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91 Stem Cells, Ethics, and Bioartificial Organs This includes developing theories and processes around stem cells and developing and using bioartificial organs. During this research, there is the chance that some of these animals may experience harm. How much depends greatly on the way they are treated and the research involved. Many countries have strict guidelines as to when and how animals can be used in research. These are often based around the 3Rs principle of replacement, reduction, and refinement.
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Key Idea: Using animals in scientific and medical research helps to understand and test new theories and medicines, but must be done in a way that minimises animal discomfort. The use of animals in scientific research has played a vital role in many advances in science and medicine. Animals (often specially bred rats or mice) are used as models of how a human system might work and are the basis for preliminary research that might later be applied to humans.
The 3Rs of ethical research
Stem cells, bioartificial organs and ethics ``Bioartificial organs are grown using a scaffold implanted
The 3Rs are guiding principles for the use of animals in research, testing, and teaching. Animals should only be used when there are no alternatives, any harm must be measured against the benefits, and those harms must be minimised.
``Replacement: Can animals be replaced in the research?
In many cases computer modelling can produce highly accurate results and can easily be used to identify unforeseen problems and refine tests. This reduces the need for animal testing, so that it occurs in the latter stages of the research (if at all).
with stem cells. These are cultured to grow and differentiate around the scaffold to produce a functional three dimensional organ (or part of an organ). Currently only simple organs or sections of organs can be grown but research is constantly producing new developments (e.g. new materials and techniques).
``Ethical issues can arise from this kind of research. Often animals are used to practice and develop techniques and this can cause them considerable distress (see below).
``Reduction: Only the minimum number of animals needed ``Refinement: Investigations should be reviewed to identify
where the number of animals used could be reduced. This information can then be applied to refining subsequent investigations.
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to produce reliable or statistically significant data should be used.
Engineered vascular tissue (blood vessel). The scaffold can be seen supporting the outer cells.
Using bioartificial tissue to replace a jaw
Bones can be replaced using titanium but this means a loss of bone marrow, which plays an important role in the body. In 2016, researchers began trials on growing new bone for transplant.
``The experiment was carried out on Yucatan
miniature pigs because the jaw structure is similar to humans. The researchers took part of a cattle thigh bone and removed all the cells and tissue, leaving just the bone structure. They then carved the bone into the shape of part of the pig mandible.
Bovine thigh bone decelled and carved to shape.
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Pig stem cells
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``This bone scaffold was seeded with pig stem cells and placed into a bioreactor. The cells developed into bone cells and grew into and around the scaffold (this took about 3 weeks). The matching part of the pig mandible was removed and the bioartificial jawbone implanted.
Bone scaffold seeded with stem cells and grown in bioreactor.
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Bone implanted into pig.
``Six months later the implants had fully grafted and the pigs were able to use their jaw normally.
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1. As a group discuss why the experiment on pigs jaws above was carried out and its pros and cons. Discuss likely ethical issues in relation to the pigs and if you think the experiment was worth carrying out. Summarize your discussion below: