Bone mimetic resorption plates: A reliable method to quantify osteoclast resorption in vitro

Area of Science:

• Biotechnology
• Cell Biology
• Biomaterials

Background:

• Osteoclasts are crucial for bone remodeling, but excessive activity leads to osteoporosis and fractures.
• Current in vitro assays for osteoclast resorption rely on scarce dentin wafers.
• There is a need for alternative, reproducible methods to assess osteoclast activity for research and drug development.

Purpose of the Study:

• To develop and validate a novel "bone mimetic" resorption assay plate as an alternative to dentin wafers.
• To establish a reproducible in vitro method for quantifying osteoclast resorptive activity.
• To enable efficient screening of potential therapeutics targeting osteoclast function.

Main Methods:

• Tissue culture plates were coated with bovine serum albumin (BSA) and treated with mineralizing solutions to create a bone-like substratum.
• Osteoclasts were differentiated from RAW264.7 cells and mouse bone marrow monocytes (BMMs) on the assay plates.
• Resorption was quantified using an ImageJ macro to analyze brightfield images of the mineral substratum.

Main Results:

• The "bone mimetic" assay plate demonstrated minimal resorption by non-osteoclast cells.
• Significant osteoclast-mediated resorption of the assay plate substratum was observed within 10-14 days.
• Zoledronic acid, a bisphosphonate drug, effectively inhibited osteoclast resorption in this assay.

Conclusions:

• The developed "bone mimetic" resorption assay plate provides a practical and consistent method for quantifying osteoclast activity.
• This assay serves as a valuable tool for studying osteoclast biology and evaluating anti-resorptive agents.
• The protocol offers a reproducible alternative to traditional dentin-based assays, addressing substrate scarcity.