MicroCT Analysis of Collagen Type XXIV’s Role in Craniofacial Development

Objectives: Collagen type XXIV is a recently discovered fibrillar collagen. We hypothesized that it may affect the development of bone formation. By comparing collagen type XXIV-knockout (KO) and wild-type (WT) mice mandibles through x-ray micro-computerized tomography (µCT) analysis, we were able to investigate the effect type XXIV collagen exerts on the development of bone. The goal of this study was to characterize collagen type XXIV’s impact on formation of the mandible.
Methods: 3D images of each samples from wild type and collagen XXIV-null mice were rendered from contoured DICOM files’ conversion to individual PLY files, by using Materialise Mimics software. PLY files were transfigured to topographical “masks” of the 3D images through the use of an open-source software, MeshLab. Landmarks that have been previously validated were selected for use in this study. Measurements between these landmarks were then used for statistical analysis. The dataset was rendered in triplicate. The right and left mandibles were used from six mice, giving us a total of twelve samples. The average of the three data sets were separated by group and ages of the mice. The 6 month old and 1 year old mice data were combined together. Paired T tests were run to determine if there were any left/right differences within the groups. Mann Whitney tests were performed between groups 1 and 2 for each of the eight landmarks. P < .05 was the level of statistical significance.
Results: There were no statistically significant differences between KO and WT mice in any measurements. There were, however, statistically significant left/right differences in 3 measurements of the collagen XXIV-null animals.
Conclusions: The loss of function of the col2a1 gene may not have an effect on the overall size of the mandible, but may affect symmetry. Larger studies with more animals will have to be undertaken to get a better understanding.