Tissue (image) University of California - San Diego Caption Tissue spins in a beaker at the end of the cleansing process that removes all of the cells. The process retains the tissue's structural proteins, a key component of the hydrogel. Credit Photo Credit: UC San Diego Jacobs School of Engineering. Usage Restrictions Credit required Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.