Rapid Fabrication of Anatomically-Shaped Bone Scaffolds Using Indirect 3D Printing and Perfusion Techniques

Abstract

Fused deposit modeling (FDM) 3D printing technology cannot generate scaffolds with high porosity while maintaining good integrity, anatomical-surface detail, or high surface area-to-volume ratio (S/V). Solvent casting and particulate leaching (SCPL) technique generates scaffolds with high porosity and high S/V. However, it is challenging to generate complex-shaped scaffolds; and solvent, particle and residual water removal are time consuming. Here we report techniques surmounting these problems, successfully generating a highly porous scaffold with the anatomical-shape characteristics of a human femur by polylactic acid polymer (PLA) and PLA-hydroxyapatite (HA) casting and salt leaching. The mold is water soluble and is easily removable. By perfusing with ethanol, water, and dry air sequentially, the solvent, salt, and residual water were removed 20 fold faster than utilizing conventional methods. The porosities are uniform throughout the femoral shaped scaffold generated with PLA or PLA-HA. Both scaffolds demonstrated good biocompatibility with the pre-osteoblasts (MC3T3-E1) fully attaching to the scaffold within 8 h. The cells demonstrated high viability and proliferation throughout the entire time course. The HA-incorporated scaffolds demonstrated significantly higher compressive strength, modulus and osteoinductivity as evidenced by higher levels of alkaline-phosphatase activity and calcium deposition. When 3D printing a 3D model at 95% porosity or above, our technology preserves integrity and surface detail when compared with FDM-generated scaffolds. Our technology can also generate scaffolds with a 31 fold larger S/V than FDM. We have developed a technology that is a versatile tool in creating personalized, patient-specific bone graft scaffolds efficiently with high porosity, good scaffold integrity, high anatomical-shaped surface detail and large S/V.

Hexagonal pore geometry and the presence of hydroxyapatite enhance deposition of mineralized bone matrix on additively manufactured polylactic acid scaffolds

“…Generally, the incorporation of minerals such as HA into polymers has shown to increase the elastic moduli and yield strength in FDM printed scaffolds. Grottkau et al found 38% increase in the yield strength and 46% in the compressive modulus of 20% HA-PLA porous composites compared to PLA analogues [61]. Pitjamit et al using non-porous scaffolds of PLA/ PCL filled with 5 and 15% wt.…”

A review of biomimetic scaffolds for bone regeneration: Toward a cell‐free strategy

“…Sr/BG-G/nHAp Freeze-drying Oryan et al [7] SrHAp/CS Lei et al [39] Sr/MgP bioceramics Solid state sintering Sarkar et al [9] Zn-MBGNs Microemulsion-asisted sol-gel Neščáková et al [10] dECM/BCP Freeze-thaw /SDS solution immersion Kim et al [13] CS/G/A-dECM MOIP-PLGA Thermal-induced phase separation Shen et al [95] HA-MA/PLGA Controlled directional cooling/ lyophilization Dai et al [97] RAFSs Electrospinning Shin et al [98] SiO2 NF-CS Sol-gel electrospinning/ lyophilization Wang et al [111,112] SiO2-CaO NF/CS PLA/PLA-HA 3D printing/casting/salt leaching Grottkau et al [260] BG-CFS Solvothermal method/3D printing Dang et al [116] Ca-P/polydopamine nanolayer surface 3D printing Ma et al [134] MoS2 nanosheets and AKT bioceramic 3D printing/hydrothermal method Wang et al [117] nHA/GO/CS Modified Hummer's method/ lyophilization Ma et al [30] BPs-PLGA Solvent exfoliation/ solvent evaporation Tong et al [118] Hierarchical intrafibrillarly mineralized collagen(HIMC) Two steps self-assembly Liu et al [29] CFO@BFO/PLLA Microfluidic device/hydrothermal / sol-gel Mushtaq et al [150] Fe3O4/MBG/PCL Co-precipitation/3D printing Zhang et al [157] PVDP/CoFe2O4 Solvent casting Fernandes et al [262] nHA/Fe3O4 NPs-CS/COL Crystallization/freeze-drying Zhao et al [263] Ti/W/TiO2 Two-photon lithography(TPL) direct laser writing Maggi et al [27] Porine demineralized bone matrix scaffolds Decalcification Hu et al [175] [193] rGO/BG/osteoblast-specific aptamer Evaporation-induced self-assembly/ heat-treating/reciprocating oscillation Wang et al [203] Van-pBNPs/pep@pSiCaP-Ti Adapted with permission [31]. Fig.9 Schematic illustration of the construction of nHA/GO particles, nHA/GO/CS scaffolds, and their bio-applications.…”

“…Both composite scaffolds were fabricated by sol-gel electrospinning, followed by a lyophilization technique[111,112]. Grottkau et al reported the creation of anatomically shaped bone scaffolds using 3D printing molds as well as PLA and PLA-HA casting and salt leaching.This technique is a superior tool in constructing personalized, patient-specific bone graft scaffolds with various excellent characteristics[260].…”

Recent Advances in Regenerative Tissue Fabrication: Tools, Materials, and Microenvironment in Hierarchical Aspects

“…Artificial bone and bone scaffolds have been bioengineered through extrusion‐based 3D bioprinting with several biomaterials, and synthetic polymers, such as polylactic acid–hydroxyapatite (PLA–HA) [ 72 ] and polycaprolactone (PCL), [ 71 ] are common polymers used as bioinks. Artificial bone was fabricated through indirect 3D bioprinting via a molding process, [ 72 ] with the mold being fabricated using extrusion‐based 3D printing and the artificial bone being fabricated using the molding process. Perfusion is an additional step introduced to produce a highly, evenly porous scaffold to generate higher cell distribution, cell proliferation, and cell viability.…”

“…These characteristics are summarized in Table 1. That extrusionbased 3D bioprinting has been used to bioengineer several parts of the human body, e.g., bone, [71,72] skin, [73,74] cartilage, [75][76][77] and adipose [78] and neural tissues, [79,80] is noteworthy.…”