Multiscale Approach to Understand the Multiphysics Phenomena in Bone Adaptation - Multiscale Computer Modeling in Biomechanics and Biomedical Engineering - page 36

2.2.1 Lining Cells
The bone lining cells (BL) are located on the walls of the Volkmann and Haversian
canals as well as on endosteal and periosteal zones of bone. They are undiffer-
entiated original cells from the mesenchyme that can differentiate into osteoblastic
cells. These stem cells are increasingly used in bone tissue engineering to generate
tissue to be grafted [ 50 ].
2.2.2 Osteoblastic Cells
Osteoblastic cells (OBL) are mono-nucleate cells that are responsible for bone
formation. Osteoblasts produce osteoid, which is composed mainly of Type I
collagen and are also responsible for mineralization of the osteoid matrix. During
the remodelling process, some osteoblasts are trapped in the bone matrix and thus
form a lacuna where they become osteocytes (OCY). Furthermore, some osteo-
blasts at the remodelling surface become bone lining cells.
2.2.3 Osteocytes
Osteocytes (OCY) are the result of the evolution of osteoblast embedded in
lacunae. Scattered in the bone volume, they are networked to each other via long
cytoplasmic extensions (osteocyte process) that occupy tiny canals called cana-
liculi. This endows osteocytes with a star-shaped configuration. In the canaliculi
which are used for paracrinal communication, exchange of nutrients and dispose of
waste products, osteocytes can also communicate through gap junctions by the
transmission of chemical agents.
2.2.4 Osteoclasts
Osteoclasts (OCL) are multinucleated cells that destroy bone tissue by removing
its mineralized matrix and breaking up the organic bone (collagen). This process is
known as bone resorption and is regulated by several hormones, including calci-
tonin from the thyroid gland, parathyroid hormone from the parathyroid gland, and
growth factor interleukin 6.
2.3 Stages of Bone Remodelling Process
The processes of bone resorption and bone growth are taking place continuously
throughout the skeletal system to protect it from daily wear. Bone remodelling is a
cyclic progress that lasts approximatively 4 months when considering mature