Recombinant Human Follistatin

Recombinant Human Follistatin (rhFST) is a valuable tool for a wide range of research applications due to its well-characterized biological functions and regulatory roles. Here are several key reasons why you should consider using recombinant human follistatin in your research:

1. Regulation of TGF-β Family Signaling

Follistatin is a natural antagonist of several members of the transforming growth factor-β (TGF-β) superfamily, including activin, myostatin (GDF-8), BMPs, GDF-11, and TGF-β1. By neutralizing these signaling molecules, follistatin can modulate cellular processes such as differentiation, proliferation, and apoptosis, making it essential for studies involving these pathways.

2. Muscle Growth and Regeneration

Follistatin is a potent inhibitor of myostatin, a negative regulator of muscle growth. Administration of recombinant follistatin has been shown to increase muscle mass and strength in animal models, making it a key molecule for research into muscle wasting diseases, muscular dystrophies, and regenerative medicine.

3. Anti-inflammatory and Anti-fibrotic Effects

Follistatin has demonstrated anti-inflammatory and anti-fibrotic properties in various disease models. It can suppress inflammation and fibrosis in tissues, which is relevant for research on chronic inflammatory diseases, organ fibrosis, and tissue repair.

4. Neuroprotection and Neural Regeneration

Studies have shown that follistatin can reduce neuro-inflammation and promote the differentiation of oligodendrocyte progenitors, suggesting its potential in neuroprotective and neural regeneration research.

5. Reproductive Biology and Endocrinology

Follistatin plays a critical role in reproductive biology by regulating follicle-stimulating hormone (FSH) secretion and follicle development. It is widely used in studies related to ovarian function, fertility, and reproductive disorders.

6. Versatility in Experimental Models

Recombinant human follistatin is compatible with a variety of experimental systems, including cell culture, tissue explants, and in vivo animal models. It can be used in bioassays, ELISA standards, and functional studies across multiple species.

7. Therapeutic Development

Due to its broad biological activities, follistatin is a promising therapeutic target for conditions such as muscle wasting, fibrosis, inflammation, and metabolic disorders. Research with recombinant follistatin can help elucidate mechanisms and support the development of novel therapeutics.

8. High Purity and Consistency

Commercially available recombinant human follistatin is produced under controlled conditions, ensuring high purity, consistent activity, and reproducibility across experiments.

9. Support for Diverse Research Areas

Follistatin is relevant to research in cancer biology, cell signaling, developmental biology, regenerative medicine, and more, making it a versatile reagent for interdisciplinary studies.

In summary, recombinant human follistatin is a powerful and flexible tool for investigating TGF-β family signaling, muscle biology, inflammation, fibrosis, neuroprotection, and reproductive endocrinology, with broad applicability across experimental models and research fields.

Recombinant Human Follistatin can be used as a standard for quantification or calibration in ELISA assays, provided it is well-characterized, and its concentration is accurately known. This is a common practice in research ELISAs for quantifying Follistatin in biological samples.

Supporting details and best practices:

• ELISA kits for human Follistatin often use recombinant human Follistatin as the standard for generating calibration curves. These standards are typically produced in insect cells (e.g., Sf21) or other recombinant systems and are validated to ensure that the standard curve generated with recombinant protein is parallel to that obtained with natural Follistatin.
• Parallelism and quantification: Studies and kit documentation indicate that recombinant Follistatin produces standard curves that are parallel to those generated with natural Follistatin, supporting its use for relative quantification. This means you can use recombinant Follistatin to calibrate your assay and quantify unknowns, assuming your ELISA is validated for this purpose.
• Isoform specificity: Most ELISA kits recognize multiple Follistatin isoforms (FS288, FS300, FS315). Ensure the recombinant standard matches the isoform(s) your assay detects.
• Standard preparation: Reconstitute the recombinant protein according to the manufacturer’s instructions, using the same buffer or diluent as recommended for your ELISA standards. Prepare a dilution series covering the expected concentration range in your samples.
• Validation: If you are developing your own ELISA or using a non-kit-based assay, validate that the recombinant standard yields a linear, reproducible standard curve and that sample dilution curves are parallel to the standard curve (to confirm matrix compatibility and assay accuracy).
• Research use only: Most recombinant Follistatin proteins and ELISA kits are for research use only and not for diagnostic applications.

Limitations and considerations:

• Glycosylation and post-translational modifications may differ between recombinant and natural Follistatin, potentially affecting antibody recognition in some assays. However, most commercial ELISAs are validated to ensure equivalence between recombinant and natural forms.
• Matrix effects: If your sample matrix is complex (e.g., serum, plasma), confirm that the recombinant standard behaves similarly to endogenous Follistatin in your assay system.

Summary:
You can use recombinant human Follistatin as a standard for ELISA quantification, provided it is well-characterized, matches the isoform detected by your assay, and you validate its performance in your specific ELISA system.

Recombinant human follistatin has been validated for a wide range of applications in published research, primarily as a functional antagonist of activin and related TGF-β family members. The most commonly validated applications include bioassays (cell-based functional assays), in vivo studies (animal models), and as a standard or reagent in ELISA and other immunoassays.

Key validated applications in published research:

• Bioassays (Cell-based Functional Assays):

  • Used to assess the neutralization of activin or myostatin signaling in various cell types, including muscle cells, chondrocytes, osteoblasts, and stem cells.
  • Evaluated for its ability to promote or inhibit differentiation (e.g., myogenesis, osteogenesis, oligodendrocyte differentiation).
  • Studied for effects on cell migration, recruitment, and proliferation, particularly in the context of tissue repair and regeneration.

• In Vivo Studies (Animal Models):

  • Administered systemically or locally to investigate effects on muscle mass, bone formation, fibrosis, and inflammatory responses in mice, rats, and other species.
  • Used in disease models such as myocardial infarction, acute pancreatitis, inflammatory bowel disease, and muscle degenerative disorders.

• ELISA and Immunoassays:

  • Employed as a standard or control protein for quantifying follistatin or activin in biological samples.

• Other Biochemical and Analytical Applications:

  • Used in SDS-PAGE and functional screening assays to confirm activity and purity.
  • Applied in protein engineering studies to modify pharmacokinetic properties or binding affinities.

• Tissue Engineering and Regenerative Medicine:

  • Incorporated into biomaterial scaffolds or hydrogels for controlled delivery in bone tissue engineering and wound healing models.

• Mechanistic Studies:

  • Utilized to dissect signaling pathways involving activin, BMPs, myostatin, and related factors in developmental biology and disease contexts.

Summary Table: Validated Applications of Recombinant Human Follistatin

Notes:

• The specific isoform (e.g., FST288, FST315, FST300) and experimental context may influence the choice of application and observed effects.
• Most studies use recombinant human follistatin in either carrier-free or BSA-containing formulations, depending on the assay requirements.

If you need protocols or more detailed application-specific information, please specify the intended use or biological system.

To reconstitute and prepare Recombinant Human Follistatin protein for cell culture experiments, dissolve the lyophilized protein at a concentration of 100 μg/mL in sterile PBS containing at least 0.1% human or bovine serum albumin (BSA) as a carrier protein. This helps prevent protein loss due to adsorption to tube walls and stabilizes the protein during handling and storage.

Step-by-step protocol:

• Centrifuge the vial briefly before opening to ensure all powder is at the bottom.
• Add sterile PBS (phosphate-buffered saline) containing 0.1% BSA to achieve the desired concentration (typically 100 μg/mL).
• Gently pipette the solution down the sides of the vial to fully dissolve the protein. Do not vortex, as vigorous agitation can denature the protein.
• Allow the protein to dissolve for 15–30 minutes at room temperature with gentle mixing.
• If particulates remain, mix at room temperature for 2–3 hours or overnight at 4 °C on a rocker platform.
• Aliquot the reconstituted solution to avoid repeated freeze-thaw cycles.
• For short-term storage (up to one week), keep at 2–8 °C.
• For long-term storage, aliquot and freeze at −20 °C to −80 °C, ideally in the presence of carrier protein (BSA, HSA, or FBS) to maintain stability.
• If using in serum-free culture, avoid animal-derived carrier proteins and consider alternatives such as trehalose.

Additional notes:

• Always consult the specific product’s Certificate of Analysis (CoA) or datasheet for recommended buffer and concentration, as formulations may vary.
• For dilution to working concentrations, use buffer containing carrier protein to prevent loss of activity.
• Avoid repeated freeze-thaw cycles, which can degrade the protein.

Summary Table:

This protocol ensures optimal recovery, stability, and biological activity of recombinant human follistatin for cell culture applications.