Editors' ChoiceTissue Engineering

A Sweet Way to Construct Vascular Networks

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Science Translational Medicine  22 Aug 2012:
Vol. 4, Issue 148, pp. 148ec152
DOI: 10.1126/scitranslmed.3004771

Confectioners are masters of the materials science of sugar. By carefully controlling the type, concentration, and especially the temperature of various sugars, an expert candy-maker can produce a dizzying array of different sweets. Now, Jordan Miller and fellow bioengineers have taken a page out of the confectioner’s book, blending food science, materials science, and biology to tackle a persistent challenge in tissue engineering: the need for vascular networks in engineered tissues. Without perfusable vascular networks, three-dimensional (3D) engineered tissues cannot survive.

In the approach described by Miller et al., a sacrificial network of filaments with diameters of 150 to 750 μm was created by using carbohydrate glasses and a 3D printer—in effect, a carefully engineered and precisely organized candy. These networks could then be surrounded by different cell-laden biomaterials or biopolymers and dissolved away to generate engineered tissues with a network of open, interconnected conduits. Particular care was taken to systematically develop carbohydrate glasses that were strong, stiff, and optically clear, which are requirements for retaining the network’s shape while polymerizing biomaterial matrices around them. The channels were coated with endothelial cells to mimic the vasculature. The final construct was able to maintain viable and metabolically active primary rat hepatocytes (liver cells) in the core of the densely populated 3D tissue construct.

Engineered tissues still require considerable development before they reach the clinic, but they will depend on simple and adaptable strategies for generating vasculature in them, such as the sweet one reported by Miller and colleagues. Notably, this approach is compatible with a wide range of the most popular matrix materials used in tissue engineering, from photopolymerized synthetic hydrogels to protein-based extracellular matrices, all of which can be applied to carbohydrate glass networks prepared in advance. In particular, the technology would be expected to accelerate the translational development of engineered tissues with complex 3D architectures and significant metabolic demands, such as the liver.

J. S. Miller et al., Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues. Nature Mat.1 July 2012 (doi:10.1038/nmat3357). [Full Text]

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