TB-500 Fragment (17-23) 10mg

What Is TB-500 Fragment (17-23)?

TB-500 Fragment (17-23), also called fequesetide or (17) (LKKTETQ) (23), represents the smallest portion of the thymosin beta-4 molecule that retains the larger protein’s active binding domain. Research indicates that this synthetic derivative of thymosin beta-4 is capable of binding to actin, the molecule inside of cells that is responsible for cell structure, movement (a.k.a. migration), and replication. By altering the function of actin in cells, TB-500 Fragment (17-23) has been shown to modulate the immune response and alter cell migration patterns. This, in turn, can lead to large-scale changes in tissue/organ structure and function. In animal models, these changes have been shown to accelerate wound healing, decrease inflammation, promote blood vessel growth, reduce scar formation, improve musculoskeletal function, and even help to slow or reverse the course of certain disease conditions.

TB-500 Fragment (17-23) The Role of Actin in Cell Function

To understand how TB-500 fragment (17-23) works, it is necessary to understand the molecule actin. Actin is the most abundant protein in eukaryotic cells (the cells that make up our bodies) and is important in mediating many protein-protein interactions, including cell movement, maintenance of cell shape, vesicle and organelle movement, cell signaling, cell junctions, and regulation of cell division. Actin, along with myosin, is one of the two proteins involved in muscle contraction.</span>

Actin can be found in two forms: monomeric and polymerized. Monomeric actin is the most basic form of the protein and can be thought of as the storage form. Pools of monomeric actin are managed by actin-binding proteins like profilin and thymosin beta-4.

Polymerized actin is often referred to as a microfilament, and this form of the protein is responsible for most of actin’s functions within the cell. The transition from monomeric to polymeric form is controlled by profilin and thymosin beta-4. Profilin ensures that monomeric actin can only bind to one end of the growing filament. Thymosin beta-4 promotes the polymerization of G-actin into F-actin, where F-actin is the version of actin that can form polymeric microfilaments. Thus, thymosin beta-4 acts as both a protector of G-actin in its resting state and helps to promote its elevation to an active state when necessary.

One area in which TB-500 fragment (17-23) is likely to have a great deal of benefit is in the growth and regeneration of muscle tissue. In animal models of muscle injury, TB-500 fragment (17-23) activates satellite cells, which are versatile stem cells responsible for muscle repair. TB-500 administration encourages satellite cells to enter the cell cycle and multiply, likely through the Akt pathway discussed later in this article. This heightened satellite cell activity aids in the regeneration of damaged muscle fibers and the formation of new myofibers, thus enhancing muscle repair.

Moreover, TB-500 fragment (17-23) facilitates the migration of satellite cells to the site of muscle injury, where they can participate in the muscle repair process. Early research in muscle repair has suggested that TB-500 fragment (17-23) undergoes chemical modification at the injury site, transforming into a chemoattractant for differentiated myoblasts (muscle cells derived from satellite cells). This encourages migration to the injury site. It is worth noting that satellite cells are not exclusive to muscle tissue but are also found in the central and peripheral nervous systems.

TB-500 Fragment (17-23) and Musculoskeletal Performance

Muscle fibers are made up primarily of actin and myosin filaments. In order for muscle to contract, myosin pulls against the actin filaments and the entire muscle fiber gets shorter. When these fibers are damaged, the muscle itself heals in two ways. The first way in which muscle heals is to repair the damage and add supporting fibers in the area. This is controlled by existing muscle cells. The second way in which muscle heals is via the addition of an entirely separate, new muscle fiber. This second process is controlled by muscle stem cells, called myoblasts or satellite cells.

Muscle growth occurs quite well with existing muscle cells and, in fact, a great deal of performance is gained through the hypertrophy of the fibers that these cells control. There is, however, a limit to how large a muscle fiber can get, however, because it because inefficient for material to move from the muscle cells into the dense fibers that they control. At some point, further increases in performance demand an increase in the number of muscle fibers and thus in the number of cells that support them. This latter process, called hyperplasia, relies entirely on myoblasts.

Fortunately, TB-500 Fragment (17-23) is a short peptide and member of the class of cell-penetrating peptides. Cell-penetrating peptides are able to directly cross cell membranes, without the need for special transport apparatus, and can even penetrate the nuclear membrane [9], [10]. As a cell-penetrating peptide, TB-500 Fragment (17-23) is likely superior as an exogenously administered agent compared to natural Thymosin Beta-4. Its small size and increased bioavailability likely allow it to more easily reach areas where its effects can be most beneficial, thus leading to increased rates of muscle recovery and growth following training, injury, and other muscle-building stimuli. In short, TB-500 Fragment (17-23) likely has a superior effect on muscle performance compared to Thymosin Beta-4. Indeed, TB-500, which is closely related to TB-500 Fragment (17-23), has shown positive effects on functional recovery in animal models [11]. These animals have shown significant improvements in muscle strength, muscle endurance, and motor function compared to control groups [12].

TB-500 Fragment (17-23) and Cell Signaling

Cell signaling is the way in which cells send information to one another to coordinate their activities. This signaling is carried out though the release and uptake of chemical messengers at specific places and specific times. Specifically, TB-500 fragment (17-23) modulates activity of the Akt and Bcl-XL pathways.

The Akt pathway is well known for its ability to alter cell survival rates by interfering with the process of apoptosis (programmed cell death). It is worth noting that interfering with apoptosis is not desirable in all settings. In the case of senescence, for instance, inhibiting apoptosis can lead to tissue and organ dysfunction that are the hallmarks of the aging process. Alternatively, inhibiting apoptosis among fibroblasts engaged in wound repair can lead to increased rates of wound healing and better aesthetic outcomes. Thus, it is best to selectively modulate the Akt pathway, which is precisely what TB-500 fragment (17-23) does[8], [9].

The role of Akt in cell survival goes beyond simply inhibiting apoptosis, however. Research shows that Akt promotes the transition from G1 to S phase in the cell cycle. This is a necessary step for DNA synthesis to occur and one of the bottlenecks in the process of cell division. By speeding up this transition, the Akt pathway (and therefore TB-500 fragment (17-23)) increases rates of cell proliferation. In the case of injury and wound healing, this translates into increased proliferation of fibroblasts, endothelial cells, and other cells needed to rebuild tissue[10].

TB-500 Fragment (17-23): Summary

TB-500 and TB-500 Fragment (17-23) are very similar to one another and share many of the same properties. Other peptides appear to be potent anti-inflammatories and encourage the growth, proliferation, and migration of various cells necessary for tissue repair. Their actions seem to be nearly universal, providing increased growth and migration of cells in a range of organs including the skin, muscles, heart, and brain. By reducing inflammation and boosting cell activity, both TB-500 and TB-500 Fragment (17-23) act much like their parent molecule thymosin beta-4 to stimulate the repair of damaged tissue and restore baseline functionality in various tissues.

The chemical structure of TB-500 Fragment (17-23) is slightly modified from TB-500, which itself is heavily modified from thymosin beta-4. These modifications make TB-500 Fragment (17-23) the smallest of the three peptides and provide it with improved shelf-life and increased bioavailability.

Storage Instructions:

All of our products are manufactured using the Lyophilization (Freeze Drying) process, which ensures that our products remain 100% stable for shipping 3-4 months reconstituted (mixed with bacteriostatic water) to maintain stability. After reconstitution, the peptides will remain stable for up to 30 days.

Lyophilization is a unique dehydration process, also known as cryodesiccation, where the peptides are frozen and then subjected to low pressure. This causes the water in the peptide vial to sublimate directly from solid to gas, leaving behind a stable, crystalline white structure known as lyophilized peptide. The puffy white powder can be stored at room temperature until you're ready to reconstitute it with bacteriostatic water.

Once peptides have been received, it is imperative that they are kept cold and away from light. If the peptides will be used immediately, or in the next several days, weeks or months, short-term refrigeration under 4C (39F) is generally acceptable. Lyophilized peptides are usually stable at room temperatures for several weeks or more, so if they will be utilized within weeks or months such storage is typically adequate.

However, for longer term storage (several months to years) it is more preferable to store peptides in a freezer at -80C (-112F). When storing peptides for months or even years, freezing is optimal in order to preserve the peptide’s stability.