Yesterday's television fantasy is becoming tomorrow's reality. New bionic man may not be blessed with superhuman strength, but one day the injured may be able to move their paralysed limbs by the power of thought - and a tiny implanted computer.
Synthetic tissues could begin to merge with flesh to restore failing organs, artificial blood could carry oxygen from the lungs, cochlear implants could directly stimulate "hearing" in the brain, and cameras implanted in the retina could restore some vision to the blind.
Mechanical helpers could keep failing hearts beating, artificial livers could prolong patients' lives and artificial tendons might tether wasting muscle to bones. The catch is that the Six Million Dollar Man will cost nearer $6bn - and the tissue engineers who will repair tomorrow's humans have a long way to go.
William Craelius, a biomedical engineer at Rutgers University, reports in Science today - in a roundup of the science of tissue engineering and artificial implants - that the pace of miniature electronics could turn Captain Hook's metal menace into something more touchy-feely. He has already developed an artificial hand and mechanical fingers which can be coupled to surviving nerve endings.
"At this pace, within the decade, the processing for complex bionic activity will be implantable in the brain or elsewhere in the body," he said. "Human machine-communication could soon lose its distinction as the number one obstacle to bionics."
However, Larry Hench and Julia Polak of Imperial College, London, foresee a new era in "biomaterials" - implants which will switch on genes and get failing tissues growing again. Surgeons have been fitting patients with metal, glass and ceramics for decades. But half to a third of skeletal prostheses and artificial heart valves fail within 10 to 25 years, bringing sufferers back for surgery.
The London tissue engineers have tested a bioactive material which "activated" important genes in bone cells that grew on it. "In the future we may only need to implant the carefully calculated chemical ingredients of the biomaterial, rather than a finished biomaterial itself, in order to repair tissue," Professor Hench said.
Scientists in Washington and Los Angeles are working on auditory brainstem implants to restore at least some hearing in people without a functioning auditory nerve. The first could be fitted into a human later this year.
German scientists at Tubingen believe that electronics might help the blind see. Normal vision requires tiny natural instruments which pick up light waves and convert them to signals to the brain. A tiny camera and processing unit could send information to a chip on top of the retina, which would convert the data to delicate electrical impulses and stimulate the optic nerve. Patients have already been fitted with artificial hearts, but two researchers in Cleveland, Ohio, argued in Science that small, magnetically suspended blood pumps in the arteries and veins could be powered through skin by batteries. They could be combined with stem cell transplants or gene therapy to speed up the healing of the heart muscle.
