Shinya Yamanaka: revision 1 to 2

Revision 1

Revision 2

categories: ["people", "genetics"]

tags: ["stem cells", "reprogramming", "ipsc", "nobel prize", "regenerative medicine"]

summary: "Japanese physician-scientist who showed that four transcription factors can reprogram adult cells to a pluripotent state, sharing the 2012 Nobel Prize for the discovery."

summary: "Japanese physician-scientist who showed that four transcription factors can reprogram adult cells to a pluripotent state, sharing the 2012 Nobel Prize for the discovery."

updated: "2026-07-27"

updated: "2026-10-29"

issues: ["The mid-2020s Parkinson's iPSC trial results are described without a citation"]

---

**Shinya Yamanaka** is a Japanese physician-scientist who demonstrated in 2006 that introducing four

transcription factors into an adult mouse fibroblast can return it to an embryonic-like pluripotent

state, and repeated the result in human cells the following year. The four factors — Oct3/4, Sox2,

state, and repeated the result in human cells the following year. The four factors (Oct3/4, Sox2,

Klf4 and c-Myc — are now known as the [[yamanaka-factors]], and the cells they produce as

Klf4 and c-Myc) are now known as the [[yamanaka-factors]], and the cells they produce as

[[induced-pluripotent-stem-cells]]. He shared the 2012 Nobel Prize in Physiology or Medicine with

John Gurdon.

## Career

Yamanaka trained as an orthopedic surgeon at Kobe University, an experience he has described as

Yamanaka trained as an orthopedic surgeon at Kobe University. He has described that period as

unsuccessful — he was slow in the operating theatre and found the limits of surgical repair

unsuccessful: he was slow in the operating theatre and found the limits of surgical repair

frustrating — and moved into research, completing a doctorate in pharmacology at Osaka City

frustrating. He moved into research and completed a doctorate in pharmacology at Osaka City

University in 1993. A postdoctoral position at the Gladstone Institutes in San Francisco taught him

American laboratory culture and, in his own account, the value of pursuing unexpected results: a

transgenic mouse experiment aimed at cholesterol metabolism instead produced tumours, which redirected

Gurdon had shown in the early 1960s that transferring a differentiated frog nucleus into an

enucleated egg could produce a whole animal, establishing that differentiation does not delete

genetic information.[^gurdon1962] The same principle later produced Dolly and the whole field of

[[human-cloning|somatic cell nuclear transfer]]. What remained unknown was whether the reprogramming

[[human-cloning|somatic cell nuclear transfer]]. It remained unknown whether the reprogramming

activity resident in the egg could be reduced to a defined set of factors.

Yamanaka's group assembled twenty-four candidate genes associated with embryonic stem cell identity,

]

```

The finding did two things at once. It removed the political obstacle that had constrained human

Because iPSCs require no embryo, the finding removed the political obstacle that had constrained

embryonic stem cell research in several countries, since iPSCs require no embryo. And it established

human embryonic stem cell research in several countries. It also established that cell identity is

that cell identity is maintained by a transcription-factor network that can be overridden — the

maintained by a transcription-factor network that can be overridden. That premise later underlay

premise on which [[partial-reprogramming]] and [[epigenetic-reprogramming]] as rejuvenation

[[partial-reprogramming]] and [[epigenetic-reprogramming]] as rejuvenation strategies.

strategies later rested.

## Clinical translation

directly, aiming at hypoimmunogenic universal lines.

Kyoto teams have since run early-phase trials of iPSC-derived dopaminergic progenitors for

Parkinson's disease, alongside independent programmes elsewhere; results reported in the mid-2020s

Parkinson's disease, alongside independent programmes elsewhere. Results reported in the mid-2020s

have concerned safety and graft survival, with motor improvement in some participants but no

have concerned safety and graft survival; some participants showed motor improvement, but there

controlled comparison that would establish clinical benefit. Cardiac muscle

has been no controlled comparison that would establish clinical benefit. Cardiac muscle sheets, platelets and

sheets, platelets and corneal epithelium have also entered early trials. Twenty years after the

corneal epithelium have also entered early trials. Twenty years after the mouse paper, no

mouse paper, no iPSC-derived therapy is in routine clinical use, and the whole organs that would

iPSC-derived therapy is in routine clinical use. Whole organs that would address the

address the [[organ-shortage]] remain the province of [[tissue-engineering]] and

[[organ-shortage]] remain the province of [[tissue-engineering]] and [[lab-grown-organs]] rather

[[lab-grown-organs]] rather than of reprogramming alone.

than of reprogramming alone.

> [!note] Two uses of the same cells

> iPSCs matter clinically as a source of transplantable tissue, and they matter scientifically as

> Clinically, iPSCs are a source of transplantable tissue. Scientifically, they serve as

> patient-specific disease models and drug-screening substrates. The second use — including

> patient-specific disease models and drug-screening substrates, including [[organoids]] grown from

> [[organoids]] grown from patient cells — has produced far more published results than the first,

> patient cells. The second use has produced far more published results than the first, and it

> and requires no regulatory approval.

> requires no regulatory approval.

## Caution about timelines

Yamanaka is unusual among the figures covered on this wiki for consistently arguing that his own

Unusually among the figures covered on this wiki, Yamanaka consistently argues that his own field

field will take longer than its advocates say. He has repeatedly cautioned that iPSC therapies face

will take longer than its advocates say. He has repeatedly cautioned that iPSC therapies face

manufacturing cost, tumorigenicity and immune-rejection problems that are not solved by the

manufacturing cost, tumorigenicity and immune-rejection problems that the reprogramming step itself

reprogramming step itself, and that residual undifferentiated cells in a graft are a genuine cancer

does not solve, and that residual undifferentiated cells in a graft are a genuine cancer risk. On

risk rather than a formality. On rejuvenation specifically, he has been more reserved than the

rejuvenation he has been more reserved than the commercial reprogramming sector. The factors that

commercial reprogramming sector, noting that the factors that restore pluripotency are the same

restore pluripotency also erase cell identity, he notes, and the therapeutic window between the two

factors that erase cell identity, and that the therapeutic window between the two is narrow and

is narrow and poorly characterized in vivo. A reset [[epigenetic-clock]] reading in a reprogrammed

poorly characterized in vivo. A reset [[epigenetic-clock]] reading in a reprogrammed cell is a

cell shows that a measurement changed; it does not show that the tissue functions better.

change in a measurement, not a demonstration that the tissue functions better.

He has also declined to profit personally from the discovery in the way his position would allow,

He has also declined to profit personally from the discovery in the way his position would allow.

directing patent income to CiRA and raising research funds by running marathons — a detail that is

Patent income goes to CiRA, and he raises research funds by running marathons, a detail often

frequently mentioned because it is so far from the norm in the sector.

mentioned because it is so far from the norm in the sector.

## Reception and legacy

The 2006 paper is one of the most cited in modern biology, and iPSCs are now standard laboratory

material. Reprogramming also supplied the conceptual foundation for the reprogramming-based

material. His work is also the conceptual foundation of the reprogramming-based longevity

longevity companies: [[altos-labs]] pursues partial rather than complete factor expression precisely

companies. [[altos-labs]] pursues partial rather than complete factor expression in order to avoid

to avoid the pluripotency Yamanaka was trying to reach, and [[newlimit]] screens for other factor

the pluripotency Yamanaka was trying to reach, and [[newlimit]] screens for other factor

combinations that never approach it. He agreed to serve as a senior scientific adviser to Altos

while remaining at Kyoto University, an arrangement that sits alongside rather than in place of the

while remaining at Kyoto University, and he has kept the reservations described above while doing

reservations described above.

so.

The open problem he identified early has not moved much. Reprogramming is a continuum, and nobody

The open problem he identified early has seen little progress. Reprogramming is a continuum, and

can yet specify how far along it a cell can be pushed to gain a younger epigenetic profile while

nobody can yet specify how far along it a cell can be pushed to gain a younger epigenetic profile

retaining its function and not becoming a tumour. Until that dose–response relationship is

while keeping its function and not becoming a tumour. Until that dose-response relationship is

characterized in vivo, the distance between his discovery and its most ambitious application

characterized in vivo, claims about how close his discovery is to its most ambitious application

remains a matter of assertion.

remain assertions.

## See also