Regenerative Medicine and Stem Cell Therapies

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1 Regenerative Medicine and Stem Cell Therapies

2 Regenerative Medicine Major component of successful regenerated / tissue engineered organs Scaffolds A critical element is the binding of the repopulating cells to a skeleton that approximates or is exactly like the organ being replaced or repaired Many reports of delivered stem cells not staying anchored, migrating to new sites or simply not surviving Artificial vs natural materials Early attempts often included the need to surgically remove the scaffold after cells / tissue / organ became established

3 Regenerative Medicine Scaffolds Several different materials have been discovered / developed that have the characteristic of dissolving Decellularization (aka, recellularization) Typically uses sodium dodecyl sulfate (SDS) and PBS to remove cells Leaves complex natural scaffold and extensive capillary system The matrix releases chemical signals that lead to the repopulation by stem cells and generation of a functional organ Successful human trials Bladder trachea

4 Regenerative Medicine Scaffolds - decellularization Successful animal trials Lungs kidneys Heart Tengion trials in animals where a partially repopulated organ (e.g., kidney) is returned to the animal donor species where indoginous signals lead to growth of functional organ

5 Regenerative Medicine Scaffolds Decellularization Some controversy re: immune response Inflammation Macrophage T-cell (T H 1 Vs T H 2) both allogeneic and xenogeneic Considered a steping stone technology Currently unable to create a totally artificial scaffold Eventually, will be successful, removing the need for donor organs

6 Regenerative Medicine Using Stem Cells aka, tissue-engineering Approaches Seeding scaffolds to grow and differentiate into organs May or may not include other multi- and/or uni-potent cells What are the required / desired signals for proper differentiation?

7 Regenerative Medicine Approaches Direct delivery Injection at the actual site of injury Via the bloodstream Applications in pre- and clinical trial Several heart conditions Bone repair diabetes

8 Stem cell types in therapies Human embryoninc stem cells Mostly used in research, little to none in clinical trials More nebulous is the role of umbilical cord cells Adult stem cells 2 types, multipotent (aka, tissue specific) Mesenchymal cells Sourced from bone marrow, adipose tissue, et al Induced Pluripotent Stem Cells (ipscs)

9 Adult Stem Cells Tissue specific stem cells Difficult to find, isolate and expand Little investigation into the use of these cells for therapeutic use Mesenchymal stem cells Easy to obtain Adipose tissue has nominally the highest density From humans liposuction waste Easy to expand Basic stem cell culture techniques Easy to manipulate

10 Mesenchymal Stem Cells Autologous and allogeneic Patient specific Real possibilities for production Therapies (tissue-engineering) Cardiomyocyte replacement following myocardial Infarct (MI) Bone - muscle Cartilage - marrow stroma Tendon - other connective tissue

11 Mesenchymal Stem Cells (MSC) Secrete spectrum of bioactive molecules Many are immunosuppressive => allogeneic treatments Query is it the MSC that is the agent of repair or the bioactive molecules; can the cells be eliminated in favor of just the appropriate bioactive molecules? Provide a regenerative microenvironment for a variety of injured adult tissues to limit the area of damage and to mount a self-regulated regenerative response Can be delivered to sites of injury by the bloodstream, i.e., by injection

12 Induced Pluripotent Stem Cells (ipsc) Theoretically, from any somatic cell by reprogramming Yamanaka cocktail Oct4, Klf4, SOX2, c-myc (aka, OKSM) High potential for Proliferation Self-renewal Pluripotent differentiation Patient-specific therapy Avoid immune rejection or harsh immunosuppressive drugs Fewer ethical issues

13 Induced Pluripotent Stem Cells (ipsc) Possible to correct genetic defect Genetically alter ( fix ) somatic cell CRISPR/CAS-9 Reprogram into ipsc Return normal cell to patient Already done in rodents Model for sickle cell anemia Generate dopaminergic neurons to mitigate Parkinson s disease (rat model)

14 Induced Pluripotent Stem Cells (ipsc) Used to make some disease models Often difficult to find in animal models or cell culture assays Modified (CRISPR/ CAS-9) to generate cell-level models Cardiomyocytes with heart disease Juvenile on-set type I diabetes Parkinson s disease ALS other

15 Induced Pluripotent Stem Cells (ipsc) Many challenges still faced OKSM reprogramming efficiency is low Some cell systems, 0.001% up to 1% Practice and experimentation is improving this aspect When using multiple or even single carrier Commonly use lentivirus, up to four Random genome insertion Increased risk that the insertion point is in a critical site In a gene Causes oncogene activation

16 Induced Pluripotent Stem Cells (ipsc) Many challenges still faced Tumorogenicity is still a problem Some success in leaving out the c-myc insert C-Myc is a major source of the oncogenic activity There is no current practical strategy for Consistant ipsc differentiation Purification of desired differentiated cell product Failure to meet clinical standards Recent study indicates that ipscs may be more immunogenic than originally thought.