3D tissue and organ printingIB MYP Biology: Revision notes
Section 1
What is bioprinting?
Bioprinting is a type of 3D printing that builds living tissue. A computer-controlled nozzle deposits bioink, a gel containing living cells and nutrients, in thin layers. The layers build up into the shape of a tissue or organ.
- A tissue is a group of similar cells doing a job (for example skin).
- An organ is made of several tissues working together (for example a kidney).
Section 2
How tissue is printed
- Cells are taken from the patient or grown from stem cells and mixed into a gel to make bioink.
- A computer design tells the printer where to place each layer.
- The nozzle prints the layers of cells, one on top of another.
- The printed tissue is kept in a warm incubator with nutrients so that the cells stay alive, respire and grow together.
The cells of a printed tissue divide by mitosis, so the tissue can grow and join up.
Section 3
Uses in transplants
Printing tissues and organs from a patient's own cells could:
- Reduce the rejection of transplants, because the cells carry the patient's own antigens
- Mean patients do not need lifelong immunosuppressant drugs
- End the shortage of donor organs and long waiting lists
Printed skin has been used to treat burns, and printed cartilage has been tested.
Section 4
Uses in drug testing
Printed human tissue, such as liver tissue, can be used to test new drugs to see if they are harmful or work.
- The tissue is human, so it may respond more like a human than animal tests
- It reduces the number of animals used in testing
- Many samples can be tested quickly at different concentrations
- It is less useful for whole-body effects, because it is only a piece of tissue
Section 5
Current limits
- Blood vessels: thick tissues and organs need a network of blood vessels to supply every cell with oxygen and nutrients, and these are very hard to print.
- Complexity: organs contain many types of cell in precise patterns.
- Cost: printers and materials are expensive.
- Testing: printed organs have not yet been used in patients, and long-term safety is not known.
- Ethics: questions about fair access and where cells come from.
When you evaluate bioprinting, include both a benefit (such as less rejection) and a limit (such as blood vessels or cost), then give a judgement.
That's the notes covered.
Carry on to the next subtopic.
Exam questions on 3D tissue and organ printing
- A hospital research laboratory in Singapore uses a bioprinter to make small pieces of human skin. A computer controls a nozzle that deposits a gel containing living human skin cells and nutrients, one thin layer at a time, to build up the tissue. The printed skin is then placed in a warm incubator.Explain why the printed skin must be kept in a warm incubator with nutrients after printing.2 marks
- In many countries, patients with kidney failure wait years for a donor kidney. A donated organ must match the patient's tissue type, otherwise the patient's immune system may attack it and reject it, so patients take drugs that weaken their immune system for the rest of their lives. Researchers hope one day to print a replacement kidney using cells taken from the patient.Describe two advantages of a printed kidney made from the patient's own cells compared with a donor kidney.2 marks
- A pharmaceutical company wants to test a new drug for its effect on the liver. Scientists print human liver tissue and place 20 samples of it in each of four solutions containing 0, 10, 50 and 100 micromolar concentrations of the drug for 48 hours. They then count the percentage of cells that are still alive. The mean percentages of living cells were 98%, 95%, 71% and 32% respectively.Explain why the scientists included samples with 0 micromolar of the drug and used 20 samples at each concentration.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).