Question

1. Describe the importance of stem cells for maintaining healthy tissues. Now, describe the hierarchy of cells, tissues, organs, and organ systems. Explain the goal of regenerative medicine and the role of stem cells in meeting this goal. Compare and contrast the use of stem cells, drugs, and biodegradable scaffolding for regenerative therapies. Finally, explain how two stem cells with identical genomes can become specialized cells with very different functions.

2. Describe where embryonic and adult (somatic) stem cells are found. Compare and contrast the differentiation potential of adult and embryonic stem cells. Now, explain why embryonic stem cells may have greater therapeutic potential than adult stem cells. Explain why the use of embryonic stem cells is controversial. Outline somatic cell nuclear transplantation (SCNT) and describe the two possible outcomes of the process. Describe induction of stem cells. Finally, discuss the significance of induced pluripotent stem cells from both scientific and ethical standpoints.

Answer 1

1.)

a.) Stem cells have a huge role in maintaining healthy tissues. As cells gets damaged due to various stress of metabolic reactions, injuries etc, stem cells replace these damaged cells with newer healthy version to continue the normal functioning.

b.) cells > tissues > organs > organ systems. (explanation - cells come together to form tissues. Similar tissue group to form organ to perform a particular function. When different organs come together an organ system is made say for example digestive system which consists of organs like stomach, duodenum etc)

c.) Regenerative medicine employs replacing or re-engineering of damaged tissue or organ of an organism to restore normal functioning of the body. Stem cells have revolutionized this branch of science due to their ability to form cells and tissues of different lineages depending on the signals and cues provided.

d.)

Biodegradable scaffold- It is a 3D porous substrate which guide growth of new tissues. It faciliates attachment, differentiation and proliferation of cells.Since it is biodegradable, the newly formed cells replace the scaffold. These scaffolds are seeded with stem cells and drugs/growth factors for the purpose of growth and formation of new tissue and organ.

e.) Two stem cells with identical genomes can become specialized cells with different functions. This process is known as differentiation. Well, this is because apart from cell's DNA, during differentiation a cells take cues from the environment. This includes molecules, chemicals secreted by nearby cells, signaling cues, physical contact with cells and proteins which initiates epigenetic changes in cell's DNA. That is some genes are activated (due to the presence of activation marks like acetylation) in some cells while the same genes are silenced (due to the presence of silencing marks like methylation) in other cells depending on the epigenetic marks and modification. Due to which same cell can become either a neural lineage or muscle lineage depending on the cues it gets.