Somatic Cell Nuclear Transfer (Cloning) Efficiency 

Compiled by Lesley Paterson, 
Scientific Secretary to Ian Wilmut, 
Gene Expression and Development, 
Roslin Institute
Aug01

The overall efficiency of cloning is typically between 0 and 3 % (number of live offspring as a percentage of the number of nuclear transferred oocytes), irrespective of the species, the donor cell type or technique. However, this is the cumulative result of losses at each stage of the cloning process, of which there are several. The following tables provide a summary of the data for each published report on somatic cell (fetal to adult cells) nuclear transfer to date (but does not include the cloning data from commercial companies). Where the appropriate data was made available, the table provides cloning efficiency for each major stage of the process:

% Embryos formed from NT Oocytes: % of morula and/or blastocysts formed from the number of NT (nuclear transfer) oocytes created. The number of NT oocytes is the number of oocytes that were enucleated and injected or fused with donor nuclei. In some reports, only the number of oocytes cultured, or surviving activation or injection is given and the figures are denoted by * with a corresponding footnote.

No. Implantation Sites: This column refers to mice only, and shows how many fetuses implanted into the uterus but were subsequently reabsorbed.

No. Pregnant (no. of recipients): This column is provided for each livestock species. The time of pregnancy confirmation is species dependent. (no. of recipients) refers to the total number of recipients to which embryos were transferred.

No. Pregnancies Lost: Refers to the number of recipients which had lost their fetuses at various stages throughout gestation.

Live Offspring (% embryos transferred): Refers to the number of live offspring born and is also given as a % of the total number of embryos transferred (normally morula or blastocyts, however some studies transfer 2, 4, and 8 cell).

No. Survived: Refers to the number of live offspring which survived.

CE: Cloning Efficiency is the number of live offspring expressed as a % of the total number of NT oocytes (this is generally the number of oocytes injected or fused but depending on the data this may refer to, for example, the number of oocytes surviving injection or the number cultured. Furthermore it should be noted that in many studies, not all of the embryos that developed are transferred to recipient females).

Ref: The subscript refers to the reference bibliography provided at the bottom of this article.

	% Embryos No. Live Offspring Donor Donor formed from Implantation (% embryos No. CE Cell Age Cell NT Oocytes Sites transferred) Survived Ref Adult Cumulus 31 22 1.3% (2.2%) 1 86 80 1.1 % (2.3%) 2 42.1% 7 4 5.8% (23.3%) 3 3 0 ? (0.7%) 4 46.0% 6 ? 0.9% (2.0%) 5 7 ? 2.3% (2.7%) 5 52.8% 9 ? 2.8% (5.3%) 5 . Fibroblasts 3 1 0.4% (1.1%) 6 21.8%* 134 5 5 0.3% (1.7%) 7 . Newborn Sertoli 23.6%** 235 16 11 0.9% (3.6%) 8 . Fetal Fibroblasts 16.4% 73 5 2 0.2% (1.1%) 9 Gonad 55.1% 6 5 1.5% (2.7%) 2 . No. of NT oocytes except * no. of surviving oocytes, ** no. oocytes cultured
	%Embryos No. Live Donor Donor formed Pregnant No. Offspring CE Cell Cell from NT (no. Pregnancies (% embryos No. Age Type Oocytes recipients) Lost transferred) survived Ref Adult Cumulus 39.4% 3 0 5 2 5% (3) (83.3%) 10 6 3 3 3 0.9% (34) (7.3%) 11 Oviduct 39.3% 2 0 3 2 2% (2) (75%) 10 4 2 2 2 0.8% (14) (11.8%) 11 Uterine 3 2 2 0 2% (7) (14.2%) 11 Granulosa 69.4% 10 10 1.8% (10%) 12 2 1 0.5% (2.7%) 13 Mammary 16.1% 2 1 1 1 0.4% Gland (2) (25%) 14 16.8% 4 2 2 2 0.7% (31) (4.4%) 15 . Muscle 14.2% 8 4 4 1 0.8% (20) (15.3%) 16 . Fibroblasts 53.3% 5 4 1 0 1.1% (12) (6.25%) 14 1 0 1 0 0.6% (5) (16.7%) 17 11.9% 15 9 6 4 0.5% (36) (7.4%) 18 16.5% 6 5 1 1 0.3% (11) (3.8%) 19 24 12 12 4 2.8% (48) (20.3%) 11 31.1% 6 4 2 1 0.8% (37) (4.6%) 15 . New- Fibroblasts 5 3 2 2 1.1% born (13) (12.5%) 11 . Liver 4 2 2 1 1.3% (8) (20%) 11 . Testis 1 1 0 / 0% (1) 11 . Fetal Fibroblasts 4.6% 17 11 6 6 0.3% (32) (7.6%) 20 22.7% 8 7 2 1 0.4% (12) (8.7%) 21 11.7% 5 5 0 / 0% (12) 19 2 1 1 1 3.8% (6) (14.3%) 11 . Germ Cells 22.7% 8 7 1 0 0.2% (17) (3.1%) 22 Liver 1 1 0 / 0% (3) 11 .
	%Embryos No. Live Donor Donor formed Pregnant No. Offspring CE Cell Cell from NT (no. Pregnancies (% embryos No. Age Type Oocytes recipients) Lost transferred) survived Ref Adult Granulosa 2 1 5 5 0.1% (10) (0.8%) 23 . Fetal Fibroblasts 1 1 0.2% (0.9%) 24 . Somatic 4 4 0.5% (0.7%) 25 .
	%Embryos No. Live Donor Donor formed Pregnant No. Offspring CE Cell Cell from NT (no. Pregnancies (% embryos No. Age Type Oocytes recipients) Lost transferred) survived Ref Adult Mammary 10.5% 1 0 1 1 0.4% Gland (13) (3.4%) 26 . Fetal Fibroblasts 27.3% 5 2 3 2 1.7% (16) (7.5%) 26 13.6% 11 2 7 5 1.4% (24) (10.4%) 27 39 31 4 0 ? (78) (3.3%) 28 .
	%Embryos No. Live Donor Donor formed Pregnant No. Offspring CE Cell Cell from NT (no. Pregnancies (% embryos No. Age Type Oocytes recipients) Lost transferred) survived Ref Adult Granulosa 4 7 6 ? (9) (7.3%) 29 . Cumulus 2 0 3 1 0.7% (29) (1.3%) 30 . Fetal Fibroblasts 5 0 6 3 1.6% (13) (6.2%) 31 . Somatic 3 3 1.1% (2.7%) 32 .

* no. oocytes surviving NT

REFERENCES

1. Wakayama et al. (1998). Nature, 394, 369-374;

2. Wakayama and Yanagimachi (2001). Molecular Reproduction and Development, 58, 376-383;

3. Baguisi and Overstrom (2000). Theriogenology, 6, 53, 209;

4. Zhou et al (2000). Cloning, 2, 35-43.

5. Wakayama and Yanagimachi (2001). Reproduction, 122, 49-60.

6. Wakayama and Yanagimachi (1999). Nature Genetics, 22, 127-128.

7. Ogura et al (2000). Molecular Reproduction and Development 57, 55-59.

8. Ogura et al (2000). Biology of Reproduction, 62, 1579-1584.

9. Ono et al (2001). Biology of Reproduction, 64, 44-50.

10. Kato et al (1998). Science, 282, 2095- 2098.

11. Kato et al (2000). Journal of Reproduction and Fertility, 120, 231-237. 12. Wells et al (1999). Biology of Reproduction, 60, 996-1005.

13. Wells et al (1999). Theriogenology 51, 217.

14. Zakhartchenko et al (1999). Molecular Reproduction and Development, 54, 264-272.

15. Kishi et al (2000). Theriogenology, 54, 675-684.

16. Shiga et al (1999). Theriogenology, 52, 527-535.

17. Renard et al (1999). Lancet, 353, 1489-1491.

18. Kubota et al (2000). PNAS, 97, 990-995.

19. Hill et al (2000). Biology of Reproduction, 62, 1135-1140.

20. Lanza et al (2000). Science, 288, 665-669.

21. Zakhartchenko et al (1999). Journal of Reproduction and Fertility, 115, 325-331.

22. Zakhartchenko et al (1999). Molecular Reproduction and Development, 52, 421-426.

23. Polejaeva et al (2000). Nature, 407, 86-90.

24. Onishi et al (2000). Science, 289, 1188-1190.

25. Betthauser et al (2000). Nature Biotechnology, 18, 10551059.

26. Wilmut et al (1997). Nature, 385, 810-813.

27. Schnieke et al (1997), Science, 278, 2130-2133.

28. Denning et al (2001), Nature Biotechnology, 19, 559-62.

29. Keefer et al (2000). Biology of Reproduction, 62, 218.

30. Zou et al (2001), Cloning, 2, 3544.

31. Keefer et al (2001), Biology of Reproduction, 64, 849-856.

32. Baguishi et al (1999). Nature Biotechnology, 17, 456461. 

Dolly: A report on January 4th 2002

Roslin Institute News Note 4jan02

A few weeks ago we noticed that Dolly was becoming lame in her left hind leg and she was examined by Veterinary Surgeons at the University of Edinburgh. X-rays confirmed that she has arthritis in the hip and knee of that leg. Her condition is being treated effectively with anti-inflammatory drugs and is being closely monitored by Institute vets.

"Arthritis in sheep is quite common, but it is comparatively unusual for it to be in these joints. The elbow is the most commonly affected joint," said Tim King, the Veterinary surgeon on the project. "Dolly is now five and a half years old and was the first animal to be cloned from an adult cell. In all other ways Dolly is in good health and she has produced six healthy lambs."

Professor Ian Wilmut, the leader of the team that cloned Dolly, stated, "It is not possible to know if her condition is in any way a result of her being a clone. However, this occurrence emphasises the need to monitor the health of a considerable number of clones throughout their expected life span to discover if any conditions normally associated with age develop in unusually young animals."

A group of 24 cloned calves is being monitored in the United States. In a recent publication Advanced Cell Technology reported that these clones are clones are healthy, however, the oldest calf in the study is only 4 years old.

Ian Wilmut
Tim King