By Michelle Roberts
BBC News health reporter
Katy Scivyer is living proof that transplant medicine has come a long way in the 50 years since the world's first successful human organ transplant.
Katy says her new kidney has made all the difference
She says her new kidney, donated by her sister a year ago, restored her life.
More than 45,000 UK people have had their lives saved or transformed by a kidney transplant since the pioneering surgery in the US in 1954.
It also paved the way for successful transplantation of other organs, including the heart, lung and liver.
But half a century on, many barriers to transplantation, new and old, remain.
The surgeon who performed the original operation on identical twin brothers from Boston, Joseph Murray, would later go on to win a Nobel prize for his pioneering work.
But at the time, such experimental techniques were frowned upon by many, and surgeons were carrying out operations in the middle of the night, shrouded in secrecy.
Organs were taken from monkeys and pigs to give to humans.
Meanwhile, doctors in France were taking kidneys from criminals immediately after execution by the guillotine to give to patients.
But the success rates continued to be very poor, and the doctors had been struggling to find a way to stop rejection of the transplanted organs, which were failing after a matter of hours and days in most cases.
One answer was to use donated organs from living relatives with as close a genetic make-up as possible - i.e. identical twins.
Joseph Murray found two identical twin brothers who were happy and willing to undergo the transplant operation two days before Christmas.
Increasing donor numbers
Preventing rejection without the need for life-long drugs
Finding new sources of organs - animals and 'man-made' implants
Settling ethical dilemmas such as presumed consent, altruistic donation and paying donors
"One was dying of kidney disease, the other was healthy," said Mr Murray. "It was the perfect human setup for our laboratory model."
Richard Herrick, the 23-year-old twin who received the donated kidney, went on to live for another eight years after the transplant, which was deemed a fantastic success.
His brother, Ronald, is alive and well today at the age of 73.
But it was not until scientists started using anti-rejection drugs that the technique really took off.
This allowed surgeons to widen the net to swap organs between complete strangers.
One of the figures most responsible for this transformation is Sir Roy Calne, Emeritus Professor of Surgery at the University of Cambridge.
He said: "Kidney transplantation is an extraordinary success story.
"One of my patients has been living with their kidney graft for 40 years."
Kidney transplants are now so successful in the UK that, a year after surgery, 94% of kidneys in living donor transplants are still functioning well and 87% of kidneys from people who have died are still functioning well.
Mr Vassilios Papalois, transplant surgeon at St Mary's Hospital, London, said the surgical technique used today is practically the same as it was then.
But he said future refinements would likely make the procedure even better.
"We might be able to use smaller incisions, with keyhole surgery, to remove the donor kidney, and even use robots to carry out the operation like they have been doing in heart surgery."
"We are developing better preservatives to keep donated kidneys in a viable state for longer.
"'We have machines that can tell us how well the organ is working before we transplant it and after.
"Eventually, we may be able to develop ways of inducing tolerance so people don't need anti-rejection drugs at all."
He said one of the main obstacles to transplantation at the moment was a lack of suitable donors to match the growing numbers of people needing organs.
Last year, nearly 400 people died while waiting for an organ transplant.
Currently, the most common source of organs is from patients who have died in intensive care but whose vital organs other than the brain are being maintained by medical support. These patients are referred to as heart beating donors (HBD).
But with better medical treatments and fewer fatal road accidents, the numbers of these donors is dwindling.
More emphasis is being placed on donation from living people, usually a close relative of the patient.
Mr Papalois said: "The bottom line is we need more organs.
"We need more people to be willing to donate their organs, both in life and after death.
1954 First successful kidney transplant operation performed in Boston, US
1960 First UK living donor kidney transplant, performed at Edinburgh
1963 First liver transplant in Denver, US
1967 First heart transplant operation performed by Dr Christian Barnard in South Africa
1968 First heart transplant in UK
"A possibility is taking organs from non-heart beating donors [people who have died and their heart has stopped, but without waiting for evidence of brain stem death].
"Then there is using organs from animals - xenotransplantation.
"I believe these things will happen. But there are many, many ethical questions we will have to answer.
"Is it ethical to accept a kidney from an altruistic donor, a complete stranger, in the same way we do with blood?
"Can we pay donors who give their kidneys. Should they be for sale?"
Katy Scivyer, 47, had her transplant last summer when she found out her kidneys were failing.
She says it has turned her life around.
"When I look back now to the three or four months leading up to the transplant, it was a bit of a blur.
"At the time I was still working in local government, but that was about all I was capable of doing.
"I used to go to work in the morning, come home in the evening and go straight to bed. It was very tiring.
When Katy was told she would need a new kidney, her sister volunteered to be tested to see if she would be a suitable donor.
"It was only after she started on the process that she told me about it.
"She has got children, whereas I haven't, so I was very careful not to put pressure on her at any time to make her feel obliged to do it.
"It was a big decision. She had to make it for herself."
Her sister was found to be a good match and the operation went ahead with excellent results.
"I came round from the operation feeling absolutely marvellous. It was a dramatic transformation.
"I'm completely back to normal and I can go to the gym and do all the activities that I used to do.
"I have had almost no side effects from the medication. And my sister is absolutely marvellous too. She's back to full fitness."
She urged more people to think about becoming a donor and joining the UK register.