Immediate bone forming capability of prefabricated osteogenic hydroxyapatite

Abstract

We employed culture technology, which provides bone tissue in vitro, to expand and promote the osteogenic ability of marrow cells in porous hydroxyapatite (HA). Marrow cells were obtained from rat femur and cultured in a standard medium for 10 days, then trypsinized to make composites of HA and the cells. An additional 2-week culture (subculture) was done for the composite in a standard medium with or without the addition of dexamethasone (Dex). The 2-week subcultured composites were implanted into subcutaneous sites of syngeneic rats. These implants were harvested and prepared for the biochemical analysis of alkaline phosphatase activity and bone Gla protein content, as well as histological analysis of decalcified and undecalcified sections. In Dex-treated composites, high alkaline phosphatase activity could be detected 1 week after implantation and was maintained until 8 weeks after implantation. The bone Gla protein content could also be detected 1 week after implantation, followed by a steady increase with the passage of time until 8 weeks after implantation. The histological analysis showed active bone formation even 1 week after implantation. The bone formation was evidenced by active osteoblast lining and the appearance of calcein labeling following calcein injection 1 week after implantation. Thus, Dex-treated subcultured marrow cells in pore regions of HA showed a high osteogenic response immediately after transplantation. In contrast, Dex-untreated composite did not show bone formation and contained traces of these biochemical parameters. These results indicate that the inherent osteogenic ability of marrow stromal stem cells in pore regions of HA can be stimulated using tissue culture technology; and thus, formed osteogenic HA can show immediate osteoblastic activity in in vivo situations, suggesting the applicability of the HA in clinical situations.

A Preliminary Study on a Newly Developed Cell-hybridized Artificial Bone in a Beagle Dog: Bone Marrow Stromal Cells with an Interconnected Porous Hydroxyapatite Scaffold

“…Recently, HA used as a scaffold for tissue engineering has demonstrated good bone formation. [6][7][8][9] However, because of inadequate pore connections in conventional HA, osteoconduction has been limited to the surface. 20 Generally speaking, over 10 μm in diameter will permit osteoconduction, 21 because the size of the nucleus in most mammalian cells is over 10 μ m. It has been reported that bone ingrowth penetrating into the HA was no more than 300 μ m from the interface at 4 months after implantation in humans.…”

“…These BMSCs were mixed with medium and 1 ml of BMSC solution (cell density 1.0×10 6 ) was injected into the IP-CHA scaffold. Through this method, both disc-type and cylinder-type BMSCs/ IP-CHA composites were fabricated with the use of disc-type and cylinder-type IP-CHA.…”

“…Hydroxyapatite (HA) has been widely used as a graft material with excellent biocompatibility and direct bonding to repaired bone tissue. [6][7][8][9] However, this direct bonding has been limited to the surface of the HA. Recently, a newly developed HA with an interconnected porous structure (IP-CHA) has been introduced and has been demonstrated to have substantial porosity.…”

Bioceramic Scaffolds

“…Moreover, the scaffold's porosity (exceeding 60%) and degree of pore interconnectivity directly affects the diffusion of physiological nutrients and gases [111,112]. Interestingly, the pores with smaller sizes than 1 μm are appropriate to interact with proteins and are mainly responsible for inducing the formation of an apatite-like layer in contact with simulated blood fluids.…”

The Effect of Simulated Microgravity by Three-Dimensional Clinostat on Bone Tissue Engineering

“…tion has been observed in the pore areas of the HA ceramics (9)(10)(11)(12)24,25). Importantly, the composites also exhibited healing effects when implanted into sites with Evidence suggests that mechanical stress, including gravity, is associated with osteoblast differentiation and bony defects (8).…”