TB-500
Synthetic fragment of thymosin beta-4
In a wound model, thymosin beta-4, whose active region TB-500 reproduces, sped up the regrowth of skin over the wound by 42% on day 4 and by up to 61% on day 7 (Malinda, 1999).
This 43-amino-acid protein binds actin, the building block of the cell's internal skeleton: that is what lets blood vessel cells, skin cells and stem cells migrate toward an injury.
TB-500 is studied for tissue repair and suppleness: its parent protein curbs NF-kB and limits fibrosis, and it has been tested in phase 3 in humans for corneal healing (SEER-1, 2023).
- Half-life
- A few hours in the blood; the effect on cells lasts far longer.
- Route
- Subcutaneous injection; the action is systemic, so the injection site matters little.
Technical sheet
- Family
- Synthetic fragment of thymosin beta-4
- Half-life
- A few hours in the blood; the effect on cells lasts far longer.
- Route
- Subcutaneous injection; the action is systemic, so the injection site matters little.
- Time to effect
- According to users, two to four weeks before a difference in flexibility or recovery.
- Level of evidence
- Laboratory research
Chemical identity
- Form
- Acetylated fragment 17-23 of thymosin beta-4 (Ac-LKKTETQ), values for the base form
Salt form: as stated on the lot's certificate of analysis.
Actin and cell migration
Cells hold their shape and move thanks to actin. Thymosin beta-4 keeps actin “in reserve”; TB-500 reproduces the segment that binds it (the LKKTET sequence).
It thereby eases the movement of the endothelial cells of blood vessels, the keratinocytes of the skin, and the stem cells that reach an injury.
NF-kB and fibrosis
Thymosin beta-4 dampens NF-kB and limits fibrosis: the repaired tissue stays more flexible. This is what drove research on the heart after a heart attack, when scar tissue replaces the muscle.
Studied effects and observed timelines
Suppleness in stiff areas: thymosin beta-4 limits fibrosis, the rigid scar tissue
According to users: two to four weeks
Muscle and tendon recovery: it speeds the migration of cells toward the injury
According to users: a few weeks of consistent use
Local inflammation: thymosin beta-4 curbs NF-kB, the central regulator of inflammation
According to users: first few weeks
What you may feel
- Brief fatigue or a “heavy-headed” feeling in the first few days, reported by some users.
- Mild headaches.
- Reaction at the injection site.
Stop and consult if
- Intense fatigue that persists beyond a few days.
- Pain or swelling that worsens in an injured area.
When to abstain
- Active cancer or a recent history of it: cell migration and blood vessel formation are also what a tumour relies on.
- Pregnancy or breastfeeding.
- An undiagnosed acute injury (suspected tear or fracture).
- Minors.
Anti-doping : Prohibited by the World Anti-Doping Agency (thymosin beta-4 and fragments, S2).
The effects to watch for, and how to reduce them
This sheet is educational. It replaces neither a diagnosis nor follow-up: for any medical condition, pregnancy, breastfeeding or current medication, talk to a health professional.
Thymosin beta-4 has been studied all the way through clinical trials in humans (corneal healing, cardiac research) and in numerous repair studies. TB-500 reproduces its active region; the human trials were done with the full protein.
1999 · Malinda et al., Journal of Investigative Dermatology
Experimental full-thickness wound model, thymosin beta-4 applied to the wound or injected
Regrowth of skin over the wound (re-epithelialization) rose by 42% on day 4 and by up to 61% on day 7 compared with saline; the wound also contracted more, by at least 11% on day 7.
2004 · Bock-Marquette et al., Nature
Experimental model of myocardial infarction
Thymosin beta-4 promotes cardiac cell survival and improves heart function after infarction, via cell migration and the Akt pathway. The foundational study in the field.
2010 · Goldstein et al., review in Expert Opinion on Biological Therapy
A synthesis of the work on thymosin beta-4 in healing (skin, cornea, heart)
Faster wound closure and reduced inflammation across several models; early human data on skin and the eye.
2015 · Sosne et al., RGN-259 trials
Clinical trials in humans (eye drops, dry eye and keratopathy)
Improved signs of corneal healing in humans, with good tolerability.
Are TB-500 and thymosin beta-4 the same thing?
Almost. Thymosin beta-4 is the natural 43-amino-acid protein; TB-500 reproduces its active region, the part that binds actin.
Does it need to be injected near the injury?
No: TB-500 acts throughout the body, wherever it is injected. It binds actin, which lets blood vessel cells, skin cells and stem cells migrate toward the injury. The protocol provided with the product specifies the technique.
Is it prohibited in sport?
Yes. Thymosin beta-4 and its fragments are on the World Anti-Doping Agency's list of prohibited substances.
Glossary (5)
- Actin
- A protein that forms the fibres of the cell's internal skeleton and enables its movement.
- Endothelial cell
- A cell that lines the inside of blood vessels.
- NF-kB
- A “switch” protein that triggers the inflammatory response inside the cell.
- Fibrosis
- The replacement of functional tissue with stiff scar tissue.
- Systemic
- Acting throughout the whole body, as opposed to locally.