Laser-guided direct writing for three-dimensional tissue engineering

Abstract

One of the principal limitations to the size of an engineered tissue is oxygen and nutrient transport. Lacking a vascular bed, cells embedded in an engineered tissue will consume all available oxygen within hours while out branching blood vessels will take days to vascularize the implanted tissue. One possible solution is to directly write vascular structures within the engineered tissue prior to implantation, reconstructing the tissue according to its native architecture. The cell patterning technique, laser-guided direct writing (LGDW), can pattern multiple cells types with micrometer resolution on arbitrary surfaces, including biological gels. Here we show that LGDW can pattern human umbilical vein endothelial cells (HUVEC) in two-and three-dimensions with micrometer accuracy. By patterning HUVEC on Matrigel, we can direct their self-assembly into vascular structures along the desired pattern. Finally, co-culturing the vascular structures with hepatocytes resulted in an aggregated tubular structure similar in organization to a hepatic sinusoid. This capability can facilitate studies of tissue architecture at the single cell level, and of heterotypic interactions underlying processes such as liver and pancreas morphogenesis, differentiation, and angiogenesis. ß

Review:Ex VivoEngineering of Living Tissues with Adult Stem Cells

“…Moreover, patterns of fate-controlling signals could be used to create a self-healing tissue replacement that contains undifferentiated cells for tissue maintenance and repair in addition to functionally differentiated cells. Attaining this level of detail in scaffold design will require innovations in micro-and nano-scale technology, using fabrication techniques like layer-by-layer stereolithography 122 and laser-guided direct writing 123 to produce bio-mimetic configurations of cells and cell signals. Ultimately these techniques will produce scaffolds that more closely imitate the stem cell environment in the niche and during homeostasis and tissue repair in terms of spatial architecture and the temporal pattern of cell signals.…”

3D visualization of convection patterns in lab-on-chip with open microfluidic outlet

“…Several strategies commonly used in research have been summarized in a review by (Desai et al 2007). They include the use of electric fields and dielectrophoresis (Abonnenc et al 2005;Leu et al 2005), optical trapping (Chiou et al 2005;Nahmias et al 2005), mechanical control through MEMSbased (Thielecke et al 2005) or local pressure approaches (Jeong and Konishi 2009), and the use of mixed methods (Lettieri et al 2003;Shackman et al 2007). It is well known that all common technologies have a strong impact both on the particles and on the surrounding medium, hence limiting the applicability of these techniques.…”

Laser-assisted biofabrication in tissue engineering and regenerative medicine

“…Research using this technique aims to achieve accurate cell arrangement with minimal variation for the systemic and statistical study of cell-cell interactions at single-cell level with high spatial precision. [32][33][34] Furthermore, as opposed to conventional cell patterning that constrains cells within the protein deposited area, this technique allows for natural cell migration after initial deposition thereby enabling cell-cell and cell-ECM interactions to be studied without specific cell or ECM confinement.…”