SCRM Flashcards
What are the types of stem cells?
→embryonic
→induced
→pluripotent
What is the origin of embryonic stem cells?
→pre-implantation embryo
Give examples of stem cells uses
→ Model for basic and translational studies →Cell replacement therapy →Cell differentiation →3D organoid models →Drug screening
What can endodermal line differentiate into?
→lung
→pancreas
What can mesodermal line differentiate into?
→heart muscle
→RBCs
What can ectodermal line differentiate into?
→skin
→neuron
How are tissue specific stem cells maintained?
→special supportive microenvironments called stem cell niches.
What are the features of stem cell niches?
→Supporting ECM
→neighbouring niche cells
→secreted soluble signalling factors (e.g. growth factors and cytokines)
→physical parameters; shear stress, tissue stiffness, and topography),
→environmental signals (metabolites, hypoxia, inflammation, etc.).
What are the advantages of ESCs
→pluripotent- differentiate into any type of cell
→unlimited growth potential, high cell potency
→very low probability of mutation-induced damage in DNA
What are the disadvantages of ESCs?
→higher risk of tumour creation- spontaneous disease
→risk of being genetically different from the recipient’s cells- rejection
What are the advantages of adult stem cells?
→compatible with recipient’s cells- low risk of rejection
→less risk of tumour creation
What are the disadvantages of adult stem cells?
→oligopotent, limited cell potency
→limited numbers may be obtained
→higher probability of mutation induced damage of DNA
What are the advantages of induced pluripotent stem cells?
→low risk of rejection
What are the disadvantages of iPSCs?
→low growth potential
→low risk of tumour formation
→rather limited numbers may be induced
→higher probability of mutation induced damage of DNA
What do iPSCs and ESCs have in common?
→cells have a similar global gene expression profile to that of ES cells
Describe how iPSCs are generated?
→c-Myc promotes DNA replication and relaxes chromatin structure,
→allows Oct3/4 to access its target genes.
→Sox2 and Klf4 also co-operate with Oct3/4 to activate target genes
these encode transcription factors which establish the pluripotent transcription factor network
→result in the activation of the epigenetic processes (more open chromatin) that establish the pluripotent epigenome.
What are the pluripotent factors involved in iPSCs generation?
→c-Myc
→Oct3/4
→Sox2
→Klf4
What factor does Klf4 and Sox2co-operate with?
→Oct3/4
What type of chromatin is present in pluripotent iPSCs?
→most of the chromatin exists as euchromatin
→bearing histone marks associated with transcriptional activity
What is adult cardiomyocyte turnover like?
→low
What are the two types of regenerative strategies?
→Cell transplantation
→direct stimulation of endogenous cardiomyocyte production
What is cell transplantation aimed at?
→replenishing lost cardiomyocytes.
What are the challenges of cell based regenerative therapies?
→Immune rejection, manufacture
→isolation of sufficient cells, mode of delivery
→clinical regulation all challenges.
What does cell free regenerative therapy involve?
→re-activation of developmental pathways e.g. epicardium based on models where the is no/reduced scarring and full cardiac regeneration
What is neovascularisation?
→Improved circulation to injured area
→Paracrine effects improving CM replacement
What is reactivation of epicardium important for?
→coronary blood vessels
Compare immune response of CV disease in adults and neonatal
→adults= monocytes derived macrophage, no CM proliferation, and limited vascularisation
→fibrotic scar, contractile dysfunction
→neonatal= infiltration of injury by embryonic macrophages, and cardiomyocytes proliferation, and CM revascularisation
→functional recovery
How are cardiac lineages from iPSCs made?
→Somatic cells are reprogrammed by Ymanak factors eg OCT4 and Sox2 to make iPSCs
→iPSCs exposed to GSK3b inhibition to make pre-cardiac mesoderm
→Wnt signalling inhibition to make CV progenitor cells
→exposed to TGF-b, PDGF, VEGF to make specialised cardiac cells
What is necessary for epicardial migration and coronary vasculature in developmental gene activation?
→Myocardial thymosin β4
What does addition of Tb4 to adult hearts do?
→stimulate epicardial outgrowth and neovascualarisation
What is involved in transplantation and paracrine signals in CV regeneration?
→grafting sheet cells onto a heart
→cells do not seem to integrate into the heart tissue. Instead, they may release paracrine factors that help to regenerate the damaged muscle.
What is lost in a MI?
→Epicardial expression
→FSTL1 in the epicardium has potent cardiogenic activity
What is involved in stem cell therapy for cancer?
→Effector immune cells from iPSC/ESCs e.g. engineered T and NK cells targeted for immunotherapy.
→MSCs/NSCs deliver genes, nanoparticles, and oncolytic viruses to tumour niche
→Mutation correction in vitro, drug testing in vitro before replacement in vivo.
How are burns treated?
→Generate ECM and produce paracrine signals which aid healing
What are the different types of stem cells involved in burn therapy?
→fetal fibroblasts from ESCs
→epidermal stem cells
→mesenchymal
→iPSCs
How are fetal fibroblasts used in burn therapy?
→improve skin repair due to the high expansion ability,
→low immunogenicity,
→intense secretion of bioactive substances such asFGFs, VEGFs, KGFs
What do fetal fibroblasts secrete?
→FGFs, VEGFs, KGFs
Why are epidermal stems cells used in burn therapy?
→high proliferation rate
→easy access
→keep their potency and differentiation potential for long periods.
→Generate most skin cell types for repair and regeneration
Why are MSC used in burn therapy?
→They have a high differentiation potential
→a certain degree of plasticity.
→Migrate to the injured tissues, differentiate,
→regulate the tissue regeneration by the production of growth factors, cytokines, and chemokines
Why are iPSCs used in burn therapy?
→can be differentiated into dermal fibroblasts, keratinocytes, and melanocytes
What are limbal stem cells?
→Stem cells at the edge of the cornea
What happens if limbal cells ate lost?
→cornea can no longer be repaired
How are limbal cells used to treat eye injury or disease?
→Limbal stem cells are collected from an adequately healthy donor eye
→are expanded in the laboratory to sufficient number
→transplanted into the damaged eye
→Repairs the cornea and permanently restores vision.
How is rejection avoided in eye injury therapy?
→works if the patient has a healthy section of limbus from which to collect the limbal stem cells.
How is iPSCs used to treat eye injury?
be induced to make corneal epithelial cells for transplant
→exposure to the right signals can transform fibroblast cells into limbal stem cells
What is RPE?
→Retinal pigment epithelium (RPE) is a single layer of post-mitotic cells, acting as a selective barrier to and a vegetative regulator of the overlying photoreceptor layer
What can happen to the eye without RPE?
→parts of the retina can die
How can the RPE be damaged?
→age-related macular degeneration (AMD),
→retinitis pigmentosa
→Leber’s congenital aneurosis.
How can RPEs be made?
→ESC and iPSC
How are iPSCs used to treat spinal injury?
→somatic cells biopsies from patients
→transform into iPSCs
→differentiate into different neural cells
What results do NSPCs therapy in spinal injury show?
→can form functional synaptic subnetworks whose activity patterns resemble intact spinal cord
→grafts can integrate into sites of spinal cord injury (SCI) and generate neuronal relays across lesions
