Recombinant Human SDF-1α/CXCL12

Recombinant human SDF-1α/CXCL12 is a valuable tool for research applications due to its well-characterized biological functions and broad relevance across multiple research areas.

Biological Significance and Function

SDF-1α/CXCL12 is a heparin-binding chemokine with multiple critical roles in cellular biology. This protein functions as a ligand for the CXCR4 receptor and can also bind CXCR7 and Syndecan-4. The SDF-1α/CXCR4 signaling axis regulates fundamental cellular processes including migration, survival, and development across diverse cell types.

Key Research Applications

Stem Cell and Progenitor Cell Studies

SDF-1α/CXCL12 plays essential roles in hematopoietic stem cell biology. It regulates the mobilization of CD34+ progenitor cells to peripheral blood and facilitates the homing of stem cells to their specific niches. The protein acts as a chemoattractant for CD34+ hematopoietic progenitor cells, making it invaluable for studies involving stem cell recruitment and differentiation.

Immune Cell Research

The protein demonstrates chemotactic activity for multiple immune cell populations. It is chemotactic for both peripheral blood T cells and lamina propria T cells, as well as peripheral blood B cells from healthy and rheumatoid arthritis donors. This makes it suitable for immunological studies and leukocyte migration assays.

Vascular and Angiogenesis Studies

SDF-1α/CXCL12 promotes angiogenesis and is involved in capillary tube formation of human retinal vascular endothelial cells by activating ERK1/2 and PI3K signaling pathways. This application is particularly relevant for studies of vascular development and endothelial cell biology.

Cancer Research

The CXCL12/CXCR4 axis is implicated in tumor progression, angiogenesis, metastasis, and survival. Recombinant SDF-1α/CXCL12 enables investigation of cancer cell behavior and the molecular mechanisms underlying tumor-stromal interactions.

Inflammatory and Tissue Repair Studies

SDF-1α/CXCL12 functions as a constitutive chemokine involved in inflammation in multiple tissues including lung, brain, joint, and intestine. Additionally, SDF-1α demonstrates therapeutic potential for wound healing applications when protected from proteolytic degradation.

Practical Advantages

The recombinant protein is optimized for cell culture, differentiation studies, and functional assays. Bioactivity is well-characterized, with established effective concentrations for various applications. For example, the protein chemoattracts resting human T cells with an ED₅₀ of 80-120 ng/ml, and demonstrates even greater potency on transfected cell lines expressing CXCR4.

When using recombinant SDF-1α/CXCL12, it is important to avoid repeated freeze/thaw cycles to maintain protein integrity and biological activity.

Yes, recombinant human SDF-1α/CXCL12 can be used as a standard for quantification or calibration in ELISA assays, provided it is properly validated and matched to the assay system.

Most commercial ELISA kits for human SDF-1α/CXCL12 are calibrated using highly purified recombinant human SDF-1α, typically expressed in E. coli. These kits demonstrate that recombinant SDF-1α yields standard curves that are parallel to those generated with natural SDF-1α, indicating comparable immunoreactivity and allowing for accurate quantification of both recombinant and natural forms in biological samples.

Key considerations for using recombinant SDF-1α/CXCL12 as a standard:

• Source and purity: Ensure the recombinant protein is highly purified and its concentration is accurately determined, as impurities or inaccurate quantification can affect calibration.
• Validation: Confirm that your ELISA antibodies recognize both recombinant and natural SDF-1α/CXCL12 with similar affinity. Most sandwich ELISAs for SDF-1α are validated for both forms.
• Matrix effects: When preparing standard curves, dilute the recombinant protein in the same buffer or matrix as your samples to minimize matrix effects and ensure accurate quantification.
• Parallelism: Ideally, perform a parallelism test by spiking recombinant SDF-1α into your sample matrix and comparing the dilution curves to those of the standard. This confirms that the assay quantifies both forms equivalently.

Limitations:

• Recombinant proteins may differ slightly in post-translational modifications compared to native proteins, but for SDF-1α/CXCL12, commercial ELISA kits have shown equivalent quantification for both forms.
• Always use the same recombinant protein lot for calibration throughout a study to avoid inter-lot variability.

In summary, recombinant human SDF-1α/CXCL12 is suitable as a standard for ELISA quantification, as long as the above best practices are followed and the assay is validated for both recombinant and natural forms.

Research Applications of Recombinant Human SDF-1α/CXCL12

Recombinant human SDF-1α/CXCL12 has been validated across a diverse range of biomedical research applications, reflecting its critical role in cellular signaling and tissue biology.

Cardiovascular and Vascular Applications

SDF-1α has demonstrated significant utility in cardiovascular research contexts. The protein has been evaluated as a biomarker in acute myocardial infarction, cardiac surgery, heart failure, and transplantation settings. In vascular biology, SDF-1α/CXCR4 signaling promotes capillary tube formation of human retinal vascular endothelial cells by activating ERK1/2 and PI3K pathways in vitro. Additionally, elevated SDF-1α expression in injured tissue can promote vascular remodeling via recruitment of smooth muscle progenitor cells. The protein has also been applied to wound healing applications, where protection from proteolytic degradation maintains SDF-1α bioavailability for therapeutic benefit.

Stem Cell and Regenerative Medicine

The chemokine functions as a chemoattractant for multiple cell types expressing the CXCR4 receptor, including mesenchymal stem cells, adipose-derived regenerative cells, and c-kit+ endogenous cardiac stem cells. Recombinant SDF-1α has been utilized in iPSC-derived endothelial cell studies, where the SDF-1α/CXCR4 axis facilitates cell incorporation to revascularize ischemic retina.

Oncology and Cancer Research

SDF-1α/CXCL12 has been extensively validated in cancer biology research. The CXCL12/CXCR4 axis is involved in tumor progression, angiogenesis, metastasis, and survival. Specific applications include studies on CXCR4 inhibition in pancreatic and colorectal cancers to induce integrated immune responses, investigation of CXCL12-mediated mechanisms in colorectal cancer metastasis, and evaluation of CXCR4/PD-1 combination inhibition in pancreatic ductal adenocarcinoma models. The protein has also been applied to capture CXCR4-expressing melanoma circulating tumor cells using CXCL12-loaded dermal fillers.

Hematopoietic and Immunological Applications

SDF-1α acts as a chemoattractant for human hematopoietic progenitor cells expressing CD34, giving rise to mixed and primitive progenitor types. The protein influences lymphopoiesis and has been implicated in HIV-1 infection research, as SDF-1α/PBSF functions as a ligand for the CXCR4 receptor, which serves as a co-receptor for lymphocyte-tropic HIV-1 strains.

Inflammatory and Tissue-Specific Studies

Research has examined inflammation's effects on SDF-1α regulation in pulpitis and other inflammatory conditions. The protein has been validated in functional assays examining cellular responses to hypoxia and in bioassays measuring migration and activation of hematopoietic progenitor cells and endothelial cells.

These applications demonstrate that recombinant SDF-1α/CXCL12 serves as a versatile research tool for investigating cellular migration, survival, development, and therapeutic potential across multiple disease contexts and tissue systems.

To reconstitute and prepare Recombinant Human SDF-1α/CXCL12 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). This carrier protein helps stabilize the chemokine and prevents adsorption to surfaces.

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%–1% BSA or HSA (human serum albumin) to achieve a final concentration of 100 μg/mL.
• Gently pipette the solution down the sides of the vial to dissolve. Do not vortex as vigorous mixing may denature the protein.
• Allow the protein to dissolve for several minutes at room temperature, gently swirling if needed.
• Once fully dissolved, aliquot the solution to avoid repeated freeze-thaw cycles.
• Store aliquots at 2–8 °C for up to 1 month or -20 to -70 °C for long-term storage. For additional stability, keep the protein in the presence of carrier protein.

Preparation for cell culture:

• For working concentrations, dilute the stock solution further in cell culture medium or tissue culture-grade buffer, maintaining the presence of carrier protein (BSA or HSA) if possible.
• If the protein is carrier-free, add BSA or HSA to the buffer at 0.1–1% to prevent loss of activity due to adsorption.
• Filter sterilize the final working solution if necessary, using a 0.2 μm filter.

Additional notes:

• Avoid repeated freeze-thaw cycles, as these can reduce protein activity.
• If using water for initial reconstitution (for carrier-free preparations), ensure subsequent dilution into buffered solutions with carrier protein for cell culture applications.
• Always verify the specific formulation and recommended protocol for your batch, as some preparations may differ (e.g., presence or absence of carrier protein, buffer composition).

Summary Table:

This protocol ensures optimal stability and biological activity of SDF-1α/CXCL12 for cell culture experiments.