The angiopoietin (Ang) family of growth factors includes four members, all of which bind to the endothelial receptor tyrosine kinase Tie2. Two of the Angs, Ang-1 and Ang-4, activate the Tie2 receptor, whereas Ang-2 and Ang-3 inhibit Ang-1-induced Tie2 phosphorylation. Angiopoietin-1 (Ang-1) is a secreted growth factor which binds to and activates the Tie-2 receptor tyrosine kinase. The factor enhances endothelial cell survival and capillary morphogenesis, and also limits capillary permeability. Ang-2 binds the same receptor but fails to activate it: hence, it is a natural inhibitor of Ang-1. Ang-2 destabilises capillary integrity, facilitating sprouting when ambient vascular endothelial growth factor (VEGF) levels are high, but causing vessel regression when VEGF levels are low. Tie-1 is a Tie-2 homologue but its ligands are unknown. Angiopoietin and Tie genes are expressed in the mammalian metanephros, the precursor of the adult kidney, where they may play a role in endothelial precursor growth. Tie-1-expressing cells can be detected in the metanephros when it first forms and, based on transplantation experiments, these precursors contribute to the generation of glomerular capillaries. During glomerular maturation, podocyte-derived Ang-1 and mesangial-cell-derived Ang-2 may affect growth of nascent capillaries.
After birth, vasa rectae acquire their mature configuration and Ang-2 expressed by descending li mbs of loops of Henle would be well placed to affect the growth of this medullary microcirculation. Finally, preliminary data implicate angiopoietins in deregulated vessel growth in Wilms' kidney tumours and in vascular remodelling after nephrotoxicity. Altogether, existing data suggest that VEGF-A and Angiopoietins not only have quite different roles during vascular development, but also very complementary and coordinated roles. Human Ang-1 shares approximately 97% and 60% amino acid sequence identity with mouse Ang-1 and human Ang-2, respectively.
The predicted molecular weight of Recombinant Human ANG-1 is Mr 56 kDa. However, the actual molecular weight as observed by migration on SDS Page is Mr 70 kDa.
Predicted Molecular Mass
56
Formulation
This recombinant protein was lyophilized from a 0.2 μm filtered solution in Tris-Citrate and sodium chloride (NaCl).
Storage and Stability
This lyophilized protein is stable for six to twelve months when stored desiccated at -20°C to -70°C. After aseptic reconstitution, this protein may be stored at 2°C to 8°C for one month or at -20°C to -70°C in a manual defrost freezer. Avoid Repeated Freeze Thaw Cycles. See Product Insert for exact lot specific storage instructions.
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Recombinant Human Angiopoietin-1 (Ang-1) is widely used in research because it is a key regulator of vascular development, stability, and function, making it essential for studies involving angiogenesis, vascular permeability, inflammation, and tissue regeneration.
Key reasons to use recombinant human Angiopoietin-1 in research applications:
Vascular Development and Stability: Ang-1 is critical for the maturation and maintenance of blood vessels by binding to the Tie2 receptor on endothelial cells, promoting vessel stability and reducing vascular leakage.
Anti-inflammatory Effects: Ang-1 suppresses vascular inflammation by inhibiting the expression of endothelial adhesion molecules and reducing leukocyte adhesion, which is valuable in models of sepsis, endotoxic shock, and other inflammatory diseases.
Endothelial Cell Survival: It protects endothelial cells from apoptosis and supports their survival under stress conditions, such as serum deprivation or inflammatory insult.
Angiogenesis and Tissue Repair: Ang-1 promotes angiogenesis (formation of new blood vessels) and is used in studies of wound healing, tissue engineering, and neural regeneration.
Disease Modeling and Therapeutic Research: Recombinant Ang-1 is used to model vascular pathologies (e.g., diabetic retinopathy, tumor angiogenesis, sepsis) and to evaluate potential therapeutic interventions targeting the Ang-Tie signaling axis.
Common research applications include:
Bioassays for endothelial cell function and survival.
Protein-protein interaction and receptor binding studies (e.g., Tie2 clustering and activation).
In vivo models of vascular leakage, inflammation, and tissue repair.
Functional studies in cardiovascular, cancer, and regenerative medicine research.
Summary of scientific value:Using recombinant human Angiopoietin-1 enables precise control over experimental conditions, facilitates mechanistic studies of vascular biology, and supports the development of novel therapies for vascular and inflammatory diseases.
You can use recombinant human Angiopoietin-1 as a standard for quantification or calibration in ELISA assays, provided it is of high purity, correctly quantified, and compatible with your assay system. This is a common practice in ELISA development and quantification of target proteins.
Key considerations and supporting details:
Recombinant Protein as Standard: ELISA kits for Angiopoietin-1 routinely use recombinant human Angiopoietin-1 as the calibrator or standard to generate the standard curve for quantification. This allows for accurate measurement of Angiopoietin-1 concentrations in biological samples by comparing sample absorbance to that of known standard concentrations.
Purity and Quantification: The recombinant standard must be highly pure and accurately quantified (by mass or concentration) to ensure reliable calibration. Impurities or inaccurate quantification can lead to errors in your standard curve and sample measurements.
Formulation: Recombinant proteins are available in carrier-free or carrier-added (e.g., with BSA) formulations. Carrier-free is preferred if you want to avoid interference in sensitive assays, while carrier-added may improve stability for routine use.
Assay Compatibility: The recombinant Angiopoietin-1 used as a standard should be recognized by the capture and detection antibodies in your ELISA. Most commercial ELISA kits are validated with specific recombinant standards, and using a different source or isoform may affect accuracy if there are differences in epitope recognition or post-translational modifications.
Preparation: Standards should be reconstituted and diluted according to the assay protocol, using the recommended diluent to ensure matrix compatibility and reproducibility.
Validation: If you are developing a custom ELISA or substituting the standard in a commercial kit, it is important to validate that your recombinant Angiopoietin-1 produces a linear, reproducible standard curve and that recovery and parallelism are acceptable when spiked into your sample matrix.
Summary Table:
Requirement
Details
Purity
High purity, low endotoxin, well-characterized
Quantification
Accurate mass/concentration determination
Formulation
Carrier-free or carrier-added, depending on assay needs
Antibody Compatibility
Must be recognized by ELISA antibodies
Preparation
Follow recommended reconstitution and dilution protocols
Validation
Confirm linearity, recovery, and parallelism in your assay system
In conclusion: Using recombinant human Angiopoietin-1 as a standard is standard practice in ELISA quantification, but ensure it is compatible with your assay and validated for your specific application.
Recombinant Human Angiopoietin-1 has been validated in published research for a range of applications primarily focused on vascular biology, endothelial cell function, and disease models involving vascular integrity and inflammation.
Key validated applications include:
Bioassays: Used to study angiogenesis, endothelial cell migration, tube formation, and Tie2 receptor activation in vitro.
In vivo models: Demonstrated efficacy in reducing vascular leakage, stabilizing blood pressure, and improving survival in models of sepsis and endotoxic shock.
Blood-brain barrier studies: Shown to decrease permeability of the blood-brain barrier in focal cerebral ischemia models.
Apoptosis inhibition: Validated for inhibiting serum deprivation-induced apoptosis in human umbilical vein endothelial cells (HUVECs).
Vascular architecture restoration: Used to restore vessel architecture in mice lacking mural cells.
Neural regeneration: Applied in studies promoting neural regeneration and motor function recovery after spinal cord injury.
Inflammatory response modulation: Shown to reduce inflammatory cytokine storms and organ damage in sepsis models, and to lower expression of endothelial adhesion molecules.
Protein-protein interaction and binding assays: Used for studying interactions with Tie2 and other endothelial receptors.
Western blot and SDS-PAGE: Validated for use in protein detection and characterization assays.
Representative research applications:
Vascular stabilization and permeability reduction: Angiopoietin-1 has been widely used to demonstrate its role in maintaining vascular integrity, reducing endothelial permeability, and protecting against vascular leakage in disease models such as sepsis, diabetic retinopathy, and acute lung injury.
Endothelial cell signaling: Studies have validated its use in activating Tie2 signaling, promoting endothelial cell survival, and inhibiting apoptosis.
Therapeutic candidate evaluation: Engineered variants of Angiopoietin-1 (e.g., Ang1 A451D) have been tested for enhanced therapeutic potential in vascular dysfunction and inflammatory diseases.
Summary Table of Validated Applications
Application Type
Example Models/Assays
Reference Index
Bioassay (angiogenesis, Tie2)
Endothelial cell migration, tube formation
In vivo (vascular protection)
Sepsis, endotoxic shock, cerebral ischemia
Apoptosis inhibition
HUVEC serum deprivation
Vascular architecture
Mice lacking mural cells
Neural regeneration
Spinal cord injury in rats
Inflammatory modulation
Cytokine storm, adhesion molecule expression
Protein characterization
SDS-PAGE, Western blot
In summary: Recombinant Human Angiopoietin-1 is validated for diverse applications in vascular biology, endothelial cell function, inflammation, and tissue regeneration, both in vitro and in vivo, with strong evidence supporting its use in bioassays, disease models, and protein interaction studies.
To reconstitute and prepare Recombinant Human Angiopoietin-1 protein for cell culture experiments, dissolve the lyophilized protein at 100 μg/mL in sterile PBS containing at least 0.1% human or bovine serum albumin (BSA). This protocol ensures protein stability and bioactivity for in vitro applications.
Step-by-step protocol:
Centrifuge the vial briefly before opening to collect all lyophilized material at the bottom.
Add sterile PBS (pH 7.2–7.4) containing 0.1% BSA to achieve a final concentration of 100 μg/mL.
Gently mix by pipetting; do not vortex, as vigorous mixing may denature the protein.
Allow the protein to dissolve at room temperature for 10–15 minutes, then gently invert or pipette to ensure complete dissolution.
Aliquot the reconstituted solution to minimize freeze-thaw cycles, which can degrade the protein.
Store aliquots at −20 °C to −80 °C for long-term use; short-term storage at 2–8 °C is acceptable for up to one month.
Avoid repeated freeze-thaw cycles to preserve protein integrity.
Additional notes:
If your protein is supplied without carrier protein, always add BSA or HSA at 0.1% if the final concentration is below 0.5 mg/mL to prevent adsorption and loss of activity.
For cell culture experiments, dilute the stock solution to the desired working concentration using cell culture medium or PBS with 0.1% BSA.
Always consult the specific product datasheet for any unique instructions regarding buffer composition or reconstitution, as formulations may vary.
Summary of best practices:
Use sterile PBS + 0.1% BSA for reconstitution.
Aliquot and freeze to avoid repeated freeze-thaw.
Do not vortex; mix gently.
Store appropriately as per datasheet recommendations.
This protocol supports optimal stability and bioactivity of Angiopoietin-1 for cell culture assays.
References & Citations
1. Agrawal, DK. et al. (2006) Curr Mol Med.6(8):831-41.
2. Baek, HS. et al. (2006) Exp Clin Endocrinol Diabetes. 114(8):438-43.
3. Nicosia, RF. et al. (2006) Physiol Genomics. 27(1):20-8.
4. Bates, DO. et al. (2006) Microcirculation. 13(6):423-37.
5. Krüssel, JS. et al. (2006) Reprod Fertil Dev. 18(5):509-16.
6. Lee, KJ. et al. (2006) Cancer Res. 66 (12):6167-74.
Products are for research use only. Not for use in diagnostic or therapeutic procedures.
