Recombinant Human FGF-9

Recombinant Human FGF-9 is widely used in research due to its critical roles in cell proliferation, differentiation, tissue development, and regeneration across multiple organ systems. Its application is supported by robust evidence in developmental biology, regenerative medicine, and disease modeling.

Key scientific reasons to use Recombinant Human FGF-9 in research:

• Potent Mitogenic Activity: FGF-9 is a strong stimulator of cell proliferation, particularly in fibroblasts, epithelial cells, glial cells, and various progenitor cell types. This makes it valuable for studies requiring controlled cell expansion or tissue modeling.

• Developmental and Differentiation Studies: FGF-9 is essential for the development of organs such as the kidney, lung, brain, and bone. It is used to direct the differentiation of pluripotent stem cells into specific lineages, including ureteric bud and collecting duct organoids, and to study tissue patterning and morphogenesis.

• Tissue Regeneration and Repair: Exogenous FGF-9 accelerates bone repair by promoting angiogenesis (formation of new blood vessels) and osteogenesis (bone formation), making it a key factor in skeletal regeneration models. It also supports the growth and survival of neurons and prostate tissue.

• Hair Follicle Biology: Recombinant FGF-9 induces the anagen (growth) phase in hair follicles, enhances hair follicle development, and increases skin thickness, making it useful for dermatological and hair regeneration research.

• Disease Modeling and Functional Assays: FGF-9 is implicated in cancer biology (e.g., promoting invasion and anti-apoptosis in gastric cancer cells), regulation of immune responses, and inhibition of myogenic differentiation, providing a tool for dissecting signaling pathways in health and disease.

• Versatility in Cell Culture: FGF-9 is used to maintain and expand various cell types in vitro, including mesenchymal and neural progenitors, and to support functional assays in whole cells and tissues.

• Mechanistic Studies: FGF-9’s signaling through FGFRs (fibroblast growth factor receptors) is central to understanding pathways involved in cell cycle regulation, tissue hierarchy, and vasoreactivity.

Summary of applications:

• Directed differentiation of stem cells and organoid formation
• Promotion of cell proliferation and survival
• Enhancement of tissue regeneration (bone, neural, epithelial)
• Investigation of developmental processes and disease mechanisms
• Functional assays in cell and tissue models

Using recombinant human FGF-9 provides a controlled, reproducible way to study these biological processes, enabling precise manipulation of signaling pathways relevant to development, regeneration, and disease.

Yes, recombinant human FGF-9 can be used as a standard for quantification or calibration in ELISA assays, provided it is of high purity and formulated appropriately for this application. Many commercial ELISA kits for FGF-9 quantification use recombinant human FGF-9 as the standard, and suppliers often recommend their recombinant FGF-9 proteins (especially those formulated with BSA) for use as ELISA standards.

Key considerations:

• Formulation: Recombinant FGF-9 with BSA is generally recommended for use as an ELISA standard, as BSA enhances protein stability and prevents adsorption to plasticware. Carrier-free formulations are available if BSA may interfere with your assay.
• Purity and Activity: Ensure the recombinant FGF-9 is of high purity (typically >95%) and has verified biological activity. Check the certificate of analysis for details.
• Reconstitution: Follow the supplier’s instructions for reconstitution, typically in PBS with at least 0.1% BSA to maintain stability and solubility.
• Standard Curve Preparation: Prepare a dilution series of the recombinant FGF-9 in the same buffer as your samples or as specified in your ELISA kit protocol to generate a standard curve for quantification.
• Compatibility: Confirm that the recombinant FGF-9 is recognized by the antibodies used in your ELISA. Most commercial kits are validated for both natural and recombinant FGF-9.

Limitations and Best Practices:

• Use the same recombinant FGF-9 standard throughout your experiments to ensure consistency.
• If using a custom or non-kit ELISA, validate the standard curve for linearity and parallelism with your sample matrix.
• Avoid repeated freeze-thaw cycles to maintain protein integrity.

Summary Table: Recombinant FGF-9 as ELISA Standard

If you are using a specific ELISA kit, always refer to the kit manual for any requirements regarding the standard, as some kits may require a matched standard for optimal accuracy.

Recombinant human FGF-9 has been validated for a diverse range of applications across multiple research domains:

Tissue Development and Differentiation

FGF-9 is utilized in developmental studies of tissue differentiation and mesenchymal cell culture differentiation. The protein has demonstrated particular utility in kidney organoid development, with published research showing its application in directed differentiation of ureteric bud and collecting duct organoids from human pluripotent stem cells, as well as in single-cell multiomic analysis of kidney organoid differentiation. Additionally, FGF-9 has been validated for promoting rapid and efficient differentiation of human pluripotent stem cells into intermediate mesoderm that forms tubules expressing kidney proximal tubular markers.

Angiogenesis and Vascular Biology

FGF-9 application has been shown to enhance angiogenesis and bone regeneration, demonstrating greater potency than VEGFA in certain contexts. Research has validated FGF-9 delivery during angiogenesis for producing durable, vasoresponsive microvessels wrapped by smooth muscle cells. The protein has also been documented as imparting hierarchy and vasoreactivity to the microcirculation of renal tumors.

Hair Follicle Biology

Recombinant human FGF-9 has been validated for stimulating hair growth by inducing the anagen phase in murine models, with intradermal injections enhancing hair follicle development and accelerating transition through hair cycle phases.

Cell Proliferation and Bioassays

FGF-9 induces proliferation in the Balb/3T3 mouse embryonic fibroblast cell line with an ED₅₀ of 1-5 ng/mL, making it suitable for cell proliferation bioassays. The protein has been validated in whole cell bioassay applications across multiple tissue types and species.

Cancer and Tumor Biology

Published research has validated FGF-9 for investigating its role in cancer pathways, including its effects on hepatocellular carcinoma tumorigenicity and therapy resistance, as well as its involvement in gastric cancer cell invasion and anti-apoptosis.

Reproductive and Developmental Biology

FGF-9 has been validated for studies of sex determination, with research demonstrating its requirement for maintaining SOX9 expression and its role in regulating testosterone production. Additionally, FGF-9 regulation of cyclin D1 and cyclin-dependent kinase-4 in ovarian granulosa and theca cells has been documented.

Muscle Biology

FGF-9 has been validated for investigating myogenic differentiation, with published studies demonstrating its inhibitory effects on myogenic differentiation of both murine C2C12 muscle cells and human skeletal muscle cells.

Broader Therapeutic Applications

Beyond specific tissue applications, FGF-9-derived peptides have demonstrated significant application potential in tissue repair and regeneration, cancer therapy, metabolic regulation, neural recovery, and biological delivery systems.

To reconstitute and prepare Recombinant Human FGF-9 protein for cell culture experiments, follow these steps for optimal solubility, stability, and biological activity:

1. Preparation Before Reconstitution

• Centrifuge the vial briefly (e.g., 3000 rpm for 5 minutes) to ensure all lyophilized powder is at the bottom before opening.

2. Reconstitution

• Solvent: Use sterile distilled water or sterile PBS (pH 7.2–7.4), depending on the formulation and downstream application.
• Concentration: Reconstitute to a final concentration of 100–200 μg/mL (0.1–0.2 mg/mL) as a stock solution.
• Mixing: Gently pipette up and down or swirl to dissolve. Do not vortex or shake vigorously, as this may impair biological activity.

3. Carrier Protein Addition (Recommended for Stability)

• For long-term storage or dilute working solutions, add a carrier protein such as 0.1% human or bovine serum albumin (HSA/BSA) to prevent adsorption and loss of activity.
• Alternatively, 10% FBS or 5% HSA can be used as stabilizers for further dilution.

4. Incubation

• Allow the solution to sit at room temperature for 15–20 minutes to ensure complete dissolution.

5. Aliquoting and Storage

• Aliquot the stock solution to avoid repeated freeze-thaw cycles.
• Short-term storage: 2–8°C for up to 1 week.
• Long-term storage: -20°C to -80°C with carrier protein.
• Avoid freeze-thaw cycles to preserve activity.

6. Working Solution Preparation

• Dilute the stock solution to the desired working concentration (typically 1–10 ng/mL for cell culture assays) in cell culture medium immediately before use.
• Ensure the final buffer is compatible with your cell culture system (e.g., PBS or culture medium with carrier protein).

Summary Table: Key Steps for FGF-9 Reconstitution

Additional Notes:

• Always consult the specific product datasheet or Certificate of Analysis for formulation-specific instructions.
• If the protein is supplied carrier-free, addition of a carrier protein is strongly recommended for long-term storage and dilute solutions.
• Avoid vigorous mixing and repeated freeze-thaw cycles to maintain biological activity.

These protocols ensure optimal solubility, stability, and activity of recombinant human FGF-9 for cell culture experiments.