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DOI: 10.1055/s-0038-1649289
Eigenschaften des Osteozytennetzwerks in gesundem und erkranktem Knochen
Characteristics of the osteocyte network in healthy and diseased human bonePublikationsverlauf
Publikationsdatum:
27. April 2018 (online)
![](https://www.thieme-connect.de/media/10.1055-s-00034922/201802/lookinside/thumbnails/10-1055-s-0038-1649289-1.jpg)
Zusammenfassung
Humaner Knochen ist von einem komplexen Netzwerk aus Lakunen und Kanalikuli durchzogen, welches von mechanosensitiven Osteozyten bevölkert wird. Durch Signalmoleküle und direkten Zellkontakt regulieren Osteozyten die Aktivität von Osteoblasten und Osteoklasten im Knochenumbau und modulieren so die mechanischen Eigenschaften des Knochens. Zusätzlich greifen Osteozyten in den Kalziumstoffwechsel ein und können lokal Kalzium resorbieren oder eine Mineralisierung beeinflussen. Wir diskutieren zwei Hauptfaktoren, welche die Mechanoresponsivität des Netzwerks schädigen: 1. Der Tod von Osteozyten, z. B. bei unphysiologischer Belastung, und der Mangel an Osteozyten im Alter verschlechtern die Auflösung des mechanosensitiven Netzwerk. Dies verhindert eine adäquate Instandhaltung der Gewebequalität und resultiert in gealtertem, höher mineralisiertem Knochen mit einer Häufung von Mikrorissen. 2. Der Verschluss von Lakunen mit Mineral verhindert zusätzlich den Nährstoffund Signalmolekülfluss im Netzwerk. So wird die Lebensfähigkeit anliegender Zellen behindert und die Mechanoresponsivität verringert. Da die regulierende Funktion der Osteozyten auf den Knochenumbau für eine hohe Fraktur resistenz essenziell ist, bietet sich hier ein großes Potenzial, durch Unterstützung der Osteozytenlebensfähigkeit therapeutisch und präventiv Frakturen zu bekämpfen.
Summary
In bone remodeling the bone-resorbing osteoclasts and bone-forming osteoblasts maintain the mechanical competence of bone in a balanced interaction. Additionally, the osteocyte, the most frequent osseous cell (> 25,000/mm³), resides in lacunae and is connected via channels creating an enormous nanoscale network. Osteocytes have shown exceptional mechanoresponsive and mechanosensitive behavior, allowing them to control bone repair in damaged or aged bone areas and improving the resistance to fracture. Here, we describe the following influences of aging and disease on the osteocyte lacunacanalicular network: - Mineralized lacunae may influence fluid flow and hamper mechanosensitivity, resulting in a loss of mechanical competence. - Further an increasing number of mineralized lacunae, as in aged bone tissue, could make bone more susceptible to fracture. - With a decreasing number of viable osteocytes, the network fails to detect local damages, thereby compromising bone strength. Our article highlights the major role of osteocytes in aging, disease and the preservation of bones’ strength. We found an agingand disease-related decay of the osteocyte-lacunar network to be associated with the loss of bones’ strength. The network decay results in less targeted damage repair, thus enabling increased bone fragility, a major problem in an elderly population. It is essential to unravel the involvement of the osteocyte lacuno-canalicular system in bone fragility to combat fractures with preventive and therapeutic strategies.
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