From ScienceDaily: "researchers have built pancreatic tissue with insulin-secreting cells, surrounded by a three-dimensional network of blood vessels. The engineered tissue could pave the way for improved tissue transplants to treat diabetes. The tissue [has] some significant advantages over traditional transplant material that has been harvested from healthy pancreatic tissue. The insulin-producing cells survive longer in the engineered tissue, and produce more insulin and other essential hormones ... When they transplanted the tissue into diabetic mice, the cells began functioning well enough to lower blood sugar levels in the mice. ... The well-developed blood vessel network built into the engineered tissue is key to its success, the researchers concluded. The blood vessels encourage cell-to-cell communication, by secreting growth hormones and other molecules, that significantly improve the odds that transplanted tissue will survive and function normally. ... One reason transplants fail [is] that the islets are usually transplanted without any accompanying blood vessels. ... Until the islets begin to connect with a person's own vascular system, they are vulnerable to starvation. The 3-D system developed by [the] researchers tackled this challenge by bringing together several different cell types to form a new transplantable tissue. Using a porous plastic material as the scaffold for the new tissue, the scientists seeded the scaffold with mouse islets, tiny blood vessel cells taken from human umbilical veins, and human foreskin cells that encouraged the blood vessels to develop a tube-like structure. ... The advantages provided by this type of environment are really profound ... the number of islets used to lower blood sugar levels in the mice was nearly half the number used in a typical islet transplant. Islets grown in these rich, multicellular environments lived three times as long on average as islets grown by themselves."