Organ substitutes and alternative forms of organ donor

 

In this section, we examine the most prominent proposals that have been made regarding ways in which greater numbers of organs could be acquired in order to resolve the supply problems that currently affect transplant systems worldwide. While some of the options available have been, or are likely to be, adopted in future due to the promise they hold, other possibilities are unlikely to ever be implemented, primarily due to ethical and medical concerns regarding their use. Nevertheless, the fact that these proposals have even been seriously discussed indicates the great significance with which the problems of alleviating the impediments to supply are being viewed.

 

i) Brain dead marginal donors

In the past decade, there has been considerable interest in expanding the size of the donor pool by relaxing the eligibility criteria by which brain dead patients are allowed to donate organs. While the obvious requirements that donors have functional organs and be free of infectious diseases will remain strictly enforced, it may be possible to use organs from donors excluded under conservative enrolment criteria, such as those falling outside of traditional age limits or who have medical conditions that may theoretically lead to an increased risk of organ failure in a recipient.

 

Various organs have been obtained from donors older than the age limits traditionally in force, with the result being that the maximum donation age has gradually crept up as transplant teams have gained experience and confidence from working with older organs:

 

1) As they retain their regenerative ability, maintain a degree of functional reserve and have access to a large supply of blood for replenishment, experiments have been conducted to determine the feasibility of using livers obtained from older than usual donors in younger recipients. Good results have been obtained in recipients, with the most notable case involving the normal functioning of the liver obtained from a 90 year old donor in a younger recipient 2 years after it had been grafted (when the study was concluded) [1];

 

2) In another study investigating pancreas transplants, it was concluded that “survival of pancreas grafts from marginal donors was not significantly different from grafts procured from non-marginal donors” [2]. Indeed, supposedly marginal donors may even have offered better pancreases than conventional donors, for although the total pancreas survival rate in the study was 83% after 23 months, for those donors over the age of 55 years, the graft survival rate during the relevant period was 92% [3];

 

3) Kidneys obtained from old donors have also been used with successful results. While kidney transplants from donors aged 65 years or less almost immediately gave recipients a greater expectation of survival than people on a waiting list, with those who had received kidneys from donors older than 65 years, the breakeven point in survival prospects was reached some time after the operation took place, although here too, these recipients too could expect to live longer than those on a waitlist [4]. What should be remembered with these figures is that people having transplants are always likely to have higher death rates in the short run than waitlisted patients due to risks they take concerning surgical and rejection complications, but once the graft takes hold and the underlying problems are resolved, kidney recipients will have a lower death rate compared to those on waitlists, even after transplant risks are considered [5].

 

At the other end of the age spectrum, the use of paediatric donors has also come under greater scrutiny, even though general policy is often to avoid extracting organs from children and infants. While efforts have usually focused on giving paediatric organs to other children, attention has also been given to determining the feasibility of giving these organs to adults. For example, paediatric kidneys are slowly becoming more acceptable for use in adult renal recipients, with methods constantly being revived in order to allow these small organs to grow in their new host while minimising the risks they are exposed to, such as being damaged following exposure to greater level of adult blood pressure [6]. Various studies have also been published indicating that provided they are carefully examined beforehand, organs acquired from brain dead donors who are obese or who died of various forms of poisoning can have similar graft survival rates to organs from normal cadaveric sources. In the case of poisoning, for example, while sensitive organs such as hearts and livers may need to be excluded from use, other organs can be successfully transplanted, with kidneys providing especially good results [7].

 

While organs obtained from marginal donors give statistically similar results to organs acquired from conventional sources, there are a couple of drawbacks to their use. First, they are more expensive to use, with their total cost being, on average, $10,000 greater than normal organs. This is because greater effort must be taken in carefully examining them for imperfections and potential hazards (especially if they come from poisoned donors), with an obviously greater degree of medical testing and labour time being required before they can be transplanted. In addition, as their inspection time is greater, the cold ischemia time in which they can deteriorate is also greater, which means that restoring these organs to optimal functional capacity may take longer time to achieve. Consequently, recipients are more likely to require hospitalisation and further dialysis before reaching the same level of health as they could expect with a normal cadaver organ, with obvious cost implications [8]. Secondly, it has been noted that “as the number of older donors has increased, the total number of discarded organs has also increased” [9]. This is to be expected, for as organs age and undergo constant use, they will be subject to a certain degree of disease exposure and general wear-and-tear, with the damage likely to be greater with organs that are subject to stress and which lack a capacity to regenerate themselves. For example, many older hearts may not be usable because they have been damaged by coronary artery disease, lungs may be unacceptable due to years of constant exposure to cigarette smoke and kidneys may be discarded due to damage caused by high blood pressure and other common modern maladies.

 

ii) Asystolic donors

One particular type of marginal donor that has elicited much interest as a potential source of organs has been the asystolic, or non-heart-beating, patient. Here, “the heart, and thus the circulation, of the donor has come to a standstill; this is in contrast to the heartbeating donor, in whom circulation is maintained until the last minute” [10]. While brain death is now the current standard by which death is determined, as we know, this was not always the case, with the earliest providers of cadaveric organs being donors who died according to the traditional concept of death through cessation of heartbeat. While these donors were no longer used following the change in death determination criteria, due to their apparent limited value, with the increasing problems in organ supply, the question of how to use them has been reconsidered.

 

The three main types of potential asystolic organ donors are people who are certified dead on arrival at hospitals, hospital patients forgoing life support and awaiting cardiac arrest, and patients who undergo unplanned cardiac arrests, where attempts at resuscitation have failed. As the donor’s heart is not circulating blood, the removal of organs must be performed as soon as possible in order to reduce the ischemia time, which may rule dead on arrival patients out of the donor pool as these patients may only arrive at a hospital too late for their organs to have any clinical value. Consequently, only patients who lose heart function within a hospital are likely to be suitable asystolic organ donors.

 

In order to acquire organs from these donors, some time may need to pass after the heart stops beating in order to ensure that these patients are truly dead and not merely in a swoon state. According to the proposal made by one transplant team, a patient’s death could be declared a mere two minutes after cardiopulmonary function has stopped completely, although a more conservative measure, with greater support, is to allow for a 10 minute period to pass before death is declared. This extended period is sufficient to ensure that a person definitely moves from being a patient to a corpse, with the chance of regaining heart function being totally eliminated so that surgeons are in no way responsible for removing organs from living people [11].

 

Different procedures must be followed by doctors depending on whether a patient’s death is planned or unplanned. The inherent advantage of extracting organs from people awaiting a planned cardiac arrest is that medical staff can obtain consent from the patient’s family as well as take whatever preparatory steps are required before removing life support facilities. Here, the main aim is to ensure that auto-resuscitation does not occur, with no measures being taken to resuscitate the patient. This is very different to the situation with unplanned cardiac arrests, as a medical team must do everything possible to save the patient, with cardiopulmonary resuscitation having to continue until all hope of auto-resuscitation is lost [12]. These requirements to continue resuscitation as well as wait for a set period of time after the heart has stopped beating will unfortunately hamper organ collection. While it may be possible to collect kidneys up to half an hour after the heart has stopped working, other kidneys, such as the liver and pancreas, rely greatly on a continuous flow of blood for their structural and functional integrity to be maintained, and will be irreversibly damaged within about 15 minutes of heart failure if measures are not taken to halt their destruction [13].

 

These extraction concerns have brought about a couple of ethical dilemmas concerning the amount of time that should be spent on attempting to resuscitate patients as well as whether it is advisable to insert an organ preservation solution into a potential donor before consent for donation has been requested or granted. While organs may be left in a better state if perfusion is undertaken immediately, such an action may be viewed by some people as a presumptive move showing that not enough was done to save the patient’s life, and could thus result in a refusal of consent. Finally, organs provided by non-heart-beating donors may give recipients statistically lower survival rates compared to the rates obtained using traditional donor organs, with recipients having a greater need for stronger immunosuppression treatment and dialysis than their normal counterparts too. For example, with kidneys, this difference in comparative survival rates is about 5%, although this value appears mainly in the first few months after transplantation, with survival after a couple of years being only around 2% short of the level normally achieved with brain dead cadaver donors [14]. Thus, from a general perspective, there is only a marginal decrease in the value of asystolic organs relative to conventional cadaver organs.

 

iii) Aborted foetuses

Controversial suggestions have been made that aborted foetuses could be used in the donor pool. With these donors, solid organs cannot be procured, for if the abortion is to be valid, it must be carried out in the first trimester of conception, when body parts are still not fully developed. However, tissue can be salvaged, with the main value of these foetuses lying in their potential ability to provide brain tissues and pancreatic cells for therapeutic purposes.

 

While the number of abortions performed annually means that potential supply is substantial, several key factors must be considered before foetuses are considered as a source of organs. From a technical perspective, much remains to be learned about extracting cells from these donors and ensuring that cellular transplants work successfully, so the question of using foetuses rests largely on a question of exploiting potential, rather than actual, benefits. In addition, the need to obtain fresh tissue means that foetuses obtained from spontaneous abortions cannot be used for this purpose, leaving only planned abortions to make up the donor pool. Reliance on planned abortions can lead to some awkward ethical problems revolving around the issue of abortion, with many well known points having been raised by the conflicting “right to life” and “freedom of choice” camps on this matter. It is merely sufficient to point out that if aborted tissue does have a value for transplantation purposes, then questions may have to be asked as to whether it is acceptable to allow resources obtained from one act that some people consider to be bad, i.e. abortion, to be used in the performance of an act believed to be good, i.e. a life-saving transplant [15]. In a way, this issue is similar to the problems that have arisen when deciding if the benefits obtained from Nazi medical research or animal testing is worth using, with the issue gaining an added dimension in that some women may, through coercion or financial incentives, continually conceive and abort new foetuses with the express purpose of supplying new “raw material” for transplantation.

 

iv) Anencephalic infants

In a small number of cases, newborn infants may have a neurological condition known as anencephaly. Here, the top of the skull is missing, with there being a complete lack of brain tissue, such as a cortex or nuclei, above the brain stem, although a degree of brain stem function remains, with these infants being able to perform basic functions such as breathe autonomously, cry and create facial expressions. Despite this, these infants are in a basic state of unconsciousness where they have no prospects of gaining “proper” human life, and will generally die within days of birth, usually due to respiratory failure [16].

 

Due to the general lack of brain matter and the certain prognosis of death, it has been implied that these infants should be relied upon as a new source of organ donors who could meet the needs of paediatric recipients in particular [17]. As a matter of policy, these infants would be declared dead on birth in order to permit the immediate retrieval of their organs, for once the total loss of their limited brain stem function has been formally diagnosed, it is often impossible to use their organs as they will have been severely damaged [18]. While some organs from these infants may have a limited value due to the ability to modify adult organs to suit young recipients, their organs could still be used in cases where no suitable adult organ is available or if infant recipients are unable to handle adult derived organs. In particular, they may be of great use as heart donors, where a size match is an important factor in ensuring the successful acceptance of a graft.

 

Despite their presumed value, using these infants as donors poses some possibly insurmountable problems. Due to their underdeveloped central nervous systems, the normal approach of ascertaining brain death may not work properly on these infants, for although they are not aware of their environment, they still have enough functioning neural matter at birth to be considered alive. As such, it would be illegal to remove their organs as they do not meet the full definition of a dead person, with surgeons that do so facing the possibility of being charged with murder. Ethically, declaring death at birth may also be a violation of the Hippocratic Oath, for in this situation, a declaration is motivated not by a desire to assist the dying patient, but rather by a wish to facilitate surgery and help other infants. As anencephalic infants are dying but not yet corpses, it is felt that it is only right to treat them with the same dignity and respect as accorded to people who die in other circumstances. Even if parents wish to have these infants declared dead to facilitate organ removal, ethicists have counselled against such a move, noting that if identical groups are treated differently simply for the purposes of collecting organs, a philosophical “slippery-slope” that could create more harm than benefit over the long run is likely to arise [19].

 

From a practical perspective, as this condition can be diagnosed in pregnancy, it is now possible to have an abortion in order to evade the birth of such infants. Consequently, this could lead to a noticeable fall in the number of anencephalic births, leading to a substantially lower reliance on such infants in the long term, thereby negating the effort spent on discussing whether they should be used or not. Despite the possibility of pre-birth elimination, fears have been expressed that some physicians may pressurise women to continue through the full term of pregnancy solely in order to acquire such an infant’s organs. Finally, if the general public does not fully comprehend why these infants are used as organ donors, a public outcry might erupt against what may be perceived to be the brutal exploitation of defenceless babies. The amount of adult organs that are then denied by traditional adult sources may be greater than the amount supplied by these infant donors, resulting in an obviously undesirable net decrease in donations [20].

 

v) Vegetative state patients

People who are in a persistent vegetative state lack consciousness and are thus incapable of rational comprehension or thought, which means that they have no upper brain function whatsoever. However, as their brainstem is intact and functions normally, regulating breathing and other body functions, they cannot be called brain dead in the clinical sense, for what neural matter that they do have allows them to function in a basic physical sense for many years [21].

 

Nonetheless, it has been suggested that people in this state should be considered brain dead in order to facilitate organ donation. This is because it is felt that as these people are not conscious of their environment, they are now mindless organisms rather than normal human beings, with their capacity to provide or benefit from any social interaction being essentially zero, especially since they are entirely dependent on others for survival and would, without assistance, die soon due to their retarded status [22]. Thus, from a purely utilitarian perspective, these patients are a drain on society, for although they contribute nothing to social welfare, they consume scarce resources that could be better employed elsewhere on more remediable patients. As such, if people do not leave their vegetative state after a set number of years have elapsed, then a more humane and cost-effective approach would be to remove all support from them (or, if they made provision for this while conscious, to euthenase them), with their organs then being extracted for use on others.

 

Opponents have argued that as some patients may, in rare cases, be able to leave this vegetative state and regain consciousness, it would be undesirable to give up hope and abandon them if there is a possibility, no matter how marginal, that they could regain their place in society. More generally, the issue of using these people as organ donors has renewed the debate about how to define the identity of a human being, with a reassessment taking place as to “what the intrinsic value of a person’s life is apart from any utilitarian value that the individual’s life has for society as a whole” [23]. As with anencephalic infants, there also remain questions regarding the measurement of brain death, for the fact that these individuals retain brain stem function for many years means that no matter how long they remain unconscious, they are still living beings and cannot be used as donors. Once again, the “slippery slope” argument applies, with fears being expressed that should anencephalic infants be used as donors, soon thereafter, pressure will be exerted to modify the concept of death to cover these comatose individuals as well [24].

 

vi) Alternative systems of organ donation

There are a couple of alternative non-price approaches to acquiring organs from human donors that are worth mentioning, although each uses a very narrow definition of altruism.

 

The first system worth considering is known as the solidarity model of altruistic organ donation. Here, “any person joining this program would agree to permit all usable organs to be taken for transplantation at the time of death. In return, he or she would have priority for receiving organs generated by the program that might be needed at a future date” [25]. While entry into this system is open at any period of time, it would be preferable if a candidate made a declaration of willingness to join such a programme before he is diagnosed as having end-stage organ failure, although if the person is later found to have no useful organs to offer, nothing will be done to penalise him for this [26]. Under such a system, if a potential organ recipient is not a member of this programme, he may receive an organ acquired by the programme only if there is no club member who needs this organ, as surplus organs will be transferred for allocation to patients on the general waiting list. If, however, an organ donated by a member of the programme becomes available and there are two competing recipients, one a member and the other a non-member, then, ceteris paribus, the member will receive the organ by virtue of his or her membership to the programme [27].

 

There are a few problems with this system of allocating organs on the basis of status that make it a less than desirable option of increasing organ supply. First, despite reassurances to the contrary, this system cannot be called a truly altruistic system of organ donation, as its underlying principle of self interest is contrary to the principal features of the organ procurement and allocation systems previously examined (that advocated an allocation of resources based on donor altruism). Second, there may be problems in enforcing organ removal from programme members, for although they themselves may support organ donation, their families may object to this system or oppose any organ removal, with the programme having only a small likelihood of exercising its contractual rights to organ removal due to the poor publicity that may arise. In this case, the programme will have suffered a loss, for while the dead member received an insurance benefit of knowing that he could benefit, if needed, from the provision of an organ, he will not end up paying his premium (in the form of organ removal) even though this was possible [28]. Finally, while this concept may sound feasible in theory, in practise it may fail if it becomes possible for a variety of competing programmes to be introduced, as there may be a conflict in deciding which agency should be able to receive a person’s organs if that person was a member of more than one programme at once.

 

The other option concerns the acquisition of organs from prisoners. Here, prisoners who have been sentenced to death may be given the option of donating their organs when they die in return for a delay in the date of execution or, in return for the provision of a kidney or bone marrow, they may have their original sentence commuted to one of life imprisonment without parole. While there are various ways of obtaining organs from executed prisoners, probably the most innovative proposal is to make the act of organ donation itself the method of execution. With this method, prisoners will first be anaesthetised and then have all life support removed while the body parts that would keep him alive are removed in a predefined sequence (with organs going to predefined patients that had already received pre-operative preparation).

 

In addition to being highly coercive of prisoners, several other factors make this controversial method of organ removal highly undesirable. First, knowledge that organs can be collected from a person may have legal implications on the course of justice if it can sway judges and juries into passing a death sentence on a person that might otherwise not have been considered had organ removal not been available. Second, it has been deemed highly unethical by medical bodies such as the American Medical Association, which have warned that it turns physicians into executioners rather than impartial providers of medical assistance. Third, it might also be a discriminatory option if some prisoners are medically unable to provide organs and are thus forced to assume whatever sentence is imposed upon them. Fourth, there are technical problems with this process, for not only are some execution methods inappropriate for the removal of organs, but there may also be difficulty in ascertaining when an executed prisoner becomes brain dead (in which case organ removal is impossible if it conflicts with the need to ascertain brain death) [29]. Finally, the most obvious flaw with this system is that it is really only suitable in the ever-dwindling number of countries where capital punishments remains in force.

 

vii) Xenotransplantation

Various attempts have been made to transfer animal organs into human recipients through the procedure of xenotransplantation, although all operations of this type soon failed due to the inevitable onset of immune rejection and associated complications. Despite this, research has continued, with a large number of medical institutes around the world working at developing efficient ways of overcoming the barriers that currently exist in using animal organs in humans.

 

The first recorded xenotransplants date back to the early 1900s, when various failed efforts were made to transplant animal kidneys into human recipients. In the 1960s and 1970s, efforts at xenotransplanting were renewed, this time involving the use of immunosuppression on human recipients. Here, hearts, kidneys and livers obtained from chimpanzees and baboons were grafted, yet despite the best efforts of surgeons, all these grafts were to fail, with some patients, especially heart recipients, dying due to these failures [30]. While attempts to engage in transplantation have since then been heavily regulated and subject to immense peer review, two recent procedures involving the failed placement of baboon organs in humans have been recorded. In 1984, in what was to be popularly known as the Baby Fae case, a heart from a 7 month baboon was given to an infant recipient [31], while a couple of years later, a baboon liver was placed in an HIV-positive patient whose survival prospects with a human liver were poor [32].

 

At present, most research in this field involves the performance of clinical trials where organs and tissues are transplanted between test animals of different species. In addition to identifying factors that cause rejection, efforts are being made to determine how these grafts respond to the application of different immunosuppressive therapies. Eventually, it is hoped that the results obtained from these animal trials can then be applied to humans, albeit with suitable modifications. Currently, two main categories of animal are in contention for use as possible sources of organs, each of which have their own particular attributes. 

 

1) Primates

It has long been recognised that in a genetic and evolutionary sense, primates are the closest animal relatives to the human race, which makes them obvious candidates as sources of organs. From a physiological point of view, they are similar to humans in that their organs have a similar design and function to ours, which suggests that they might not require much modification and are easily transplantable into human recipients. In addition, primates are resistant to certain diseases that may harm humans – for example, while humans with hepatitis face a high risk of autonomous re-infection with this disease if they get a new human liver [33], such a problem can be overcome with baboon livers, which are largely immune to this disease.

 

On the other hand, humans risk infection with primate diseases that can mutate into human specific forms. While the most notable example of such an adaptation is the simian immuno-deficiency virus (SIV), a closely related predecessor to HIV, similar cases may occur in future, with tests showing that other diseases that are benign in apes can be fatal if passed to humans [34]. Another flaw is that many primate organs, while physiologically similar, are not identical to human organs in terms of size, with their limited dimensions meaning that they can only be used in certain human recipients. Finally, many primates, such as chimpanzees, have a limited breeding capacity and are on the endangered list, so the supply of organs that they can provide has only limited potential for exploitation. Even then, should any primate type be available in large numbers, competing claims to use them for general scientific and medical research may be expressed, which may lead to excessive competition and greater costs in their use [35].

 

2) Pigs

Pigs constitute the other suggested source of xenotranplant suitable organs. Among large animals, pigs are not endangered and exist in large numbers, with their ability to breed with relative ease meaning that there are unlikely to be any difficulties in acquiring substantial stocks of their organs [36]. Being swine, there is also likely to be less public dissent with using their organs than there could be with primate organs, as many people may feel less uncomfortable at the extraction of organs from pigs since these animals are not too intimately related to humans [37]. Pigs also come in different sizes, which means that they can accommodate the organ requirements of a wide variety of recipients, from infants to large adults. Finally, while their organs are not as physiologically similar to those of humans as primate organs are, they are broadly compatible in function, with surgeons being able to adapt porcine organs before a transplant so that they can be made broadly compatible with their human host.

 

There are several disadvantages relating to the use of porcine organs, some of which have yet to be adequately addressed. Most importantly, pigs are distant to humans in immunological terms, with humans having a series of natural anti-pig antibodies that can result in organ rejection, even when powerful anti-rejection drugs are used. While efforts to isolate and neutralise pig genes that can trigger reactions, and develop new forms of immunosuppression, have been continuing, it is clear that “transplanting organs between species has identified an ever expanding list of incompatibilities” [38]. As a result, various firms involved in this industry have, for many years, continuously delayed the planned implementation of human trials with pig organs, as each new discovery leads to more new questions being raised, with no end concrete solutions being provided to their problems, no matter how much is learned [39]. Various physiological differences also mean that a porcine organ may not provide the same degree of function as the equivalent human organ, even if before use, with some of these organs, such as livers, having little possible medical value in human recipients [40]. Finally, there is the constant risk of infectious disease transmission, where pig diseases mutate and infect human recipients, spreading thereafter from the original organ recipients to the general population [41].

 

Xenotransplantion is a controversial area of research, with critics arguing that this procedure “is not about making sick people better. It’s about making big corporations richer” [42]. Here, it has been estimated that if xenotransplantation is actually introduced, by 2010, the market for solid organs could be worth as much as $6 billion dollars per annum [43], with the biggest beneficiaries likely to be the pharmaceutical firms that have financed much of the research in this field. The benefit to these firms is that is xenografting works, then all recipients of animal organs will have to undergo intensive immunosuppression using new drugs that have been designed solely for this purpose by these firms. Unfortunately, there appears to be lack of public debate on this issue, with governments being accused of ignoring the potential risks that could arise if an outbreak of transplant related infection took place and of trying to spring such activities on the public without an adequate assessment of the risks involved [44].

 

In addition to general clinical issues, xenotransplantation raises broader questions of whether or not it is acceptable to use animal organs in human recipients. Ethically, while society generally has no qualms about the killing of animals for the provision of food or, more tenuously, for reasons of sport or medical research, there may be some distress if it becomes publicly known that animals are being raised solely for the purpose of being killed in order to benefit dying humans. While opposition is most likely to be raised by anti-vivisectionists and environmental lobby groups, who may argue that such activities violate animal rights, it would be wise not to overlook the potential upheaval that may arise among the general public [45]. In addition to there being a general love of animals, as the ongoing debate concerning genetically modified foods show, there may also be a dislike of this science due to a lack of understanding and fear over what the outcome of such activities might be. The religious perspective on xenografts also remains unanswered. As the consumption of pigs is prohibited to Jews and Muslims, would it be acceptable for followers of these religions to have an entire pig organ working in them for the rest of their lives? Likewise, a similar question would have to be raised among Hindus and Buddhists, where the call to respect all forms of life may prevent the acceptance of any animal organs However, in the short run, if no alternative sources are made available, then the majority of people are likely adopt a pragmatic view that there is greater moral value in preserving a human life than there is in maintaining an animal life. In such a case, it is inevitable that animals will, given sufficient scientific progress, be used as a source of organs, although the day in which this actually occurs may be further away than even the most optimistic supporters of xenotransplantation may realise.  

 

viii) Artificial organs

Artificial organs are organs that are designed and manufactured by humans to either complement or substitute for organs in human patients that suffer from organ failure. While early substitutes were generally kept outside of the body, the capacity to transplant a substitute into a patient is slowly being developed.

 

The best known of these substitute organs is the dialysis machine, which is sometimes known as an artificial kidney, even though it is not actually transplanted into a patient with ESRD. There are two main types of dialysis, each of which ensure that waste products are filtered from blood on a regular basis. The first type is hemodialysis, were the veins of a patient are connected to a machine that drains dirty blood out of the body, filters the waste via a membrane with a special solution known as dialysate, and then returns the clean blood back to the patient [46]. In general, this form of treatment, which lasts for several hours per session, must be performed three times a week at a medical centre, although home based treatment is also possible. Advantages are that patients need no special training as they are regularly monitored by trained personnel, while disadvantages include the possibility of being infected with a disease left by previous users of the machine, pain, and inconvenience from having to travel to and be treated according to the schedule of the centre.

 

Alternatively, a kidney patient can undergo peritoneal dialysis, which uses a membrane in the patient’s own body as a filter. Here, dialysate is poured via a surgically implanted plastic tube into the patient’s abdomen, where filtering occurs internally, before being drained out of the body and replaced with a new solution a few of hours later. In general, replacement of this fluid, which takes about 30-45 minutes per session, must be performed 4-5 times per day, although a modified version of this therapy can be performed while asleep. While patients are free to undergo dialysis at their own convenience in their own homes and are less likely to suffer pain, disadvantages of this method are that infections passed through the connecting tube can harm patients plus it is a disruptive procedure as regular changes of dialysate are required.

 

In addition to the specific technical weaknesses associated with each of these dialysis methods, there are two major flaws that mean that dialysis is of limited value and can never be considered a proper substitute for a kidney transplant. First, from a medical perspective, dialysis itself can be detrimental to the heath of a person, with the wellbeing of a patient gradually deteriorating as the number of years spent receiving this therapy increases [47], with females and the aged having a greater mortality risk associated with being on such machines than males and the young [48]. Second, there are substantial financial expenses associated with the use of dialysis, with patients incurring significant indirect opportunity costs brought about by being unable to work while being dialysed (which amount to at least 10 hours per week in lost time). In addition, high direct medical costs are incurred that could be avoided if patients had a working kidney, with one observer estimating that “kidney transplantation costs only half as much as keeping a patient on haemodialysis for a year” [49]. While there is indeed a large sunk cost involved in the performance of transplant surgery, the ensuing marginal costs that a patient has thereafter from immuno-suppression are significantly lower than the respective marginal costs of dialysis. Although efforts to reduce these ongoing dialysis costs by reducing the amount of time actually spent on a machine can be undertaken, this is a short sighted option that is prejudicial in the long run to the patient’s health (even if it is presently undertaken more often than it was in the past). This is since there is a trade-off between the amount of time spent on dialysis and the probability of death brought about by a gradual yet definite build-up of waste products in the body, with patients who are consistently on dialysis for less than the recommended period of 3.5 hours per session having a relative mortality rate that is 17-118% higher than patients who exceed this time limit [50].   

 

Attempts have also been made to develop a working substitute of the heart, with both internal and external devices that circulate the blood being under design or in operation. While the best known of these systems is the heart-lung machine, this device cannot really be considered a proper artificial heart since its bulk and complexity means that it is only suitable for use in an operating theatre. To overcome problems in its use, smaller circulatory machines have been developed that can be connected to a patient, who is then able to move around with them as they can be fitted into what is essentially a specially adapted golf cart. While these machines are portable and can easily be inspected for blood clots and system failures, they still impose lifestyle restrictions on the patients, who must be permanently connected to them. Thus, they are often deemed merely to be temporary aids to a recipient until a human organ is available for transplantation.   

 

Rather, research into artificial hearts has concentrated on the development of autonomous devices that can be placed entirely in the chest cavity of a recipient without requiring any significant connections to outside devices. While the particular designs may differ in certain details, most artificial hearts contain two pumps that are equipped with a regulatory system in order to ensure that blood flow is adequately controlled. As with pacemakers, they contain an internal power source with an extremely long life span, while their construction is highly dependent on the utilisation of composite such as plastic composites and titanium, which are durable when exposed to adverse operating conditions.

 

Artificial hearts were first developed in the mid-1950s by scientists led by Willem Kolff, at a time when obtaining human hearts for transplantation seemed unlikely due to technical and ethical constraints. In 1969, the first transplant of an artificial heart was performed although, like subsequent operations, it was used as a temporary aid only in order to help the patient survive until a suitable human heart could be obtained. The first artificial heart intended for permanent use, which was designed by the American physician Robert Jarvick and designated the Jarvick-7, was placed into a human recipient in 1982, with the recipient surviving for 112 days with this organ. Over the course of the decade, several dozen other patients were to receive these artificial hearts, with the maximum recorded survival period with such a device standing at 620 days. However, in the late 1980s, market certification for this product was withdrawn by the FDA, which cited technical flaws in the manufacture and operation of these organs as well as dissatisfaction with the low quality of life offered to recipients as the reasons for its decision [51].

 

With the withdrawal of the Jarvick-7, several new artificial heart designs have been developed and, in some cases, used in clinical trials. One such product is the Abiomed artificial heart, which has been found in testing on calves to operate for periods of up to 100 days. While it is capable of being fitted into humans, the true potential of such a device is not yet known as clinical trials on human patients have still not taken place. An alternative product that may perform well is the Jarvick-2000, which is a redesigned and enhanced version of the earlier Jarvick-7 heart, which has already been proven to work in humans. In addition to having operated for almost 200 days in testing, another advantage of this device is that it is very small in size, which allows for it to be used in children as well, who previously had difficulty qualifying for artificial hearts [52]. Finally, we must mention the HeartMate ventricular assist device. This product is designed to ensure continued function of the left ventricle, which is a component of the heart whose failure is often the underlying cause for a person to receive a new heart. In its original form it has been used to provide support, sometimes for up to 500 days, to people waiting to receive proper hearts for transplantation, although an improved version, known as the HeartMate II, has been touted as a full substitute for patients who do not require an entire heart but only a working left ventricle [53].

 

In general, artificial hearts have major flaws that still need to be resolved, as the experience gained from the use of the initial Jarvick hearts demonstrated. First, the immune system can still be mobilised against these organs even though they have no human cells on their surface, as the recipient’s defences can still recognise that something foreign is present in the body [54]. Second, there is a high prospect of infection, for even though these organs may be produced in sterile conditions, it is still possible for commercially acquired components such as wires and pumps to carry undesired organisms. Third, internal bleeding appears to be commonplace, as the arteries may gradually lose their hold on the new graft, with blood seeping out over time due to deteriorating operating conditions. At other time, clotting of these organs can occur if blood and wastes build up along the passages of these organs. Finally, there is a significant cost factor, with the acquisition and transplantation of these organs being at least within the same price range as a normal heart transplant (coincidentally, by the late 1980s, over $250 million had been spent in the USA on developing artificial hearts with only limited success being recorded) [55].

 

In addition to these two main organs, work has also been proceeding on developing substitutes for other organs, most notably the liver and the lungs [56]. Despite several attempts to transplant these artificial organs, no notable success has been achieved, in part because these organs have failed due to reasons similar to those that have applied to the artificial hearts mentioned above. Consequently, further research will have to proceed for many years before any reliable substitute organs are developed.        

 

ix) Human cloning

One scientific concept that has long been dreamt of but only recently realised has been that of cloning, where genetically identical copies of a living creature could be created. While cloning has only been applied so far to animals, most famously Dolly the sheep, it is theoretically possible to extrapolate such work to make copies of human beings as well. In theory, cloning is ideal for transplantation as it can completely overcome any chance of an immune reaction taking place against a new organ. In essence, what happens here is that a person will have an autograft, or transplant of tissue that is a precise genetic match of his own tissue.

 

While much has been spoken of the merits of cloning humans for medical reasons, it appears that such an activity is unlikely to take place on a wide scale in the near future due to a range of problems. First, this science is still in its infancy, so the theoretical calculations regarding the feasibility of cloning have yet to be fully implemented in practise. Second, there are likely to be significant costs involved in such a procedure, which might make it too costly for widespread use, especially if all humans are to have an identical copy of themselves. Third, there is an element of time involved in growing organs that might render such a procedure worthless for people who suffer rapid organ failure and need a transplant very soon without having to wait for a copy of their failed organ to be created. Fourth, while scientists are getting better at identifying and eliminating genes that may harm a person, there is no guarantee that a cloned organ will not continue to have inherited defects that could harm the patient and lead to a repeat case of organ failure. Finally, there are major ethical concerns regarding this procedure, with the issues at stake being so great that society at large must be involved in discussing this matter, rather than only ethicists, clinicians and other “interested” parties. It is, however, suffice to ask that if it is unethical to buy an organ from a person who is acting according to his free will, what is the likelihood that it will also be even more unethical to involuntarily acquire an organ from a living creature that has been artificially created to act as a source of spare parts for another person?

 

In this section (and the previous one), we have comprehensively examined the factors that are involved in the collection and allocation of organs for transplant purposes. As was clearly demonstrated, there are major problems in all sectors of the field that significantly hamper the effectiveness of transplantation, with currently used methods being less than effective in their intended aim of making transplants more commonplace, to a large extent because no reliance is placed on market mechanisms. For example, in the sphere of procurement, the failure of traditional systems of organ donation have led to the introduction of new systems that exhibit only slight vestiges of altruistic motivations on the part of donors, while in the sphere of allocation, despite increasing efforts to ration the use of organs in the best manner possible, people are being placed on the wait lists faster than they are being removed, leading to an increasing backlog in people wanting a transplant. Various difficulties are also encountered in collecting organs from current donor sources, with most of those new sources of organs that have been proposed having only a limited scope for exploitation or being hampered by technological constraints that make their use in the near future seem unlikely. Thus, alternative ways of increasing the supply of organs need to be considered, with the following chapter looking specifically at how market structures, if properly used, can play a major role in making transplantation a more widely undertaken form of surgery than currently happens.

 

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