LONG_R3.gifLONG®R3 IGF-I (LONG R3) is 200 times more potent and two times more stable in cell culture than insulin. SAFC® is the exclusive worldwide distributor of LONG®R3 IGF-I for industrial cell culture applications.

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LONG®R3 IGF-I is a critically important mitogenic growth factor often used in mammalian cell culture to increase yield significantly.  Such growth factors are fundamental supplements to chemically-defined media.  Repligen works collaboratively and exclusively with SAFC® for the worldwide distribution of LONG®R3  IGF-I in industrial cell culture applications.

Buy now >1 gram from SAFC

LONG®R3 IGF-I is a recombinant analog of human insulin-like growth factor-I (IGF-I) that has been specifically engineered for the enhancement of cell culture performance.

  • More biologically potent in vitro than either insulin or native IGF-I
  • Increases recombinant protein production significantly
  • Ideal for both research and large-scale culture systems utilizing serum-free or low-level serum applications

All cell types that have a growth response to insulin in cell culture have the potential to respond to LONG®R3 IGF-I, providing equivalent or better performance. LONG®R3 IGF-I has been used with numerous cell types including CHO, vaccine-producing cell lines, fibroblasts and stem cells.

Cell compatibility

LONG®RIGF-I is compatible with multiple cell types.  Any mammalian cell type that responds to insulin in cell culture has the potential to respond to LONG®RIGF-I.

  • CHO clones
  • HEK 293
  • Vero
  • MDCK
  • Fibroblasts

Formats and sizes

LONG®RIGF-I is available in two formats, both stable at 2-8°C.  LONG®RIGF-I can also be milled into cell culture media for additional flexibility and convenience.

Freeze dried powder

  • 5 mg (sample size)
  • 50 mg

Ready to use liquid

  • 5 mL (sample size)
  • 100 mL 
  • 250 mL 
  • 500 mL 
  • 1L (1000 mL)

*Sample size is not fully validated. The material is filled from validated intermediate material. Stability information is inferred from the stability trials for 100mL and 50mg respectively.


LONG® technology consists of a fusion of the growth factor with a portion of growth hormone sequence. The fusion improves growth factor production without imparting its biological activity. 

A distinct biological advantage
All mammalian cells secrete IGF Binding Proteins (IGFBPs) which bind to and inhibit native IGF-I. The substitution of an arginine for glutamic acid at position three in LONG®RIGF-I, in conjunction with the 13 amino acid N-terminal extension peptide, results in > 1000 fold reduced affinity for IGFBPs, enhancing its bio-availability and effectiveness in comparison to native IGF-I.

Specificity is the key to increased productivity
Unlike insulin, LONG®RIGF-I specifically targets and activates the type I IGF Receptor (IGF-IR) resulting in greater activation of downstream signaling cascades responsible for proliferation and inhibiting apoptosis. Greater activation of these key pathways results in increased cell density, higher viability and extended cell culture productivity.

To learn more about the use of LONG®R3 IGF-I in stem cell and cell therapy applications, please contact Repligen.

  • Potent, use less product since LONG®R3 IGF-I is 200  times more potent in cell culture than insulin
  • Stable, use less product since LONG®R3 IGF-I is 2 times more stable in cell culture than insulin
  • Efficient, achieve increased cell density, higher viability and extended culture duration
  • Simple, enables more streamlined cell culture feeding strategies
  • Cost-efficient, reduces cold chain shipping and storage costs since LONG®R3 IGF-I ships at ambient conditions and stored at 2-8°C.  ICH Q7 compliant stability trials have confirmed a 5-year shelf life for both the lyophilized and liquid products, allowing customers to purchase large batch sizes.
  • Compliant, helps ensure regulatory acceptance through an animal-free manufacturing process 
  • Secure supply, mitigates risk through inventory backed by comprehensive supply chain risk management

LONG®R3 IGF-I has been shown to improve volumetric productivity in CHO cell culture by up to 62% over cell culture with no supplementation and 40% over cell culture supplemented with insulin.

LONG®RIGF-I is backed by one of the most comprehensive risk mitigation strategies for any cell culture raw material. Repligen manages a global inventory safety stock of over 2 years forecasted demand. This inventory, together with multi-site manufacturing capability, ensures an uninterrupted supply to customers.

Repligen develops and manufactures products for the biopharmaceutical industry under an ISO 9001 quality management system.  We focus on the timely delivery of high quality, consistent and robust products, and ensuring business continuity for our customers.



The LONG®RIGF-I ELISA Kit is the only commercially available kit for the quantitation of LONG®RIGF-I. Fast, accurate, and easy to use with both media and drug substance samples, this sandwich ELISA kit uses a biotinylated secondary antibody and Streptavidin-HRP for detection

  • Limited reactivity to native or recombinant IGF-1
  • No reactivity to insulin
  • Ready-to-use ELISA plate allows the assay to be run immediately without additional plate coating and blocking steps

Kit Contents:

  • LONG®R3 IGF-I coated strip plate, 96 wells
  • LONG®R3 IGF-I Standard
  • Diluent
  • Biotinylated detection antibody
  • Streptavidin Peroxidase
  • TMB Peroxidase Substrate
  • LoBind® 1.5 mL Eppendorf tubes 




LONG®R3 IGF-I is not approved or permitted for use in any human application. Repligen provides LONG®R3 IGF-I only to qualified customers expressly for use in cell culture supplementation or for other research purposes.

SAFC® is a registered trademark of Merck KGaA.

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