Category Archives: Stem Cells
Wow. Two papers published in Nature Methods have outlined a new technique which allows researchers to track development of embryos (in this case Drosophila melanogaster), in real time. By taking simulataneous multi-view microscopic images of the developing embryo, individual cells can be tracked in real time. The methods are described in more detail at Nature News here.
Have a look at the amazing results below, as a fruitfly embryo develops into a larva, ready to hatch. The two views are the dorsal (upper side) and ventral (lower side) view of the same embryo. See if you can pick a cell and watch its path of development.
Think about how this links to IB Biology topics of cell division, cell specialisation and embryonic development. How does a stem cell know what type of cell to become? If you look closely, there’s a scale bar in the bottom-right. Take a snapshot and calculate the actual length of the embryo.
For more reasons to love fruit flies, check out my mini-review of Fly: An Experimental Life by Martin Brookes.
Image source: Drosophila melanogaster, from Wikipedia.
With links to stem cells, genetic engineering and biotechnology, homeostasis and the kidney, the current science outlined in this TED Talk by Anthony Atala is amazing. It includes a demonstration of a real kidney being printed and a student who has an engineered bladder and now lives a normal life. Wow.
With huge numbers of people waiting for kidney transplants, is this the future of transplant medicine?
Thinking of kidneys, the Guardian has a link to an AP article: Mystery illness kills thousands in South America.
This visualisation of the role of breast stem cells was the winner of the award for Visual Science at this year’s Imagine Science Film Festival. Carl Zimmer was one of the judges and has posted more of the winning videos to his Discover blog.
For lots more quality visualisations, visit the Walter and Eliza Hall Institute’s YouTube channel.
The Imagine festival includes a $500 Budding Scientist award, open to High School students. Get working!
Here is a cute video called Do You Know What a Nano Is?
Yesterday, the European Court of Justice banned the issuing of patents for embyronic stem cell research, stating:
“A process which involves removal of a stem cell from a human embryo at the blastocyst stage, entailing the destruction of that embryo, cannot be patented.“
The decision has caused widespread concern amongst European stem cell researchers, yet has been welcomed by other groups on moral, ethical or religious grounds.
So why is it such a hot topic?
Use the resources here, and others that you can find, to discuss the following questions in your group. Be prepared to feed back to the class with a summary of no more than 5 minutes.
- What are (embryonic) stem cells and how do their properties facilitate research?
- Where are stem cells found? Are they all the same?
- How do stem cells eventually become differentiated and specialised?
- Outline at least one recent successful therapeutic use of stem cells.
- Identify a range of stakeholders in the debate. What are their views and reasons for them?
- Can you propose potential solutions or workable compromises that could reduce the impact of the ban on scientific research?
Some write-ups on this news story here:
About Stem Cells:
- Cell Theory, topic 2.1 resources by MrT
- Loads of interactive resources from Learn.Genetics
- SEED Magazine’s Stem Cells Cribsheet
- Stem Cell Differentiation (animation) from MCB Harvard
- Stem Cell Basics, from the National Institutes of Health
- StemCells: Seeds of Hope? video from Teachers Domain
- NewScientist special reports on Stem Cells
- Stem Cells transplants in lymphoma (animation)
Theory of Knowledge
The embryonic stem cell debate generates strong and emotive knowledge issues, which is evidenced by the fact that the case was passed all the way up to the European Court of Justice. There are many stakeholders in embryonic stem cell research, each with their own knowledge claims and beliefs.
With this recent ban on patenting methods based on the destruction of embryonic stem cells, we add the elements of patenting and intellectual ownership (and of course the knock-on effects to funding, progress and public perception).
To what extent does the embryonic stem cell debate highlight potential conflicts between the areas of knowledge of the natural sciences and ethics and between the ways of knowing of emotion and reason?
After reading through, understanding and discussing the resources, what knowledge issues can you identify?
This follows on from a related story in the USA last year:
Comments have been disabled on this post, but are open on the TOK page for the same content.
Create interactive timelines online for free with Dipity. This would be a great tool for revision of historical topics and it can be shared and embedded.
Ed Yong has a neat example on his NotExactlyRocketScience blog, of the timeline of reprogrammed (induced pluripotent) stem cell research:
Why use this?
- It’s free, visual, quick and easy
- Images, links and videos can be inserted
- You can connect it with facebook for easy logins (like SlideShare)
- Sharing is easy, embeds are possible (though not WordPress.com, again)
What could it be used for?
- Book or topic reports, such as a timeline of Darwin’s life and work.
- Mapping any time-related topic. History of the Universe, anyone?
Of course, if you’re studying History, Economics or current affairs, it would be an ideal tool.
This is the predictable and perennial question that comes up from at least one student when we are looking at stem cells, genetic engineering, cell differentiation and transplanting. Until now, the answer has (perhaps in an oversimplified way) been ‘no’.
We can use stem cell transplants to treat lymphoma. Recently a young woman had a trachea transplant based on stem cell technology. Skin grafts from a patient’s own cultured cells are also possible, as are stem cell-based bladders. However, these are all rather simple technologies.
To treat lymphoma, bone marrow cells are replaced, and are all the same. The trachea transplant was a pre-existing trachea simply coated in the patient’s stem cells to prevent immune rejection. Skin transplants are basically sheets of epidermis that cover a wound, yet do not have the intricate functions of original skin: temperature regulation, secretion, senses. The bladder is a bag.
The challenge with using stem cells to transplant a more complex organ, such as a heart, is that it is not a simple sheet made of one type of cell. It is complex 3D structure, with a range of cells performing specific tasks within the organ. These cells have differentiated to perform their functions: cardiomyocytes (beating cells), vascular endothelial cells (smooth internal surfaces) and smooth muscle cells (blood vessel walls).
How can we get the stem cells to become the right type of cell, in the right position?
The answer to this question could be the key to opening up new doors in the search for viable transplantable organs in medicine, and bears much in common with the trachea case. It also marks a return to form for the NewScientist YouTube channel, who have this short clip of the new hearts in action:
A full article to accompany the footage is here.
In a nutshell:
1. Find a suitable transplant organ, such as a pig’s heart.
2. Strip of all cells and DNA, using a detergent. Only the collagen ‘scaffold’ remains, as in the image of the decellularised heart to the right.
3. Coat the scaffold with the recipient’s stem cells.
4. Ensure that the blood supply is adequate and will provide the right signals for differentiation.
What is amazing in this case is how the cells ‘knew’ what specialised cells to become. The leader of the research group, Dr. Doris Taylor, puts it down to the mechanical stimulus of the pressure of the blood in the vessels and chambers and chemical signals from growth factors and peptides that remained on the stripped heart structure.
They even went as far as replacing a healthy rat’s heart with one of these new hybrid hearts. The rat survived for the trial, but she says they need to focus on producing more muscular hearts in order to ensure long-term survival of transplant recipients.
Food for thought:
Read the whole article and some of the links within it. Discuss these questions:
1. What are the potential uses for this kind of transplant technology?
2. What are the current limitations of this method and how might they be overcome?
3. What are the ethical issues related to using hybrid (pig-human) organs in medical transplants? How would you feel if you were the patient?
4. Who are the various stakeholders in this technology and what are their viewpoints?
Dr Doris Taylor’s research page from the University of Minnesota
NewScientist Article: Hybrid hearts could solve transplant problem
BioAlive stem cells links and resources
Can stem cells repair a damaged heart? from the NIH
Research reveals how stem cells build a heart, from Harvard news.
Sounds like JoVE is moving up in the world and making real headway in validating the video format as a legitimate format for publishing experimental protocols and results. Since my first post about them, they have (according to a recent email) been in process with PubMed and may become their first peer-reviewed video journal. They have also added RSS feed, email subscription and bookmarks (Digg, del.ici.ous, stumbleupon) to readers’ capabilities.
Most importantly, though, is that these resources are visual and well-explained. Instead of just reading about complicated protocols, we can see what is being done and it may allow more to understand the steps involved and the reasons behind the research.
Here is a nice clip (12mins) about derivation of stem cells from embryos. Hopefully, they’ll let me embed it on the blog.