Stem Cell Differentiation

Question 1

Describe Totipotent stem cells

Answer 1

• highest differential capacity = can turn into cells that form whole organism
• example = zygote

Question 2

Describe Pluripotent stem cells

Answer 2

• high capacity to differentiate
• can turn into cells from each of the germ layers but can’t differentiate into every cell = limited

Question 3

Describe multipotent stem cells

Answer 3

• have a potent but limited capacity to differentiate
• Can differentiate into multiple types of cells from a limited number of the germ layers

Question 4

Describe Unipotent stem cells

Answer 4

• only have the ability to change into a very limited number of types of cells

Question 5

Define terminal differentiation

Answer 5

• when a cell has comitted to a lineage & becomes a specific cell of that lineage

Question 6

Define Tri-lineage

Answer 6

• a stem cell is defined by its capacity to be turned into cells from each of the 3 germ layers
• usually tri-lineage refers to evidence of stem cells being stimulated to turn into cells from all germ layers

Question 7

Define Germ Layers

Answer 7

• the layers of cells that form during embyronic development

Question 8

What are the 3 main germ layers of vertebrates ?

Answer 8

• Endoderm
• Mesoderm
• Ectoderm & neural crest

Question 9

Describe the Endoderm

Answer 9

• origin of epithelial tissue which lines digestive tract & glands associated with digestive tract, lungs, bladder, thyroid & parathyroid
• also forms the following; pharynx, stomach, colon, liver, pancreas & bladder

Question 10

Describe the Mesoderm

Answer 10

• can be sub categorised into 3 regions; intermediate, paraxial & lateral plate mesoderm
• responsible for the generation of; muscle, bone, cartilage, adipose, dermis, kidney & spleen

Question 11

What are the 3 subcategories of the ectoderm?

Answer 11

• surface ectoderm
• neural crest
• neural tube

Question 12

What is the surface ectoderm responsible for developing?

Answer 12

• develops into epidermis, hair, nails, sebaeceous grlands, cornea, tooth enamel & specialised epithelium in mouth & nose

Question 13

What is the neural crest responsible for developing?

Answer 13

• develops into peripheral NS, adrenal medulla, melanocytes, facial cartilage & dentin in teeth

Question 14

What is the neural tube responsible for developing?

Answer 14

• develops into brain, spinal cord, posterior pituitary, motor neurons & retina

Question 15

Describe Embyronic Stem Cells

Answer 15

• relates to cells that originate from inner cell mass blastocysts
• usual source is left over embryo’s from fertility treatment
• high proliferative capacity & can potentially be maintained indefinitely in correct culture environment

Question 16

What are blastocysts?

Answer 16

• these are fertilised eggs grown in vitro for 4-5 days

Question 17

Describe Bone Marrow Stem Cells

Answer 17

• mesenchymal stem cell from bone marrow are often considered
• typically expresses cell amrkers such as CD29, CD44, CD73 & CD166

Question 18

Describe iPS cells

Answer 18

• induced pluripotent stem cells
• have pluripotent gene inserted into their genome by various means in the lab & then become pluripotent

Question 19

Describe Osteogenic differentiation of mesenchymal stem cells

Answer 19

• MSC give rise to osteoblasts to form bone
• process starts with commitment of osteoprogenitor cells & differentiation into pre-osteoblasts which eventually develop into mature osteoblasts
• these mature osteoblasts will become entombed in osteoid to become osteocytes

Question 20

Describe Adipogenic differentiation of mesenchymal stem cells

Answer 20

• Sinal et al characterised adipogenesis in 2 phases; determination & terminal differentiation phase
• determination = multipotent MSC commit to the adipocyte lineage & preadipocytes have a fibroblastic phenotype
• terminal differentiation = preadipocytes become adipocytes & acquire new functions; lipid synthesis & storage