The dependences of osteocyte network on bone compartment, age, and disease

Osteocytes, the most abundant bone cells, form an interconnected network in the lacunar-canalicular pore system (LCS) buried within the mineralized matrix, which allows osteocytes to obtain nutrients from the blood supply, sense external mechanical signals, and communicate among themselves and with other cells on bone surfaces. In this study, we examined key features of the LCS network including the topological parameter and the detailed structure of individual connections and their variations in cortical and cancellous compartments, at different ages, and in two disease conditions with altered mechanosensing (perlecan deficiency and diabetes). LCS network showed both topological stability, in terms of conservation of connectivity among osteocyte lacunae (similar to the “nodes” in a computer network), and considerable variability the pericellular annular fluid gap surrounding lacunae and canaliculi (similar to the “bandwidth” of individual links in a computer network). Age, in the range of our study (15–32 weeks), affected only the pericellular fluid annulus in cortical bone but not in cancellous bone. Diabetes impacted the spacing of the lacunae, while the perlecan deficiency had a profound influence on the pericellular fluid annulus. The LCS network features play important roles in osteocyte signaling and regulation of bone growth and adaptation. Researchers in the US have investigated the impact of disease and aging on the complex network that houses mechanical sensitive bone cells. The interconnected network of spaces and channels within mineralized bone allows bone cells to obtain nutrients from the blood supply and sense external mechanical signals. Identifying changes in this network is important for understanding how bone grows and adapts. Researchers led by Liyun Wang at the University of Delaware, Newark, analysed bone from old and young mice, and bones from mice affected by diabetes or deficiency in the proteoglycan perlecan. They identified network features that are not changed or altered with bone site, age, diabetes, and perlecan deficiency. Their findings help understand how bone cells communicate and the role of bone fluid flow in bone s response to mechanical forces.