Abstract
Over time, the fabrication of lattice, porous structures has always been a controversial field for researchers and practitioners. Such structures could be fabricated in a stochastic way, thus, with limited control over the actual porosity percentage. The emerging technology of 3D printing, offered an automated process that did not require the presence of molds and operated on a layer-by-layer deposition basis, provided the ability to fabricate almost any shape through a variety of materials and methods under the umbrella of the ASTM terminology “additive manufacturing”. In the field of biomedical engineering, the technology was embraced and adopted for relevant applications, offering an elevated degree of design freedom. Applications range in the cases where custom-shaped, patient-specific items have to be produced. Scaffold structures were already a field under research when 3D printing was introduced. These structures had to act as biocompatible, bioresorbable and biodegradable substrates, where the human cells could attach and proliferate. In this way, tissue could be regenerated inside the human body. One of the most important criteria for such a structure to fulfil is the case-specific internal geometry design with a controlled porosity percentage. 3D printing technology offered the ability to tune the internal porosity percentage with great accuracy, along with the ability to fabricate any internal design pattern. In this article, lattice scaffold structures for tissue regeneration are overviewed, and their evolution upon the introduction of 3D printing technology and its employment in their fabrication is described.
Highlights
In the biomedical field, the incorporation of 3D printing technology in the fabrication of highly specialized, patient-specific structures is immense
3D printing exceeds as an ideal method for scaffold fabrication, since it allows both the exact attribution of the external shape of the scaffold along with a pre-defined internal pore geometry [59]
Taylor et al report the successful 3D printing work in which NiTi powder-based inks were used for bone regeneration targeted scaffold structures that were subsequently seeded with mesenchymal stem cells derived from adult humans
Summary
The incorporation of 3D printing technology in the fabrication of highly specialized, patient-specific structures is immense. Atala is considered as immense in this field, where Dr Atala leads a team of more than 400 researchers focused on developing cell therapies, tissue engineering constructs and organs for more than 40 different areas of the body [18] He is considered as the creator of 3D bioprinters [19] and, in 2006, he and his team developed the first lab-fabricated organ (a human bladder) to be implanted into a human [20]. The literature suggests that different cell types tend to prefer specific porosity degrees and architectures [14,54] Both porosity and pore size have an effect on fluid shear stress which is a critical parameter in a scaffold structure due to its role in controlling fluid perfusion through the scaffold’s pore network. An ideal balance between mechanical behavior and porous architecture is vital towards fabricating an artificial lattice scaffold structure that will fulfill its role [50]
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