Vessel-like channels supported by poly-l-lysine tubes

Vessel-like channels fabricated by embedding sacrificial structures in three-dimensional (3D) cellular constructs and then removing the sacrificial structures have been proposed as a means of providing nutrition to the cells. Alginate gel fibers have been used in the design of such channels owing to their flexibility. However, these channels are closed during culture due to extensive shrinkage of the hydrogel structures when they contain certain cell types such as fibroblasts. Here, we describe a method for fabricating vessel-like channels supported by semi-permeable poly-l-lysine-alginate membrane tubes (PLL-tubes) in a collagen gel. PLL-coated alginate gel fibers were embedded in collagen gel and the inner alginate gel was removed. We were able to form channels in various designs-including branched structures-owing to the flexibility of the alginate gel fibers. Moreover, channels supported by PLL-tubes remained open without shrinkage of the collagen gel containing fibroblasts. These results demonstrate that 3D cellular constructs can be fabricated for culturing cells that would normally induce shrinkage of hydrogel structures.