Properties and Origin of Osteoblasts

Abstract

Osteoblastic and chondroblastic (i.e., osteogenic) cells belong to the stromal cell system, which is associated with bone marrow, and bone and is separate from the hematopoietic stem-cell system. Stromal stem cells are capable of producing reticular, fibroblastic, osteogenic, and adipose stromal lines. Marrow-derived osteogenic cells are a component of marrow stroma, which in vitro form fibroblastic-type colonies. These colonies are a heterogeneous population with varying enzymatic expressions and potencies that differentiate into fibroblastic, reticular, adipocytic, and osteogenic populations. It is postulated that these colonies are a component of the stem-and progenitor cell populations. Progenitors of osteogenic cells are widely distributed in the extraskeletal organs. On contact with an adequate inductor, they differentiate into chondro-and/or osteoblasts, thus producing ectopic (i.e., induced) cartilage and/or bone. Such osteoprogenitor cells were termed inducible osteoprogenitor cells, in contrast to the determined osteoprogenitor cells, which are present in the bone marrow stroma and produce bone spontaneously. To the class of determined osteoprogenitors also belong endosteal cells, periosteal cells, and osteoblastic established cell lines. There is no evidence of the presence of osteogenic cells in the blood and peritoneal fluid. The concept of mesenchymal cells as an osteoblastic precursor in adult organisms is open to question.

Tri-iodothyronine regulates the production of interleukin-6 and interleukin-8 in human bone marrow stromal and osteoblast-like cells

“…It is now increasingly accepted that, when compared with hOb, hBMS cells represent an earlier stage in the osteoblast life cycle (Rickard et al 1996) and that they act as the source of the osteoprogenitor cells from which the renewal of the osteoblast population at the bone surface is considered to occur via differentiation along the osteoblast lineage (Wlodarski 1990). The differences between MG63 and SaOs-2 cells are less clear.…”

C-terminal Domain (CTD) Small Phosphatase-like 2 Modulates the Canonical Bone Morphogenetic Protein (BMP) Signaling and Mesenchymal Differentiation via Smad Dephosphorylation

“…To investigate the role of SCP4 in BMP physiological responses, we first tested the effect of SCP4 on the BMP-induced osteoblast-like differentiation in C2C12 cells, as assessed by the expression of osteoblastic marker genes, such as ALP and osteocalcin (OC) (33). As shown in Fig.…”

Circulating cells with osteogenic potential are physiologically mobilized into the fracture healing site in the parabiotic mice model

“…3 Osteogenesis in successful fracture healing requires proliferation and/ or migration of osteogenic cells into the fracture callus. 4 Local bone marrow and periosteum are known to contribute to osteogenic CTPs. Another possible source of osteogenic cells is homing through systemic circulation.…”