Lecture 1: Stem Cells

Question 1

Can the adult human brain regenerate according to Ramon y Cajal?

Answer 1

The functional specialization of the brain imposed on neurons two great lacunae; proliferative inability and irreversibility of differentiation. It is this reason that once development has ended the fonts of growth and regeneration of axons and dendrites dried up irrevocably. In the adult centers the nerve paths are something fixed , ended immutable. Everything may die, nothing may be regenerated.
However:
It is for the science of the future to change, if possible this harsh decree.

Question 2

What are the main focuses of the course?

Answer 2

-How stem cell translation is being used to try to add neuronal regeneration.
-How stem cells are used to learn about neurological disorders and help us discover promising new therapeutic approaches.

Question 3

What are some important neurological conditions that will be discussed?

Answer 3

AD
Parkinson’s disease
Frontotemporal Dementia
Lysosomal Storage Disease
ALS
Huntington’s Disease
TBI
Stroke

Question 4

What is a stem cell?

Answer 4

Can do 2 things:
1) self-renew, make copies of themselves.
2) differentiate into more specialized cells.

Question 5

What are the three main types of stem cells?

Answer 5

Totipotent: whole
Pluripotent: many
Multipotent: several

Question 6

What are totipotent stem cells?

Answer 6

-Can give rise to all cell types
-Includes human embryonic cells, extra embryonic tissues (including placenta, extraemrbyonic membranes, and umbilical cord).
-Only naturally exist during the earliest stages of development within the first few cell divisions after fertilization.

Question 7

What are pluripotent stem cells?

Answer 7

-Can give rise to all cell types that exist in a body.
-Can give rise to all three germ layers
-Naturally exist during blastocyst stage of development but can be grown and expanded in culture indefinitely
-Ground-breaking experiment in 2006 discovered how to change another more mature cell type such as a skin cell into a induced pluripotent stem cell (iPSC)

Question 8

What are multipoint stem cells?

Answer 8

-Can exist in all our organs and give rise to a more limited set of cell types that is organ specific.
- They can persist as we age, however their numbers typically diminish and their ability to differentiate is sometimes impaired.
-Within the brain, neural stem cells (NSCs) are multipoint. They can self-renew and also give rise to neurons, astrocytes, and oligodendrocytes.
- Another type of multiipotent stem cells are hematopoietic stem cells that reside within the bone marrow and give rise to blood cells.
Microgrlia are hematopoietic (5-10% of brain is microglia).

Question 9

___ Stem cells are often referred to as “adult stem cells” and occur in virtually every organ and tissue.

Answer 9

Multipotent

Question 10

Pluripotent embryonic stem cells can be isolated from the ___ ___ ___ of a blastocyst.

Answer 10

inner cell mass

Question 11

_____ cells that will subsequently give rise to placenta and umbilical cord have already differentiated from the totipotent cells that were present at early stages.

Answer 11

trophectoderm

Question 12

In 1998, Dr. Jamie Thompson and colleagues figured out how to isolate and grow ___ ____ stem cells in a dish

Answer 12

pluripotent embryonic stem cells
This was the first time that a human stem cell could be grown in culture and was immortal.
Pluripotent can be changed into any type of cell.

Question 13

Describe how pluripotent embryonic stem cells are essentially immortal.

Answer 13

• Having been properly cultured and grown with the correct media, ESCS will self-renew and maintain pluripotency and continue to expand.
• Can be frozen in liquid nitrogen and shared with other researchers.
• Original H9 ESC line described in Thompson’s 1998 science paper is still being used In thousands of labs around the world.
• the next key set of experiments need to figure out how ESCs can be differentiated into more mature cell types.

Question 14

What is differentiation?

Answer 14

This is the process by which a less specialized cell becomes a more specialized cell.
(Need at least 2 to do this).

Question 15

What are the three main lineages of pluripotent stem cells?

Answer 15

Ecto- Outside
Meso- Middle
Endo- Within

Question 16

All the cells in the human body develop from these ___ main germ lineages

Answer 16

3

Question 17

Earlier decision points can __ subsequent cell fate choices

Answer 17

alter
Monsters Inc Door visual: once the PSC makes a decision into which germ lineage it wants to be it won’t change into a different layer and it will continue to become further specialized/differentiated.

Question 18

Describe what is formed from the ectoderm.

Answer 18

-Epidermis of the skin and its derivatives (including sweat glands, hair follicles)
-Epithelial lining of mouth and anus
-Cornea and lens of eye
-Nervous system
- sensory receptors in epidermis
-adrenal medulla
-tooth enamel
-epithelium of pineal and pituitary glands

Question 19

Describe what is formed from the mesoderm.

Answer 19

-notochord
-skeletal system
- muscular system
-muscular layer of stomach and intestine
-excretory system
-circulatory and lymphatic systems
-reproductive system (except germ cells)
- dermis of the skin
- lining of body cavity
- adrenal cortex
-hematopoietic system

Question 20

Describe what is formed from the endoderm.

Answer 20

-epithelial lining of digestive tract
-epithelial lining of respiratory system
-lining of urethra, urinary bladder, and reproductive system.
- liver
-pancreas
-thymus
-thyroid and parathyroid glands

Question 21

Why do stem cells often need to be differentiated for experiments? (in vitro)

Answer 21

In vitro experiments: in a dish
drug testing/screening
- to produce cell types appropriate for modeling or studying a given disease.
- to study later stages of development, organogenesis
-to study and identify cell-specific properties and functions.

Question 22

Why do stem cells often need to be differentiated for experiments? (in vivo)

Answer 22

in vivo experiments: in an animal
-to produce a cell type or precursor that is relevant for a given organ or disease.
- to improve migration/engraftment (mature stem cell into neuron requires early neuron first).
- avoid tumor formation.

Question 23

What is a teratoma?

Answer 23

-a teratoma is a tumor that contains cellular derivatives of all 3 germ layers: ectoderm, mesoderm, endoderm.
- Teratomas can be formed from embryonic stem cells induced pluripotent stem cells and teratocarcinomas.
- If you could transplant a stem cell and it forms a teratoma then you know it is a pluripotent stem cell.
Mouse models must have less robust immune cells for this to work so that the cells are not rejected.

Question 24

How can we drive differentiation of embryonic stem cells specifically towards ectoderm, mesoderm, or endoderm?

Answer 24

One way: embryoid body formation (EB)
- Commonly used to initiate spontaneous differentiation of pluripotent stem cells.
pluripotent stem cells are transferred to low attachment plates
growth factors in the media that normally maintain stem cell state are removed (FGF).
- EBs contain a mixture of cells that are spontaneously differentiating along all 3 germ cell lineages.
-You can identify cells belonging to all 3 germ cell lineages by using specific antibodies that detect proteins that are made only in that specific cell type.

Question 25

What are the main conclusions of lecture 1?

Answer 25

-Very little regeneration naturally occurs within the adult brain, but this class will focus on how stem cells are being used to try to change if possible this harsh decree
Stem cells are defined by 2 key traits: they can self-renew and they can differentiate into more specialized cells.
- Stem cells can be totipotent, pluripotent, and multipotent.
-Pluripotent stem cells can be isolated from the inner cell mass and grown in culture.
- Scientists are continuing to learn and improve upon methods to differentiate stem cells into almost every cell type.