donor who connected with him on twitter, which is believed to be the first such transplant arranged entirely through social networking. exchanges and chains are a novel approach to expand the living donor pool. in february 2012, this novel approach to expand the living donor pool resulted in the largest chain in the world, involving 60 participants organized by the national kidney registry. in 2014 the record for the largest chain was broken again by a swap involving 70 participants. the acceptance of altruistic donors has enabled chains of transplants to form. kidney chains are initiated when an altruistic donor donates a kidney to a patient who has a willing but incompatible donor. this incompatible donor then 'pays it forward' and passes on the generosity to another recipient who also had a willing but incompatible donor. michael rees from the university of toledo developed the concept of open-ended chains. this was a variation of a concept developed at johns hopkins university. on 30 july 2008, an altruistic donor kidney was shipped via commercial airline from cornell to ucla, thus triggering a chain of transplants. the shipment of living donor kidneys, computer-matching software algorithms, and cooperation between transplant centers has enabled long-elaborate chains to be formed. in 2004 the fda approved the cedars-sinai high dose ivig therapy which reduces the need for the living donor to be the same blood type (abo compatible) or even a tissue match. the therapy reduced the incidence of the recipient's immune system rejecting the donated kidney in highly sensitized patients. in carefully screened kidney donors, survival and the risk of end-stage renal disease appear to be similar to those in the general population. however, some more recent studies suggest that lifelong risk of chronic kidney disease is several-fold higher in kidney donors although the absolute risk is still very small. a 2017 article in the new england journal of medicine suggests that persons with only one kidney, including those who have donated a kidney for transplantation, should avoid a high protein diet and limit their protein intake to less than one gram per kilogram body weight per day in order to reduce the long-term risk of chronic kidney disease. women who have donated a kidney have a higher risk of gestational hypertension and preeclampsia than matched nondonors with similar indicators of baseline health. surgical procedure traditionally, the donor procedure has been through a single incision of 4–7 inches (10–18 cm), but live donation is being increasingly performed by laparoscopic surgery. this reduces pain and accelerates recovery for the donor. operative time and complications decreased significantly after a surgeon performed 150 cases. live donor kidney grafts have higher long-term success rates than those from deceased donors. since the increase in the use of laparoscopic surgery, the number of live donors has increased. any advance which leads to a decrease in pain and scarring and swifter recovery has the potential to boost donor numbers. in january 2009, the first all-robotic kidney transplant was performed at saint barnabas medical center, located in livingston, new jersey, through a two-inch incision. in the following six months, the same team performed eight more robotic-assisted transplants. in 2009 at the johns hopkins medical center, a healthy kidney was removed through the donor's vagina. vaginal donations promise to speed recovery and reduce scarring. the first donor was chosen as she had previously had a hysterectomy. the extraction was performed using natural orifice transluminal endoscopic surgery, where an endoscope is inserted through an orifice, then through an internal incision, so that there is no external scar. the recent advance of single port laparoscopy requiring only one entry point at the navel is another advance with potential for more frequent use. organ trade main article: organ trade in the developing world some people sell their organs illegally. such people are often in grave poverty or are exploited by salespersons. the people who travel to make use of these kidneys are often known as 'transplant tourists'. this practice is opposed by a variety of human rights groups, including organs watch, a group established by medical anthropologists, which was instrumental in exposing illegal international organ selling rings. these patients may have increased complications owing to poor infection control and lower medical and surgical standards. one surgeon has said that organ trade could be legalised in the uk to prevent such tourism, but this is not seen by the national kidney research fund as the answer to a deficit in donors. in the illegal black market the donors may not get sufficient after-operation care, the price of a kidney may be above $160,000, middlemen take most of the money, the operation is more dangerous to both the donor and receiver, and the buyer often gets hepatitis or hiv. in legal markets of iran the price of a kidney is $2,000 to $4,000. an article by gary becker and julio elias on "introducing incentives in the market for live and cadaveric organ donations" said that a free market could help solve the problem of a scarcity in organ transplants. their economic modeling was able to estimate the price tag for human kidneys ($15,000) and human livers ($32,000). jason brennan and peter jaworski from georgetown university have also argued that any moral objections to a market for organs are not inherent in the market, but rather the activity itself. monetary compensation for organ donors in the form of reimbursement for out-of-pocket expenses, has been legalised in 23 countries including the united states united kingdom, australia and singapore. deceased donors kidney donor cards from england, 1971–1981. the cards were made to be carried by donors as evidence that they were willing to donate their kidneys should they, for example, be killed in an accident. deceased donors can be divided in two groups: brain-dead (bd) donors donation after cardiac death (dcd) donors although brain-dead (or 'heart beating') donors are considered medically and legally dead, the donor's heart continues to pump and maintain circulation. this makes it possible for surgeons to start operating while the organs are still being perfused (supplied blood). during the operation, the aorta will be cannulated, after which the donor's blood will be replaced by an ice-cold storage solution, such as uw (viaspan), htk, or perfadex. depending on which organs are transplanted, more than one solution may be used simultaneously. due to the temperature of the solution, and since large amounts of cold nacl-solution are poured over the organs for a rapid cooling, the heart will stop pumping. 'donation after cardiac death' donors are patients who do not meet the brain-dead criteria but, due to the unlikely chance of recovery, have elected via a living will or through family to have support withdrawn. in this procedure, treatment is discontinued (mechanical ventilation is shut off). after a time of death has been pronounced, the patient is rushed to the operating room where the organs are recovered. storage solution is flushed through the organs. since the blood is no longer being circulated, coagulation must be prevented with large amounts of anti-coagulation agents such as heparin. several ethical and procedural guidelines must be followed; most importantly, the organ recovery team should not participate in the patient's care in any manner until after death has been declared. increased donors many governments have passed laws whereby the default is an opt-in system in order to increase the number of donors. since december 2015, human transplantation (wales) act 2013 passed by the welsh government has enabled an opt-out organ donation register, the first country in the uk to do so. the legislation is 'deemed consent', whereby all citizens are considered to have no objection to becoming a donor unless they have opted out on this register. with the approval of epclusa in 2020 the number of donors has increased. the medication allows for the curing of hepatitis c positive individuals which has increased the pool of available organs. animal transplants in 2022, university of alabama birmingham announced the first peer-reviewed research outlining the successful transplant of genetically modified, clinical-grade pig kidneys into a brain-dead human individual, replacing the recipient's native kidneys. in the study, which was published in the american journal of transplantation, researchers tested the first human preclinical model for transplanting genetically modified pig kidneys into humans. the recipient of the study had his native kidneys removed and received two genetically modified pig kidneys in their place. the organs came from a genetically modified pig from a pathogen-free facility. compatibility in general, the donor and recipient should be abo blood group and crossmatch (human leukocyte antigen – hla) compatible. if a potential living donor is incompatible with their recipient, the donor could be exchanged for a compatible kidney. kidney exchange, also known as "kidney paired donation" or "chains" have recently gained popularity. in an effort to reduce the risk of rejection during incompatible transplantation, abo-incompatible and desensitization protocols utilizing intravenous immunoglobulin (ivig) have been developed, with the aim to reduce abo and hla antibodies that the recipient may have to the donor. in 2004 the fda approved the cedars-sinai high dose ivig therapy which reduces the need for the living donor to be the same blood type (abo compatible) or even a tissue match. the therapy reduced the incidence of the recipient's immune system rejecting the donated kidney in highly sensitized patients. in the 1980s, experimental protocols were developed for abo-incompatible transplants using increased immunosuppression and plasmapheresis. through the 1990s these techniques were improved and an important study of long-term outcomes in japan was published. now, a number of programs around the world are routinely performing abo-incompatible transplants. the level of sensitization to donor hla antigens is determined by performing a panel reactive antibody test on the potential recipient. in the united states, up to 17% of all deceased donor kidney transplants have no hla mismatch. however, hla matching is a relatively minor predictor of transplant outcomes. in fact, living non-related donors are now almost as common as living (genetically)-related donors. procedure kidney transplant in most cases the barely functioning existing kidneys are not removed, as removal has been shown to increase the rates of surgical morbidity. therefore, the kidney is usually placed in a location different from the original kidney. often this is in the iliac fossa so it is often necessary to use a different blood supply: the renal artery of the new kidney, previously branching from the abdominal aorta in the donor, is often connected to the external iliac artery in the recipient. the renal vein of the new kidney, previously draining to the inferior vena cava in the donor, is often connected to the external iliac vein in the recipient. the donor ureter is anastomosed with the recipient bladder. in some cases a ureteral stent is placed at the time of the anastomosis, with the assumption that it allows for better drainage and healing. however, using a modified lich-gregoir technique, gaetano ciancio developed a technique which no longer requires ureteral stenting, avoiding many stent related complications. there is disagreement in surgical textbooks regarding which side of the recipient's pelvis to use in receiving the transplant. campbell's urology (2002) recommends placing the donor kidney in the recipient's contralateral side (i.e. a left sided kidney would be transplanted in the recipient's right side) to ensure the renal pelvis and ureter are anterior in the event that future surgeries are required. in an instance where there is doubt over whether there is enough space in the recipient's pelvis for the donor's kidney, the textbook recommends using the right side because the right side has a wider choice of arteries and veins for reconstruction. glen's urological surgery (2004) recommends putting the kidney in the contralateral side in all circumstances. no reason is explicitly put forth; however, one can assume the rationale is similar to that of campbell, i.e. to ensure that the renal pelvis and ureter are most anterior in the event that future surgical correction becomes necessary. smith's urology (2004) states that either side of the recipient's pelvis is acceptable; however the right vessels are 'more horizontal' with respect to each other and therefore easier to use in the anastomoses. it is unclear what is meant by the words 'more horizontal'. kidney-pancreas transplant