For instance, is osteocyte differentiation an irreversible process or can the osteocyte dedifferentiate back into an osteoblast when it is released from its lacuna? What is the fate of the osteocyte after osteoclastic resorption? Do osteocytes make dendritic contacts with cells in the marrow and vasculature? With the rapid advancement of imaging technologies and the development of more and more sophisticated fluorescent reporters, there is no doubt that
some of these questions will be answered in the very near future. Owing to the fact that osteocytes are deeply embedded in hard mineralized tissue they are less accessible compared to other cell types. As a result in vivo, biochemical data characterizing their precise role in click here bone remodeling remains limited. A number
of in vivo models have been developed to study their function. These models typically harvest large osteocyte populations and employ technologies which provide a comprehensive assessment of a selleck products large number of genes which are both up-regulated and down-regulated in response to mechanical stimulation. In this section we provide an overview of these models and highlight the strategies and new technologies which could be employed to further enhance our understanding of the osteocyte. To comprehensively assess osteocyte gene expression in
a mouse model for load induced bone Orotidine 5′-phosphate decarboxylase adaptation, current state-of-the-art approaches extract large populations of osteocytes from loaded bone and perform micro-array-analysis to quantify the expression levels of tens of thousands of different genes. Using this technology, probable molecular networks describing osteocyte function and interactions with other cell types are constructed. This is achieved via the use of data mining techniques to search literature pertaining to relevant genes/proteins together with various statistical algorithms. For example, using the recently established mouse tail loading model [53] Wassermann et al. [54] dynamically loaded the sixth caudal vertebra (C6) of C57BL/6 (B6) mice and harvested a large number of osteocytes (> 10,000) from mechanically stimulated trabecular bone. Following isolation of high quality mRNA from osteocytes and the application of micro-array-analysis, patterns of gene expression were quantified for short and extended periods of loading. Analysis of 34,000 different genes revealed that hundreds of genes were differentially expressed [55]. Comparison of global osteocyte gene expression between sham-loaded and loaded groups for a single bout of loading revealed a total of 287 up-regulated and 52 down-regulated genes.