Stem Cell Biology and Ethics Quiz

Overview of Stem Cell Therapies

• The presentation focuses on stem cell therapies, their current applications, and associated challenges
• Learning outcomes include defining stem cells, classifying stem cell types, describing therapeutic applications, and discussing current limitations
• The lecture will cover parts on what stem cells are, stem cell classification, translation to the clinic, and current applications of stem cell therapies

Stem Cell Therapies: Regenerative Medicine

• Why use stem cells? A major shortage in donated organs and the incompatibility of available organs necessitates the search for alternatives like stem cell therapies. 103,223 people are on the national transplant waiting list in the U.S.
• How do stem cells work? Stem cell therapies aim to repair/replace tissues or organs, rather than merely treating symptoms. This involves replacing damaged or defective cells with new, healthy ones.
• Stem cell sources: Isolated or induced stem cells are vital for this application

What are Stem Cells?

• Stem cells exhibit two defining qualities: self-renewal (ability to create more stem cells of the same type) and differentiation (the ability to develop into special cell types)
• There exist varying types of stem cells, including hematopoietic stem cells, mesenchymal stem cells among others

Stem Cell Classification

• Totipotent: Stem cells capable of giving rise to an entire organism (e.g., a zygote)
• Pluripotent: Stem cells generating all three germ layers (mesoderm, endoderm, and ectoderm) (e.g., embryonic stem cells, induced pluripotent stem cells)
• Multipotent: Generating multiple cell types within a specific lineage or tissue (e.g., adult stem cells)

Embryonic Stem Cells (ES Cells)

• Murine ES cell lines were first established in 1981
• Human ES cell lines were first derived in 1998
• ES cells are derived from excess IVF eggs donated for research

ES Cells and their Potential

• ES cells proliferate indefinitely, maintaining their pluripotent state
• They can differentiate into various cell types including neurons, blood cells, cardiomyocytes, and liver cells
• Essential for in vitro studies of developmental processes otherwise not assessable
• Crucial in disease modeling research (genetic diseases, human-host pathogen interactions, organoid research)
• Hold great potential in advancing cell therapy (transplantation to patients of cells differentiated from ES cells)

Limitations of ES Cells

• Ethical concerns arise around using human blastocysts (which are destroyed to obtain ES cells). Strict regulations may be in place in various regions.
• Allogeneic transplantation of ES cells (from a different organism) can trigger immune rejection if the human leukocyte antigen (HLA) haplotypes do not match.
• Biobanking (creating a bank of ES cells with common HLA haplotypes) offers a solution to the immune rejection problem. A significant number of HLA-typed cell lines (150) are required to cover a large section of the population.
• Somatic cell nuclear transfer (SCNT) can be used to create cells with a matching patient HLA. The technique involves the reprogramming of adult cells.

Somatic Cell Nuclear Transfer (SCNT)

• John B. Gurdon's pioneering work in this field earned him the Nobel Prize for the discovery in 2012 of reprogramming mature cells into pluripotent ones
• The process of SCNT includes steps where a nucleus is transferred from a donor cell to an enucleated egg cell to generate a new embryo. Dolly the sheep (1996) is a significant example

Therapeutic Cloning

• An application of SCNT
• Using the body's own cells to create needed cells

Induced Pluripotent Stem Cells (iPSCs)

• In 2006, Shinya Yamanaka's lab showed that fully differentiated somatic cells can be reprogrammed into a pluripotent stem cell state. This is a crucial discovery in stem cell research.
• iPSCs offer advantages analogous to ES cells but without the ethical concerns or the need for donor eggs.
• iPS cells are easily accessible and vastly renewable (no limit to obtaining more iPSCs). Cell numbers are not a limitation; they can be made and stored.
• iPSCs can be generated from a variety of somatic cells (blood, keratinocytes, fibroblasts, hepatocytes). This allows iPSCs to be personalized to the patient (or non-immunogenic).

Limitations of iPSCs

• Risk of incomplete differentiation of some iPSC-derived cells
• Potential for genomic and epigenetic alterations in iPSC-derived cells.
• Risk of tumorigenicity due to insufficient silencing of oncogenic transcription factors like Myc and Klf4
• Personalized medicine may present challenges in terms of practical application, with some needing 10 months or more of the wait and nearly US$1 million in costs for retinal pigment epithelium (RPE) iPSC-derived cell operations.

Multipotent Stem Cells

• Multipotent stem cells generate multiple types of cells within a specific lineage or tissue (e.g., adult stem cells)
• Sources (e.g., brain, spinal cord, liver, blood vessels, pancreas, skin epithelia) are often hard to isolate

Hematopoietic Stem Cells (HSCs)

• Most widely transplanted stem cells in stem cell therapies
• Transplanting HSCs to the bone marrow replenishes the patient's hematopoietic system.
• HSCs have been widely used in treating diseases like leukemia.

History of HSC Transplantation

• The aftermath of World War II led to methods for reversing the death effect from radiation, which involved transplanting bone marrow.
• In 1956, Dr. E. Donnall Thomas performed the first successful HSC transplant, curing leukemia in an identical twin recipient.

Considerations for HSC Transplantation

• Graft-versus-host disease (GVHD)
• Conditioning regimens (1980s and 1990s)

Autologous vs. Allogeneic HSC Transplantation

• Autologous uses the patient's own cells.
• Allogeneic involves using cells from a donor, which can lead to graft-versus-host disease.

Indications for HSC Transplantation

• Several diseases, including malignancies (multiple myeloma, leukemia) and non-malignant disorders (autoimmune diseases), are treatable with HSC transplantation.

Mesenchymal Stem Cells (MSCs)

• MSCs differentiate into osteocytes, chondrocytes, and adipocytes.
• A variety of markers on the surfaces of MSCs have been identified but remain debated.
• Numerous clinical trials have investigated MSC use (nearly 1,000).

Mesenchymal Stem Cells (MSCs) - Clinical Use

• MSCs exhibit anti-inflammatory properties that can be used for tissue repair.
• They show short-term existence and thus can be allogeneically used in the clinic.
• Current MSC clinical trials focus on their immunomodulatory properties. Differences in their description and manufacturing processes exist.

Lecture Overview (Part 2)

• Translation to the clinic
• Current applications of stem cell therapies

Translation to the Clinic

• Consideration of translating stem cell therapies from research settings to real clinical applications.
• Overcoming the scarcity of stem cells
• Protocols for obtaining cells of interest
• Assessing safety of materials to be transplanted
• Efficient delivery methods

How to Overcome the Scarcity of Stem Cells

• Using alternate sources like cord blood, which contains HSCs. Cord blood can reduce HLA matching demands, lower GVHD risk, and increase donor availability.
• Expansion methods (i.e., expanding hematopoietic stem cells ex vivo: utilizing extracellular matrices, co-cultures, culture conditions, and small molecules like UM171, to enhance the growth of HSCs).

How to Design Protocols to Obtain Cells Relevant for Transplants from Stem Cells

• Implementing Good Manufacturing Practices (GMP) compliant protocols for optimal differentiation of cells from pluripotent stem cells
• Ensuring cells of interests are obtained (e.g., assessing markers)
• Conducting functionality testing for the cells

How to Ensure the Safety of Transplanted Material

• Identifying genomic integrity (checking for genomic insults, CNVs, SNP reprogramming errors and genetic mosaicism)
• Implementing a quality control list for iPSCs (e.g., short tandem repeat analysis, residual vector testing, karyotype, bacterial and viral testing, flow cytometry, phenotypic assays, and histone modification/DNA methylation)

How to Efficiently Deliver the Cells

• Creating and using bioengineered delivery systems such as biomaterials (cell sheets, injectable hydrogels, porous scaffolds nanoscaffolds, surface engineered materials, microencapsulation, and microengineered hydrogels) and using organoids.
• Exploring delivery strategies using transdifferentiation (reprogramming or differentiating cells into the desired cell type).

Disease Examples

• Parkinson's disease, utilizing either fetal tissue grafts or iPSCs. Lund University pioneered this area of research. Regulatory approval for a phase I Ila clinical trial of a new stem cell therapy for Parkinson's (STEM-PD) was secured
• IPSC-derived cell therapies are being trialled for various diseases (nervous system disorders, respiratory system disorders, immune system disorders).

Summary of Stem Cell Clinics

• There are numerous stem cell research labs throughout the world.
• The U.S. has businesses selling unproven or unlicensed stem cell interventions. This highlights the critical need for proper quality control checks.

Test your knowledge on embryonic stem cells, their characteristics, and ethical concerns surrounding their use. This quiz covers important concepts, methods, and challenges in stem cell research and therapy applications.