Performance/Muscle

IGF-1 LR3

Research Reagent · Laboratory Use Only

Quick Answer

What does current research show about IGF-1 LR3 and its biological mechanisms?

IGF-1 LR3 is a synthetic analogue of Insulin-like Growth Factor 1 with an extended half-life (~20–30 hours vs ~12–15 minutes for native IGF-1). Research indicates it binds IGF-1 receptors to promote cellular proliferation, differentiation, and anti-apoptotic signalling. Preclinical studies examine its role in muscle hypertrophy and metabolic regulation (PubMed: 8621576).

PMID41418663↗DOI10.1016/0303-7207(92)90159-4↗⟳ Reconstitution Calculator
Scientific AbstractPMID 41418663 · 2026

Introduction

Volumetric muscle loss (VML) resulting from severe extremity injuries in combat remains a significant clinical challenge, particularly in austere environments. Current research emphasizes the development and evaluation of definitive treatments, largely neglecting acute stabilization strategies. To address this unmet need, this study investigated the efficacy of delivering insulin-like growth factor 1 long arginine 3 (IGF1-LR3) via a synthetic in situ forming hydrogel muscle void filler (MVF) to enhance muscle recovery after VML.

Methods

Adult male Lewis rats underwent VML surgery, followed by implantation of a polyethylene glycol-acrylate MVF containing either soluble or poly(lactic-co-glycolic acid) (PLGA)-encapsulated IGF1-LR3 at a low (28 μg) or high (280 μg) dose, or no IGF1-LR3 (control). Neuromuscular function was assessed via isometric torque measurements. Muscle tissue was analyzed using wheat germ agglutinin and picrosirius red staining for fiber size, count, and fibrosis. Statistical analysis was performed using ANOVA with Holm-Šídák post hoc testing.

Results

High-dose PLGA-encapsulated IGF1-LR3 resulted in increased muscle weight compared to the control group at 28 d post implantation. However, no differences were observed in specific torque or maximum torque production between any experimental groups. Histological analysis revealed no changes in muscle fibrosis or fiber size or count of IGF1-LR3 compared to controls.

Conclusions

The addition of IGF1-LR3 in an MVF did not enhance neuromuscular function or muscle fiber hypertrophy. Further studies are needed to optimize IGF1-LR3 delivery or alternative hypertrophy-inducing soluble factors.

Source:10.1016/0303-7207(92)90159-4
Mechanistic Research SummaryCurated from PubMed

This data is for laboratory research purposes only. Not for human or animal consumption.

What is IGF-1 LR3?

Insulin-like growth factor 1 long arginine 3 (IGF-1 LR3) is a synthetic analog of endogenous insulin-like growth factor designed for extended biological half-life and enhanced receptor binding affinity. This study evaluated its efficacy as a therapeutic agent for volumetric muscle loss (VML) recovery when delivered via synthetic hydrogel muscle void fillers.

Mechanism of Action

IGF-1 LR3 activates the IGF-1 receptor signaling pathway, which promotes muscle protein synthesis, myocyte proliferation, and anti-apoptotic signaling in skeletal muscle tissue. The extended arginine 3 modification increases circulating stability and receptor engagement duration compared to native IGF-1, theoretically enhancing anabolic effects in injured muscle beds. In this study, delivery occurred via polyethylene glycol-acrylate hydrogel matrix with sustained-release poly(lactic-co-glycolic acid) (PLGA) microencapsulation.

Observed Laboratory Results

  • Muscle weight increase: High-dose PLGA-encapsulated IGF-1 LR3 (280 μg) demonstrated statistically significant increases in muscle wet weight at 28 days post-implantation compared to vehicle control in a rat VML model.
  • Torque production unchanged: No significant differences in isometric torque, specific torque, or maximum voluntary contraction were observed across all IGF-1 LR3 treatment groups versus controls.
  • Histological measures null: Quantitative analysis using wheat germ agglutinin and picrosirius red staining revealed no statistically significant alterations in myofiber cross-sectional area, fiber count, or collagen deposition (fibrosis markers) between IGF-1 LR3-treated and control groups.

Conclusion

Despite modest gains in muscle mass, IGF-1 LR3 delivery via hydrogel muscle void filler did not translate to improved neuromuscular function or structural muscle recovery metrics in acute VML injury, suggesting the need for optimization of delivery kinetics, dosing regimens, or investigation of alternative myogenic growth factors.

Clinical Research ParametersHuman Study Registry

No registered clinical trials or indexed human study data currently available for IGF-1 LR3 via ClinicalTrials.gov or PubMed. This compound may be at preclinical or early research stages.

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Research Compliance Notice

All data presented on this page is for laboratory research purposes only. IGF-1 LR3 is referenced here as a research reagent. This page does not constitute medical advice, clinical guidance, or endorsement of any compound for human or animal use. All referenced studies are available via PubMed (PMID: 41418663) and the DOI-linked journal publication. Researchers must consult applicable institutional and regulatory frameworks before conducting any protocols.

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