Question

A common injury to bone occurs when a bone breaks, or fractures. What do you suppose would be the role of osteoclasts and osteoblasts during the repair process of a fracture?

Answer 1

Role of osteoclasts

• Osteoclasts are the special cells that degrade bone which initiates normal bone remodeling also mefiate bone loss in pathological conditions through increasing their resorptive activity.
• They regulate the diffrentiation of osteoblasts and the movement of hematopoietic stem cells from the bone marrow to the blood stream.
• Osteoclasts also participates in immune responses and help to secreate cytokines which is capable of affecting their own functions and those of other cells in inflamattory and neoplastic processes affected to bones.

Role of osteoblasts

• While balance between bones are carried out by osteoclasts,Osteoblasts carry out bone formation.
• Osteoblasts not only play a lead role in bone formation but also synthesizing multiple bone matrix proteins.
• pro-inflammatory cytokines such as IL-1 and TNF-alpha, cause an imbalance in bone metabolism, by favoring bone resorption via the induction of RANKL and ICAM-1 on osteoblasts, and these signals originates from immune system ​​​​​​. Such signals are primarily carried out by osteoblasts to tranmit to bones to induce osteoclast maturation which results in secondary osteoporosis.