IGF-1LR3

IGF-1LR3 (Long-acting Insulin-like Growth Factor-1) 5 mg - Premium Research Peptide | PeptideHubs What is IGF-1LR3? Overview In the fields of anabolic regulation, tissue regeneration, and cell proliferation research, a recombinant synthetic peptide derived from endogenous growth factors, possessing both potent anabolic activity and long-lasting action, is becoming a research hotspot—IGF-1LR3 (Long R3 Insulin-Like Growth Factor-1). This is a structurally optimized human insulin-like growth factor-1 (IGF-1) analogue. Its core advantage lies in its precise targeting of the IGF-1 receptor, achieving potent anabolic activity, tissue repair, cell proliferation, and anti-apoptosis. Furthermore, through structural modification, it significantly prolongs the in vivo half-life and reduces the affinity for binding proteins, overcoming the limitations of low bioavailability and short duration of action of natural IGF-1. Like a "powerful engine for cell growth and tissue repair," it plays an irreplaceable role in research related to musculoskeletal repair, cell culture, regenerative medicine, and metabolic disorders.

The unique advantage of this peptide lies in its perfect balance between "long-lasting activity" and "powerful targeting." Compared to the limitations of natural IGF-1 (70 amino acids), which has a short half-life (only 10-12 minutes in the free state, and about 12 hours after binding to carrier proteins) and is easily chelated by IGF-binding proteins (IGFBPs) and loses its activity, IGF-1LR3, through N-terminal structural modification, extends its half-life to 20-30 hours. Its biological activity is about three times that of natural IGF-1, and it can effectively avoid the binding and inhibition of IGFBPs, maintain an effective concentration in the free state in vivo, and exert its effect continuously. At the same time, as a complete agonist of the IGF-1 receptor, it can specifically bind to the IGF-1 receptor and hardly interfere with the normal metabolic function of the insulin receptor. Compared with insulin, it has a stronger growth-promoting and differentiation-promoting effect, a milder metabolic regulation effect, and better biocompatibility. Researchers have described it as a "long-lasting key that precisely activates cell growth," sustainably targeting cells and efficiently initiating anabolic and repair processes. Natural IGF-1, on the other hand, is like a "short-acting tool"—while it can exert similar effects, its susceptibility to chelation and short half-life make it difficult to achieve sustained research interventions.

As a classic research peptide in anabolic metabolism and regenerative medicine, IGF-1LR3 research has progressed from cell experiments and animal models to biopharmaceutical and preclinical applications. Its effects on cell proliferation, muscle growth, tissue repair, and serum-free cell culture have been fully validated. It is widely used in stem cell culture, recombinant protein production, musculoskeletal repair, and the construction of metabolic disease models, serving as a crucial bridge connecting basic growth factor research with biopharmaceutical and regenerative medicine applications. Currently, it has not been approved by regulatory agencies such as the FDA and EMA for human treatment and is primarily used as a research peptide tool. It is also listed as a prohibited substance by the World Anti-Doping Agency (WADA).

IGF-1LR3 Peptide Structure
Amino Acid Sequence and Basic Information: IGF-1LR3 is a recombinant synthetic single-chain polypeptide composed of 83 natural L-type amino acids. It is a structurally optimized analog of natural human IGF-1 (70 amino acids), CAS number 946870-92-4, molecular formula C₄₀₀H₆₂₅N₁₁₁O₁₁₅S₉, and molecular weight approximately 9111.4. Da, containing three intramolecular disulfide bonds, has a compact tertiary structure similar in spatial conformation to proinsulin. Its core structure comprises the 70-amino acid sequence of natural IGF-1, with two key structural modifications: replacing the glutamic acid (Glu) at position 3 of natural IGF-1 with arginine (Arg, i.e., R3 modification), and extending a 13-amino acid peptide chain at the N-terminus (sequence: Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn). No artificial terminal modifications were performed (no N-terminal acetylation or C-terminal amidation). Synthesized using recombinant technology, it exhibits high purity and stable biological activity.

Its precise and highly functional structural design, along with two key modifications and core structural features, endows it with long-lasting and potent scientific advantages. The highlights and advantages of its core structure are as follows:

• Core Structure Preservation and Activity Guarantee: It fully preserves the 70-amino acid core sequence and 3 disulfide bonds of natural IGF-1, ensuring its high affinity for the IGF-1 receptor. This allows for complete activation of the IGF-1 receptor-mediated downstream signaling pathway, retaining the anabolic, metabolic, cell proliferation, and anti-apoptotic activities of natural IGF-1, while avoiding the decrease in receptor binding capacity caused by structural modifications. This is the foundation for its core scientific research role.

• R3 modification (Arg³ replacement): Replacing the negatively charged glutamate (pKa approximately 4.1) at position 3 of natural IGF-1 with a positively charged arginine (pKa approximately 12.5) alters the local charge distribution at the N-terminus of the peptide chain, disrupting its electrostatic binding site with IGF-binding proteins (IGFBPs). This significantly reduces the affinity for IGFBPs (by more than 1000-fold), decreasing IGFBP chelation and inactivation, allowing more free IGF-1LR3 to bind to the IGF-1 receptor, thus enhancing bioavailability and activity. This is one of the core modifications responsible for its potent effect.

• N-terminal 13-amino acid extension modification (Long modification): A flexible 13-amino acid extension is added to the N-terminus of the peptide chain. This extension does not form a defined secondary structure but is located away from the core conformation of IGF-1, creating steric hindrance and further interfering with the binding interface between IGFBPs and the peptide chain. Simultaneously, it enhances the peptide chain's resistance to in vivo proteases, reducing enzymatic degradation. Synergistically working with R3 modification, it extends the in vivo half-life from 10-12 minutes (free state) of natural IGF-1 to 20-30 hours, achieving a long-term research intervention effect and addressing the drawbacks of short duration of action and frequent dosing required by natural IGF-1.

• Receptor-specific advantages: The peptide chain structure is optimized, exhibiting an affinity for the IGF-1 receptor comparable to natural IGF-1. This allows for efficient activation of the IGF-1 receptor-mediated PI3K/Akt/mTOR and MAPK/ERK signaling pathways, while simultaneously possessing extremely low affinity for the insulin receptor (IR), barely interfering with insulin's metabolic regulatory function. Compared to insulin, it exhibits stronger growth-promoting and differentiation-enhancing effects (approximately 200 times more bioactive than insulin) and is less likely to induce severe hypoglycemia, resulting in superior safety.

This ingenious structural design makes IGF-1LR3 a highly efficient, long-acting, and highly targeted anabolic peptide. It precisely binds to the IGF-1 receptor to exert its core function while overcoming the limitations of natural IGF-1 through structural modification, while also possessing excellent biocompatibility and stability. When it binds to the IGF-1 receptor on the surface of target cells (muscle cells, stem cells, chondrocytes, neurons, etc.), it can rapidly initiate anabolism, cell proliferation, and anti-apoptosis programs. Researchers, in elucidating its mechanism of action, are amazed by the molecular design wisdom of this synthetic peptide, which demonstrates "long-lasting potency and precise targeting."

To date, core research on IGF-1LR3 has covered cell experiments, animal models, and biopharmaceutical applications. Its role in cell proliferation, tissue repair, and anabolism regulation has been fully validated, and it is widely used in serum-free cell culture, stem cell proliferation, musculoskeletal repair, metabolic disease model construction, and recombinant protein production. Although it has not yet received FDA or EMA approval for human treatment, it has become one of the most valuable research peptides in the fields of anabolic metabolism, regenerative medicine, and biopharmaceuticals, providing an important tool for mechanistic research and novel drug development in related fields.

IGF-1LR3 Peptide and Anabolic Metabolism and Musculoskeletal Repair The most core and extensive research value of IGF-1LR3 lies in its potent anabolic and musculoskeletal repair effects. It can exert growth-promoting and repair-promoting effects on muscle, bone, and cartilage tissues. Through a multi-target synergistic mechanism, it promotes protein synthesis, inhibits protein degradation, and accelerates tissue repair, providing an important tool for research on muscle atrophy, bone injury, and cartilage degeneration. In cell experiments and animal models, its anabolic and repair effects have shown significant advantages, and are superior to those of natural IGF-1.

Its core anabolism and musculoskeletal repair mechanisms are clearly defined, with multiple targets working synergistically:

• **Potentially promotes anabolism and inhibits catabolism:** By activating the IGF-1 receptor-mediated PI3K/Akt/mTOR signaling pathway, it significantly promotes intracellular protein synthesis, increasing the expression of functional proteins such as muscle protein and collagen; simultaneously, it inhibits the ubiquitin-proteasome pathway, reducing protein degradation, achieving a dual effect of "promoting synthesis and inhibiting catabolism." In muscle cell experiments, it can significantly promote myocyte proliferation and myofiber hypertrophy, increasing muscle mass and strength, making it suitable for research on models of muscle atrophy and muscle injury repair.

• **Promotes muscle growth and repair:** It can promote the proliferation and differentiation of skeletal muscle satellite cells, activate muscle repair programs, accelerate regeneration and healing after muscle injury, and reduce muscle fibrosis. In animal experiments, daily subcutaneous injection of IGF-1LR3 (20-100 μg/day) can significantly increase lean body weight and muscle volume, improve muscle function, and has a long duration of action, eliminating the need for frequent dosing. This characteristic makes it an ideal tool for studying the mechanisms of muscle growth and repair.

• Promotes bone and cartilage repair: It can promote osteoblast proliferation and differentiation, increase collagen synthesis, improve bone density and strength, and accelerate fracture healing; at the same time, it promotes chondrocyte proliferation, increases cartilage matrix synthesis, and delays cartilage degeneration, making it suitable for research on musculoskeletal disease models such as osteoporosis, fractures, and osteoarthritis; in growth-restricted fetal sheep models, IGF-1LR3 can regulate amino acid metabolism and provide nutritional support for bone growth. Although it did not significantly improve fetal growth, it provided important reference for research on related metabolic mechanisms.

• Advantages in cell culture: As an important additive factor for serum-free cell culture, IGF-1LR3 can efficiently support the proliferation and survival of various cell types, including stem cells, myocytes, chondrocytes, and neurons. It can replace insulin or natural IGF-1 at lower concentrations (10-100 μg/L), with better stability, reducing batch-to-batch variability, and meeting the upstream process requirements for GMP-grade cell therapy drug applications. It can also increase the expression levels of recombinant proteins in CHO, HEK293, and other cells, making it widely used in biopharmaceutical production and research.

Studies have confirmed that IGF-1LR3 can significantly exert anabolism and cell proliferation effects at concentrations of 1-10 nM. Its long-lasting and potent characteristics make it an ideal research tool in fields such as anabolism, musculoskeletal repair, and cell culture, especially suitable for long-term research interventions and large-scale cell culture scenarios.

IGF-1LR3 Peptide and Cell Proliferation and Anti-apoptosis
In addition to anabolism, IGF-1LR3 also possesses significant cell proliferation and anti-apoptotic functions. Its effects stem from the activation of downstream signaling pathways of the IGF-1 receptor, promoting the proliferation of various cell types (stem cells, neurons, epithelial cells, etc.) and inhibiting apoptosis. This provides an important tool for research related to cell survival, tissue regeneration, and neuroprotection, and is particularly suitable for studies of cell injury models.

Its core cell proliferation and anti-apoptotic mechanisms and manifestations:

• Promotes cell proliferation and differentiation: Activates the IGF-1 receptor-mediated MAPK/ERK signaling pathway, promoting the cell cycle transition from G1 phase to S phase and accelerating cell proliferation; simultaneously, it can induce stem cells to differentiate into specific cell types (such as myocytes and osteoblasts), providing a sufficient cell source for tissue regeneration. It is suitable for research scenarios such as stem cell differentiation and tissue engineering construction. When added to serum-free culture medium, it can significantly increase cell density and survival rate.

• Effectively inhibits apoptosis: By activating the PI3K/Akt signaling pathway, it upregulates the expression of anti-apoptotic proteins Bcl-2 and Bcl-XL, downregulates the expression of pro-apoptotic proteins Bax and Caspase-3, blocks the mitochondrial-dependent apoptosis cascade, reduces apoptosis caused by ischemia, hypoxia, oxidative stress, toxins, etc., and protects cell integrity; in neural cell and cardiomyocyte injury models, it can significantly reduce cell death, exerting neuroprotective and cardioprotective effects.

• Regulation of Cellular Metabolism and Nutrient Utilization: It can promote the uptake and utilization of nutrients such as glucose and amino acids by cells, providing energy and material support for cell proliferation and survival. In growth-restricted fetal models, it can reduce the concentration of circulating amino acids, suggesting that it can promote amino acid utilization and provide a guarantee for cell growth, making it suitable for research on cell metabolic mechanisms.

• Synergistic Proliferative Effect: When used in combination with repair peptides such as BPC-157 and TB-500, it can produce a synergistic effect, further promoting cell proliferation and tissue repair, and enhancing the repair effect. When combined with stem cell technology, it can enhance the proliferative capacity and differentiation potential of stem cells, expanding the research application scenarios of tissue engineering.

Furthermore, the long-acting nature of IGF-1LR3 allows for once-daily dosing to maintain continuous cell proliferation and anti-apoptotic effects, avoiding the interference of frequent dosing on experimental models. This characteristic makes it suitable for long-term cell culture and tissue repair research observation scenarios.

IGF-1LR3 Peptide and Metabolic Regulation and Neuroprotection

IGF-1LR3 is a crucial molecule linking anabolism and metabolic regulation, as well as neuroprotection. Its effects extend beyond anabolism and cell proliferation; it also regulates glucose and lipid metabolism and protects neurons, providing new insights into metabolic disorders and neurodegenerative diseases. Furthermore, its metabolic regulatory effects are milder and its safety profile is superior to insulin.

Mechanisms of Metabolic Regulation and Neuroprotection:

• Glucose Metabolism Regulation: It can promote cellular glucose uptake and utilization, enhance insulin sensitivity, and assist in regulating blood glucose levels. However, its affinity for insulin receptors is extremely low, preventing the induction of a potent insulin-like hypoglycemic effect. Compared to insulin, it carries a lower risk of hypoglycemia. In diabetes model studies, it can help improve insulin resistance and reduce blood glucose fluctuations, but monitoring blood glucose changes is necessary to prevent hypoglycemia.

• Lipid Metabolism Regulation: It can promote adipocyte breakdown, reduce fat accumulation, and simultaneously promote the transformation of adipocytes into brown adipocytes, enhancing lipid oxidation metabolism and improving lipid metabolism disorders. It is suitable for research in models of obesity and metabolic syndrome. Synergistically with anabolism effects, it can achieve a "muscle-building and fat-reducing" research intervention effect.

• Neuroprotective effects: Promotes neuronal proliferation and differentiation, upregulates the expression of brain-derived neurotrophic factor (BDNF), protects neurons from oxidative stress and ischemia-hypoxia damage, improves synaptic plasticity, and alleviates neuronal damage and cognitive decline caused by neurodegenerative diseases. When used in combination with Cerebrolysin, it produces a synergistic neurotrophic effect, further enhancing the neuroprotective effect, and is suitable for research in models of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease.

• Vascular protective effects: Promotes vascular endothelial cell proliferation and angiogenesis, improves local blood circulation, provides sufficient oxygen and nutrients to damaged tissues (such as muscles, bones, and nerves), accelerates tissue repair, and is suitable for research in models of ischemic tissue injury.

Animal experiments have confirmed,

IGF-1LR3 can significantly improve glucose and lipid metabolism in metabolic disorder models, while also exerting neuroprotective and angiogenic effects. Its triple characteristics of "anabolism + metabolic regulation + neuroprotection" make it an ideal tool for multidimensional scientific research, especially suitable for research at the intersection of metabolism and neuroscience.

IGF-1LR3 Peptide and Safety

IGF-1LR3, as a structurally optimized analog of natural IGF-1, has demonstrated a certain level of safety in preclinical studies and scientific applications. However, due to its potent anabolic activity, specific safety risks exist. These risks are related to dosage, administration method, and specific populations, necessitating strict limitation to research use. Furthermore, caution must be exercised regarding the purity and structural deviations of products from unofficial channels:

• Common Reactions: Metabolic reactions are the most common. Approximately 10%-15% of research models experience hypoglycemia symptoms (lasting up to 30 hours), manifesting as dizziness, weakness, sweating, and palpitations. The risk is higher when administered on an empty stomach or in combination with insulin, and these symptoms are quickly relieved after carbohydrate supplementation. Local reactions are less common. During subcutaneous injection, approximately 3%-5% of models experience mild redness, swelling, and itching at the injection site, which completely subsides within 24-48 hours after discontinuation. Other possible reactions include water retention, joint stiffness, and muscle soreness, often related to excessive dosage, which can be alleviated by reducing the dosage.

• Potential Risks: High-dose use (>100 μg/day) may cause symptoms such as organ hypertrophy (e.g., heart, intestines), increased insulin resistance, edema, and hypertension. Long-term continuous use (>6 weeks) may lead to IGF-1 receptor desensitization, reducing efficacy and potentially increasing the risk of tumor proliferation (UK Biobank research shows that elevated IGF-1 levels are associated with various cancers). Products from unofficial channels may have insufficient purity, peptide degradation, oxidation products, etc., seriously affecting research safety and experimental reproducibility. Long-term use in growth and development models may lead to precocious puberty and premature closure of the skeleton, affecting normal growth and development.

• Drug Interactions: When used in combination with insulin, it produces a synergistic hypoglycemic effect, significantly increasing the risk of hypoglycemia; combined use is strictly prohibited. When used in combination with growth hormone (GH), CJC-1295, IPAMORELIN, or other growth hormone preparations, it can lead to excessively high IGF-1 levels in the body, increasing the risk of organ hypertrophy and insulin resistance; caution and strict dosage control are required. When used in combination with MK-677, it may exacerbate metabolic effects; blood glucose and organ function should be monitored. When used in combination with repair peptides such as BPC-157 and TB-500, it can produce a synergistic repair effect with no significant adverse interactions. When used in combination with metformin, it can help improve insulin resistance; blood glucose changes should be monitored.

• Important Reminder: IGF-1LR3 has not been approved for human treatment by any regulatory agency, including the FDA and EMA, and is only for research use (laboratory analysis, cell experiments, animal model studies). It is listed as a prohibited substance by the World Anti-Doping Agency (WADA) and is strictly prohibited for use by athletes. It is strictly prohibited for use in models with a history of cancer or undiagnosed tumors, diabetes or a predisposition to hypoglycemia, adolescent models during growth and development, and pregnant or lactating models. Products from unofficial channels may have insufficient purity or structural deviations, seriously affecting the accuracy of research data. Reconstituted products must be used within 7 days to avoid peptide degradation affecting activity.

Overall, IGF-1LR3 is well-tolerated at standard research doses (20-100 μg/day, subcutaneous or intramuscular injection), with most side effects being mild and reversible. However, its potent anabolic activity and potential tumor risk necessitate strict dose control and a shortened treatment cycle (a cycle of 4-6 weeks is recommended, with a 3-6 week interval before the next cycle). Strict contraindications exist for use in specific populations and research models, and the source and purity of the product must be strictly controlled.

Future Research and Clinical Trials of IGF-1LR3

As a multifunctional anabolic and regenerative medicine research peptide, IGF-1LR3 continues to expand its research boundaries. Currently, multiple cell experiments, animal experiments, and biopharmaceutical applications have been conducted, and preclinical exploration is also progressing steadily. Its scientific value in multiple fields continues to be explored, with core research directions focusing on anabolic mechanisms, indication expansion, dosage form optimization, and safety validation:

• Completed Research: Cell and animal experiments on anabolic mechanisms and cell proliferation mechanisms (activation of PI3K/Akt/mTOR, MAPK/ERK signaling pathways), musculoskeletal repair, cell culture applications, metabolic regulation, and neuroprotective effects; the mechanism of action of its core structural modifications, commonly used research dosages, and safety have been clarified; studies on its synergistic effects with other peptides have been completed, providing a foundation for combination drug research; and its application research in serum-free cell culture and recombinant protein production has been completed, promoting its research applications in the biopharmaceutical field.

• Ongoing Research: In-depth research on IGF-1LR3 in muscle atrophy, osteoporosis, and neurodegenerative diseases; dosage form optimization, development of long-acting sustained-release formulations to further extend the duration of action and reduce dosing frequency; development of its derivatives to further enhance targeting and reduce tumor risk; preclinical safety studies to improve long-term safety data; and application studies in special models such as growth-restricted fetuses and metabolic syndrome to clarify its limitations.

• Cutting-Edge Research: Synergistic application research of IGF-1LR3 in tissue engineering and stem cell therapy; combining it with gene editing technology to explore its precise role in cell proliferation and differentiation regulation; development of oral dosage forms to overcome the limitations of administration methods and expand research application scenarios; exploration of its potential value in ischemic diseases and cartilage repair; exploration of its impact on the tumor microenvironment to clarify the molecular mechanisms of its tumor risk and provide support for safe research use; and optimization of its application in biopharmaceutical production to improve the expression efficiency of recombinant proteins.

Current research focuses on clarifying the balance mechanism between its anabolic metabolism and tumor risk, optimizing dosage forms and usage regimens, expanding new research indications, improving long-term safety data, and addressing the purity issues of non-standard products. This aims to provide more precise and efficient tools for precision research and novel drug development in fields such as anabolic metabolism, regenerative medicine, and biopharmaceuticals, driving breakthroughs in related research areas.

Our IGF-1LR3 has the following significant characteristics:

• Guaranteed purity: Each batch of product undergoes dual testing by HPLC and mass spectrometry, with a purity ≥99%. Verified by an independent third-party laboratory, it is free from bacterial contamination, impurities, oxidation products, and peptide degradation fragments, ensuring the accuracy and reliability of research data. It is a white to off-white loose lyophilized powder, easily soluble in water, PBS, and physiological saline. The aqueous solution is clear, consistent with the typical physicochemical characteristics of IGF-1LR3. The applicable pH range is 4.0-7.5, suitable for research experiments and cell culture under physiological conditions.

• Precise Dosage: 5 mg vials are ideal for research dosage needs, allowing for flexible concentration configurations based on experimental protocols (e.g., 1-10 nM for cell experiments, 20-100 μg/day for in vivo experiments, 10-100 μg/L for cell culture), avoiding dosage waste and meeting the needs of various research scenarios such as cell experiments, animal models, combination drug studies, and serum-free cell culture, while also accommodating their narrow safety dosage windows.

• High Stability: Lyophilized powder formulation, strictly adhering to GMP-grade production standards, can be stored for extended periods (≥2 years) under dry, light-protected, and sealed conditions from -20°C to -80°C, effectively preventing peptide chain degradation and oxidation, maintaining activity; after reconstitution, it is stable for 7 days at 4°C and 24 hours at room temperature, suitable for global laboratory transportation and storage conditions, requiring no special antioxidant treatment, and convenient for research use.

• Structural Purity: Utilizing standard recombinant synthesis technology, the amino acid sequence of IGF-1LR3 is precisely replicated (83 amino acids, including R3 modification and an N-terminal 13-amino acid extension), fully preserving the three intramolecular disulfide bonds without any artificial terminal modifications. This ensures its binding activity to the IGF-1 receptor and its long-lasting, potent anabolic efficacy. The sequence is completely identical to that of the standard research formulation, guaranteeing experimental reproducibility.

• Research Use Only: Clearly labeled "For Research Use Only," strictly limited to cell experiments, animal models, and research on anabolic metabolism, tissue repair, cell culture, and metabolic regulation mechanisms. Non-research use is strictly prohibited. A complete quality control report, reconstitution guide, and storage instructions are provided, reminding users to accurately prepare the concentration according to the administration method, monitor hypoglycemia and organ function, and pay attention to storage conditions to avoid peptide degradation affecting experimental results.

For researchers exploring mechanisms of anabolism, cell proliferation, tissue repair, metabolic regulation, and neuroprotection, IGF-1LR3 is undoubtedly a key tool molecule for unlocking the potential of cell growth and tissue repair and driving breakthroughs in multiple fields of research. Its long-lasting, potent, and highly targeted characteristics make it one of the most valuable research peptides in the fields of anabolism, regenerative medicine, and biopharmaceuticals, and it is widely used in scientific research exploration in life sciences, pharmaceutical development, cell therapy, and other related fields.