Modular tissue engineering: fabrication of a gelatin-based construct.

Modular tissue-engineered constructs are assembled from sub-millimetre-sized cylindrical modules which are seeded with a surface layer of endothelial cells. The resulting construct is permeated by a network of interconnected, endothelial cell-lined channels to facilitate blood perfusion and nutrient delivery. To provide adequate stiffness, yet consist of a substrate suitable for endothelial cells, modular constructs were fabricated from gelatin, the denatured form of collagen. Gelatin modules containing HepG2 cells or spheroids were fabricated using a sieving process. A surface layer of bovine aortic endothelial cells completely covering the modules was generated within 1 week of seeding. Modules were assembled into constructs within a flow circuit and flow rate-pressure difference profiles measured. Fluid perfusion resulted in negligible construct compaction, even at high flow rates. It was necessary, however, to crosslink the gelatin modules with glutaraldehyde to prevent dissolution at 37 degrees C. This resulted in a significant loss of cell viability within the modules. A strategy to enable non-toxic crosslinking of the gelatin modules is required to fabricate constructs containing viable cells. 2007 John Wiley & Sons, Ltd