From UPSC perspective, the following things are important :
Prelims level : Organoids
Mains level : Stem cells and their applications
- Scientists have raised ethical concerns over growing of mini-brains or organoids in the laboratory that can perceive or feel things.
What is an Organoid?
- Organoids are a group of cells grown in laboratories into three-dimensional, miniature structures that mimic the cell arrangement of a fully-grown organ.
- They are tiny organ-like structures that do not achieve all the functional maturity of human organs but often resemble the early stages of a developing tissue.
- Most organoids contain only a subset of all the cells seen in a real organ, but lack blood vessels to make them fully functional.
- In the case of brain organoids, scientists have been able to develop neurons and even make specific brain regions such as the cerebral cortex that closely resemble the human brain.
- The largest brain organoids that have been grown in the laboratory are about 4 mm in diameter.
How are organoids grown in the laboratory?
- Organoids are grown in the lab using stem cells that can become any of the specialised cells seen in the human body.
- They could be grown from stem cells taken from the organ or adults cells that have been induced to behave like stem cells, scientifically called induced pluripotent stem cells (iPSC).
- Stem cells are provided with nutrients and other specific molecules to grow and become cells resembling a specific organ.
- The growing cells are capable of self-organising into cellular structures of a specific organ and can partly replicate complex functions of mature organs.
- Organoids of the brain, small intestine, kidney, heart, stomach, eyes, liver, pancreas, prostate, salivary glands, and inner ear to name a few have already been developed in the laboratory.
Significance of Organoids
- Organoids offer new opportunities to studying proteins and genes that are critical for the development of an organ.
- This helps in knowing how a mutation in a specific gene causes a disease or disorder.
- Researchers have used brain organoids to study how the Zika virus affects brain development in the embryo.
- Scientists are already using stem cells taken from tumours to grow organoids that are poised to develop cancer.
- The ability to grow organoids using cancer stem cells allows researchers to study the genes, proteins and signalling pathways that cancer cells use to develop and grow.
- They are also using healthy organoids to identify and verify the gene mutations that cause cancer.
Why are scientists concerned?
- Researchers have turned to generating organoids using stem cells. They have been successful in generating organoids of increasing “complexity and diversity”.
- Since the organoids closely resemble mature tissues, it opens up new vistas.
- Organoids can be used to study the safety and efficacy of new drugs and also test the response of tissues to existing medicines.
- Organoids will bring precision medicine closer to reality by developing patient-specific treatment strategies by studying which drugs the patient is most sensitive to.
- Since the use of animals during drug development studies is becoming increasingly difficult, the focus has been on refining, reducing and replacing them.
What are the ethical challenges of growing organoids?
- Scientists argued that the largest brain that has been grown in the laboratory is only 4 mm in diameter and contains only 2-3 million cells.
- In comparison, an adult human brain measures 1,350 cubic cm, and has 86 billion neurons and another 86 billion non-neuronal cells and a similar number of non-neuronal cells.
- The authors argue that organoids do not have sensory inputs and sensory connections from the brain are limited.
- Isolated regions of the brain cannot communicate with other brain regions or generate motor signals.
- Thus, the possibility of consciousness or other higher-order perceptive properties [such as the ability to feel distress] emerging seems extremely remote.