Stem cells, cloning and regenerative medicine

The first principle

Every cell in the body carries the same genome, yet a neuron and a skin cell look and work nothing alike, because each switches on a different set of genes. A stem cell is a cell that has not yet committed to one set: it can divide to make more of itself and can also turn into specialised cells. Regenerative medicine rests on this one fact, since a cell that can still choose its fate can replace tissue that is lost, and cloning rests on its converse, which is that a committed nucleus can be reset to the beginning.

The core

What makes a cell a stem cell

• Two defining properties. A stem cell must be able to self renew, dividing to give at least one daughter that is still a stem cell, and it must be able to differentiate into one or more specialised cell types; a cell that does only one of these is not a stem cell.
• Potency is the range of fates. A totipotent cell, such as the zygote and the cells of the first few divisions, can form the whole embryo and the placenta; a pluripotent cell, such as those of the inner cell mass of the blastocyst, can form every cell of the body but not the placenta; a multipotent cell can form the cells of one family, as a haematopoietic stem cell forms all blood cells; and a unipotent cell forms one type, as a skin or muscle precursor does.
• Differentiation is a change in gene expression, not in genes. Signals switch transcription factors on and off and chemical marks on the DNA fix the pattern, so a liver cell keeps its full genome but reads only the liver part.

Where stem cells come from

• Embryonic stem cells are taken from the inner cell mass of a blastocyst about five days after fertilisation, usually a spare embryo from in vitro fertilisation; they are pluripotent and grow without limit, but taking them destroys the embryo.
• Adult or tissue stem cells live in bone marrow, blood, fat, skin, the gut lining and umbilical cord blood; they are multipotent, scarce and harder to grow, but they raise no embryo question and a patient's own cells are not rejected.
• Induced pluripotent stem cells (iPSCs) are ordinary adult cells, such as skin cells, reprogrammed to a pluripotent state by switching on a few transcription factors. Shinya Yamanaka showed this in mouse cells in 2006, and he shared the 2012 Nobel Prize in Physiology or Medicine with John Gurdon, who had shown in frogs that a specialised nucleus could be reset. Made from the patient, iPSCs avoid both rejection and the embryo, though reprogramming can leave errors that raise a cancer risk.

Cloning

• Somatic cell nuclear transfer (SCNT) removes the nucleus from an egg, puts in the nucleus of a body cell from the animal to be copied, and triggers the egg to divide; the egg's cytoplasm resets the nucleus so it behaves like a zygote's. Dolly the sheep, born in Scotland in 1996, was the first mammal cloned from an adult cell this way.
• Reproductive cloning places that embryo in a surrogate mother to produce a whole animal, while therapeutic cloning stops at the blastocyst to harvest stem cells that match the donor; reproductive cloning of humans is banned almost everywhere, including in India.
• A clone is a genetic copy, not an identical one. Its mitochondrial DNA comes from the egg donor, and incomplete resetting of the nucleus makes cloning inefficient, with many embryos failing.
• Cloning in India has been used for livestock: the National Dairy Research Institute at Karnal produced a cloned buffalo calf in 2009, with the aim of multiplying high yielding animals.

Dimensions

• Medical. Stem cells can replace what the body cannot repair, such as the insulin making cells lost in type 1 diabetes, heart muscle after an attack or retinal cells in macular degeneration, and they give laboratories human tissue on which to test drugs.
• Ethical. The moral status of the embryo divides opinion, which is why many countries fund only work on spare embryos and limit culture to 14 days; iPSCs eased this debate but raised new ones, such as chimeras and gametes made from body cells.
• Legal and regulatory. In India a stem cell product is treated as a new drug, so it needs approval from the Central Drugs Standard Control Organisation (CDSCO) under the Drugs and Cosmetics Act 1940 and the New Drugs and Clinical Trials Rules 2019, while research must follow the guidelines of the Indian Council of Medical Research (ICMR) and the Department of Biotechnology (DBT).
• Economic. Cell therapies are made one patient at a time in sterile facilities, so they cost lakhs to crores of rupees, and India's lower manufacturing cost is an opening for its industry.
• Social. Clinics selling unproven stem cell injections for autism or spinal injury exploit the hope of desperate families.

In practice

• The one established therapy. Haematopoietic stem cell transplantation, commonly called a bone marrow transplant, has been standard treatment for decades for leukaemia, lymphoma, thalassaemia and aplastic anaemia; cells come from the patient, a matched donor or cord blood.
• The National Guidelines for Stem Cell Research, 2017, issued by ICMR and DBT, sort research into permissible, restricted and prohibited areas. Deriving cell lines from spare embryos is permissible, creating embryos only to obtain stem cells is restricted, and human reproductive cloning, germline gene therapy and culturing a human embryo beyond 14 days are prohibited. Cord blood is the only material that may be banked commercially, under a CDSCO licence, and the guidelines state that storing it privately for a child's own future use has no scientific basis.
• The Supreme Court in Yash Charitable Trust v Union of India (January 2026) held that stem cell therapy for autism spectrum disorder cannot be offered as a routine or commercial service and may be given only inside an approved and regulated clinical trial.
• The Ministry of Health and Family Welfare's advisory of September 2026 followed the judgement and asked States and Union Territories to permit stem cell therapy as standard care only for conditions on an approved list, and to act against clinics under the Clinical Establishments Act 2010.
• Engineered cells are the newest therapies. NexCAR19, developed by ImmunoACT, a company incubated at the Indian Institute of Technology Bombay with Tata Memorial Hospital, was approved by CDSCO in October 2023 as India's first chimeric antigen receptor (CAR) T cell therapy for certain B cell blood cancers; its mechanism belongs to the gene therapy note.
• Beyond single cells. Organoids are tiny organ like clusters grown from stem cells to study disease; three dimensional (3D) bioprinting lays down cells layer by layer on a scaffold to build tissue; and xenotransplantation uses organs from gene edited pigs, of which a pig kidney was transplanted into a living patient in the United States in 2024.

Issues and way forward

• Unproven clinics. Clinics fill the gap between what stem cells may one day do and what is proved, because patients cannot judge evidence and enforcement was weak; the 2026 judgement and advisory let States cancel registrations, and a public list of approved indications would help patients check.
• Tumours and rejection. Pluripotent cells that are not fully differentiated can form tumours called teratomas, and donor cells are rejected unless matched, so every product needs long follow up and India needs banks of iPSC lines matched to common tissue types.
• Cost and scale. Cell therapies are made patient by patient, so cost limits access, and shared public manufacturing facilities of the kind the bioeconomy policy funds are the main lever.
• Thin trial capacity. Few Indian centres can run the long trials regenerative products need, so stronger ethics committees and registration of every trial with the Clinical Trials Registry of India would build trust.
• Ethics that move with the science. Embryo models built from stem cells and gametes made from body cells raise questions the 2017 guidelines did not foresee, so the guidelines need regular expert review.

Common confusions

• Embryonic stem cells and iPSCs. Both are pluripotent, but embryonic cells come from a blastocyst that is destroyed, while iPSCs are made from an adult's own cells and need no embryo.
• Reproductive and therapeutic cloning. Both begin with nuclear transfer, but reproductive cloning implants the embryo to make a whole organism, and therapeutic cloning stops at a few days to obtain matched stem cells.
• Totipotent and pluripotent. A totipotent cell can make the embryo and the placenta, while a pluripotent cell can make every body cell but not the placenta.
• Stem cell therapy and gene therapy. Stem cell therapy replaces cells, while gene therapy changes genes; CAR T cells are both, since a patient's cells are genetically altered and returned.
• Cloning and gene editing. Cloning copies a whole genome unchanged, while gene editing changes a chosen sequence within a genome.

For the exam

• Keyword bank: self renewal, potency, pluripotent, induced pluripotent stem cells, haematopoietic stem cell transplant, somatic cell nuclear transfer, therapeutic cloning, organoids, 3D bioprinting, xenotransplantation, teratoma, cord blood banking, National Guidelines for Stem Cell Research 2017, CAR T cell therapy, informed consent.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction with data: CAR T cell therapy cost over Rs 3 crore abroad, while India's own NexCAR19, approved in October 2023, was expected to cost about Rs 30 to 35 lakh, showing how local manufacture brings such therapy within reach.
  • Introduction with a source: In Yash Charitable Trust v Union of India (2026), the Supreme Court held that stem cell therapy for autism may be offered only within an approved clinical trial, not as a commercial service.
  • Conclusion: Stem cells promise to repair what medicine could only manage, but the promise holds only if regulation keeps unproven therapies out of clinics while public investment brings proven ones to patients.
  • Conclusion: India's task is to turn its low cost of cell manufacture and its clear 2017 guidelines into trials, banks of matched cell lines and affordable therapies, so that regenerative medicine does not become a treatment only for the rich.