Engineering of capillary-like structures in tissue constructs by electrochemical detachment of cells.

A major challenge in the development of functional thick tissues is the formation of vascular networks for oxygen and nutrient supply throughout the engineered tissue constructs. This study describes an electrochemical approach for fabrication of capillary-like structures, precisely aligned within micrometer distances, whose internal surfaces are covered with vascular endothelial cells. In this approach, an oligopeptide containing a cell adhesion domain (RGD) in the center and cysteine residues at both ends was designed. Cysteine has a thiol group that adsorbs onto a gold surface via a gold-thiolate bond. The cells attached to the gold surface via the oligopeptide were readily and noninvasively detached by applying a negative electrical potential and cleaving the gold-thiolate bond. This approach was applicable not only for a flat surface but also for various configurations, including cylindrical structures. By applying this approach to thin gold rods aligned in a spatially controlled manner in a perfusion culture device, human umbilical vein endothelial cells (HUVECs) were transferred onto the internal surface of capillary structures in collagen gel. In the subsequent perfusion culture, the HUVECs grew into the collagen gel and formed luminal structures, thereby forming vascular networks in vitro.

Electrochemical desorption of self-assembled monolayers for engineering cellular tissues.

Adherent cells, cell sheets, and spheroids were harvested noninvasively from a culture surface by means of electrochemical desorption of a self-assembled monolayer (SAM) of alkanethiol. The SAM surface was made adhesive by the covalent bonding of Arg-Gly-Asp (RGD)-peptides to the alkanethiol molecules. The application of a negative electrical potential caused the reductive desorption of the SAM, resulting in the detachment of the cells. Using this approach greater than 90% of adherent cells detached within 5 min. Furthermore, this approach was used to obtain two-dimensional (2D) cell sheets. The detached cell sheets consisted of viable cells, which could be easily attached to other cell sheets in succession to form a multilayered cell sheet. Moreover, spheroids of hepatocytes of a uniform diameter were formed in an array of cylindrical cavities at a density of 280 spheroids/cm(2) and were harvested by applying a negative electrical potential. This cell manipulation technology could potentially be a useful tool for the fabrication and assembly of building blocks such as cell sheets and spheroids for regenerative medicine and tissue engineering applications.