In May 2024, researchers from Fudan University in China announced that they had successfully developed a method using specialized inhibitors to freeze and preserve various brain organoids or human brain tissues, allowing for the "frozen" human brain to function normally after being taken out and thawed after 18 months. Currently, it is reported that hundreds of individuals worldwide have chosen to have their bodies frozen, hoping to be eventually "revived" in the future, but there are still no successful cases to date.

In 2018, scientists succeeded in reviving ancient roundworms that had been frozen for thousands of years in Siberia's permanently frozen ground. Additionally, some higher organisms, such as frogs, snakes, and bears, can hibernate and survive at extremely low metabolic rates. The North American wood frog, who spends nearly eight months hibernating every year, can survive being frozen for two months at -4°C.

But can humans be frozen for thousands of years and then revived, just like roundworms? At this point, it still seems unrealistic.

As warm-blooded animals, humans are unable to dehydrate as quickly as cold-blooded animals can, nor can they regulate the concentration of "cryoprotectants" in their bodies. A drop in human body temperature can lead to serious problems, making it impossible to minimize metabolic functions effectively. Even if the survival rate of cells after being "frozen and thawed" is as high as 99%, containing nearly 86 billion neurons, the human brain would still lose about 860 million neuronsand potentially impact its intricate functions. Therefore, judging from the current technology level, it is still not possible to "revitalize" human beings after they have been "frozen".

In May 2024, Dr. Shao Zhicheng and his team at Fudan University announced that they had successfully thawed and restored a human brain to normal vitality after freezing it for 18 months without damaging neuronal structures or affecting neural functions, through their new method "MEDY," which involves the usage of a selective inhibitor to preserve brain organoids and human brain tissues. This methodcan protect synaptic function and inhibit endoplasmic reticulum-mediated apoptotic pathways, allowing large-scale and reliable storage of a wide range of neurological organoids and living brain tissues.

Currently, the United States has two major human cryopreservation companies, which report that hundreds of individuals worldwide have been authorized to freeze their bodies in liquid nitrogen at -196°C, awaitingpotential future"revival." However, there have been no successful thawing cases to date. Most of the "frozen individuals" were elderly and some suffered from terminal illnesses, which often further reduces the likelihood of successful thawing.

In a word, to fulfill the aspiration to achieve human "revival" through "freezing and thawing", we still have a long way to go, in terms of technology, ethics, and legal considerations. (Source: ChinaScience Communication)

Source: Lingnan on the Cloud

中国成功实现“冰封人脑”18个月

2024年5月，中国复旦大学的研究人员宣布，已成功研究出一种使用特制的抑制剂来冷冻保存各种脑类器官或人类脑组织的方法，实现“冰封”人脑18个月后再取出解冻仍保持正常。据了解，目前全世界已有数百个人选择了将自己的身体冰冻起来，以期穿越至未来得以“复活”，但真正成功的案例依然为零。

2018年，科学家们将在西伯利亚永久冻土中冻结了数万年的古老线虫成功“复活”了。此外，即使是再高等一些的动物，比如蛙、蛇、熊之类，它们可以进行冬眠，也能在保持极低新陈代谢水平的状态下持续生命；还有一种生活在阿拉斯加地区的北美林蛙，每年冬眠将近8个月，在-4℃低温条件下冰冻2个月后解冻依然能够存活。

人类能不能也像线虫一样冰冻几万年后再解冻“复活”呢？目前来看，这还是不现实的。

人类作为恒温动物，无法像这些冷血变温动物一样快速脱水，也无法自然调节体内“冰冻保护剂”的浓度，人体体温一下降就会出问题，做不到将新陈代谢能力降至最低。而且，即便“冰冻-解冻”后的细胞存活率高达99%，但对于有将近860亿个神经元的人脑来说，也会有8.6亿个神经元死亡，这可能也会影响大脑精密运作的正常功能。所以，从目前的技术来看，仍无法令人类在“冷冻”后再“复活”。

2024年5月，我国复旦大学邵志成博士的研究团队宣布，他们成功用一种选择性抑制剂来冷冻保存各种脑类器官或人类脑组织的方法（MEDY），实现“冰封”人脑18个月后取出解冻并恢复正常活力，该方法不会破坏神经细胞结构或影响神经功能活动。这种方法能够实现保护突触功能并抑制内质网介导的凋亡途径，从而大规模且可靠地储存多种神经类器官和活体脑组织。

美国目前拥有两家最大的人体冷藏公司，据他们透露，目前全世界已有数百人授权将自己的身体冰封在-196℃液氮罐中，等待“复活”。但至今依然没有解冻成功的案例。而绝大多数“冷冻人”生前便已是老年人，有些还患有绝症和严重疾病，他们自身条件的不理想往往会进一步降低“解冻”的成功率。

人体“冰冻-解冻”实现“复活”的愿望，无论是在技术、伦理还是法律方面，都还有很远的路要走。（来源 科普中国）

文｜钱昱       
翻译｜洪婷
英文审校｜赵凡