We're a fair way from being able to produce a complete replacement for the functions of human body - a very sane goal if you'd like to live a lot longer - but the checklist of what can be replaced is getting longer by the month. From the New Scientist: "More and more of the body is becoming, if not obsolete, then certainly replaceable. But which of our body parts can be engineered today, and which will we have to make do with? ... Implants that copy the simple structural job of skeletal tissue are the easiest to build ... by culturing normal or stem cells it is now possible to grow pretty much any type of tissue. Some complete organs have already been grown from scratch. ... Other parts of the body's plumbing network, such as the lymphatic system, are becoming replaceable too. Last year, mice were implanted with an artificial lymph node made from collagen and cells taken from a gland in newborn mice. ... Implants can also help the blind see, by stimulating the retina, optic nerve or the brain's visual cortex. ... Other research seeks to replace entire limbs with robotic replacements."