A Synthetic Capillary

Abstract

Tissue engineering strives to create functional tissue for organ replacement and regenerative medicine by combining living cells with a porous scaffold that promote growth and differentiation. Recent attempts to replace tissue with autologous cells on a biodegradable scaffold have been frustrated by inflammatory and healing responses. We speculate that without vascularization and hierarchical organization, gradients in effector molecules and basic nutrients can develop in engineered tissue due to the competition between convection and diffusion, cell consumption and production that compromises cell function and viability. In particular, once implanted in the patient, the cells in the engineered tissue consume the available oxygen and nutrients within a few hours, while it can take several days for the growth of new blood vessels (angiogenesis) to deliver nutrients to the implant. We have created using “live cell lithography” an in vitro model that emulates the in vivo microenvironment found in human capillaries with micron-scale precision. To create a capillary, we used a microfluidic to convey human umbilical vein endothelial cells (HUVECs) into multiple microarrays of optical tweezers, which are used to precisely position cells in a 3D hydrogel scaffold (see figure).View Large Image | View Hi-Res Image | Download PowerPoint Slide