Long-term and room temperature operable bioactuator powered by insect dorsal vessel tissue

Abstract

We present a bioactuator powered by insect dorsal vessel tissue which can work for a long time at room temperature without maintenance. Previously reported bioactuators which exploit contracting ability of mammalian heart muscle cell have required precise environmental control to keep the cell alive and contracting. To overcome this problem, we propose a bioactuator using dorsal vessel tissue. The insect tissue which can grow at room temperature is generally robust over a range of culture conditions compared to mammalian tissues and cells. First, we confirm that a dorsal vessel tissue of lepidoptera larva Ctenoplusia agnata contracts spontaneously for at least 30 days without medium replacement at 25 °C. Using the dorsal vessel tissue cultured under the same conditions, we succeed in driving micropillars 100 µm in diameter and 1000 µm in height for more than 90 days. The strongest displacement of the micropillar top occurs on the 42^nd day and is 23 µm. Based on these results, the contracting force is roughly estimated as 4.7 µN which is larger than that by a few mammalian cardiomyocytes (3.4 µN). Definite displacements of more than 10 µm are observed for 58 days from the 15^th to the 72^nd days. The number of life cycles can be roughly calculated as 7.5 × 10⁵ times for the average frequency of about 0.15 Hz, which is no less than that of conventional mechanical actuators. These results suggest that the insect dorsal vessel tissue is a more promising material for bioactuators used at room temperature than other biological cell-based materials.