Quantitative architectural description of tissue engineering scaffolds

Abstract

Arguably one of the most specialised subtopics in porous materials research is that of tissue engineering scaffolds. The porous architecture of these scaffolds is a key variable in determining biological response. However, techniques for characterising these materials tend to vary widely in the literature. There is a need for a set of transferable and effective methods for architectural characterisation. In this review, four key areas of importance are addressed. First, the definition and interpretation of pore size are considered in relation to fluid transport properties, by analogy with filtration research. Second, the definition of interconnectivity is discussed using insight obtained from cement and concrete research. Third, the issue of data scalability is addressed by consideration of percolation theory, as implemented for the study of geological materials. Finally, emerging techniques such as confocal and multiphoton microscopy are discussed. These methods allow the three-dimensional observation of pore strut arrangement, as well holding great potential for understanding changes in pore architecture under dynamic conditions.

MicroCT analysis of connectivity in porous structures: optimizing data acquisition and analytical methods in the context of tissue engineering

“…Micro-computed tomography (MicroCT) provides an obvious tool for the characterization of tissue-engineering scaffolds and development in image analysis, particularly pioneered by Ashworth et al [2][3][4], has allowed for its application as a predictive tool for cell migration. However, the results from any MicroCT analysis should be treated with a degree of caution.…”

Measurements and micro-mechanical modelling of the response of sintered titanium foams

“…Titanium-foams are strong, stiff and biocompatible; as such, they are a candidate material for prosthetics and bone replacement (Hutmacher 2000, Ashworth et al 2014) and several authors have investigated different cellular materials for use in medical implants (e.g. (Eppley andSadove 1990, Karageorgiou andKaplan 2005) (Navarro et al 2008), (Arabnejad Khanoki and Pasini 2012), (Markaki et al 2003)).…”

Strategy for achieving standardized bone models

“…Macroporous structure. Representation of the types of pore space depending on their connection to the surface of the material (open, closed, and blind‐ended; Ashworth et al, ) for (a) an ideal structure composed of channels, (b) a tortuous porous network and a scaffold composed of (c) spherical interconnected pores or (d) rods. (e) and (g) show corresponding images of scaffolds composed of interconnected macropores (obtained by PMMA skeleton and organic foam impregnation, respectively), (f) and (h) show scaffolds composed of intertwined fibers obtained by robocasting (from Martinez‐Vazquez, Pajares, Guiberteau, and Miranda, ) and fiber spunbonding (from VanGordon et al, ).…”

“…Used alone, porosity is a poor predictor of biological responses. In particular, mass transport and shear stress values, which are key factors affecting cell fate and tissue development, cannot be evaluated based on the porosity value alone; other architectural parameters must be provided (Ashworth, Best, & Cameron, 2014;Bohner, Loosli, Baroud, & Lacroix, 2011).…”