PEG-MGF 5mg

Product status information

Chemical reagent intended exclusively for laboratory tests (Research Use Only). It is not a medicinal product, dietary supplement or food. It is not intended for use on humans or animals. Sales only to registered research units and laboratories.

Skeletal muscle has a remarkable ability to repair itself after mechanical damage – after intense eccentric exercise or micro-injury, muscle fibers launch a regeneration program in which a pool of dormant stem cells called satellite cells play the leading role. One of the earliest molecular signals of this program is Mechano Growth Factor (MGF) — splice variant of the IGF-1 gene, released locally in response to mechanical load.

It is this peptide that has attracted the attention of researchers in muscle physiology and regenerative biology for two decades, first through the work of Geoffrey Goldspink’s team, which characterized its expression and role in tissue repair. Native MGF, however, has an important limitation: as a linear peptide, it is rapidly degraded – its half-life in the biological environment is measured in minutes.

To extend compound exposure in experimental protocols, a mold was developed pegylated – PEG-MGF, in which a polyethylene glycol (PEG) chain was attached to the peptide molecule. Pegylation is a classic strategy in protein pharmacology: it increases the hydrodynamic mass of the molecule, shields it from proteases, and slows renal clearance, shifting the half-life from minutes to days.

For the researcher, this means prolonged and more stable exposure in the model, without the need for frequent dosing. This reagent is supplied in a vials with lyophilisate, nominal content 5 mg of peptide, in line Endogenic Pro-Body. The lyophilized form – a dry, sublimated powder – is a classic format of the peptide reagent with the highest storage stability: the peptide deprived of water does not hydrolyze or aggregate, and the researcher independently determines the working concentration at the stage of reconstitution with bacteriostatic water.

Regulatory status

PEG-MGF is not registered as a medicine in any jurisdiction – it is not authorized by the EMA, FDA or EFSA for any indication. As a growth factor with an anabolic profile, it is found on WADA prohibited list, class S2 (peptide hormones, growth factors and related substances) and is a permanently prohibited substance – both during and outside competition. Communication of the product as a “peptide for muscle mass”, “regeneration support for athletes” or “natural anabolic” is contrary to the Research Use Only framework and is unacceptable.

To understand PEG-MGF, you need to start with the IGF-1 gene. The insulin-like growth factor type 1 gene is affected alternative splicing — from one gene, a cell can produce several different protein variants, depending on the physiological context. The two most important are mature, circulating IGF-1 (the hepatic, systemic form, acting through the IGF-1R receptor) and IGF-1Ec — a variant that arises locally in the muscle in response to a mechanical stimulus.

This variant, after post-translational processing releasing a 24-amino acid peptide of the C-terminal E-domain, was called Mechano Growth Factor. The research analog of this signaling axis is anabolic IGF-1 LR3 — reproduces the action of mature, systemic IGF-1, which makes it a natural reference point in work on the IGF-1 family. The name is not accidental.

MGF is a molecular readout mechanotransduction — the process in which a muscle cell converts physical force (stretching, tension, microdamage to the sarcolemma) into a biochemical signal. After eccentric loading or fiber damage, the expression of the IGF-1Ec variant increases rapidly in the first hours, overtaking the expression of mature IGF-1. This temporal sequence suggested to researchers that MGF had a function early corrective signal — starts the regeneration program before systemic IGF-1, responsible for the later growth phase, comes into action.

A central observation in the literature concerns mechanistic distinctiveness. The works of Yang and Goldspink (2002) and Hill and Goldspink (2003) indicate that MGF E-domain peptide acts partially independently of the IGF-1R receptor — the early phase of its activity (stimulation of myoblast proliferation, mobilization of satellite cells) does not fully coincide with the classic signaling of mature IGF-1 (differentiation, hypertrophy).

In other words: the same gene encodes two tools with separated functions in time – MGF “wakes up and multiplies” stem cells, mature IGF-1 “differentiates and enlarges”. This separation of roles makes MGF a valuable tool for studying the early stages of muscle regeneration. The pharmacological and biological profile of MGF and its pegylated form covers several axes of activity studied in models:

• Satellite cell activation and proliferation — mobilization of muscle stem cells after mechanical damage
• Action partially independent of IGF-1R — a separate mechanism in the early regeneration phase, temporally separated from mature IGF-1 signaling
• Support for repairs and hypertrophy in models — influence on markers of muscle fiber repair
• Neuroprotection — studies in models of neuronal damage (ischemia, amyotrophic lateral sclerosis)
• Pegylation as a pharmacokinetics modifier — extending compound exposure from minutes to days

Chemically, PEG-MGF is a pegylated form of the 24-amino acid peptide of the C-terminal E-domain of the IGF-1Ec variant.

• Common name: PEG-MGF, pegylated MGF, pegylated Mechano Growth Factor
• Full name: Pegylated Mechano Growth Factor (IGF-1Ec E-domain peptide conjugated with polyethylene glycol)
• Synonyms: PEG-MGF, IGF-1Ec (parent form), MGF E-domain peptide
• MGF core sequence (24 aa): Tyr-Gln-Pro-Pro-Ser-Thr-Asn-Lys-Asn-Thr-Lys-Ser-Gln-Arg-Arg-Lys-Gly-Ser-Thr-Phe-Glu-Glu-Arg-Lys – with attached PEG group (sequence and PEGylation confirmation for verification in the batch COA)
• CAS number: no standard CAS number for the pegylated form (to be verified in the batch COA)
• Molecular weight: dependent on the mass of the peptide core and the degree of pegylation (length and number of attached PEG chains) – the binding value is given by the COA of the batch
• Chemical class: pegylated peptide; IGF-1 splice variant (IGF-1Ec E-domain) with attached polyethylene glycol
• Supplied form: 5 mg lyophilisate in a vial, for reconstitution with bacteriostatic water; purity ≥98% HPLC

Origin and research context: MGF was characterized as a mechanically induced splice variant of the IGF-1 gene in the work of Geoffrey Goldspink’s group at the turn of the century. It has been shown that the expression of the IGF-1Ec variant increases in muscle after loading and injury, and the released E-domain peptide stimulates myoblast proliferation separately from mature IGF-1 (Yang, Goldspink 2002; Hill, Goldspink 2003).

The pegylated form was created as a response to a practical laboratory problem: the native peptide is too unstable to ensure stable exposure in longer protocols. The addition of polyethylene glycol extended the half-life, which made PEG-MGF a more convenient research tool than native MGF.

SCIENTIFIC PERSPECTIVE

Most data on MGF comes from cellular models (myoblast cultures, C2C12 lines) and animal models (rat, mouse – models of muscle overload and damage). Observations regarding satellite cell activation, myoblast proliferation, and neuroprotection require interpretation in the context of the research model. Data comparing the pegylated form with the native form mainly concern the pharmacokinetic profile (prolonged half-life) and not confirmed clinical effectiveness. Extrapolation to humans is not valid – PEG-MGF has not been the subject of completed clinical trials as a medicinal product.

PEG-MGF works through several parallel axes, the common denominator of which is the early phase of muscle regeneration. The starting point lies in the biology of satellite cells.

Satellite cell activation and proliferation. Satellite cells are a quiescent pool of muscle stem cells located between the basement membrane and the sarcolemma of the fiber. At rest, they remain in an inactive state; After mechanical damage, the fibers are activated, divide (myoblast proliferation) and some of them differentiate, merging with the existing fiber or creating new ones.

MGF, released locally after loading, is one of the signals triggering this cascading program – in cell models, the E-domain peptide stimulates myoblast proliferation while delaying their premature differentiation, which increases the pool of available repair cells before the differentiation phase (Yang, Goldspink 2002). This is a feature that places compound at the core of the class’ interest peptides for regeneration in models of muscle tissue repair.

The action is partially independent of the IGF-1 receptor. This is what distinguishes MGF from mature IGF-1. Classic IGF-1 signals through the IGF-1R receptor and the PI3K/Akt and MAPK pathways, leading to differentiation and hypertrophy. The MGF E-domain peptide acts separately in the early regeneration phase – the literature indicates a mechanism that does not fully overlap with the classic IGF-1R cascade, which explains the temporal separation of functions: MGF dominates in early proliferation, mature IGF-1 in later differentiation and growth (Hill, Goldspink 2003).

Pegylation – Increased half-life. This is the essence of the difference between PEG-MGF and native MGF. The native peptide is linear and small, so it is rapidly subject to plasma proteolysis and renal filtration – its half-life is measured in minutes. The addition of polyethylene glycol increases the hydrodynamic radius of the molecule, shields the peptide bonds from proteases, and slows clearance, shifting the half-life from minutes to hours and days. In research protocols, this translates into prolonged and more stable exposure of the compound without the need for frequent dosing.

Support for repairs and hypertrophy in models. In animal models of muscle overload and damage, the effect of MGF on markers of fiber repair and on parameters of muscle hypertrophy was observed – a phenotype interpreted as the result of an enlarged pool of satellite cells in the early regeneration phase (Kandalla et al.). This is a direction close to research on anabolic peptides and mechanisms of hypertrophy in preclinical models.

Neuroprotection. Outside muscle, MGF has been studied in neuronal injury models of cerebral ischemia and amyotrophic lateral sclerosis (ALS). The literature describes the effect of MGF on the survival of motor neurons and nerve cells under stress conditions (Dluzniewska et al.), which expands the compound’s area of ​​interest beyond muscle physiology.

IMPORTANT DISTINCTION

Two pairs of concepts require separation. Firstly, PEG-MGF and native MGF they differ primarily in their pharmacokinetic profile: pegylation extends the half-life from minutes (native MGF) to hours-days (pegylated form), which concerns exposure in the model, not the separate biological activity of the peptide core. Secondly, MGF and mature IGF-1 are two splice variants of the same gene with separated functions: MGF (E-domain peptide) acts partially independently of the IGF-1R receptor in early satellite cell proliferation, mature IGF-1 – through IGF-1R in differentiation and hypertrophy. “Regeneration support” and “satellite cell activation” in this description refer only to in vitro and in vivo observations in cellular and animal models.

This is not a guarantee of effect in humans. PEG-MGF in the lyophilized vial remains a molecular tool for laboratory research.

PEG-MGF as an RUO reagent is used in several areas of muscle physiology and regeneration biology. The lyophilized vial format is useful when the researcher needs to independently define the starting concentration of the stock solution – reconstitution to a selected volume allows the molarity to be adjusted to a specific test, and the extended half-life of the pegylated form simplifies protocols that require stable exposure over time.

• Biology of satellite cells and myoblasts. Myoblast cultures (C2C12 lines, primary satellite cells), proliferation and differentiation tests, expression measurements of myogenic markers (MyoD, myogenin, Pax7). PEG-MGF as a tool for studying the early phase of muscle stem cell mobilization.
• Models of muscle repair and hypertrophy. Animal models of overload, mechanical damage and atrophy. Endpoints: fiber cross-sectional area, satellite cell density, protein synthesis markers, histology of regenerative tissue.
• Mechanotransduction and splicing of IGF-1. Studies on the regulation of alternative splicing of the IGF-1 gene in response to a mechanical stimulus – separation of the expression of the IGF-1Ec variant (MGF) from mature IGF-1 in time and tissue space.
• Experimental neuroprotection. Models of cerebral ischemia and amyotrophic lateral sclerosis (ALS) – studies on the survival of motor neurons and nerve cells under the influence of MGF.
• Pharmacokinetics of pegylated peptides. Comparative studies of the exposure profile of the pegylated and native forms – the impact of the degree of pegylation on the half-life, clearance and stability of the compound in the model.

PEG-MGF is a pegylated peptide form of the C-terminal E-domain of the splice variant IGF-1Ec – or Mechano Growth Factor, a local muscle repair signal released in response to mechanical load. The best documented profile of this compound is activation and proliferation of satellite cells in the early phase of regeneration, the action is partially independent of the IGF-1 receptor, time-separated from the function of mature IGF-1 (proliferation and differentiation).

Pegylation solves the workshop problem of native MGF – it extends the half-life from minutes to hours to days, ensuring more stable exposure in research protocols. Additional directions include models of muscle hypertrophy and neuroprotection (ischemia, ALS). The 5 mg lyophilized form in a vial provides the highest storage stability and freedom to select the working concentration during reconstitution.

HPLC purity ≥98%, MS Q-TOF with pegylation confirmation, COA for each batch. Regulatory Status – Research Use Only; lack of registration as a medicine; DEFECT S2 (growth factor) – permanently prohibited substance.

1. Goldspink G (2005). Mechanical signals, IGF-I gene splicing, and muscle adaptation. PubMed
2. Hill M, Goldspink G (2003). Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation following local tissue damage. PubMed
3. Yang SY, Goldspink G (2002). Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. PubMed
4. Dluzniewska J, Sarnowska A, Beresewicz M, Johnson I, Srai SK, Ramesh B, et al. (2005). A strong neuroprotective effect of the autonomous C-terminal peptide of IGF-1 Ec (MGF) in brain ischemia. PubMed
5. Kandalla PK, Goldspink G, Butler-Browne G, Mouly V (2011). Mechano Growth Factor E peptide (MGF-E), derived from an isoform of IGF-1, activates human muscle progenitor cells and induces an increase in their fusion potential at different ages. PubMed