在一次医疗急救中，医生将一颗猪心移植到一名患者体内，为挽救他的生命做最后的努力。马里兰州一家医院周一表示，在这一高度实验性的手术三天后，他的情况良好。

虽然现在知道手术是否真的有效还为时过早，但这标志着长达几十年的探索有一天使用动物器官进行拯救生命的移植迈出了一步。马里兰大学医学中心的医生说，移植表明，来自转基因动物的心脏可以在人体内发挥作用，而不会立即产生排斥反应。

57岁的马里兰州杂工大卫·班尼特(David Bennett)告诉美联社，病人知道不能保证实验会成功，但他快死了，没有资格接受人类心脏移植，没有其他选择。

“要么死，要么做这个移植。我想活下去。我知道这是瞎猜，但这是我最后的选择，”根据马里兰大学医学院提供的一份声明，班尼特在手术前一天说。

周一，班尼特在与心肺机相连的情况下自主呼吸，以帮助他的新心脏。接下来的几周将是至关重要的，因为班尼特从手术中恢复过来，医生会仔细监测他的心脏情况。

捐献用于移植的人体器官严重短缺，这促使科学家们试图找出如何使用动物器官来替代。据负责监督美国移植系统的联合器官共享网络称，去年，美国的心脏移植数量刚刚超过3800例，创下历史新高。

马里兰大学动物对人类移植项目的科学负责人穆罕默德·莫休丁博士说:“如果这种方法奏效，将会有源源不断的器官供应给正在遭受痛苦的患者。

但是之前这种移植——或者说异种移植——的尝试失败了，主要是因为患者的身体迅速排斥了动物器官。值得注意的是，在1984年，婴儿Fae，一个垂死的婴儿，带着狒狒的心脏生活了21天。

这次的不同之处在于:马里兰州的外科医生使用了一颗经过基因编辑的猪的心脏，去除了其细胞中的一种糖，这种糖导致了超快的器官排斥反应。几家生物技术公司正在开发用于人体移植的猪器官;用于周五手术的那台来自联合治疗公司的子公司Revivicor。

“我认为你可以把它描述为一个分水岭事件，”UNOS首席医疗官大卫·克拉森博士在谈到马里兰的移植时说。

尽管如此，克拉森警告说，这只是探索这一次异种移植是否最终可行的第一步。

负责监督此类实验的美国食品药品监督管理局允许在所谓的“同情使用”紧急授权下进行手术，这种授权在患者处于危及生命的情况下没有其他选择时可用。

黑斯廷斯中心的研究学者卡伦·马斯克(Karen Maschke)说，在将移植扩大到更多患者之前，分享从这次移植中收集的数据至关重要。在美国国立卫生研究院的资助下，她正在帮助为首次临床试验制定伦理和政策建议。

“在没有这些信息的情况下匆忙进行动物对人类的移植是不明智的，”马斯克说。

多年来，科学家已经从灵长类动物变成了猪，对它们的基因进行修补。

就在去年9月，纽约的研究人员进行了一项实验，表明这种猪可能为动物对人类的移植提供希望。医生们暂时将猪的肾脏附着在一具已死亡的人体上，看着它开始工作。

在next朗根健康中心领导这项工作的罗伯特·蒙哥马利博士说，马里兰的移植使他们的实验更上一层楼。

“这是一个真正了不起的突破，”他在一份声明中说。“作为一名心脏移植接受者，我自己也患有遗传性心脏疾病，听到这个消息以及它给我的家人和其他患者带来的希望，我感到非常激动，他们最终会被这一突破所拯救。”

上周五的手术在巴尔的摩医院进行了7个小时。实施手术的巴特利·格里菲斯医生说，病人的情况——心力衰竭和心跳不规则——使他没有资格接受人类心脏移植或心脏泵。

在向班尼特提供这一选择之前，格里菲斯已经在五年内将猪心移植到大约50只狒狒身上。

“和这位先生在一起，我们每天都学到很多东西，”格里菲斯说。“到目前为止，我们对继续前进的决定感到高兴。他也是:今天脸上笑容灿烂。”

猪心脏瓣膜也已经在人类身上成功使用了几十年，班尼特的儿子说他的父亲大约十年前就收到了一个。

至于心脏移植，“他意识到所做工作的重要性，他真的意识到了它的重要性，”小大卫·班尼特说。“他活不下去了，或者可以撑一天，或者可以撑几天。我的意思是，我们现在处于未知之中。”

In 1st, US surgeons transplant pig heart into human patient

In a medical first, doctors transplanted a pig heart into a patient in a last-ditch effort to save his life and a Maryland hospital said Monday that he's doing well three days after the highly experimental surgery.

While it’s too soon to know if the operation really will work, it marks a step in the decades-long quest to one day use animal organs for life-saving transplants. Doctors at the University of Maryland Medical Center say the transplant showed that a heart from a genetically modified animal can function in the human body without immediate rejection.

The patient, David Bennett, a 57-year-old Maryland handyman, knew there was no guarantee the experiment would work but he was dying, ineligible for a human heart transplant and had no other option, his son told The Associated Press.

“It was either die or do this transplant. I want to live. I know it’s a shot in the dark, but it’s my last choice,” Bennett said a day before the surgery, according to a statement provided by the University of Maryland School of Medicine.

On Monday, Bennett was breathing on his own while still connected to a heart-lung machine to help his new heart. The next few weeks will be critical as Bennett recovers from the surgery and doctors carefully monitor how his heart is faring.

There’s a huge shortage of human organs donated for transplant, driving scientists to try to figure out how to use animal organs instead. Last year, there were just over 3,800 heart transplants in the U.S., a record number, according to the United Network for Organ Sharing, which oversees the nation’s transplant system.

"If this works, there will be an endless supply of these organs for patients who are suffering,” said Dr. Muhammad Mohiuddin, scientific director of the Maryland university's animal-to-human transplant program.

But prior attempts at such transplants — or xenotransplantation — have failed, largely because patients’ bodies rapidly rejected the animal organ. Notably, in 1984, Baby Fae, a dying infant, lived 21 days with a baboon heart.

The difference this time: The Maryland surgeons used a heart from a pig that had undergone gene-editing to remove a sugar in its cells that’s responsible for that hyper-fast organ rejection. Several biotech companies are developing pig organs for human transplant; the one used for Friday's operation came from Revivicor, a subsidiary of United Therapeutics.

“I think you can characterize it as a watershed event,” Dr. David Klassen, UNOS’ chief medical officer, said of the Maryland transplant.

Still, Klassen cautioned that it’s only a first tentative step into exploring whether this time around, xenotransplantation might finally work.

The Food and Drug Administration, which oversees such experiments, allowed the surgery under what’s called a “compassionate use” emergency authorization, available when a patient with a life-threatening condition has no other options.

It will be crucial to share the data gathered from this transplant before extending it to more patients, said Karen Maschke, a research scholar at the Hastings Center, who is helping develop ethics and policy recommendations for the first clinical trials under a grant from the National Institutes of Health.

“Rushing into animal-to-human transplants without this information would not be advisable,” Maschke said.

Over the years, scientists have turned from primates to pigs, tinkering with their genes.

Just last September, researchers in New York performed an experiment suggesting these kinds of pigs might offer promise for animal-to-human transplants. Doctors temporarily attached a pig’s kidney to a deceased human body and watched it begin to work.

The Maryland transplant takes their experiment to the next level, said Dr. Robert Montgomery, who led that work at NYU Langone Health.

“This is a truly remarkable breakthrough," he said in a statement. "As a heart transplant recipient, myself with a genetic heart disorder, I am thrilled by this news and the hope it gives to my family and other patients who will eventually be saved by this breakthrough.”

The surgery last Friday took seven hours at the Baltimore hospital. Dr. Bartley Griffith, who performed the surgery, said the patient’s condition — heart failure and an irregular heartbeat — made him ineligible for a human heart transplant or a heart pump.

Griffith had transplanted pig hearts into about 50 baboons over five years, before offering the option to Bennett.

“We’re learning a lot every day with this gentleman,” Griffith said. “And so far, we’re happy with our decision to move forward. And he is as well: Big smile on his face today.”

Pig heart valves also have been used successfully for decades in humans, and Bennett’s son said his father had received one about a decade ago.

As for the heart transplant, “He realizes the magnitude of what was done and he really realizes the importance of it,” David Bennett Jr. said. “He could not live, or he could last a day, or he could last a couple of days. I mean, we’re in the unknown at this point.”