rather than the peptide.
Thymosin Beta 4 (TB4) Dosing Protocol (for Research)
TB4 use is still investigational, and the ideal dosing regimen has not yet been established. Hence, researchers differ in their exact dosing protocols. Below is a suggested protocol for research use.
| Phase | Dose & frequency |
|---|---|
| Weeks 1-2 | 0.5 mg daily |
| Week 3 and beyond | 1 mg daily |
Shown for education. A licensed clinician should set any actual dose. Compare protocols across peptides in the peptide dosage chart.
Common questions about Thymosin β4 (TB4)
What is Thymosin Beta-4 (TB4)?
Thymosin beta 4 (TB4) is a naturally occurring peptide comprised of 43 amino acids that is best known for its ability to control the cell cytoskeleton, and consequently, cell migration (i.e. movement) and tissue repair.
What is Thymosin Beta-4 (TB4) used for?
Areas studied include: Investigational use for aiding in wound healing and tissue repair, especially muscles, tendons, ligaments; Reducing inflammation; Ocular (eye) surface healing, when applied topically.
How does Thymosin Beta-4 (TB4) work?
Thymosin beta 4 (TB4) is a naturally occurring peptide in the human body, encoded by a gene on the X chromosome. Because of this, males only inherit one copy of the gene from their mother, while females inherit one copy from each parent.
What are the side effects of Thymosin Beta-4 (TB4)?
Clinical trials have shown that thymosin beta 4 (TB4) is well-tolerated, with side effects mostly related to the injection rather than the peptide.
What is the dosage of Thymosin Beta-4 (TB4)?
One commonly referenced research protocol is: Weeks 1-2: 0.5 mg daily; Week 3 and beyond: 1 mg daily. Shown for education only; a licensed clinician should set any actual dose. See the dosing table.
How do you mix (reconstitute) Thymosin Beta-4 (TB4)?
Wipe the vial tops with alcohol, add bacteriostatic water slowly so it runs down the inside of the glass, then roll the vial gently until the powder dissolves; don’t shake it. See the step-by-step guide with diagrams for the pen and syringe methods.
How much bacteriostatic water do you add to Thymosin Beta-4 (TB4)?
There is no single correct amount. We recommend 2.1 mL: about 0.1 mL is lost during transfer, leaving roughly 2.0 mL of usable solution. You can add more or less (most peptide vials hold up to 3 mL); just enter the amount in the dose calculator. See the step-by-step mixing guide.
Is Thymosin Beta-4 (TB4) FDA-approved?
No. Thymosin β4 (TB4) is not FDA-approved in the US (status as of October 2026).
References
- Xue B, et al. Structural basis of thymosin-β4/profilin exchange leading to actin filament polymerization. Proc Natl Acad Sci U S A. 2014 Oct 28;111(43):E4596-605. View source
- Sosne G, et al. 0.1% RGN-259 (Thymosin ß4) 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 Dec 29;24(1):554. View source
- Wang X, et al. A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers. J Cell Mol Med. 2021 Sep;25(17):8222-8228. View source