Stem Cells Converted Into Lung Tissue.


Lung transplant recipients have a relatively low 10 year survival rate of about 28%. Cellular rejection of the donor organ occurs about 90% of the time, which brings additional obstacles for the patient and doctors. This might be about to change, as functional lung tissue has been created from human stem cells. The research comes from Hans-Willem Snoeck from the Columbia Center for Translational Immunology and was published in the current edition of Nature Biotechnology.

A couple of years ago, Dr. Snoeck was able to convert stem cells into the precursor endoderm cells that can eventually differentiate into lung cells. This was done with human embryonic stem cells as well as human induced pluripotent stem cells, which involve a bit more work but are easier to come by. Those precursor cells were shown to actually differentiate into six different respiratory tissues, including the coveted type II alveolar cells. which facilitate gas exchange and produce surfactant.

Type 2 alveolar cells, also called pneumocytes, are responsible for producing surfactant, the compound that allows the lungs to remain inflated with air. These type II cells also aid in gas exchange and lung repair.

The lung tissue produced by stem cells could give researchers a unique perspective to study the tissue and learn more about how lung diseases originate. This could lead to better treatment options for lung diseases.

If treatments do not work and transplant becomes inevitable, physicians can use the patient’s own cells to provide a new disease-free organ. This eliminates both the potential for cellular rejection as well as the stress of waiting on the transplant list. To make a replacement lung, researchers would first remove the patient’s lung and decellularize it, leaving only a cartilaginous scaffold. The stem cells would then be used to coat the scaffold and regrow functional tissue to be put back into the patient.

Though it is a long way from getting implanted into a human body, these results are exciting. A patent has been filed by Columbia University for their technique of converting induced pluripotent stem cells into the functional tissue.

Macitentan and Morbidity and Mortality in Pulmonary Arterial Hypertension.


Current therapies for pulmonary arterial hypertension have been adopted on the basis of short-term trials with exercise capacity as the primary end point. We assessed the efficacy of macitentan, a new dual endothelin-receptor antagonist, using a primary end point of morbidity and mortality in a long-term trial.

METHODS

We randomly assigned patients with symptomatic pulmonary arterial hypertension to receive placebo once daily, macitentan at a once-daily dose of 3 mg, or macitentan at a once-daily dose of 10 mg. Stable use of oral or inhaled therapy for pulmonary arterial hypertension, other than endothelin-receptor antagonists, was allowed at study entry. The primary end point was the time from the initiation of treatment to the first occurrence of a composite end point of death, atrial septostomy, lung transplantation, initiation of treatment with intravenous or subcutaneous prostanoids, or worsening of pulmonary arterial hypertension.

RESULTS

A total of 250 patients were randomly assigned to placebo, 250 to the 3-mg macitentan dose, and 242 to the 10-mg macitentan dose. The primary end point occurred in 46.4%, 38.0%, and 31.4% of the patients in these groups, respectively. The hazard ratio for the 3-mg macitentan dose as compared with placebo was 0.70 (97.5% confidence interval [CI], 0.52 to 0.96; P=0.01), and the hazard ratio for the 10-mg macitentan dose as compared with placebo was 0.55 (97.5% CI, 0.39 to 0.76; P<0.001). Worsening of pulmonary arterial hypertension was the most frequent primary end-point event. The effect of macitentan on this end point was observed regardless of whether the patient was receiving therapy for pulmonary arterial hypertension at baseline. Adverse events more frequently associated with macitentan than with placebo were headache, nasopharyngitis, and anemia.

CONCLUSIONS

Macitentan significantly reduced morbidity and mortality among patients with pulmonary arterial hypertension in this event-driven study.

Source: NEJM

 

Rationing Lung Transplants — Procedural Fairness in Allocation and Appeals.


Organ transplantation requires explicit rationing and relies on public trust and altruism to sustain the organ supply. The well-publicized cases of two pediatric candidates for lung transplants have shaken the transplant community with emergency legal injunctions arguing that current lung-allocation policy is “arbitrary and capricious.” Although the resulting transplantation seemingly provided an uplifting conclusion to an emotional public debate, this precedent may open the floodgates to litigation from patients seeking to improve their chances of obtaining organs. These cases questioned the potential disadvantaging of children and the procedural fairness in lung allocation. But legal appeals exacerbate inequities and undercut public trust in the organ-transplantation system.

The controversy began when the parents of Sarah Murnaghan, a critically ill 10-year-old awaiting a lung transplant for cystic fibrosis, appealed through her physicians to the Organ Procurement and Transplantation Network (OPTN) for an exception to the policy that restricts lung-transplant candidates younger than 12 years to receiving organs from donors younger than 12. When this appeal failed, the Murnaghans appealed to the media, politicians, and finally a federal judge to grant access to the larger pool of lungs from adult donors. They argued that mistreatment of pediatric candidates for transplants would probably result in Sarah’s death. The merits of the case were never argued, since during the 10-day temporary injunction, Murnaghan received two lung transplants from adult donors. She has had serious complications, including pneumonia, and required a tracheostomy.

In 2005, to improve equity and efficiency, the OPTN switched from prioritization based on waiting time, a first-come–first-served approach that often prioritized less-urgent cases for organs, to an approach that incorporated consideration of urgency. After a 5-year review, the OPTN had developed a lung allocation score (LAS) using medical factors that predict disease severity and the likelihood of dying on the waiting list.1 Such scores were assigned only to patients 12 or older, because there were insufficient data to support their applicability to younger populations, owing to their different diagnoses and limited outcomes data. Thus, patients younger than 12 were excluded from consideration for adolescent and adult donors’ lungs (which are allocated according to the LAS and geography) and limited to use of pediatric donors’ lungs, which are allocated according to two priority levels (different degrees of urgency based on medical criteria) and geography.

The LAS policy has increased lung-transplantation rates and reduced mortality on the waiting list among older patients.2 Pediatric patients, however, continue to have higher waiting-list mortality and are less likely to receive transplants.

Unadjusted Relative Risk of Dying While on the Waiting List or Becoming Too Sick to Receive a Lung Transplant (Panel A) and Relative Likelihood of Receiving a Lung Transplant (Panel B), According to Age Group, September 12, 2010 to March 11, 2013.), despite wider geographic sharing of pediatric organs and the use of urgency levels — primarily because there are few pediatric donors. The supporters of the “under-12 rule” argue that it promotes equity and efficiency because of its aggregate benefits. They also cite the problematic discrepancy in lung size between adult donors and pediatric recipients. Furthermore, as a treatment for cystic fibrosis (the most common diagnosis among pediatric candidates for lung transplants), transplantation has been shown in several retrospective studies to have only marginal benefit, owing to improvements in medical management (although some data suggest otherwise).3 Lung transplantation in pediatric patients is also associated with high postoperative morbidity and mortality, largely because of the recipients’ underlying diagnoses.

Nevertheless, appeals to list children for adult organs have merit. First, designating age 12 as the cutoff arbitrarily disadvantages some children because age is a poor proxy for size. Younger patients who meet the size requirements and could benefit from adult lungs should be considered eligible. Second, in allocating other organs, we often prioritize children, partly on the basis of “fair innings” considerations (equalizing people’s chances of living until a given age) and partly because of the unique importance for physical and cognitive development that a transplant may confer. These arguments also apply to lung transplantation. Third, transplanting lungs into children is similarly efficient to doing so in adults, since their graft-survival rates are similar. Lobar resection can facilitate transplantation of adult lungs into smaller pediatric patients — also with similar results.4 Finally, given the scarcity of pediatric lung transplants, the data necessary for optimal validation of the LAS in this population may never be available. Without conclusive data, we should err on the side of inclusion, not exclusion from access to a broader supply of lifesaving organs. Currently, only 30 children in the United States await lung transplants, and only 11 of them are 6 to 11 years of age. The change that would occur by allowing these children access would most likely have little effect on nonpediatric candidates.

In response to objections that children are unfairly disadvantaged, the OPTN will review its lung-allocation policy during the next year and allow expedited appeals to an expert lung-allocation board in the interim. Candidates approved during this period will gain access to the full pool of lungs on the basis of the LAS and geographic location, while maintaining their pediatric priority.

Are the organ-allocation and appeals processes fair? Despite this case, we believe they are. An ethical framework that is gaining traction in health policy, Accountability for Reasonableness (A4R), offers an approach for achieving fairness and legitimacy in allocating health resources.5 A4R requires transparency about the objectives of and evidence for decisions, consensus about the relevance of rationales used in resource allocation, a process for reevaluating and revising criteria in light of new evidence, and procedures for enforcing these conditions in the deliberative process. This approach claims that a fair deliberative process results in outcomes that are acceptable to all.

A4R has limitations in Murnaghan’s case, including those resulting from the limited data regarding lung-transplantation outcomes in the pediatric population. But generally, organ allocation follows A4R’s tenets: it is public, transparent, revisable, enforceable, and open to appeals, and it incorporates key stakeholders. Organ-allocation algorithms seek to balance equity and efficiency. Committees comprising medical and ethics experts, transplant recipients and donors, and other key stakeholders meet in a predictable and transparent way. They deliberate and issue reports and policy recommendations that are opened to public comment. Policies are enforced and revised regularly on the basis of new evidence.

Transplant candidates and their families go to great lengths to obtain lifesaving treatment. They should be assured of fair process and, in cases of error or newly available information, allowed to appeal decisions. Appeals waged through federal courts and the court of public opinion, however, undermine fairness. Judicial appeals grant discretionary access to wealthier people, exacerbating disparities and discrimination. Moreover, appeals are inefficient, complicating allocation and leading to longer allocation times, poorer matches due to expansion of criteria, and greater difficulty in managing the waiting list. Lawsuits also inappropriately saddle courts with decisions about health policy. Finally, appeals reduce transparency and predictability, undermining the public perception of fairness, which could reduce donation rates.

Although the OPTN’s allowance of appeals to an expert panel is preferable to judicial appeals, it is problematic. Relying on physicians to appeal on behalf of candidates leaves patients of lower socioeconomic status, those less informed about their options, and those lacking advocates vulnerable to worse treatment. Physicians may also fear that accepting the responsibility of mounting appeals means assuming greater risk of poor outcomes and subsequent audits, which may also result in disparities.

To prevent unequal treatment, absent better data, we believe the OPTN should expand its policy to automatically assign an LAS to pediatric candidates and put those meeting the size and LAS criteria for adult and adolescent organs on the waiting list. Lung transplants should be allocated on the basis of the LAS and size match, with consideration of lobar resection for small recipients of adult lungs. Children should retain preference for lungs from pediatric donors.

Overall, we believe that the organ-allocation process is fundamentally fair, in part because of procedures in place to revise and modify allocation. It is because of this fair process that errors can be discovered and addressed. Our proposed changes would provide more lifesaving lungs to children; they would also provide useful data for the 1-year policy review and could ensure equal treatment for all children awaiting lung transplants.

 

Source: NEJM

 

 

Sarah Murnaghan gets lung transplant.


lung

A severely ill 10-year-old girl to whom a US judge granted a prime spot on the adult transplant list despite her youth has received a new set of lungs.

Sarah Murnaghan’s family said they were “thrilled” the six-hour surgery to implant adult lungs went smoothly and that she had done “extremely well”.

The family had challenged a US policy relegating under-12s to the bottom of the adult organ donation list.

Analysts have warned the judge’s decision set a dangerous precedent.

The Obama administration declined to intervene in Sarah’s case, arguing transplant policy should be made by doctors and scientists rather than the government.

Children under 12 have priority for paediatric lung donations, but far fewer paediatric lungs are donated than adult lungs.

‘Close to the end’

Sarah’s surgery began around 11:00 local time (15:00 GMT) on Wednesday in Philadelphia.

“Her doctors are very pleased with both her progress during the procedure and her prognosis for recovery,” the family said in a statement about seven hours later.

Her aunt Sharon Ruddock told reporters the lungs had been resized to fit her small body, but her recovery time would probably be extensive because the girl had been unconscious and breathing through a tube since Saturday as her condition deteriorated.

Complications from lung transplants can include rejection of the new lungs and infection.

 “Start Quote

It’s important that people understand that money, visibility, being photogenic… are factors that have to be kept to a minimum”

Dr Arthur Caplan,Bioethicist

Since Sarah’s case came to light, the national organisation that sets organ transplant policy has created a special appeal and review system for young patients.

About 30 children under the age of 11 are on the waiting list for a lung transplant, according to the Organ Procurement and Transplantation Network, out of a total of 1,650 potential lung recipients.

Last week, US District Judge Michael Baylson, who is independent of the Obama administration, ruled Sarah and another child at Children’s Hospital in Philadelphia, 11-year-old Javier Acosta, eligible for a better spot on the adult list.

He found that the US policy amounted to improper age discrimination.

Both children suffer from with cystic fibrosis, a chronic lung disease. Sarah’s condition had worsened significantly in the last 18 months, diminishing her lung capacity to 30%.

Last month she was admitted to the intensive care unit in hospital. Doctors told the Murnaghans that if Sarah were an adult, she would probably be at “the very top” of the lung transplant list.

Ms Ruddock said she was sure that had Sarah not been put on the adult list, “we would have lost her”.

“She was very close to the end,” she said.

US patients on organ waiting lists as of 12 June 2013

  • Kidney: 96,555
  • Pancreas: 1,180
  • Kidney/Pancreas: 2,089
  • Liver: 15,736
  • Intestine: 264
  • Heart: 3,506
  • Lung: 1,650
  • Heart/Lung: 46

Source: Organ Procurement and Transplantation Network

Some analysts warned the intervention of politicians and judges in the cases would set a dangerous precedent.

Dr Arthur Caplan, a bioethicist at New York University Langone Medical Center, said children fared worse than adults after lung transplants, one of the reasons for the existing policy.

“In general, the road to a transplant is still to let the system decide who will do best with scarce, lifesaving organs,” Dr Caplan said.

“And it’s important that people understand that money, visibility, being photogenic… are factors that have to be kept to a minimum if we’re going to get the best use out of the scarce supply of donated cadaver organs.”

Before Sarah, only one lung transplant from a donor older than 18 to a recipient younger than 12 had taken place in the US since 2007, according to US government data.

Source: BBC