This research aimed to develop a mouse ex vivo model for the study of periodontal disease.
Periodontal disease can lead to loss of teeth. It affects up to 20% of the world’s population and is associated with inflammation. Investigating the behaviour of inflammatory cells and how inflammation influences bone metabolism during disease should lead to new treatments and diagnostic methods.
Current systems for understanding periodontal disease rely on animal models. These have provided information on host/bacterial interactions, however, they are limited by differences in dental anatomy and oral microbiota and difficulties associated with translation to man. In vitro models using rodent cells are used to study some aspects of periodontal disease but without the complex cell/cell and host/bacterial interactions their use is limited. Given the small tissue volume available from the rodent mandible (lower jaw), obtaining a sufficient quantity of viable cells can necessitate using large numbers of animals, typically 25 to 50 mice per study. An ex vivo model would address these limitations, and significantly reduce the number of animals used.
Research details and methods
Approximately ten slices of mouse periodontal tissue were removed from a single animal and placed in culture. Culture conditions were manipulated to support the growth of a wide population of cells (for example, mesenchymal, osteoclastic and innate immune cells) which can be transplanted into, or exist naturally within, the system.
Key impacts and findings
The ex vivo model mimics the in vivo response to exogenous factors such as inflammatory cytokines, with key hallmarks of disease progression, including increased bone resorption, cell death and cytokine induction, observed. Some preliminary data on the model’s response to pharmaceutical agents was also obtained.
A typical in vivo study of periodontal disease with five time points uses five animals per time point. Ten mandibular slices can be obtained from a single mouse and this means that with the ex vivo model there is an 80% reduction in the number of animals used.
- Research Review 2011: A new ex vivo mouse model of periodontal disease
The objective of this application is to develop a cost effective, reproducible ex vivo culture model of the mouse mandible whereby all tissue and cells are in situ to investigate inflammatory cell behaviour and how inflammation influences bone metabolism during disease processes such as periodontal disease. This will significantly reduce the amount of in vivo animal experimentation and overcome practical and ethical difficulties associated with current animal models.
Following development of the ex vivo model, the culture conditions will be manipulated to support the growth of a wide population of cells (mesenchymal, osteoclastic, innate immune) which may be transplanted to, or exist naturally within, the system. The model will then be used to study the effects of bacterial LPS and inflammatory cytokines on the cells supported in the different culture conditions to investigate the effects on cell behaviour, pro-inflammatory cytokine production and bone metabolism.
This study will significantly reduce the amount of unnecessary animal experimentation currently used to study inflammatory cell activity in diseases such as periodontal disease. It will also overcome the many practical and ethical issues associated with current animal models. The results will be essential in advancing our understanding of molecular pathogenic mechanisms associated with inflammatory destructive diseases, including periodontal disease and rheumatoid arthritis (RA). It has strong potential to translate into clinical practice, contributing to the development of novel therapies, underpinning the identification of new diagnostic biomarkers and will have widespread application in the reduction of animal experimentation in a number of human disease states.
Roberts JL, Maillard JY, Waddington RJ, Denyer SP, Lynch CD, Sloan AJ (2013) Development of an ex vivo coculture system to model pulpal infection by Streptococcus anginosus group bacteria. Journal of Endodontics 39(1): 49-56 doi:10.1016/j.joen.2012.09.005
Sloan AJ, Taylor SY, Smith EL, Roberts JL, Chen L, Wei XQ, Waddington RJ (2013) A novel ex vivo culture model for inflammatory bone destruction. Journal of Dental Research 92(8): 728-34 doi:10.1177/0022034513495240
Sloan AJ, Lynch CD (2012) Dental tissue repair: novel models for tissue regeneration strategies. Open Dentistry Journal 6: 214-219 doi:10.2174/1874210601206010214
Sloan AJ, Smith EL, Locke M, Waddington RJ (2010) An ex vivo rodent mandible culture model for bone repair. Tissue Engineering 16: 1287-1296 doi:10.1089/ten.TEC.2009.0698
Sloan AJ, Singhrao SK, Smith EL, Archer CW (2010) Technical advances in the sectioning of dental tissue and of on-section cross-linked collagen detection in mineralised teeth. Microscopy Research and Technique 73 (8): 741-5 doi:10.1002/jemt.20815
Principal investigatorProfessor Alastair Sloan
Co-InvestigatorProfessor Rachel Waddington
Dr Xiao-Qing Wei