Development and Transplantation of a Mineralized Matrix Formed by Osteoblasts in Vitro for Bone Regeneration

Abstract

The use of extracellular matrix materials as scaffolds for the repair and regeneration of tissues is receiving increased attention. The current study was undertaken to test whether extracellular matrix formed by osteoblasts in vitro could be used as a scaffold for osteoblast transplantation and induce new bone formation in critical size osseous defects in vivo. Human osteoblasts derived from alveolar bone were cultured in six-well plates until confluent and then in mineralization media for a further period of 3 weeks to form an osteoblast-mineralized matrix complex. Histologically, at this time point a tissue structure with a "connective tissue"-like morphology was formed. Type I collagen was the major extracellular component present and appeared to determine the matrix macrostructure. Other bone-related proteins such as alkaline phosphatase (ALP), bone morphogenetic protein (BMP)-2 and -4, bone sialoprotein (BSP), osteopontin (OPN), and osteocalcin (OCN) also accumulated in the matrix. The osteoblasts embedded in this matrix expressed mRNAs for these bone-related proteins very strongly. Nodules of calcification were detected in the matrix and there was a correlation between calcification and the distribution of BSP and OPN. When this matrix was transplanted into a critical size bone defect in skulls of immunodeficient mice (SCID), new bone formation occurred. Furthermore, the cells inside the matrix survived and proliferated in the recipient sites, and were traceable by the human-specific Alu gene sequence using in situ hybridization. It was found that bone-forming cells differentiated from both transplanted human osteoblasts and activated endogenous mesenchymal cells. This study indicates that a mineralized matrix, formed by human osteoblasts in vitro, can be used as a scaffold for osteoblast transplantation, which subsequently can induce new bone formation.

Osthole-Mediated Cell Differentiation through Bone Morphogenetic Protein-2/p38 and Extracellular Signal-Regulated Kinase 1/2 Pathway in Human Osteoblast Cells

“…It has been well documented that stimulation of osteoblast cell differentiation is characterized mainly by increased expression of ALP, type I collagen, and osteocalcin (Xiao et al, 2004). The action of BMPs is mediated by heterotetrameric serine/ threonine kinase receptors and the downstream transcription factors SMAD1/5/8.…”

Early gene and protein expression associated with osteoblast differentiation in response to fish collagen peptides powder

“…Therefore, osteopontin might not be a mineralization-specific factor. Xiao et al reported that nodules of calcification produced from osteoblasts are detected in the matrix, and that there is a correlation between calcification and the distribution of bone sialoprotein and osteopontin 19) . In addition, the osteopontin secreted from the basolateral surfaces of osteoclasts might act as an autocrine factor by binding to the αVβ3-integrin 20) .…”

The in vitro and in vivo effects of the low molecular weight fucoidan on the bone osteogenic differentiation properties

“…To determine the mechanism underlying the promotion of mineralization by LMW fucoidan, the gene expression of markers of osteoblastic differentiation was studied using cultured 7F2 cells in the absence or presence of LMW fucoidan for 48 h. BMPs are a group of growth factors also known as cytokines and as metabologens, which stimulate osteoblast cell differentiation mainly by increased expression of ALP and osteocalcin (Xiao et al 2004). Our data showed that the expression of BMP-2 significantly increased 2.28 ± 0.06 fold upon treatment with LMW fucoidan at 2 mg/ml (Fig.…”