Design and fabrication of standardized hydroxyapatite scaffolds with a defined macro‐architecture by rapid prototyping for bone‐tissue‐engineering research

Abstract

This investigation describes the production and characterization of calcium phosphate scaffolds with defined and reproducible porous macro-architectures and their preliminary in vitro and in vivo bone-tissue-engineered response. Fugitive wax molds were designed and produced using a rapid prototyping technique. An aqueous hydroxyapatite slurry was cast in these molds. After sintering at 1250°C and then cleaning, dimensional and material characterizations of the scaffolds were performed. The resulting scaffolds represented the design, and their dimensions were remarkably consistent. A texture inherent to the layer-bylayer production of the mold was impressed onto the vertical surfaces of the scaffolds. The surface roughness (R a ) of the textured surfaces was significantly greater than that of the nontextured surfaces. Material analyses revealed a ␤-TCP phase in addition to hydroxyapatite for the molded ceramics. Non-molded control ceramics exhibited only hydroxyapatite. Thirty scaffolds were seeded with cultureexpanded goat bone-marrow stromal cells (BMSCs) and implanted subcutaneously in nude mice for 4 or 6 weeks. Histology revealed mineralized bone formation in all the scaffolds for both implantation periods. After 4 weeks, bone was present primarily as a layer on scaffold surfaces. After 6 weeks, the surface bone formation was accompanied by bone budding from the surface and occasional bridging of pores. This budding and bridging bone formation almost always was associated with textured scaffold surfaces. However, the area percentage of bone in pores was similar for the 4-and 6-week implantation periods.

Fabrication and Characterization of Poly(Propylene Fumarate) Scaffolds with Controlled Pore Structures Using 3-Dimensional Printing and Injection Molding

“…19,23,25 This machine could precisely control the slice thickness using 2 thermoplastic materials. The lost mold technique we used was based on selective solubility of 2 materials in different solvents.…”

“…Another approach using the SFF technique is to fabricate temporarily negative molds and cast the scaffold by using biomaterial suspensions. [16][17][18] Based on the original scaffold design, negative molds were removed after they were cast by biomaterials such as collagen, 19 ceramics, [20][21][22][23] polymers, 24 or their composites. 25 Several studies have demonstrated that this method was capable of fabricating scaffolds with controlled internal structures as well as external shapes.…”

“…25 Several studies have demonstrated that this method was capable of fabricating scaffolds with controlled internal structures as well as external shapes. 19,20,22,23,25,26 Most scaffolds using a temporary mold have been fabricated by sintering ceramic or freezing a dispersion of collagen cast into the mold, which required a relatively high or low temperature condition. Furthermore, 10-20% shrinkage was found in the resulting scaffolds fabricated using those materials.…”

Progress in organ 3D bioprinting

“…Until now, there are many reviews on this subject [83][84][85][86][87][88][89] . Numerous studies have focused on producing 3D printed bone regenerative scaffolds (or substitutes) in a customdesigned manner [90,91] .…”

Bone and cartilage tissue engineering for facial reconstructive surgery

“…Ceramics are well known to induce differentiation of potentially osteogenic cells towards the osteogenic lineage [62][63][64][65][66][67] and they are able to bridge large bony defects in human if combined with MPC [68]. Even if it seems to be possible to design a standardized hydroxyapatite ceramic scaffold with the help of rapid prototyping techniques [69], the architecture of a given scaffold (i.e., the size and the interconnectivity of the pores) as well as the mechanical properties can be controlled much…”