A lab at the Hannover Medical School in Germany is one of several experimenting with 3-D printing of skin cells; another German lab has printed sheets of heart cells that might some day be used as patches to help repair damage from heart attacks. A researcher at the University of Texas at El Paso, Thomas Boland, has developed a method to print fat tissue that may someday be used to create small implants for women who have had breast lumpectomies. Dr. Boland has also done much of the basic research on bioprinting technologies. “I think it is the future for regenerative medicine,” he said.

Dr. D’Lima acknowledges that his dream of a cartilage printer — perhaps a printhead attached to a robotic arm for precise positioning — is years away. But he thinks the project has more chance of becoming reality than some others.

“Printing a whole heart or a whole bladder is glamorous and exciting,” he said. “But cartilage might be the low-hanging fruit to get 3-D printing into the clinic.”

One reason, he said, is that cartilage is in some ways simpler than other tissues. Cells called chondrocytes sit in a matrix of fibrous collagens and other compounds secreted by the cells. As cells go, chondrocytes are relatively low maintenance — they do not need much nourishment, which simplifies the printing process.