Osteoblastok

Osteoblasts are bone-forming cells derived from mesenchymal stem cells in the periosteum and bone marrow. They proliferate and differentiate into mature osteoblasts that line active bone formation surfaces and coordinate matrix production.

They synthesize osteoid, the organic part of the bone matrix, which is rich in type I collagen and non-collagenous proteins. Osteoblasts secrete alkaline phosphatase and other enzymes that promote mineralization, leading to the deposition of calcium phosphate as hydroxyapatite crystals within the osteoid.

Osteoblast differentiation is regulated by transcription factors such as Runx2 and Osterix, and signaling pathways including Wnt/β-catenin. Hormonal and mechanical factors modulate activity: parathyroid hormone, vitamin D, and mechanical loading generally promote bone formation, while other signals influence remodeling balance. Osteoblasts also express RANKL and osteoprotegerin (OPG), coordinating remodeling with osteoclasts.

As mineralization proceeds, some osteoblasts become embedded in the matrix as osteocytes within lacunae, while others become bone lining cells on surfaces or undergo apoptosis. This dynamic contributes to bone strength and mineral homeostasis.

Clinical relevance: altered osteoblast function affects bone formation and density, contributing to metabolic bone diseases. Markers of osteoblast activity include alkaline phosphatase and osteocalcin. Therapeutic approaches aim to enhance osteoblast activity or signaling, including anabolic agents and modulators of Wnt signaling, to improve bone mass and quality. In Polish terminology, the cells are commonly referred to as osteoblasty, while the English term is osteoblasts.