Stem Cells and Cloning
How cloning research connects to the wider field of stem-cell science — and where induced pluripotent stem cells have changed the picture.
Stem cells and cloning are often discussed in the same breath, which is both fair and confusing. They overlap, but they are not the same field. Most stem-cell research has nothing to do with cloning. Most cloning research is more about cells than about people. Untangling the two makes a lot of the public conversation easier to follow.
What stem cells are
A stem cell is an unspecialised cell that can both renew itself and give rise to more specialised cells. Different stem cells have different ranges of possibility:
- Pluripotent stem cells can become almost any cell type in the body. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are pluripotent.
- Multipotent stem cells can give rise to a more limited family of cells. Blood-forming stem cells in bone marrow are a familiar example.
- Tissue-specific (adult) stem cells maintain particular tissues throughout life.
The promise of stem-cell research is to use this flexibility to study disease, screen treatments, and potentially repair damaged tissues.
Where cloning comes in
Two threads of cloning research touch stem cells:
1. Therapeutic cloning
Researchers use somatic cell nuclear transfer to produce early-stage cells from which pluripotent stem cells can be derived. The resulting cells share nuclear DNA with the donor of the body cell — useful for studying donor-specific disease biology and potential cell-based therapies. This is a research technique, tightly regulated, and not a clinical service. See our therapeutic cloning page.
2. Reproductive cloning
Reproductive cloning, by contrast, is not about cells in a dish. It is about producing a living organism. Stem cells are not the goal; they are just one early stage on the way. Reproductive human cloning has not been done and is broadly prohibited. See our reproductive cloning page.
How induced pluripotent stem cells changed the picture
In 2006–2007, Shinya Yamanaka and colleagues showed that ordinary adult cells could be reprogrammed in a dish into pluripotent stem cells, without an embryo. These induced pluripotent stem cells (iPSCs) have several practical advantages:
- They can be made from a small skin or blood sample.
- They sidestep many of the ethical concerns associated with embryonic stem-cell research.
- They are easier and faster to produce at scale.
iPSCs are now the workhorse of much regenerative-medicine research. They have not replaced embryonic stem cells entirely, and they are not without their own technical limitations, but they have reduced the practical case for therapeutic cloning as a way to produce donor-matched pluripotent cells.
Key takeaway
Cloning and stem-cell research overlap, but most stem-cell research does not involve cloning, and most cloning research is about cells rather than people. Induced pluripotent stem cells have absorbed much of what therapeutic cloning was once expected to do.
What this work is still pursuing
The serious research agenda around stem cells today includes:
- Building better models of human disease in a dish.
- Understanding how cells lose and acquire identity during development.
- Exploring carefully limited cell-replacement strategies for conditions like macular degeneration, Parkinson’s disease, and type-1 diabetes.
- Working out the long-term safety and reliability of iPSC-derived cells.
None of this is reproductive cloning. Most of it is not therapeutic cloning either. Stem-cell research is its own large, technical field, with its own ethical and regulatory frameworks.