Zhong Zhong and Hua Hua

Zhong Zhong (Chinese: 中中; pinyin: Zhōng Zhōng, born 27 November 2017) and Hua Hua (Chinese: 华华; pinyin: Huá Huá, born 5 December 2017) are a pair of identical crab-eating macaques (also referred to as cynomolgus monkeys) that were created through somatic cell nuclear transfer (SCNT), the same cloning technique that produced Dolly the sheep in 1996. They are the first cloned primates produced by this technique. Unlike previous attempts to clone monkeys, the donated nuclei came from fetal cells, not embryonic cells.[1][2][3][4][5] The primates were born from two independent surrogate pregnancies at the Institute of Neuroscience of the Chinese Academy of Sciences in Shanghai.[6]

Zhong Zhong and Hua Hua
中中 / 华华

Zhong Zhong and Hua Hua at nearly 2 months of age
Species	Macaca fascicularis
Sex	Female
Born	Zhong Zhong 27 November 2017 (age 3 years) Hua Hua 5 December 2017 (age 3 years) Shanghai, China
Nation from	China
Known for	First primates to be cloned using the somatic cell nuclear transfer method

Background

Since scientists produced the first cloned mammal Dolly the sheep in 1996 using the somatic cell nuclear transfer (SCNT) technique, 23 mammalian species have been successfully cloned, including cattle, cats, dogs, horses and rats.[4] Using this technique for primates had never been successful and no pregnancy had lasted more than 80 days. The main difficulty was likely the proper programming of the transferred nuclei to support the growth of the embryo.[3] Tetra (born October 1999), a female rhesus macaque, was created by a team led by Gerald Schatten of the Oregon National Primate Research Center using a different technique, called "embryo splitting". She is the first "cloned" primate by artificial twinning, which is a much less complex procedure than the DNA transfer used for the creation of Zhong Zhong and Hua Hua.[7]

In January 2019, scientists in China reported the creation of five identical cloned gene-edited monkeys, using the same cloning technique that was used with Zhong Zhong and Hua Hua, and the same gene-editing CRISPR-Cas9 technique allegedly used by He Jiankui in creating the first ever gene-modified human babies Lulu and Nana. The monkey clones were made in order to study several medical diseases.[8][9]

Process

Zhong Zhong and Hua Hua were produced by scientists from the Institute of Neuroscience of the Chinese Academy of Sciences in Shanghai, led by Qiang Sun and Muming Poo.[1] They extracted nuclei from the fibroblasts of an aborted fetal monkey (a crab-eating macaque or Macaca fascicularis) and inserted them into egg cells (ova) that had had their own nuclei removed.[1] The team used two enzymes to erase the epigenetic memory of the transferred nuclei of being somatic cells. This crucial reprogramming step allowed the researchers to overcome the main obstacle that had precluded the successful cloning of primates until now.[3] They then placed 21 of these ova into surrogate mother monkeys, resulting in six pregnancies, two of which produced living animals.[1] The monkeys were named Zhong Zhong and Hua Hua, a reference to Zhonghua (Chinese: 中华, a Chinese name for China). Although the success rate was still low, the methods could be improved to increase survival rate in the future.[3] By comparison, the Scotland-based team that created Dolly the sheep in 1996 required 277 attempts and produced only one lamb.[10]

The scientists also attempted to clone macaques using nuclei from adult donors, which is much more difficult. They implanted 42 surrogates, resulting in 22 pregnancies, but there were still only two infant macaques, and they died soon after birth.[1]

Implications

According to Mu-ming Poo, the principal significance of this event is that it could be used to create genetically identical monkeys for use in animal experiments. Crab-eating macaques are already an established model organism for studies of atherosclerosis,[11] though Poo chose to emphasize neuroscience, naming Parkinson's disease and Alzheimer's disease when he appeared on the radio news program All Things Considered in January 2018.[12]

The birth of the two cloned primates also raised concerns from bioethicists. Insoo Hyun of Case Western Reserve University questioned whether this meant that human cloning would be next. Poo told All Things Considered that "Technically speaking one can clone human[s] ... But we're not going to do it. There's absolutely no plan to do anything on humans."[12]

See also

• List of animals that have been cloned

References

1. Liu, Zhen; Cai, Yijun; Wang, Yan; Nie, Yanhong; Zhang, Chenchen; Xu, Yuting; Zhang, Xiaotong; Lu, Yong; Wang, Zhanyang; Poo, Muming; Sun, Qiang (24 January 2018). "Cloning of Macaque Monkeys by Somatic Cell Nuclear Transfer". Cell. 172 (4): 881–887.e7. doi:10.1016/j.cell.2018.01.020. PMID 29395327. Retrieved 24 January 2018.
2. Scholarly sources:
   • Normile, Dennis (24 January 2018). "These monkey twins are the first primate clones made by the method that developed Dolly". Science. doi:10.1126/science.aat1066. Retrieved 24 January 2018.
   • Cyranoski, David (24 January 2018). "First monkeys cloned with technique that made Dolly the sheep – Chinese scientists create cloned primates that could revolutionize studies of human disease". Nature. 553 (7689): 387–388. doi:10.1038/d41586-018-01027-z. PMID 29368720.
3. Maron, Dina Fine (24 January 2018). "First Primate Clones Produced Using the "Dolly" Method – The success with monkeys could ignite new ethical debates and medical research". Scientific American. Retrieved 24 January 2018.
4. Kolata, Gina (24 January 2018). "Yes, They've Cloned Monkeys in China. That Doesn't Mean You're Next". The New York Times. Retrieved 25 January 2018.
5. Popular sources:
   • Briggs, Helen (24 January 2018). "First monkey clones created in Chinese laboratory". BBC News. Retrieved 24 January 2018.
   • Hotz, Robert Lee (24 January 2018). "China Breaks a Cloning Barrier: Primates – The development heralds the possibility of genetically engineered primates for drug testing, gene editing and brain research". The Wall Street Journal. Retrieved 24 January 2018.
6. Staff (24 January 2018). "Meet Zhong Zhong and Hua Hua, the first monkey clones produced by method that made Dolly". Science Daily. Cell Press. Retrieved 25 January 2018.
7. White-house, David (14 January 2000). "Scientists 'clone' monkey". BBC News. Retrieved 24 January 2018.
8. Science China Press (23 January 2019). "Gene-edited disease monkeys cloned in China". EurekAlert!. Retrieved 24 January 2019.
9. Mandelbaum, Ryan F. (23 January 2019). "China's Latest Cloned-Monkey Experiment Is an Ethical Mess". Gizmodo. Retrieved 24 January 2019.
10. Genetic Science Learning Center. "The History of Cloning". University of Utah. Retrieved 24 January 2018.
11. Phillips, Kimberley A.; Bales, Karen L.; Capitanio, John P.; Conley, Alan; Czoty, Paul W.; ‘t Hart, Bert A.; Hopkins, William D.; Hu, Shiu-Lok; Miller, Lisa A.; Nader, Michael A.; Nathanielsz, Peter W.; Rogers, Jeffrey; Shively, Carol A.; Voytko, Mary Lou (10 April 2014). "Why Primate Models Matter". American Journal of Primatology. 76 (9): 801–27. doi:10.1002/ajp.22281. PMC 4145602. PMID 24723482.
12. • Rob Stein (24 January 2018). "Chinese Scientists Clone Monkeys Using Method That Created Dolly The Sheep". National Public Radio. Retrieved 24 January 2018.

External links

• "Gallery of cloned animals". Archived from the original on 12 March 2016.
• "Researchers clone monkey by splitting embryo".