- Following are the different ways of obtaining human stem cells-
(A) Cells from morula are dispersed and cultured to give rise pluripotent stem cells.
(B) Isolated inner cell mass of a blastocyst are cultured and they become pluripotent stem cells.
(C) The primordial germ cells from a fetus are collected and cultured, which grow into pluripotent stem cells.
(D) Stem cells are collected from adult tissues and grown in specific manner to develop into
pluripotent stem cells.
Which of the above cell type(s) is extensively used for somatic cell gene therapy in human?
(1) (A) and (B) (2) (B) only
(3) (B) and (D) (4) (D) onlyThe correct answer is (4) (D) only.
Somatic cell gene therapy in humans primarily uses stem cells from adult tissues (somatic/adult stem cells), not embryonic or fetal pluripotent cells.
Understanding each stem cell source
(A) Cells from morula → pluripotent stem cells
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Morula-stage embryos are pre‑implantation; dispersing their cells gives embryonic stem–like cells.
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These are pluripotent but embryonic, associated with major ethical and regulatory issues.
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They are used mainly in research, not in routine human somatic gene therapy.
(B) Inner cell mass (ICM) of blastocyst → pluripotent stem cells
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Classic source of embryonic stem (ES) cells.
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Again, powerful pluripotent cells, but because they are embryo‑derived, they raise ethical concerns and tumor‑formation risks, so they are not the main clinical platform for human somatic gene therapy.
(C) Primordial germ cells from fetus → pluripotent stem cells
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Fetal germ cells can give rise to embryonic germ (EG) cells, also pluripotent.
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Harvesting them requires fetal tissue, which is ethically and practically problematic; these cells remain largely experimental, not front‑line in therapy.
(D) Stem cells from adult tissues grown to pluripotent state
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This describes adult/somatic tissue stem cells and, by extension, reprogrammed induced pluripotent stem cells (iPSCs) derived from adult cells.
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Clinically, hematopoietic stem cells, mesenchymal stem cells, and other adult stem cells are widely used for ex vivo somatic gene therapy, where cells are taken from the patient, genetically modified, and re‑infused.
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Because they are autologous or adult-derived, they avoid embryo ethics and reduce immune rejection, making them the mainstay of current somatic gene therapy trials.
Why option (4) is correct
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The question asks which cell types are extensively used for somatic cell gene therapy in humans.
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Among the listed options, only adult tissue–derived stem cells (D) match the cells actually used in most clinical and near‑clinical gene-therapy protocols.
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Thus, the best answer is (4) (D) only.
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