Because patient bone defects are usually varied and complicated in geometry, it would be preferred to fabricate custom-made artificial bone grafts that are anatomically specific to individual patient defects. Using a rabbit femoral segment as a bone reconstruction model, we successfully produced customized ceramic scaffolds by stereolithography, which not only had an anatomically correct external shape according to computed tomography data but also contained an interconnecting internal network of channels designed for perfusion culture. Rabbit bone marrow stromal cells were isolated and cultured with these scaffolds using a novel oscillatory perfusion system that was stereolithographically fabricated to fit well to the unique scaffold shapes. After five days of three-dimensional culture with oscillatory perfusion, the cells attached and proliferated homogenously in the scaffolds. However, control cells inside the scaffolds cultured under static conditions were dead after prolonged in vitro culture. Cellular DNA content and alkaline phosphatase activities were significantly higher in the perfusion group versus the static group. Therefore, anatomically correct artificial bone can be successfully constructed using stereolithography and oscillatory culture technology, and could be useful for bone engraftment and defect repair.

The technique of microautoradiography at the electron microscope scale is used to describe the local repartition of hydrogen introduced by cathodic charging in an Fe-Ti alloy (0.15 Wt% Ti). The role of previous heat treatments of the alloy is studied. Different kinds of trapping sites for hydrogen are observed, mainly decorated dislocations, grain boundaries and interfaces between TiC precipitates and the matrix. A qualitative measurement of the quantity of trapped hydrogen and of the degassing rate leads to a classification of the traps with respect to their interaction energy with hydrogen. The consequence of carbon-hydrogen interactions on the further cracking sensitivity of the alloy, as influenced by the thermal history and carbide repartition, is discussed.

Porous beads of bioactive ceramics such as hydroxyapatite (HAp) and tribasic calcium phosphate (TCP) are considered a promising scaffold for cultivating bone cells. To realize this, α-TCP/HAp functionally graded porous beads are fabricated with two main purposes: to maintain the function of the scaffold with sufficient strength up to the growth of new bone, and is absorbed completely after the growth. HAp is a bioactive material that has both high strength and strong tissue-adhesive properties, but is not readily absorbed by the human body. On the contrary, α-TCP is highly bioabsorbable, resulting in a scaffold that is absorbed before it is completely replaced by bone. In this study, we produced porous, bead-shaped carriers as scaffolds for osteoblast culture. To control the solubility in vivo, the fabricated beads contained α-TCP at the center and HAp at the surface. Cell adaptability of these beads for bone tissue engineering was confirmed in vitro. It was found that α-TCP/HAp bead carriers exhibit low toxicity in the initial stages of cell seeding and cell adhesion. The presence of HAp in the composite bead form effectively increased ALP activity. In conclusion, it is suggested that these newly developed α-TCP/HAp beads are a promising tool for bone tissue engineering.

Porous ceramic scaffolds with shapes matching the bone defects may result in more efficient grafting and healing than the ones with simple geometries. Using computer-assisted microstereolithography (MSTL), we have developed a novel gelcasting indirect MSTL technology and successfully fabricated two scaffolds according to CT images of rabbit femur. Negative resin molds with outer 3D dimensions conforming to the femur and an internal structure consisting of stacked meshes with uniform interconnecting struts, 0.5 mm in diameter, were fabricated by MSTL. The second mold type was designed for cortical bone formation. A ceramic slurry of beta-tricalcium phosphate (β-TCP) with room temperature vulcanization (RTV) silicone as binder was cast into the molds. After the RTV silicone was completely cured, the composite was sintered at 1500°C for 5 h. Both gross anatomical shape and the interpenetrating internal network were preserved after sintering. Even cortical structure could be introduced into the customized scaffolds, which resulted in enhanced strength. Biocompatibility was confirmed by vital staining of rabbit bone marrow mesenchymal stromal cells cultured on the customized scaffolds for 5 days. This fabrication method could be useful for constructing bone substitutes specifically designed according to local anatomical defects.

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