Yoshiki Sasai

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Yoshiki Sasai
Yoshiki Sasai, circa 2012.jpg
Yoshiki Sasai, circa 2012
Born5 March 1962
Hyogo, Japan
Died5 August 2014(2014-08-05) (aged 52)
Kobe, Hyogo, Japan
Alma materKyoto University
AwardsOsaka Science Prize
Inoue Prize for Science
Scientific career
Doctoral advisorShigetada Nakanishi

Yoshiki Sasai (笹井 芳樹, Sasai Yoshiki, 5 March 1962 – 5 August 2014) was a stem cell biologist. He developed methods to guide human embryonic stem cells (hESCs) into forming brain cortex, eyes (optic cups), and other organs in tissue culture. Sasai worked at the Riken Center for Developmental Biology (CDB) in Kobe, and was Director of the Laboratory for Organogenesis and Neurogenesis. Following his involvement in the 2014 STAP cell controversy, Sasai was found at Riken dead from an apparent suicide.

Early life and education[edit]

Yoshiki Sasai was born in 1962 in Hyogo, Japan. He received his medical degree from Kyoto University's School of Medicine in 1986. In 1993 Sasai was awarded a PhD from the Kyoto University School of Medicine, and served a residency at Kobe Municipal General Hospital.


Sasai worked as a research fellow at Edward M. De Robertis's laboratory at UCLA School of Medicine until 1996.[1] Sasai became an associate professor at Kyoto University in 1996, and a full professor in 1998. In 2003 he moved to the RIKEN Center for Developmental Biology as Director of the organogenesis and neurogenesis group.[2]

Sasai was known for developing methods to grow stem cells into organ-like structures.[3][4][5][6][7][8][9][10][11] In 2012, Sasai became the first stem cell researcher to grow an optic cup from human cells.[12]

STAP controversy[edit]

In 2014 Sasai was a co-author on two papers published in Nature, shortly thereafter retracted, that described stimulus-triggered acquisition of pluripotency or "STAP" cells.[13][14][15]

A subsequent investigation by Riken found that Sasai's co-author, Haruko Obokata, had committed scientific misconduct in the STAP cell experiments, and criticized Sasai for inadequate supervision of Obokata.[16][17][18] In response to the Riken investigation, Sasai described himself as "overwhelmed with shame",[19] and following a month of hospitalization was found dead from an apparent suicide by hanging on August 5, 2014.[20][21][22][23]

Awards and honours[edit]

2010 Osaka Science Prize for his work on in vitro recapitulation of brain development

2012 Inoue Prize for Science.[2]

2013 Hans Sigrist Prize[24]

See also[edit]


  1. ^ "Brief Resume of Dr. Yoshiki Sasai". News & Media. Riken. Retrieved 26 August 2014.
  2. ^ a b "Sayer Vision Research Lecture and Award 2012". National Eye Institute. Retrieved 6 July 2013.
  3. ^ Cyranoski, D. (2012). "Tissue engineering: The brainmaker". Nature. 488 (7412): 444–6. Bibcode:2012Natur.488..444C. doi:10.1038/488444a. PMID 22914148.
  4. ^ Alvarez-Buylla, Arturo (2014). "Yoshiki Sasai (1962–2014) Stem-cell biologist who decoded signals in embryos". Nature. 513 (7516): 34. doi:10.1038/513034a. PMID 25186892.
  5. ^ Yoshiki Sasai's publications indexed by the Scopus bibliographic database. (subscription required)
  6. ^ Kawasaki, H; Mizuseki, K; Nishikawa, S; Kaneko, S; Kuwana, Y; Nakanishi, S; Nishikawa, S. I.; Sasai, Y (2000). "Induction of midbrain dopaminergic neurons from ES cells by stromal cell-derived inducing activity". Neuron. 28 (1): 31–40. doi:10.1016/s0896-6273(00)00083-0. PMID 11086981. S2CID 14248134.
  7. ^ Piccolo, S; Sasai, Y; Lu, B; De Robertis, E. M. (1996). "Dorsoventral patterning in Xenopus: Inhibition of ventral signals by direct binding of chordin to BMP-4". Cell. 86 (4): 589–98. doi:10.1016/s0092-8674(00)80132-4. PMC 3070603. PMID 8752213.
  8. ^ Sasai, Y; Lu, B; Steinbeisser, H; Geissert, D; Gont, L. K.; De Robertis, E. M. (1994). "Xenopus chordin: A novel dorsalizing factor activated by organizer-specific homeobox genes". Cell. 79 (5): 779–90. doi:10.1016/0092-8674(94)90068-X. PMC 3082463. PMID 8001117.
  9. ^ Watanabe, K.; Ueno, M.; Kamiya, D.; Nishiyama, A.; Matsumura, M.; Wataya, T.; Takahashi, J. B.; Nishikawa, S.; Nishikawa, S. I.; Muguruma, K.; Sasai, Y. (2007). "A ROCK inhibitor permits survival of dissociated human embryonic stem cells". Nature Biotechnology. 25 (6): 681–686. doi:10.1038/nbt1310. PMID 17529971. S2CID 8213725.
  10. ^ Bouwmeester, T; Kim, S; Sasai, Y; Lu, B; De Robertis, E. M. (1996). "Cerberus is a head-inducing secreted factor expressed in the anterior endoderm of Spemann's organizer". Nature. 382 (6592): 595–601. Bibcode:1996Natur.382..595B. doi:10.1038/382595a0. PMID 8757128. S2CID 4361202.
  11. ^ Sasai, Y; Kageyama, R; Tagawa, Y; Shigemoto, R; Nakanishi, S (1992). "Two mammalian helix-loop-helix factors structurally related to Drosophila hairy and Enhancer of split". Genes & Development. 6 (12B): 2620–34. doi:10.1101/gad.6.12b.2620. PMID 1340473.
  12. ^ Dvorsky, George. "Scientists spark the growth of a human eye with stem cells". io9. Retrieved 6 July 2013. Moreover, Sasai's breakthrough marks the first time that such a complicated feat was done with human cells.
  13. ^ Obokata, Haruko; Wakayama, Teruhiko; Sasai, Yoshiki; et al. (2014). "Stimulus-triggered fate conversion of somatic cells into pluripotency". Nature. 505 (7485): 641–647. doi:10.1038/nature12968. PMID 24476887. S2CID 4463394.
  14. ^ Obokata, Haruko (2014). "Retraction: Stimulus-triggered fate conversion of somatic cells into pluripotency". Nature. 511 (7507): 112. Bibcode:2014Natur.511Q.112O. doi:10.1038/nature13598. PMID 24990753.
  15. ^ Lawrence, Janet (July 2, 2014). "Nature journal retracts stem cell paper citing "critical errors"". Reuters. Retrieved July 2, 2014.
  16. ^ Ishii, Shunsuke et al. (March 31, 2014) Report on STAP Cell Research Paper Investigation. riken.jp
  17. ^ "Stem cell debacle déjà vu". Bio Edge. April 6, 2014. Retrieved April 6, 2014.
  18. ^ Schlanger, Zoe (April 1, 2014). "Haruko Obokata, Who Claimed Stem Cell Breakthrough, Found Guilty of Scientific Misconduct". Newsweek. Retrieved April 1, 2014.
  19. ^ Rasko, John; Power, Carl; What pushes scientists to lie? The disturbing but familiar story of Haruko Obokata; The Guardian; [1]
  20. ^ "Japanese stem cell scientist Yoshiki Sasai found dead in apparent suicide", The Independent, 5 August 2014. Accessed 6 August 2014
  21. ^ "Japanese Stem-Cell Scientist Yoshiki Sasai Is Dead". Wall Street Journal. 5 August 2014.
  22. ^ Collateral damage: How one misconduct case brought a biology institute to its knees. Nature, 30 April 2015, 520 (600-603).
  23. ^ Asahi Shinbun Digital, August 4, 2014
  24. ^ "Hans Sigrist Prize Winners". The Hans Sigrist Foundation. 2019-04-03. Retrieved 2020-09-02.