Primary human osteoblasts (HOB) are isolated from femoral trabecular bone tissue from the knee or hip joint region. They stain positive for alkaline phosphatase and can be mineralised using mineralisation medium.

Osteoblasts are of mesenchymal origin and are mainly responsible for bone formation and remodeling. In vivo, they produce a collagen type I rich extracellular matrix called the osteoid. During their development, osteoblasts undergo a maturation process called osteogenesis. When they become encased in the bone matrix, they stop proliferating and become osteocytes.