lecture 5 - mesenchymal stem cells Flashcards
What are the characteristics of young MSCs in culture?
They form adherent, spindle-shaped, fibroblastic colonies in culture. Early cultures express multiple mesenchymal lineage markers: lack of commitment
What are the three main lineages that MSCs can differentiate down?
Adipogenic (fat), chondrogenic (cartilage) and osteogenic (bone) - they all require different regulatory signals
What conditions are required for differentiation down these pathways?
Adipogenesis - IBMX, dexamethasone, insulin and indomethacin
Chondrogenesis - high density, TGF-B3, serum-free
Osteogenesis - dexamethasone, B-glycerol phosphate, ascorbate, BMP-2 and bFGF
What are the defining characteristics of MSCs?
Adherence to plastic in culture, expression of CD105, CD73 and CD90, lack of expression of other CDs, differentiation into bone, cartilage and fat
These markers are not exclusive to MSCs and selection based on them can produce a mixed population of cells
Why is heterogeneity important?
Important when selective source of therapeutic cells: easy to isolate from bone marrow and fat, but difficult to isolate from cord blood
What is the importance of the MSC niche?
Niche is vital for the cell - all cells are in subtly different environments
Complex interplay of these conditions throughout the body
Evidence suggests MSCs exist in a perivascular niche
How can phenotype of MSCs be regulated (experiment)?
When cultured on a soft surface over time, they formed spindly projections (neuronal-like)
The stiffer the surface, the more the cells spread out over the substrate
Neuronal genes were unregulated on the soft substrate
Therefore, can conclude that stiffness of substrate affects the fate of the cell
What are the three possible roles of MSCs?
Providing daughter cells that differentiate and participate in repair
Homing to distant sites of injury
Secretion of factors that support wound repair by recruiting other cell types and modulating the immune response
What are the roles of MSCs in paracrine functions?
extracellular vesicles may play a significant role in the paracrine functions of MSCs, educating target cells
They fuse with the recipient cell and release their content - the mRNA is released into the host of the recipient cell, and it is translated into protein
IL10 is then produced
What are some medical applications of MSCs?
They have immunomodulatory functions - may be useful in treatment or prevention of GVHD. Potential therapy following stroke, heart attack or other injury. Tissue engineering
How can MSCs be used in myocardial infarction?
Could potentially recruit cardiac progenitor cells and cardiac stem cells
Could undergo cardiac myogenesis to regenerative heart tissue
How are MSCs implicated in cancer?
Inflammatory cytokines are strongly involved in mobilisation of MSCs and homing to tumours
MSCs can differentiate into a number of different useful cells, but in a tumour, they can differentiate into cells that promote the growth of the tumour
Hypoxia, ECM composition, extracellular acidity and inflammatory component of the storm are crucial mediators of the outcome of MSC action in tumours
How can MSCs be primed?
Toll-like receptors - activate immune cells via binding of pathogen-derived molecules
Secretion pattern of LPS-treated (LPS = antagonist) cells appears to favour pro-inflammatory mediators
How can MSCs be used as a cancer treatment?
Combination cell-gene therapy
MSCs transfected with a gene called TRAIL - will induce apoptosis in cells
Because they home to tumour sites, they localise themselves at the tumour and start producing an anti-tumour protein
Targeted cell-based therapy that find their way to the tumour
can also be used to deliver micro-RNAs - help down regulate various aspects that promote tumour growth and survival
they release the drugs into the microenvironment of the tumour
