Osteoclast Derivation from Mouse Bone Marrow
November 6th, 2014
Osteoclasts are the principal bone-resorbing cell in the body. An ability to isolate osteoclasts in large numbers has resulted in significant advances in the understanding of osteoclast biology. In this protocol, we describe a method for isolation, cultivating and quantifying osteoclast activity in vitro.
The overall goal of this procedure is to isolate osteoclasts from mouse bone marrow in large numbers. This is accomplished by first harvesting bones from euthanized mice. Next, the cells are liberated from the bone marrow by using a mortar and pestle to crush the bones in facts buffer.
Then the bone marrow solution is layered onto the density gradient cell separation medium and density gradient cell separation is carried out. Finally, the layer containing the cells of interest is aspirated and the cells are placed in bone marrow microphage induction medium. Ultimately trap staining is used to show the presence of a large number of osteoclasts.
The implications of this technique extend toward diseases associated with altered osteoclast function, which can range in severity from lethal neonatal disease due to failure to form a marrow space for hematopoiesis to more commonly encounter pathologies such as osteoporosis because it produces a reliable method of isolating a large number of osteoclasts from mouse bone marrow. To begin, bring 10 milliliters of commercially available density gradient cell separation, medium to room temperature in a 50 milliliter conical tube. Place a 50 milliliter aliquot of fax buffer at room temperature to be used with the density gradient cell separation medium.
After preparing additional media and euthanizing a C 57 black six mouse, according to the text protocol, position the mouse on a dissection board and use 70%ethanol. To spray it, harvest the fera tibia hum eye and spine. Then place the bones in facts buffer on ice.
Next, using clean tissue paper, remove the muscle and soft tissue from the bones. Place the bones into a mortar and pestle with three milliliters of facts buffer and gently crush them. Then aspirate the bloodstained fluid and pass it through a 70 micrometer strainer into a 50 milliliter conical tube.
Add an additional five milliliters of effects buffer to the crushed bone and crush further before transferring the liquid through the strainer into the 50 milliliter tube. Continue with this process until the fluid no longer stains red before pelleting the bone marrow at 200 Gs for five minutes at four degrees Celsius. To perform a gradient separation, aspirate the supernatants from the cell pellet and use 10 milliliters of fax buffer to resus.
Suspend the pellet, tilt the conical tube of room temperature density gradient cell separation medium to about 30 degrees, and using an electric pipette with the tip of the pipette against the inner top surface of the tube. Slowly layer the bone marrow solution onto the medium using a room temperature centrifuge with no acceleration or deceleration. Spin the gradient at 200 Gs for 15 minutes.
Then aspirate the cloudy middle layer, which contains the cells of interest and transfer them into a new conical tube. Add 20 milliliters of ice cold fax buffer to wash the cells. Then use one milliliter of bone marrow microphage stimulating medium to resuspend the final cell pellet following cell counting.
Placed two milliliters of microphage stimulating medium into each well of a 24 well plate. Then add 200, 000 cells to each well, a cell density that will ensure adequate in vitro osteoclast culturing. Gently agitate the plate and incubated at 37 degrees Celsius without changing the medium for three days.
After the third day, change the medium to bone marrow osteoclast induction medium and begin to change it daily for five to seven days. At which point large multinucleated osteoclasts should be visible. Refer to the text protocol for staining and the resorption assay as seen here.
A high number of osteoclasts can be confirmed using tartrate resistant assay. Phosphotates staining osteoclasts are visualized as large purple cells with multiple nuclei using the protocol demonstrated in this video. It is common to isolate osteoclasts with as many as 30 nuclei per cell.
Using a mineralized surface is considered the gold standard method for assessing osteoclast resorptive activity in vitro. In this figure, brightfield microscopy at 10 x magnification demonstrates a percentage of mineralized surface or resorptive pits that are formed as outlined in black, which allows for determination of osteoclast resorptive capacity. After watching this video, you should have a good understanding of how to reliably isolate a large number of osteoclasts from mouse bone marrow.
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Overview
This protocol outlines a method for isolating osteoclasts from mouse bone marrow in large quantities. The process involves harvesting bones, liberating cells, and using density gradient separation to obtain osteoclasts for further study.
Key Study Components
Area of Science
- Bone biology
- Cell isolation techniques
- Osteoclast activity quantification
Background
- Osteoclasts are essential for bone resorption.
- Understanding osteoclast biology is crucial for insights into bone diseases.
- Isolation techniques have advanced the study of these cells.
- This protocol aims to enhance the yield of osteoclasts for research.
Purpose of Study
- To isolate osteoclasts from mouse bone marrow.
- To cultivate osteoclasts in vitro for experimental analysis.
- To quantify osteoclast activity using specific staining methods.
Methods Used
- Harvesting bones from euthanized mice.
- Crushing bones in facts buffer to liberate cells.
- Performing density gradient cell separation.
- Using bone marrow microphage induction medium for cell culture.
Main Results
- Successful isolation of osteoclasts in large numbers.
- Effective cultivation of osteoclasts in vitro.
- Demonstration of osteoclast presence through trap staining.
- Quantification of osteoclast activity achieved.
Conclusions
- The protocol provides a reliable method for osteoclast isolation.
- It facilitates further research into osteoclast biology.
- Potential applications in studying bone-related diseases.
Frequently Asked Questions
Executive Industry Relevance
Reliable in vitro derivation of osteoclasts from mouse bone marrow enables high-confidence interrogation of bone resorption mechanisms and disease-relevant cellular phenotypes. This capability is critical for target validation and mechanistic de-risking in early-stage bone disease drug discovery. The method supports portfolio decisions by providing scalable access to functional osteoclasts for quantitative assessment of therapeutic hypotheses.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct testing of bone resorption hypotheses in a controlled system.
- Supports mechanistic de-risking by isolating osteoclast-specific effects.
- Facilitates functional target validation for bone disease pathways.
- Provides a platform for comparative analysis of genetic or pharmacological perturbations.
Screening & Assay Development
- Generates validated osteoclast populations for downstream resorption assays.
- Enables standardization of quantitative TRAP staining and resorption pit assays.
- Supports reproducible, scalable workflows for compound screening.
- Allows for robust evaluation of osteoclast-modulating agents.
Translational & Preclinical Research
- Aligns in vitro osteoclast function with disease-relevant bone remodeling endpoints.
- Provides continuity from cellular mechanism to preclinical model validation.
- Enables risk-adjusted advancement of bone-targeted therapeutic candidates.
- Supports translational biomarker development for bone resorption activity.
Pipeline & Workflow Integration
This osteoclast derivation protocol fits at the interface of early discovery and preclinical research, bridging target validation, assay development, and translational studies in bone biology.
- Discovery Biology: Supports hypothesis-driven testing of osteoclast-mediated bone resorption mechanisms.
- Screening: Provides standardized, quantitative readouts for compound or genetic screening.
- Analytics: Enables measurement of multinucleation, TRAP positivity, and resorptive capacity for comparative analysis.
- Translational Research: Facilitates alignment of in vitro findings with in vivo bone remodeling and disease models.
- Enterprise Reuse: Establishes a reusable workflow for osteoclast isolation across multiple discovery programs.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in bone resorption target validation and mechanistic studies.
- Operational Value: Delivers standardized, reproducible osteoclast cultures at scale.
- Strategic Value: Improves go/no-go decision quality for bone disease programs by reducing biological ambiguity.
- Portfolio Impact: Enables risk-adjusted prioritization of osteoclast-targeted therapeutic candidates.
Implementation Considerations
- Requires expertise in primary cell isolation and bone marrow handling.
- Needs access to density gradient separation and cell culture infrastructure.
- Demands cross-team standardization of TRAP staining and resorption assays.
- May require adaptation for different mouse strains or disease models.
- Dependent on careful quantification and validation of osteoclast identity and function.
