From the Times: "Over the past decade increasing understanding of both adult and embryonic stem cells has opened a new frontier for science through regenerative medicine. As research has revealed how the body's master cells can be coaxed to form new tissue, it has raised the prospect of producing new organs to replace those that have been damaged. Growing new cells with specialised functions, however, is only the first hurdle that has to be cleared before regenerative medicine can help patients. A clump of cells is rarely, by itself, much use to anybody. They also need to be properly plumbed into blood vessels, to be protected from the body's immune system and to be structured in a shape that allows them to perform. This means that regenerative medicine is not reliant only on the cell biologists who can coax stem cells to make the right sort of tissue. It also needs engineers and immunologists. It is by its nature an interdisciplinary field. ... As fast as this technology is advancing, however, there is still a long way to go before scientists can re-create more complex organs. Professor Hollander said: 'The early successes have involved organs without moving parts or complicated biology.' The creation of new breasts, windpipes and bladders is an amazing step forward for medicine, but it remains a different challenge to grow new hearts or livers."