L4 - Stem Cells & Reproductive Ethics

what are stem cells

unspecialised cells that can reproduce indefinitely and differentiate into one or more specialised cells types

what are the 2 types of stem cells

embryonic and adult stem cells

what can stem cells do

generate tissues, organs or organisms

how many stem cell potencies is there

4

totipotent and example

generates all of the tissues of the embryo and the extra embryonic tissue such as the placenta, e.g. the zygote

pluripotent

generates cells from all three germ layers but not the extra embryonic tissue, e.g. embryonic stem cells

multipotent and example

ability to differentiate into multi lineages but not to all germ layers, e.g. mesenchymal stem cells

unipotent and example

ability to differentiate along only one lineage, e.g. most adult stem cells in differentiated undamaged tissues

what kind of stem cells are used in regenerative medicine and tissue engineering

totipotent and pluripotent stem cells

what type of potency do adult stem cells have

multipotent and unipotent

when are multipotent stem cells used

in treatments for blood disorders and tissue repair

when are unipotent stem cells used

for tissue-specific regeneration and repair

autologous

taken from an individual and returned to the same person

Allogenic

taken from an individual and returned to a different person

reproductive cloning - somatic cell nuclear transfer

the nucleus of a somatic cell from a donor organism is inserted into an egg cell that has had its nucleus removed. it is replaced with a nucleus of a differentiated cell. the egg is then stimulated to divide and develop into an embryo which can then be implanted into a surrogate mother to develop into a full organism

non-reproductive human cloning

the embryo is cultured for a short period and used to drive embryonic stem cells, these cells have the potential to develop into any cell type in the body offering possibilities for tissue repair, organ regeneration and the treatment of various diseases

what cells can be reprogrammed into induced pluripotent stem cells

somatic cells

what are the 2 major uses of human induced pluripotent stem cells

cell therapy - patients own cells reprogrammed into ips cells to replace nonfunctional tissue and for research and discovery - provide the cellular model of the disease to understand the disease/ develop treatments

who introduced ips cells and how

shinya yamanka achieved reprogramming of mature mammalian cells into stem cells by introducing a few genes

what are the advantages and disadvantages of ips cells

advs - can now make person specific cell lines and no embryos damaged, ethical alternative to human embryonic stem cells

disadvs - genetically modified and potential oncogenesis or damage to host genome

what are the ethical implications associated with stem cell research

embryonic stem cells are developed from embryos, harvesting them results in the destruction fo the embryo raising ethical concerns for individuals that think life begins during contraception

Stem cell research offers hope for treating diseases like Parkinson’s, spinal cord injuries, diabetes, and heart disease. Do the potential medical benefits justify the use of embryos in research

Access to treatments may not be accessible to everyone, risk of deepening healthcare inequalities, how can we ensure a fair distribution of the benefits

Regenerative medicine stem cell use

tissue and organ regeneration and mesenchymal stem cells repair bone and cartilage

treatment of degenerative diseases stem cell use

neurodegenerative disease - stem cells may replace lost neurons or support neural regeneration.

mesenchymal stem cells repair bone and cartilage

Blood disorders and cancer stem cell use

hematopoietic stem cells are used to treat leukemia and lymphoma, cancer treatment - replacing blood after chemotherapy

gene therapy stem cell use

Gene-editing tools like CRISPR can be used on patient-derived stem cells to correct genetic mutations before transplantation.

drug testing and disease modelling stem cell use

personalised medicine - stem cell derived tissues can be used as models for drug testing and new therapies

how are induced pluripotent stem cells created

adult somatic stem cells can be reprogrammed back into a pluripotent state

1. a sample of adult cells are collected by a donor

2. specific genes are introduced into the adult cells using methods like viral vectors

3. these genes reprogram the cells dna, turning it back into a pluripotent state

4. colonies of ipsc begin to form, these are then isolated and expanded