Stem Cells Flashcards
What is a stem cell?
- Indefinite Self-Renewal
- Differentiation into different types of cells
2 types of stem cells
Embryonic Stem Cells
Tissue Committed Stem Cells (adult or fetal)
Types of tissue committed stem cells
- Hematopoeitic (bone marrow)
- Messenchymal (bone marrow)
- Intestinal epithelial stem cells (intestines)
- Skin (Hair follicle)
- Neural stem cells (brain)
- Endothelial Progenitor (bone marrow)
Life cycle of Embryonic Stem Cell-ESC
Fertilized egg –> blastocyst –> ES cell colony –> Endoderm/mesoderm/ectoderm
What was the TRADITIONAL stem cell dogma?
Pluripotent -> multipotent -> differentiated
Cannot go the opposite way
What is the modern stem cell dogma?
Differentiated to Pluripotent possible!
How to generate human induced pluripotent stem cells?
collect blood –> transducer PBMC’s with STEMCCA –> Plate PBMC’s onto MEFs –> Pick iPSC colonies
What are iPSCs?
Induced pluripotent stem cells that can be generated directly from adult cells
They have been genetically reprogrammed to an embryonic stem cell-like state by being forced to express genes and factors
What are ESC?
Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of a blastocyst
What are multipotent cells?
They can develop into more than one cell type but are limited
I.e.: adult stem cells and cord blood stem cells
Blood cell development process
1) Hematopoietic stem cells (HSC- multipotent from mesodermal)
2) CMP (progenitor cell for granulocytes, monocytes, erythrocytes)
3) MEP- Megakaryocyte Erythroid Precursor cell
4a) Erythroblast –> Red Blood Cells
4b) Megakaryocyte –> Platelets
How are platelets generated in Vivo?
Bone Marrow Vascular endothelium produces SDF1 and FGF4 (chemokines) that promote Megakaryocyte homing and adhesion
Endothelial layer is sinusoidal- proplatelets are extended into the vasculature through these gaps
Shear forces cause the distal tip of the proplatelet to bleb off into circulation –> fully realized platelets
IPSC derived megakaryocytes can form these pro-platelets
Gene editing to transform mutated stem cells
Use Zinc-finger nuclease to cut out mutated part of the cell leading to corrected molecule
can be used for sickle cell
3 examples of cell specification
Hepatic
IPSC –> definitive endoderm –> hepatic lineage
Cardiac
IPSC –> cardio-meso –> cardiomyocyte
Neuronal
IPSC –> Neuro/ecto –> Neuron
IPSC for drug discovery
Patient with genetic disease –> collect peripheral blood from patient –> reprogramming virus –> reprogram into patient specific iPSC –> genetically identical disease-specific iPSC –> differentiate disease-specific iPSC into target cells –> utilize patient-specific target cells to screen for novel therapeutics
