Layer-by-layer approach for a uniformed fabrication of a cell patterned vessel-like construct.

Successful tissue engineered small diameter blood vessels (SDBV) require manufacturing systems capable of precisely controlling different key elements, such as material composition, geometry and spatial location of specialized biomaterials and cells types. We report in this work an automated methodology that enables the manufacture of multilayer cylindrical constructs for SDBV fabrication that uses a layer-by-layer deposition approach while controlling variables such as dipping and spinning speed of a rod and biomaterial viscosity. Different biomaterials including methacrylated gelatin, alginate and chitosan were tested using this procedure to build different parts of the constructs. The system was capable of controlling dimensions of lumen from 0.5 mm up to 6 mm diameter and individual layers from 1 μm up to 400 μm thick. A cellular component was successfully added to the biomaterial in the absence of significant cytotoxic effect which was assessed by viability and proliferation assays. Additionally, cells showed a homogenous distribution with well-defined concentric patterns across the multilayer vessel grafts. The challenging generation of inner endothelial cells of approximately 20-30 μm of thickness was achieved. Preliminary experimental evidences of microstructural alignment of the biomaterial were obtained when the dipping approach was combined with the rod rotation. The study demonstrated the wide versatility and scalability of the automated system to easily and rapidly fabricate complex cellularized multilayer vascular grafts with structural configuration that resembles natural blood vessels.