Evaluate use of stem cells on treating human disorders
Laura Armstrong & Joe Wolfensohn
Teachers
Recall Questions
This topic requires prior knowledge of stem cells and iPS cells from A-level Biology. Test your knowledge on these topics below.
What are induced pluripotent stem cells (iPS cells)?
Adult somatic cells that are genetically reprogrammed to become pluripotent like embryonic stem cells.
What is a transcription factor
A protein that can bind to DNA at a promoter region to initiate transcription.
Bone marrow stem cells are multipotent, what does this mean?
Bone marrow stem cells can differentiate into a limited number of cell types- the blood cells- red blood cells, white blood cells and platelets.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains Evaluate use of stem cells on treating human disorders or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Medical Potential of Stem Cells
Stem cells can regenerate tissues, replace damaged cells, and model diseases. They could even be used to grow whole organs for transplant. However, each type of stem cell brings its own ethical, technical, and biological implications.
Embryonic Stem Cells (ESCs)
Advantages
- Pluripotent: Can differentiate into any body cell - ideal for repairing a wide range of tissues.
- Large supply from embryos (e.g. in IVF clinics).
- Can be grown and maintained relatively easily in culture.
Disadvantages / Issues
- Ethical concerns: Requires destruction of human embryos - some view this as destroying potential life.
- Risk of immune rejection: Cells are genetically different from the recipient.
- Risk of tumour formation: Due to their high rate of cell division.
- Legal and funding restrictions in some countries due to ethical debate.
Example Uses
- Retinal repair in macular degeneration.
- Generation of insulin-producing beta cells for diabetes.
Adult Stem Cells
Advantages
- Fewer ethical concerns: No embryos are used.
- Can be obtained from the patient’s own body (e.g. bone marrow), so no risk of rejection.
- The adult can give consent to use their stem cells.
- Already in use - e.g. bone marrow transplants are standard treatments for blood cancers.
Disadvantages / Issues
- Multipotent, not pluripotent: Limited to forming specific cell types (e.g. blood, skin).
- May accumulate mutations with age or be less effective in older patients.
- Scarcity: Some tissues have very few accessible stem cells.
Example Uses
- Bone marrow transplants.
- Experimental treatments for heart disease using cardiac stem cells.
Induced Pluripotent Stem Cells (iPS Cells)
Advantages
- Pluripotent: Like embryonic stem cells, can differentiate into most body cell types.
- Created from adult somatic cells - no embryo destruction required.
- Body cells can be taken from the patient themselves, reducing risk of immune rejection and they can provide consent.
Disadvantages / Issues
- The reprogramming process is complex and often does not work.
- Uses viral vectors that may randomly integrate into the genome, causing mutations or disrupting genes that regulate the cell cycle (such as tumour suppressor genes).
- Increases cancer risk.
- Cells may lose stability over time or differentiate unpredictably.
Example Uses
- Potential for treating Parkinson’s, type 1 diabetes, and spinal cord injuries.
- In vitro disease modelling and drug testing.
Comparative Evaluation Table
|
Aspect |
Embryonic Stem Cells |
Adult Stem Cells |
iPS Cells |
|
Potency |
Pluripotent |
Multipotent / Unipotent |
Pluripotent |
|
Ethical concerns |
High (embryo destruction) |
Low |
Low (no embryos used) |
|
Rejection risk |
Yes (unless matched or genetically altered) |
No (if from same patient) |
No (as body cells taken from patient) |
|
Tumour risk |
High (uncontrolled cell division of stem cells) |
Low (Their ability to self-renew and divide is more tightly regulated) |
High (viral vectors used and uncontrolled cell division of stem cells) |
|
Availability |
Readily available (from IVF embryos) |
Limited; some tissues hard to access |
Requires lab manipulation; not yet widely available |
|
Technical ease |
Easy to grow and maintain in lab |
Difficult to isolate and grow |
Technically complex; improving with research |
|
Legal limitations |
Subject to strict regulation in many countries |
Generally accepted |
Generally accepted |
Key Terms
- Pluripotent: Can differentiate into any body cell type.
- Multipotent: Can differentiate into several related cell types.
- iPS Cell: A somatic cell reprogrammed to a pluripotent state.
- Regenerative Medicine: The use of stem cells to replace, repair, or regenerate damaged tissues.
No answer provided.
Exam Tip
Be prepared for application and evaluate style questions on this topic. Make sure to practice the question provided below!
No answer provided.
Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of both men and women. Affected individuals have proteinuria (high quantities of protein in their urine).
Scientists investigated the use of transplanted stem cells to treat AS in mice.
The scientists set up four experimental groups.
Group A – 40 wild type* mice
Group B – 40 AS mice
Group C – 40 AS mice that received stem cells from AS mice
Group D – 40 AS mice that received stem cells from wild type mice
*Wild type mice are mice not affected by AS.
After 20 weeks, the scientists measured the quantity of protein in the urine using a scale from 0 (lowest quantity) to +++++ (highest quantity).
The results the scientists obtained are shown in below table.
|
Group |
Maximum quantity of protein in urine at 20 weeks |
Percentage of mice with this quantity of protein |
|
A |
0 |
100 |
|
B |
+++++ |
97.5 |
|
C |
+++++ |
100 |
|
D |
++ |
68 |
Using all the information, evaluate the use of stem cells to treat AS in humans. (5 marks)
Model answer:
- Effective as group D / mice that received wild type stem cells have lower protein (than B/C)
- Not fully effective as group D has higher protein than group A
- Do not know all results for other mice in group D / Only shows results for 68% of mice
- Some of group D may have been cured / Some of D may have died
- Do not know actual / numerical quantity of protein
- Investigation only on mice / Investigation not on humans
- Rejection / an immune response may occur
- Only shows results for 20 weeks / short-time period / long-term effects not known
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!