Question

What is somatic cell nuclear transfer (SCNT)? (b) What is the difference between mammalian inner cell mass (ECM) cells and embryonic stem (ES) cells? (c) What are the consequences of Sox2 downregulation in mouse embryonic stem cells? (d) What are mesenchymal stem cells, to which cell type(s) can they differentiate, and where can they be found in humans?

Answer 1

1. What is somatic cell nuclear transfer (SCNT)?

Somatic cell nuclear transfer is a technique to create a viable embryo by transferring nucleus of a somatic cell to an enucleated (without nucleus) ovum or egg. The nucleus is then programmed to become a zygote nucleus with the help of cytoplasmic factors. The zygote is then developed to blastocyst stage in order to obtain the inner cell mass and stem cells that can be used for the purpose of therapeutic cloning or reproductive cloning.

2. What is the difference between mammalian inner cell mass (ECM) cells and embryonic stem (ES) cells?

This Inner cell mass is the mass of cells inside the primordial embryo that ultimately forms definitive structures of the growing fetus. The zygote formed after fertilization, undergoes cleavage, increasing the number of cells and reaches 8-cell stage and further undergoes compaction to reach 16 cell stage. Further cleavage results in development of blastocyst that is characterized by an outer trophoblast layer(trophoblast), a fluid-filled cavity (blastocoel) and an inner cell mass (ICM).

Embryonic stem cells are cells derived from the inner cell mass of embryo before it is implanted into the nucleus. ES cells are pluripotent and have the ability to differentiate into three primary germ layers ectoderm, endoderm, and mesoderm.

3. What are the consequences of Sox2 downregulation in mouse embryonic stem cells?

SOX2 is a transcription factor that maintains the pleuripotency of embryonic stem cells. Sox2 is a critical factor in the formation of pluripotent cells in early embryos and embryonic development. Downregulation of SOX2 in mice suppresses the pleuripotency of these cells resulting in their differentiation.

4. What are mesenchymal stem cells, to which cell type(s) can they differentiate, and where can they be found in humans?

Mesenchymal stem cells are multipotent stem cells that have the ability to produce some specialized cell of the body, but not all types. Mesenchymal cells can differentiate into cartilage, bone and fat cells. In humans, they are primarily found in the bone marrow but can also be isolated from peripheral blood, cord blood, and fetal liver and lung.