Landmark kidney swap transplants have been carried out by surgeons on two couples who did not know each other.Roma Horrell, 57, from Cambridgeshire, received a kidney from an unnamed woman from the Lothians in Scotland during surgery at Addenbrooke's Hospital in Cambridge on July 4.Just hours later, the Scottish woman's husband had a kidney transplanted at Edinburgh Royal Infirmary which had been donated by Mrs Horrell's husband, Peter, 55.Mrs Horrell said: "Everything has improved enormously. I can eat what I want, I can enjoy cooking, we can go on holiday. Life is normal again. I feel as though I've got hope for the future."A change in the rules last year led the Human Tissue Authority (HTA) to allow strangers to donate to each other.Previously living donor transplants have occurred only between relatives or people with a close emotional relationship, such as couples living together.The new type of "swap" transplant will usually be of kidneys, because it is difficult or impossible to use other types of organs without harming the live donor.Experts hope up to 200 more kidney patients a year could benefit from this kind of transplant in the future. In the first few years, around 50 extra patients are expected to benefit.Transplants on a second set of couples are already planned, with a third in the pipeline.© Independent Television News Limited 2007. All rights reserved.