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Applications of micro-CT and MR microscopy to study pre-clinical models of osteoporosis and osteoarthritis
R D Kapadia1, G B Stroup, A M Badger
1Department of Physical and Structural Chemistry, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA. Rasesh_D_Kapadia@SBPHRD.COM
Abstract:
There is a tremendous unmet therapeutic need for the treatment of osteoporosis and osteoarthritis. The ovariectomized rat and the guinea pig are widely used animal models for the evaluation of new therapeutics for osteoporosis and osteoarthritis, respectively. We have utilized X-ray micro-CT techniques to quantitatively evaluate the differences in trabecular bone in the rat proximal tibia following ovariectomy and treatment with estrogen (17-B-estradiol). Results demonstrate a loss of trabecular bone and architecture following ovariectomy (p < 0.001), and a marked inhibition of trabecular bone loss in the estrogen treated group (p < 0.001). A similar change in architecture can be visualized in images obtained by high resolution MR microscopy. In addition, a good correlation was observed between the values of trabecular bone fraction (BV/TV) in the rat tibiae as obtained from 3-dimensional micro-CT data and 2-dimensional static histomorphometry (r = 0.89, 0.73, 0.79 for sham, OVX, and treated groups, respectively). Micro-CT images were also obtained from a set of lumbar vertebrae from sham operated and ovariectomized rats. Significant bone loss can be measured as early as 8 weeks following ovariectomy (p < 0.005). Micro-CT and MR images were also obtained to study age related changes in the stifle joint of the guinea pig. Significant boney changes can be seen in the tibia and femur from the animals at various ages. Changes in cartilage and joint space can also be visualized in the images. The utility of micro-CT imaging in evaluating the mouse skeletal system is illustrated by obtaining morphological and architectural details from high resolution images of the mouse hind limb and proximal tibia, respectively. The results demonstrate the advantages that multi-dimensional imaging techniques can offer in evaluating bone and joint related changes in animal models of osteoporosis and osteoarthritis.
Insights
X-ray micro-CT and MR microscopy effectively evaluate bone loss in osteoporosis and osteoarthritis animal models. These imaging techniques quantitatively assess therapeutic effects on trabecular bone architecture and joint changes.
Area of Science:
- Biomedical Imaging
- Orthopedics
- Pharmacology
Background:
- Osteoporosis and osteoarthritis present significant unmet therapeutic needs.
- Ovariectomized rats and guinea pigs are established models for evaluating osteoporosis and osteoarthritis treatments, respectively.
Purpose of the Study:
- To quantitatively evaluate trabecular bone differences in ovariectomized rats and age-related changes in guinea pig stifle joints using X-ray micro-CT and MR microscopy.
- To assess the efficacy of estrogen treatment in preventing bone loss in an osteoporosis model.
Main Methods:
- Utilized X-ray micro-CT and high-resolution MR microscopy to analyze bone structure in rat tibiae and lumbar vertebrae, and guinea pig stifle joints.
- Correlated 3D micro-CT data with 2D histomorphometry for trabecular bone fraction (BV/TV) measurements.
- Examined mouse skeletal systems to illustrate the utility of multi-dimensional imaging.
Main Results:
- Ovariectomy in rats led to significant trabecular bone loss and architectural changes (p < 0.001).
- Estrogen treatment markedly inhibited bone loss in ovariectomized rats (p < 0.001).
- Significant bone loss was measurable in rat vertebrae as early as 8 weeks post-ovariectomy (p < 0.005).
- Micro-CT and MR imaging revealed age-related bony and joint changes in guinea pigs and detailed skeletal morphology in mice.
Conclusions:
- Multi-dimensional imaging techniques like X-ray micro-CT and MR microscopy are valuable tools for evaluating bone and joint changes in animal models of osteoporosis and osteoarthritis.
- These methods provide quantitative and qualitative insights into therapeutic interventions and disease progression.