Cell therapy using an array of ultrathin hollow microneedles

Cell transplantation traditionally employs needles to inject donor cells into tissues to treat certain diseases. However, it is difficult for the current method to achieve multiple parallel equidistant injections, which are ideal for cell therapy. This paper presents a new cell transplantation method using an array of ultrathin microneedles. The main characteristic of the needles is their high aspect ratio: each needle is 500 mu m long, and has a 50 mu m diameter and a very thin wall (2 mu m-thick SiO2 and 1.5 mu m-thick Si3N4). An array of such microneedles was successfully used to inject fluorescently labeled Mardin-Darby canine kidney cells into rat liver tissue. Viability of the cells inserted using this method was verified after 5 days. Preliminary results show that this type of microneedle array can be used for cell therapy.