Bioactive Sclerostin ELISA Assay Kit

$550.00

The human bioactive Sclerostin immunoassay is a 3.5 hour, 96-well, sandwich ELISA for the quantitative determination of bioactive Sclerostin in human serum, EDTA plasma, and citrate plasma. The Eagle Biosciences Bioactive Sclerostin ELISA Assay Kit is for research use only and not to be used in diagnostic procedures.

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Bioactive Sclerostin ELISA Assay Kit

For Research Use Only

Size: 1×96 wells
Sensitivity: LOD: LOD: (0 pmol/l + 3 SD): 1.9 pmol/l; LLOQ: 1.3 pmol/l
Dynamic Range: 0 to 320 pmol/l
Incubation Time: > 4 hours
Sample Type: Serum, EDTA plasma, and citrate plasma (cell culture and urine protocol available)
Sample Size: 20 µL
Controls Included

Product Developed and Manufactured by Biomedica


Unit conversion: 1 pg/ml = 0.044 pmol/l (MW: 22.5 kD)

Additional Information

Assay Background


Sclerostin is a 22.5 kDa secreted glycoprotein that functions as a potent inhibitor of Wnt signaling. It acts by binding to the Wnt-coreceptor LRP5/6 thus inhibiting bone formation by regulating osteoblast function and promoting osteoblast apoptosis. The Sclerostin protein consists of two flexible N- and C-terminal arms and a cystine-knot with three loops, whereas the second loop binds to the LRP5/6 complex (3,4). Sclerostin is classically considered to be a monomeric protein, but data from Hernandez and colleagues (5) postulate that circulating sclerostin has a dimeric configuration. In addition, it is not yet well documented if also Sclerostin fragments circulate, but the comparison of different Sclerostin ELISAs suggest that fragments exist as well.

As the epitope of the monoclonal capture antibody utilized in the bioactive Sclerostin ELISA is located in loop 2, the binding region to the LRP 5/6 complex, all Sclerostin molecules (including potential fragments) containing this receptor binding region can be detected.

Sclerostin is nearly exclusively produced in osteocytes. Mutations in the Sclerostin (SOST) gene can cause sclerosteosis and van Buchem disease which are bone dysplasia disorders characterized by progressive skeletal overgrowth. Sclerostin levels are altered in response to hormonal stimuli or due to pathophysiological conditions. Sclerostin concentrations are increased in disorders such as hypoparathyroidism, Paget’s disease, multiple myeloma and in cancer induced bone diseases. Sclerostin levels are decreased in primary hyperparathyroidism, as well as by the mechanical stimulation of bone. Several studies have found a positive association between sclerostin and bone mineral density. Sclerostin levels in chronic kidney disease (CKD) patients are up to 4-fold increased compared to patients without CKD and increase with CKD stage and declining kidney function. In CKD patients, renal elimination of sclerostin increases with decreasing renal function. In dialysis patients, sclerostin is an independent predictor of bone loss. Numerous studies have shown that serum sclerostin levels are also associated with cardiovascular events. A monoclonal sclerostin antibody for the treatment of osteoporosis is currently undergoing clinical trials. For reviews please see references.

Assay Principle


This kit is a sandwich enzyme immunoassay for the quantitative determination of bioactive sclerostin in human serum and plasma samples (EDTA, citrate). In a first step, assay buffer is pipetted into the wells of the microtiter strips. Thereafter, STD/sample/CTRL are pipetted into the wells, which are pre-coated with the recombinant human monoclonal Sclerostin antibody. Any bioactive Sclerostin present in the STD/sample/CTRL binds to the pre-coated antibody in the well. After incubation, a washing step is applied where all non-specific unbound material is removed. In a next step, the conjugate (anti sclerostin-HRPO) is pipetted into the wells and reacts with bioactive Sclerostin present in the sample, forming a sandwich. After another washing step, the substrate (TMB Tetramethylbenzidine) is pipetted into the wells. The enzyme catalysed colour change of the substrate is directly proportional to the amount of bioactive sclerostin. This colour change is detectable with a standard microtiter plate ELISA reader. A dose response curve of the absorbance (optical density, OD at 450 nm) versus standard concentration is generated, using the values obtained from the standards. The concentration of bioactive sclerostin in the sample is determined directly from the dose response curve.

Assay Procedure


  1. Pipette 100 μl ASYBUF (Assay buffer, red cap) into each well.
  2. Add 20 μl STD/SAMPLE/CTRL (Standard/Sample/Control) in duplicate into respective well. Swirl gently.
  3. Cover tightly and incubate for 2 hours at room temperature (18-26°C).
  4. Aspirate and wash wells 5x with 300 μl diluted WASHBUF (Wash buffer). After final wash, remove remaining WASHBUF by strongly tapping plate against paper towel.
  5. Add 100 μl CONJ (Conjugate, amber cap) into each well. Swirl gently.
  6. Cover tightly and incubate for 1 hour at room temperature (18-26°C) in the dark.
  7. Aspirate and wash wells 5x with 300 μl diluted WASHBUF (Wash buffer). After final wash, remove remaining WASHBUF by strongly tapping plate against paper towel.
  8. Add 100 μl SUB (Substrate, blue cap) into each well. Swirl gently.
  9. Incubate for 30 min at room temperature (18-26°C) in the dark.
  10. Add 50 μl STOP (Stop solution, white cap) into each well. Swirl gently.
  11. Measure absorbance immediately at 450 nm with reference 630 nm, if available.

Expected Values


Values from apparently healthy individuals:
Median Serum (n=411): 24.14 pmol/l
This value lies between calibration point 2 and 3 of the standard curve. It is recommended to establish the normal range for each laboratory.

Manual

Product Manual


Publications

Citations


  • Sclerostin and Wnt signaling-the pathway to bone strength. Ott SM, J Clin Endocrinol Metab, 2005; 90(12):6392-6395.
  • SOST is a ligand for LRP5/LRP6 and a Wnt signaling inhibitor. Semenov M et al., J Biol Chem, 2005; 280(29):26770-26775.
  • Characterization of the structural features and interactions of sclerostin: molecular insight into a key regulator of Wnt-mediated bone formation. Veverka V et al., J Biol Chem, 2009; 284:10890-10900.
  • Characterization of the Interaction of Sclerostin with the Low Density Lipoprotein Receptor-related Protein (LRP) Family of Wnt Co-receptors. Holdsworth G et al., J Biol Chem, 2012; 284(16), 287(32): 26464-26477.
  • New insights into the location and form of sclerostin. Hernandez P et al., Biochem Biophys Res Commun, 2014; 446 (4):1108-1113.
  • Association of circulating sclerostin with bone mineral mass, microstructure, and turnover biochemical markers in healthy elderly men and women. Durosier C et al., J Clin Endocrinol Metab, 2013; 98 (9):3873-3883.
  • Circulating sclerostin levels are decreased in patients with endogenous hypercortisolism and increase after treatment. van Lierop AH et al., J Clin Endocrinol Metab, 2012; 97:E1953-E1957.
  • The Osteocyte: An Endocrine Cell … and More. Dallas SL et al., Endocrine Rev, 2013; 34:658-690.
    Sclerostin in mineralized matrices and van Buchem disease. van Bezooijen RL et al., J Dent Res, 2009; 88(6):569-574.
  • Patients with Van Buchem disease, an osteosclerotic genetic disease, have elevated bone formation markers, higher bone density, and greater derived polar moment of inertia than normal. Wergedal, JE et al., J Clin Endocrinol Metab, 2003; 88:5778.
  • Circulating sclerostin in disorders of parathyroid gland function. Costa AG et al., J Clin Endocrinol Metab, 2011; 96: 3804-3810.
  • Serum sclerostin levels in Paget’s disease and prostate cancer with bone metastases with a wide range of bone turnover. Yavropoulou MP et al., Bone, 2012; 51:153-157.
  • Elevated circulating sclerostin correlates with advanced disease features and abnormal bone remodeling in symptomatic myeloma: reduction post-bortezomib. Monotherapy. Terpos E et al., Int J Cancer, 2012; 131:1466-1471.
  • Patients with primary hyperparathyroidism have lower circulating sclerostin levels than euparathyroid controls. Van Lierop AH et al., Eur J Endocrinol, 2010; 163:833-837.
  • Mechanical stimulation in vivo reduces osteocyte expression of sclerostin. Robling AG et al., J Musculoskelet Neuronal Interact, 2006; 6(4):354.
  • Association of serum sclerostin with bone mineral density, bone turnover, steroid and parathyroid hormones, and fracture risk in postmenopausal women: the OFELY study. Garnero P et al., Osteoporos Int, 2013; 13; 24(2):489-494.
  • Sclerostin and its association with physical activity, age, gender, body composition, and bone mineral content in healthy adults. Amrein K et al., J Clin Endocrinol Metab, 2012; 97:148-154.
  • Sclerostin and Dickkopf-1 in renal osteodystrophy. Cejka D et al., Clin J am Soc Nephrol, 2012; 6: 877-882.
    The Relation between Renal Function and Serum Sclerostin in Adult Patients with CKD. Pelletier S et al., Clin J am Soc Nephrol, 2013; 8 (5): 819-823.
  • Renal elimination of Sclerostin increases with declining kidney function. Cejka D et al., J Clin Endocrinol Metab, 2014; 99(1):248-255.
  • Bone mineral density and serum biochemical predictors of bone loss in patients with CKD on dialysis. Malluche HH et al., Clin J Am Soc Nephrol, 2014; 9:1254-1262.
  • Serum sclerostin and adverse outcomes in nondialyzed chronic kidney disease patients. Kanbay M et al., J. Clin. Endocrinol Metab, 2014; 99:E1854-E1861.
  • Sclerostin: Another bone-related protein related to all-cause mortality in haemodialysis? Viaene L et al., Nephrol Dial Transplant, 2013; 28:3024-3030.
  • Clinical utility of anti-sclerostin antobodies. McClung MR, Bone, 2017; 96:3-7.
  • Sclerostin measurement in human disease: Validity and current limitations. Costa AG et al.,; Bone, 2017; 96:24-28.
  • Hormonal and systemic regulation of sclerostin. MT Drake and S Khosla, Bone, 2017; 96:8-17.