![]() ![]() Relatively smaller pores and larger specific surface area assist cell attachment as shown in a study with collagen-glycosaminoglycan scaffolds that attachment of osteogenic cells was increased with decreasing mean pore size and increasing specific surface area. Given a scaffold with constant porosity, a decrease in the mean pore size will cause pore channels to narrow, which may inconvenience cell migration despite an increase in the surface area. The interconnection of the pores is also an important parameter that defines the effects of porosity and pore size. Additionally, porosity needs to be controlled for each application since an increase in porosity leads to a relative decrease in the mechanical properties. High porosity assists nutrient and waste diffusion that is one of the critical factors for vascularization and tissue ingrowth. Porosity and pore size define the surface area per volume (Fig. A large surface area assists cell attachment and proliferation. Given the critical role of microstructure on the performance of scaffolds, characterization of the microstructure is indispensable, and Micro-CT is an outstanding instrument to characterize the microstructure of scaffolds. 3D Microstructural metrology of scaffolds used in tissue engineering with tomography The investigation of soft tissues is relatively challenging due to their low contrast in conventional micro-CT imaging thus it may require an extra effort such as employing high-atomic-number element probes or contrast agents. Micro-CT has frequently been used in bone studies, and typically, the investigated parameters include volume, microstructural features, and mineral density. Within the field of tissue engineering it has a place in many application domains including (i) scaffold characterization, (ii) in vivo small laboratory animal tissue characterization including assessment of bone turnover using 4D micro-CT data, and tumor detection, (iii) ex vivo characterization of human tissues and animal tissues. Today, a search on “micro-CT” in PubMed yields more than 10,000 items by being used in many fields. Conventionally, the samples can be analyzed almost without any sample preparation process generally in a non-destructive way. Micro-computed tomography (micro-CT) is a high-resolution CT that has a pixel size typically between 1 μm and 50 μm, and allows to investigate the microstructure of samples using X-rays. Tomography is defined as a method by which an object’s 3D image that corresponds to its internal structure is obtained. Certainly, the functional performance of a scaffold in vivo not only depends on its microstructure but also on all other factors involved in tissue engineering which are very complex and probably not yet completely known. Scaffolds host and interact with cells, and the design of a scaffold affects the entire behavior of the cells including adhesion, growth, migration, differentiation, and matrix synthesis. Differences in the design of 3D scaffolds such as composition, surface chemistry, architecture, and mechanical properties, can yield to almost countless different scaffolds. To achieve the regeneration of functional tissues, as in nature, complete understanding and biomimicry of those 3D architectures are necessary. In nature, structural materials including animal and human tissues have complex hierarchical architectures at multiple scales from nano to macro. Future studies that will include micro-CT characterization of scaffolds should report the important details of the method, and the derived quantitative and qualitative information can be maximized. Micro-CT offers a unique microstructural analysis of biomaterials, notwithstanding the associated challenges and limitations. In this work, we also analyzed the original papers that were published in 2016 through a systematic search to address the need for specific improvements in the methods section of the papers including the amount of provided information from the obtained results. This review highlights the relationship between the scaffold microstructure and cell behavior, and provides the basics of the micro-CT method. ![]() Micro-computed tomography (micro-CT) provides a powerful platform to analyze, visualize, and explore any portion of interest in the scaffold in a 3D fashion without cutting or destroying it with the benefit of almost no sample preparation need. ![]() Thus, characterization of the scaffolds is highly required. Given the fact that most of the cells used in tissue engineering are anchorage-dependent, their behavior including adhesion, growth, migration, matrix synthesis, and differentiation is related to the design of the scaffolds. Cell behavior is the key to tissue regeneration. ![]()
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