Recombinant Human FGF-4

Recombinant Human FGF-4 is widely used in research due to its critical roles in stem cell biology, embryonic development, tissue regeneration, and disease modeling. Its recombinant form offers high purity, batch-to-batch consistency, and reliable bioactivity, making it preferable for reproducible experimental results.

Key scientific applications and rationale include:

• Promotion of Stem Cell Proliferation and Differentiation: FGF-4 is essential for the self-renewal and expansion of embryonic stem cells and is often included in stem cell culture media to maintain pluripotency or direct lineage specification, depending on concentration and context.
• Developmental Biology and Organogenesis: FGF-4 is a key regulator during embryogenesis, particularly in limb outgrowth, patterning, and maintenance of the trophectoderm and primitive endoderm. It is used to study signaling pathways such as FGFR and SHH, and to model developmental processes in vitro.
• Tissue Regeneration and Repair: FGF-4 supports the growth and survival of various cell types, including fibroblasts and endothelial cells, and is investigated for its potential in tissue engineering and regenerative medicine.
• Angiogenesis Research: FGF-4 is a potent promoter of angiogenesis, making it valuable for studies on blood vessel formation and related pathologies.
• Disease Modeling and Oncology: Altered FGF-4 expression is implicated in tumorigenesis, and its use in vitro allows for the investigation of oncogenic signaling and cancer cell biology.
• Organoid and 3D Culture Systems: Recombinant FGF-4 is frequently used in organoid cultures to mimic in vivo tissue architecture and function, benefiting from its high activity and reproducibility.

Advantages of using the recombinant form:

• High purity and defined activity reduce experimental variability.
• Batch-to-batch consistency ensures reproducibility, which is critical for sensitive applications such as organoid culture and stem cell differentiation.
• Animal-free production options are available, minimizing the risk of contamination and supporting translational research.

In summary, recombinant human FGF-4 is a versatile and reliable tool for studies in developmental biology, stem cell research, tissue engineering, and disease modeling, offering superior consistency and activity compared to native or crude preparations.

Yes, you can use Recombinant Human FGF-4 as a standard for quantification or calibration in ELISA assays, provided that the recombinant protein is highly purified, well-characterized, and its concentration is accurately known. The standard curve in an ELISA assay is typically generated using a serial dilution of a known concentration of the recombinant protein, which allows for the quantification of FGF-4 in your samples by comparing their signal to the standard curve.

Several ELISA kits for Human FGF-4 (such as those from Invitrogen, Abcam, and RayBiotech) are designed to use recombinant Human FGF-4 as the standard. The standard curve is constructed by plotting the optical density (OD) values of the standards against their known concentrations, and the concentration of FGF-4 in your samples is then interpolated from this curve.

It is important to ensure that the recombinant FGF-4 standard is compatible with the antibodies used in your ELISA kit and that it is properly reconstituted and diluted according to the manufacturer's instructions. Additionally, the standard should be stored appropriately to maintain its stability and activity.

In summary, Recombinant Human FGF-4 is suitable for use as a standard in ELISA assays for the quantification of FGF-4, as long as it meets the necessary quality and compatibility criteria.

Recombinant Human FGF-4 has been validated in published research for several key applications, primarily in the fields of stem cell biology, tissue engineering, cell signaling, and disease modeling.

Validated Applications in Published Research:

• Promotion of Embryonic Stem Cell Proliferation and Differentiation:
  FGF-4 is widely used to support the proliferation and maintenance of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), as well as to direct their differentiation into specific lineages, including endodermal, mesodermal, and ectodermal derivatives.

• Bioassays and Cell Culture:
  FGF-4 is routinely used in bioassays to assess its mitogenic activity, such as stimulating proliferation in NIH/3T3 fibroblast cells, and in cell culture systems to maintain or expand various cell types, including fibroblasts, epithelial cells, and endothelial cells.

• Organoid and Tissue Engineering:
  It is used in protocols for generating organoids from pluripotent stem cells, such as lung and liver organoids, and for engineering liver-like tissues in vivo, demonstrating its role in tissue regeneration and modeling.

• Investigation of Angiogenesis:
  FGF-4 has been applied in studies of angiogenesis, the process of new blood vessel formation, due to its ability to stimulate endothelial cell proliferation and migration.

• Signaling Pathway Studies:
  FGF-4 is used to dissect fibroblast growth factor receptor (FGFR) and Sonic Hedgehog (SHH) signaling pathways, both in normal development and disease contexts.

• Immunomodulation and Disease Models:
  Recent research has validated recombinant FGF-4 in modulating immune responses, such as regulating macrophage polarization (M1/M2) in models of autoimmune hepatitis, and in studies of liver inflammation and injury.

Representative Published Research Applications:

• Stem Cell Differentiation:

  • Generation of lung organoids from human pluripotent stem cells.
  • Differentiation of pluripotent stem cells into intermediate mesoderm and kidney tubule cells.
  • Long-term self-renewal and hepatic differentiation of ES/iPS-derived hepatoblast-like cells.

• Disease Modeling and Therapy:

  • Amelioration of liver inflammation and modulation of macrophage phenotypes in experimental autoimmune hepatitis models.
  • Engineering of liver-like tissue for cell therapy in hemophilia B.

• Cancer Research:

  • Studies on FGFR signaling in breast cancer resistance mechanisms.

Summary Table: Applications of Recombinant Human FGF-4

These applications are supported by both primary research articles and product validation data from multiple sources. If you require protocols or more detailed references for a specific application, please specify the intended use.

Reconstitution Protocol

Recombinant Human FGF-4 is supplied as a lyophilized powder and requires proper reconstitution before use in cell culture experiments. Centrifuge the vial briefly before opening to concentrate the powder at the bottom of the tube. Avoid vortexing, as this can denature the protein; instead, gently pipette the reconstitution solution down the sides of the vial.

The standard reconstitution concentration is 100 μg/mL in sterile PBS. For formulations containing carrier protein (typically bovine serum albumin), reconstitute in sterile PBS containing at least 0.1% human or bovine serum albumin. For carrier-free variants, reconstitute in sterile PBS without additional carrier protein. Alternative reconstitution approaches include using sterile distilled water or aqueous buffers containing 0.1% BSA, with concentrations ranging from 0.1 to 0.2 mg/mL depending on your specific application.

Aliquoting and Storage

Minimize freeze-thaw cycles by preparing single-use aliquots immediately after reconstitution. Store working aliquots containing at least 10 μL of protein solution at -20°C to -80°C for extended storage. For short-term use, reconstituted protein can be stored at 4°C and used within 1 month, or stored at -20°C to -80°C for 3 months.

The lyophilized protein itself should be stored at -20°C upon arrival, though short-term storage at 4°C (up to 6 months) or room temperature (up to 30 days) is permissible. Use a manual defrost freezer rather than automatic defrost models to prevent unintended thawing cycles.

Biological Activity and Application Considerations

Recombinant Human FGF-4 stimulates cell proliferation with an ED₅₀ of 0.25-1.25 ng/mL in NR6R-3T3 mouse fibroblast cell lines. The protein plays a key role in embryonic stem cell self-renewal and proliferation, and is commonly included in embryonic stem cell media. It can promote stem cell proliferation or aid differentiation depending on context and concentration. The protein is also suitable for fibroblast and epithelial cell culture, angiogenesis investigations, and studies of FGFR and SHH signaling pathways.