不久前的一則新聞讓整個互聯網沸騰了——意大利神經外科醫生塞爾吉奧?卡納韋羅和中國哈爾濱醫科大學的任曉平醫生實施了世界首例成功的人類頭部移植手術（不過此次手術是在尸體上進行的，讓人不免聯想到弗蘭肯斯坦和他的怪物）。卡納韋羅稱，此次手術是成功的，它標志著完整的甚至是活體的頭部移植術可能“即將來臨了”，將來，由于種種疾病導致身體徹底損壞的病人或許將能等來一具新的身體。

不過近幾年來，卡納韋羅和任曉平的研究也為他們招來了不少懷疑聲浪，有不少學者既質疑換頭術在科學上是否可行，同時又對它的倫理影響提出擔憂。一些知名醫生甚至公然否定了“換頭術”的可行性。不過在各種批評聲中，據稱卡納韋羅和任曉平已經相繼在老鼠甚至猴子身上成功進行了頭部移植手術。

可以想見，要成功實施“換頭術”，必然會面臨很多重大阻礙。且不說要對頭部和頸部組織、神經細胞和脊髓進行橋接，確保新的身體“能用”，患者能不能挺過這樣一次耗時極長的手術也是個大問題，就算堅持下來了，腦袋和新身體會不會產生嚴重的排異反應也是個未知數。

拿目前極具開拓性且已經經過臨床驗證的生物工程為例——比如用基因技術操縱血癌患者的免疫細胞，將其變成抗癌細胞，然后重新注入患者體內。就是這種貌似理論上無懈可擊的技術，也會導致嚴重的毒副作用。而一個新的頭部和大腦會給身體帶來什么樣的長期影響，或者反過來，一具新身體會給頭部和大腦帶來什么樣的長期影響，也依然是未知數，結果是高度難以預測的。

神經科學家迪恩?伯內特就在一篇專欄文章里指出，卡納韋羅聲稱的一些以往的成功案例，其實與現實情況并不完全相符。比如那只實施了換頭術的猴子并沒有恢復真正的意識。

不過好消息是，器官移植領域最近確實也是喜訊不斷。比如最近世界上的首例換臉術宣告成功了。另外，未來人們很有可能能夠用上從轉基因的豬身上培養的器官。

作者：Sy Mukherjee

譯者：賈政景

The Internet was abuzz on Friday with news that famed—and controversial—Italian neurosurgeon Sergio Canavero and partner Dr. Xiaoping Ren of Harbin Medical University in China had performed the world’s first successful human head transplant(albeit with the major caveat that it was done on a corpse, raising comparisons to Dr. Frankenstein and his monster). Canavero claims the procedure was a success and a sign that full-on, presumably live head transplant surgeries are “imminent,” with the potential to help people who suffer from diseases which have caused their bodies to waste away.

But Canavero and Ren have prompted plenty of skepticism over the years from critics challenging both the scientific feasibility and ethical implications of head transplants, with some prominent doctors rejecting the notion that such a procedure is even possible. Canavero and Ren have played up reported successes in performing mice, monkey, and even rat head transplant operations.

There are, as you might imagine, a number of massive obstacles to successfully completing a head transplant surgery. Not only would head and neck tissue, nerve cells, and spinal cords have to be grafted together to create functional units; the patient going through such an extensive procedure would have to stay alive for long enough for it to work and then have to hope that his or her new body doesn’t reject the head of a biological stranger.

Considering that even groundbreaking, clinically proven biological re-engineering—like new genetic technologies which involve manipulating blood cancer patients’ immune cells into becoming cancer killers before re-inserting them into the body—can cause serious, toxic side effects, it’s an open question what the long-term effects of an entirely new head and brain would have on a body (or vic versa); such interactions would be highly unpredictable.

And as neuroscience Dr. Dean Burnett points out in a scathing op-ed, Canavero’s outsized claims about past successes may not exactly align with the realities of his accomplishments. For instance, Burnett notes, the monkey head transplant procedure didn’t result in a being with actual consciousness.

There have, however, been other kinds of recent milestones in the transplant space, including one of the most extensive face transplants ever done and the prospect of human organ donations from genetically modified pigs.