Stem cells and organoids

Defining properties of a stem cell

Self-renewal and ability to differentiate into specialized cell types

During grastrulation, the primitive streak forms and the embryo is re-organized into

The tree germ layers: mesoderm, endoderm, and ectoderm

Embryonic stem cells are derived from this structure

From the blastocyst inner cell mass

Describe John Gurdon experiment

He transplanted the nucleus of a differentiated intestinal epithelial cell from a tradpole into an enucleated frog egg, which developed into a normal tradpole

Gurdon’s experiment demostrated that …

The nucleous of a differentiated cel, still contains all the genetic information needed to genérate an entire organism

Name the 4 yamanaka transcription factors

Sox2 Oct3/4 Klf4 c-Myc

Yamanaka factors are used for …

Reprogramming adult somatic cells: generating iPSCs (induced pluripotent stem cells)

Explain what the teratoma assay tests

It tests pluripotent by injecting candidate stem cells into a mouse and checking whether the generated tumor contains differentiated derivates of all tree germ layers

Endoderm

Internal layer, gives rise to digestive tube

mesoderm

Mid layer, gives rise to musscle, bones, blood and connective tissue

ectoderm

External layer, gives rise to skin and nervious system

What happens after gastrulization

Implantation of the embryo

The chimera assay is considered the most stringent functional test of pluripotency because it shows that injected stem cells can

Contribute to multiple tissues of developing embryo, including the germline

A commonly used molecular marker to confirm that a cell line is pluripotent

Expression of yamanaka transcription factors: SOX2 OCT4 and NANOG

Totipotent cell type that can give rise to both embryo and extra-embryonic tissues

Zygote

Dolly the ship was significant because

She was the first mammal cloned from the nucleous of an adult differentiated somatic cell

T/F Mature, differentiated cells can be reprogrammed tombecome pluripotent

True

T/F commited progenitor cells can selfrenew and divide rapidly

F: they do divide rapidly but can not self renew

Hemaopoietic stem cells, wich give rise to blood cell líneages, reside primarily in the

Bone marrow

Embryonic stem cells are pluripotent because:

They can give rise to all body cell types but not extra-embryonic tissues such as the placenta

Tissue (adult) stem cells (such as hematopoietic stem cells) are best described as:

Multipotent cells, Able to genérate múltiple but not all cell types

Spermatogonial stem cells, which give rise to superm cells, are an example of which potency category?

Unipotent

Name the potency categories seen in class

Totipotent, pluripotent, multipotent, oligopotent and unipotent

What is the result of stem cell asimeric divission

2 dauughter stem cells, expanding the stem cell pool

What is the Hayflick limit?

The stablished limit of how many times most differentiated human stem cells in culture can divide before entering to senescence due to loss of telomers (50 times aprox)

Why can differeniated cells not divide indefinitely, while stem cells can?

Hayflick limit: stem cells still have telomerase activity

Describe types of Stem Cell divisions

Asymetric: One stem cell and one differentiated cell, Symetric self renewal: Two stem cells, Symetric differentiation div: two differetiated cells

It is also known as consumptive division

Symetric differentiation division (two differentiated cells)

T/F: iPSC are pluripotent

T: iPSC Pluripotent Stem Cells

T/F: Stem Cells produce Commited progenitores

T

T/F: Commited progenitores have nule or limited self-renewal

T

2007 Nobel price in physiology or medicine awarded to Capecchi, Evans and Smithies

For discovering the principales for introducing specific gene modifications in mice by the use of ESC with viruses

T/F: iPSC need embryonic stem cells to be generated

F

T/F Reprogramming is a slow and inefficient process: Only a very small fraction of the starting cells give rise to iPS colonies

T

T/F: Epigenetic marks and DNA methilation are good molecular tests for cell pluripotency

T

Describe Chimera Assay for funcional test of PSC

Starting with GPF + PSC, that are injected in a blastocyst and transfer to a pseudo pregnant female: expected to generate chimera offspring and GPF observation in al cell types (from the 3 layers: ectoderm, mesoderm and endoderm), even in germline cells

Describe Yamanaka experiment

It started with mouse specialized cells (mouse embryonic fibroblast from conective tissue), which were forced to express defined transcriptional factors through retroviral infection, resulting in iPS.