Ch 3 - Stem Cells and Regenerative Medicine Flashcards
List the three main classes of naturally occuring stem cells
- Embryonic stem cells (ESC)
- Adult Stem Cells (ASC)
- Foetal/perinatal stem cells (FSC)
4th category - Induced pleuripotent stem cells (IPSC)
List and describe the different types of potency of stem cells
-** Totipotent** - Can differentiate into cells from each of the germ layer lineages (endoderm, mesoderm, ectoderm) as well as extra-embryonic tissue
-** Pleuripotent** - Capacity to differentiate into cells from more than one germ layer lineage but NOT extraembryonic tissues
- **Multipotent **- Differentiation is restricted to the germ layer lineage from which they originate
List concerns regarding the use of embryonic stem cells
- Ethical concerns regarding harvesting
- Tumourigenic potential of teratoma formation when implanted into immune compromised adult animals due to dysregulated cell division and differentiation
List the three best-characterisied examples of adult stem cells
- Haematopoietic stem cells
- Mesenchymal stem cells
- Neural stem cells (dentate gyrus of the hippocampus)
Where are perinatal stem cells harvested from?
-Umbilical cord
- Amniotic fluid
- Foetal membranes
These are multipotent but may have superior expansion potential, increased plasticity and superior immune privilages when compared to ASC
How are induced pleuripotent stem cells generated?
By directly reporgramming adult somatic cells. Retroviral and lentiviral vectors most commonly used (risk of insertional mutagenesis or oncogene transformation). Adenoviral and sendai viral vectors have been successfully used for integration-free viral delivery to overcome these issues
Where do mesencymal stem cells reside?
In all adult somatic tissue in perivascular locations
Describe the 2 morphologically diverse mesencymal stem cell populations within a single colony
- Small, rapidly self-renewing cells (RS cells)
- Larger, more slowly replicating cells
RS cells are superior at slineage-specific differentiation and predominate for the first 4-5 passages/replication cycles
List the 4 features which define a mesencymal stem cell
- Adhere to tissue culture plastic and exhibit a spindle-shaped appearance
- Form colonies of cells from single parent cells
- Express a specific set of surface marker proteins that exlude it from haematopoeitic lineages
- Ability to differentiate into osteoblasts, adipocytes and condrocytes (i.e trilineage differentiation)
What features of mesenchymal stem cells make them excellent candidates for regenerative medicine?
- Can be isolated from adult tissues
- Undergo rapid, but not limitless, proliferation to produce massive numbers of cells
- Unlikely to induce an immune response when used in an autologous manner
- Produce a number of anabolic and antiinflammatory agents (TSG-6, IL-1ra, PGE2)
What to canine MSCs require to undergo consistent, robust, osteogenic potential?
BMP-2
Where are MSCs most commonly isolated from in humans?
In animals?
- Bone marrow aspirates
- Lipoaspirates
Animals
- Bone marrow aspirates
- Enzymatic digestion of adipose tissue
What is an alternative to culture-expanded mesencymal stem cells?
Unprocessed, minimally manioulated preparations of tissues that can be rapidly generated at point of care eg. Bone marrow concentrate (BMC) or stromal vascular fraction (SVC)
What are the options of MSC administration?
- Intravascular infusion (cytotherapy) - less than 5%of cells successfully migrate to location of injury and survive
- Direct implantation/injection (eg, seed onto a scaffold, intra-articular injection) ‘tissue engineering’
What are the main limitations/concerns regarding mesenchymal stem cell therapy in small animals
- Gaps in knowledge
- Inherent variability in product
- Access to facilities and expertise
- Increasing federal oversight (FDA has banned in humans in many states)
- Unknown safety - stimulate growth of neoplasms? Increased risk of infection?
- Administration of IV bolus has risk of microvascular embolisation and ischaemia
- Current lack of strong evidence
Kadiyala et al…
First describes osteogenic and chondrogenic differentiation of bone marrow derived canine MSC
2005, Volk et al…..
Evaluated osteogenic differentiation potential of marrow-derived MSC in 19 dogs - necessary to supply with BMP-2
2008, Neupane et al…
Completed most comprehensive characterisation of adipose-derived mesenchymal cells. Tend to proliferate more rapidly, preparation and handling effects proliferation rates
2007 Black et al…
Evaluated effect of single intra-articular injection of stromal vascular fraction celss in 18 dogs with hip OA - significant improvement in lameness and function at 3m
Follow-up study - Single injection in 14 dogs with elbow OA - outcomes improved 30-40% comapred to baseline
Nishida et al…
Weekly injections of bone marrow derived MSC into spinal cord lesion causing lack of deep nociception. No complications but no improvement
Penha et al….
treated 4 dogs with longstanding neuro dysfunction from IVDD with intralesional bone marrow derived MSC. Reportedly improvements at 18m but not changes on MRI and were also having long-term physio
Studies evaluation MSC treatment in cats…
- Quimby et al - Safetly of systemically administered adipose derived stem cells to cats with CKD - adverse rxn from allogenic thawed cells at higher dose
- Webb et al - allogenic MSC for Tx of chronic enteropathy. 5/7 significant improvement or resolution
- Arzi et al - Cats with chronic gingivostomatitis Tx with 2 injections of autologout adipose derived MSC. 5/7 either complete remission or sunstantial improvement.
