Advanced material strategies for tissue engineering scaffolds

Abstract

Tissue engineering seeks to restore the function of diseased or damaged tissues through the use of cells and biomaterial scaffolds. It is now apparent that the next generation of functional tissue replacements will require advanced material strategies to achieve many of the important requirements for long-term success. Here we provide representative examples of engineered skeletal and myocardial tissue constructs in which scaffolds were explicitly designed to match native tissue mechanical properties as well as to promote cell alignment. We discuss recent progress in microfluidic devices that can potentially serve as tissue engineering scaffolds, since mass transport via microvascular-like structures will be essential in the development of tissue engineered constructs on the length scale of native tissues. Given the rapid evolution of the field of tissue engineering, it is important to consider the use of advanced materials in light of the emerging role of genetics, growth factors, bioreactors, and other technologies.

Figure 1

Anisotropic three-dimensional woven scaffold for cartilage tissue engineering. (A) Scanning electron micrograph; (B,C) Safranin-O stained histological section of scaffold with cultured bovine calf articular chondrocytes. Cells are round with black nuclei and are embedded in a red-orange extracellular matrix; scaffold is colored lighter pink. Scale bars: 1 mm (A), 500 μm (B), and 50 μm (C). Adapted with permission from [25] Copyright 2007, Nature Publishing Group (A), and from [105] Copyright 2006, Mary Ann Liebert, Inc. (B)

Figure 2

Accordion-like honeycomb scaffold for myocardial tissue engineering. (A) Scanning electron micrograph. (B) Confocal micrograph of the scaffold with cultured rat heart cells. Cells and filamentous actin are colored green, cell nuclei are colored blue, and the scaffold is colored blue. Scale bars 200 μm. Adapted with permission from [62] Copyright 2008, Nature Publishing Group.

Figure 3

Microfluidic device design and fabrication. (A) Silicon micromachined master used for compression molding. (B,C) Microfluidic devices constructed using a stack of laminated sheets, each layer comprising a planar bifurcated microchannel network and connected to adjacent layers using vertical through-holes (not shown). The fluidic structures are intentionally offset to illustrate the stacking process. Perfusion is demonstrated by fluorescein dye (B) and tracer particles (C). (D) Multi-compartment device comprised of intravascular (*) and extravascular (**) spaces and a porous membrane positioned between these two compartments (arrow). Scale bars: 500 μm (A,B) and 100 μm (C,D). Adapted from [85] Copyright 2004, Wiley-VCH (A,B).

Figure 4

Collagen organization in relation to the articular surface of native cartilage, as shown in a transverse section by polarized light microscopy. Reproduced with permission from [94]. Copyright 2008, Elsevier.

Figure 5

Perimysial collagen organization in relation to opposing surfaces of the myocardium, as shown in a curved, transmural plane (A). Collagen can be seen forming long, intra-laminar cords (B and E), spanning the cleavage planes separating adjacent layers (D), and fusing into tendonous structures near the edges of the laminae (C). Reproduced with permission from [44]. Copyright 2008, The American Physiological Society.