6 January 2015

Bone resorption assay

Useful assay for the research of skeletal metabolism

Bone resorption results in a transfer of calcium from bone fluid to the blood which can be measured. Cosmo Bio USA offers an bone resorption assay kit for the measurement of bone resorption activity using a fluoresceinated calcium phosphate-coated plate (patent pending). This kit can be used for studies of bone metabolism (e.g. osteoporosis) and drug assessment.

The coated calcium phosphate is first bound to fluoresceinamine-labeled chondroitin sulfate (FACS), which is released from the calcium phosphate layer into conditioned medium by osteoclastic resorption activity. Bone resorption activity is evaluated by simply measuring the fluorescence intensity of the conditioned medium. This assay provides a rapid evaluation system unlike that of the traditional pit assay.

Product features

  • Bone resorption activity is evaluated by the fluorescence intensity of the medium
  • Cell morphology can be microscopically observed
  • Pit area can be analyzed after the assay
  • Sterilized components are ready-to-use for the assay
  • Bone resorption plate is an alternative to ivory slice

Differentiation into osteoclast by RANKL

Osteoclastic differentiation of RAW264 cells induced by RANKL (100 ng/mL) was evaluated by measuring the fluorescence intensity of the conditioned medium.  Photographs show pit formation on the calcium phosphate (CaP) coating with or without RANKL stimulation.(●: with RANKL, ○: without RANKL, *: p<0.05, **: p<0.001)

Bone resorption activity and RANKL concentration

RANKL-dependent increase of fluorescence intensity of the conditioned medium (left) and pit area (right) from RAW264 cells in fluoresceinamine-labeled chondroitin sulfate (FACS)/ calcium phosphate (CaP)-coated plates (mean ± SD, n = 3, **: p<0.001).

Evaluation of test substances for treating osteoporosis

The inhibitory effects of Pamidronate and β-Estradiol on calcium phosphate resorption induced by RANKL (100 ng/mL) were measured by fluorescence intensity (left) and pit area (right) (mean ± SD, n = 3, *:p<0.05, **: p<0.001).

Bone resorption assay products

Bone Resorption Assay Kit 24 (CSR-BRA-24KIT)
Bone Resorption Assay Plate 24 (CSR-BRA-24P)
Bone Resorption Assay FACS (CSR-BRA-FACS1)
Bone Resorption Assay Buffer (CSR-BRA-B1)


  • Miyazaki T, Miyauchi S, Anada T, Imaizumi H, Suzuki O. Evaluation of osteoclastic resorption activity using calcium phosphate coating combined with labeled polyanion. Anal Biochem. 2011;410(1):7-12.
  • Kim J-L, Kang S-W, Kang M-K, et al. Osteoblastogenesis and osteoprotection enhanced by flavonolignan silibinin in osteoblasts and osteoclasts. J Cell Biochem. 2012;113(1):247-259.
  • Miyazaki T, Miyauchi S, Tawada A, Anada T, Suzuki O. Effect of chondroitin sulfate-E on the osteoclastic differentiation of RAW264 cells. Dent Mater J. 2010;29(4):403-410.

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