Stem cells

Embryonic stem cells

How they are made

• 1) Sperm cell fertilises egg cell to produce a zygote
• 2) multiple zygotes then group together to form an embryo
• 3) These are known as embryonic stem cells and can differentiate into any type of specialised cell.

Extraction

• 1) extract embryonic stem cells from embryo
• 2) grow embryos in a laboratory
• 2) stimulate embryos to differentiate into specialised cell patient requires
• 3) replace patients faulty cells with new specialised cells

Adult stem cells

• Extracted from bone marrow of humans
• Can only differentiate into blood cells: RBCs, WBCs, platelets
• comes directly from patient so there is no lack of supply
• no risk of rejection as cells come directly from the patient

Plant stem cells

• Meristems - continually
• Meristems extracted from plants in tip of roots and tip of shoots
• Can be used to grow new plants quickly and economically
• Can be used to revive extinct plant species
• Rare plants can be mass produced for the benefit of farmers

Concerns

clinical

• No guarantee that treatment will be successful - rejection (embryo)
• Hard to find bone marrow donators - painful surgery
• Difficult for scientists to store embryos
• Stem cells can become contaminated and pass viruses onto patients
• could divide uncontrollably thus forming tumour

Ethical

• “thou shalt not kill” - opposes religious views
• embryo could develop into a human

\