Consider the following statements:
1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
2. A person’s genome can be edited before birth at the early embryonic stage.
3. Human induced pluripotent stem cells can be injected into the embryo of a pig.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 2 only
(d) 1, 2 and 3
Ans: d
Explanation:
Gene editing is a type of gene therapy that removes, disrupts, alters, or corrects faulty elements of DNA within a gene of interest. Gene editing uses technology designed to make targeted changes inside the cell.
Somatic gene therapy and germ line gene therapy
Gene therapy can be divided into somatic gene therapy and germ line gene therapy, depending on the cells in which the genetic material is altered
Somatic cells are the cells which make up the vast majority of tissues in the body except for sex cells (eggs and sperm). In the case of somatic gene therapy the genetic material of human cells are altered. Such alterations cannot be genetically transferred.
Reproductive cells, known as germline cells or germ cells, are those sex cells (eggs and sperm) that pass on genes from parents to their children.
Our reproductive cells, known as germline cells or germ cells, are those sex cells (eggs and sperm) that pass on genes from parents to their children. Germline gene editing involves altering the specific genes of an egg, sperm cell, or early embryo (i.e., up to five days after fertilization) in a laboratory dish. Germline gene editing removes, disrupts, alters, or corrects faulty elements of DNA within a gene in sex cells.
In the case of germ line gene therapy the genetic material of gametes are altered. The alterations are transferred to the offspring and are therefore genetically transferred.
Hence, statements 1 & 2 are correct.
Embryo editing
Early embryos only have a few cells, so the number of targeted cells for editing would be much smaller. As the embryo develops, those few edited cells would divide, and divide again, and could theoretically result in the birth of a child with many cells having the desired edit.
An alternative to the embryo editing approach would be to edit the germ cells (egg or sperm) of one of the parents with the goal of then using in vitro fertilization (IVF) to create a fertilized embryo that has the desired genetic change
Clinical use of germline gene editing is prohibited in the United States, Europe, the United Kingdom, China, and many other countries around the world.
Embryonic stem cells (ESCs).
These are pluripotent stem cells derived from embryos. As ESCs are pluripotent they retain the ability to self-renew and to form any cell in the body. ESCs have the advantage of versatility due to their pluripotency, but the use of embryos in the development of therapeutic strategies raises some ethical concerns.
In addition, stem cell lines generated from embryos are not genetically matched to the patient which can increase the chance that the transplanted cell is rejected by the patient’s immune system.
Human stem cells can integrate into developing pig embryos, a finding that could lead to new ways of growing human organs and studying early human development.
Human and pig pluripotent stem cells have emerged as promising tools in regenerative medicine. Compared to mice, pigs offer a more relevant animal model due to their genetic and physiological similarities to humans.
In addition, the integration of human PSCs into pig embryos and the use of pig PSCs for generating humanized pig organs through blastocyst complementation or blastoid formation have opened up new avenues for organ transplantation.
Hence, statement 3 is correct.
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