We would BEE nothing without you...

Where oh where have all those bees gone?

A lot of energy has been spent on trying to find out what is happened to our collapsing bee populations. The demise of bees is not just devastating due to the general loss of biodiversity on this planet we call Earth, but it also has huge implications for our survival as a species!

And this is because bees are the most important pollinators. Pollinators ensure our food crops produce food. This article tells a sad tale of how common agricultural practices are currently having a terrible impact on the very critter that is fundamental to our agricultural production.

This amazing talk of Sir Ken Robinson animates the outdated nature of our present educational system and demands a change. I think it is very insightful and inspired.

Well done Sir!

New type of spinal cord stem cell discovered: Research provides new target for regenerating parts of the central nervous system

A news article on my recent publication. How exciting!!

New type of spinal cord stem cell discovered: Research provides new target for regenerating parts of the central nervous system

Publication citation:
Petit A, Sanders AD, Kennedy TE, Tetzlaff W, Glattfelder KJ, et al. (2011) Adult Spinal Cord Radial Glia Display a Unique Progenitor Phenotype. PLoS ONE 6(9): e24538. doi:10.1371/journal.pone.0024538

Mending Broken Hearts

On the verge of Valentines Day, here is a heart-warming story from the LA Times about how scientists are learning how to rebuild and restore broken hearts.

Stem cells for broken hearts

By Eryn Brown, Los Angeles Times 

February 7, 2011

By expanding and manipulating the heart stem cell population (called cardiac progenitor cells), or by differentiating primitive (pluripotent) stem cells, researchers are regrowing precious heart muscle tissue in hopes of reversing life-threatening scars in heart attack patients.

This article highlights the potential of stem cell research by showcasing how this work can save lives.
A great read!

...thanks a bunch to Ben for the link.

Express Yourself!

No, not you! I was talking about your cells! That's right, cells are expressive. Cells are opinionated, and cells effectively convey their inner most feelings to achieve and communicate a specific state of being. Well... sort of.

A cell expresses itself through its genes. We have already learned all about genes and how they are strings of 'words' that make up DNA. We know that genes encode proteins that do the work in the cell. We know that the specific genes a cell uses determines it's fate (i.e. a liver cell uses genes important for metabolism while a white blood cell uses genes for immunity). But what we haven't covered yet is how the cell knows which genes to use and which genes not to use.

This is not an easy topic to cover in a short blog post. The convoluted process of using genes (which is called 'gene expression' - hence my oh-so-clever title) involves several complex pathways that are integrated from all parts of the cell. Deconstructing this process can involve some very heavy science. But we are not here for heavy science, we are here for a fun, easy and educational read. And I will try to make this as painless as possible.

Sources of signals that are used to communicate between cells.
This includes short-range and long-range signals. 

The first step in turning on a gene involves a signal. You see, cells are constantly sensing their environment and looking for signals from their neighbours. Signals, which tell the cell to turn on or off a gene, come from other cells (either directly or indirectly) and come in the form of proteins. Signals are specific types of proteins that are used by cells to communicate to each other. These proteins can be tethered to the outside of a cell or they can be released into the environment for long-distance communication. Signals are usually received at the outside edge the cell and they activate specific pathway inside the cell which change the cells state or activity. The pathway that is activated depends on the signal.

Once a signal is received by a cell a sequence of events is initiated like a classical domino effect. The sequence of events is called 'signal transduction'. Essentially, the signal proteins connects with another protein in order to activate it, this active protein might turn off another protein which moves through the cell to connect with a different protein and another protein and another ... until finally the pathway of proteins leads to a specific gene being turned on or off. All of the work is done by a sequence of proteins. The specific set of proteins that are active in any given cell determine which genes that cell turns on and expresses.

Signals from the environment are sensed by the cell.
The specific signal activates a specific pathway of proteins
that control the expression of specific genes. 

What? Wait a second! I am sure right now you are saying, "WTF Ashley! Like... I mean... like you just finished telling me that genes make proteins, and now you are saying that proteins control genes. Like OMG! Like. What are you talking about?" To this I say, "Yes, I know this is all very confusing (especially if you talk like that!), and I don't know if I can make it less confusing (considering your pea-sized brain!), but I will try."

Lets give a simple example. Lets say that at the beginning of a cell's life it turns on all of its genes and has all of its proteins around. This cell can do just about anything. Then, a couple of hours later, a neighbouring cell sends out a signal telling that cell how to behave. The specific signal activates a specific pathway of proteins. The sequence of proteins eventually instruct the cell to stop making proteins for immunity (i.e. they turn off immunity genes) and start making more proteins for metabolism. The result: the cell uses liver genes, makes liver proteins and acts like a liver cell. Viola!

However, this example is a little over-simplified. What the example fails to address is that most cells don't start off making all their proteins (thanks to epigenetics- a topic for another blog!) and cells have to integrate dozens of different signals at any given time. This is because cells exist in large 'communities' and they are constantly receiving conflicting signals from their different neighbours. That is why, it is the specific set of proteins that are active in any given cell at any given time that determine which genes that cell turns on and how that cell behaves. Essentially, it is a complex math problem. Lets say that signal A turns on pathway A and signal B turns on pathway B. It depends on how much of either signal is present that determines which pathway gets turned on.  As I warned you, this is all very complicated!

This diagram is a nice example of the complexity of signal transduction  pathways and how multiple signals are integrated in a cell at any given time. By responding to all the different signals in the environment the cell knows which genes to turn on and which genes to turn off. 

In fact, scientists have been struggling to understand signaling pathways since the beginning of modern science! There are many researchers who have dedicated their entire lives to figuring out the details of a single pathway. And we still know very little about these pathways. For instance, one incredibly important signal protein (called Wnt) has been studied extensively by dozens of famous scientists, and although we have an idea of the protein pathway it activates and we have some ideas about the changes it causes in some types of cells we still don't know which genes it turns on and off in the cells! To be frank, there are very few pathways that we have successfully mapped.

Currently, a lot of research surrounds this topic and aims to discover exactly how cells integrate all the different signals in their environment, and how different combination of signals affect different types of cells. By understanding how a cell expresses itself we can one day learn how to control a cell. Because it's the set of genes a cell uses that determines how the cell behaves, all we need to do is change the genes being expressed in order to change the behaviour of the cell. This can be very important for treating injuries and curing diseases.

This video gives an upclose and personal view on how signals are moved through cells.

Related articles

• Cellular Communication (uwinnipeg.ca)
• An introduction to signal transduction (scq.ubc.ca)
• Scientists view genome as it turns on and off inside cells (sciencedaily.com)
• Global view of blood cell development reveals new and complex circuitry (physorg.com)
• Discovery of a mechanism that controls the expression of a protein involved in numerous cancers (eurekalert.org)

A Stem Cell Story - A Movie

This video provides an amazing overview of the topics covered in the previous posts:
         Stem Cells- what are they and why do I care?
         Potential of Stem Cells: from the embryo to the adult

"A Stem Cell Story"

I think it is clear, easy to follow, and overall a great synopsis of my personal favorite topic: Stem Cells
A must see for those interested in learning more!

The Potential of Stem Cells: from the embryo to the adult

We all know that we grow in our mother's bellies and begin as a tiny little egg in their womb. We know that it took 9 months to change this tiny little egg into a complete human being with arms, legs, eyes and ears. We know that when we are born we pretty much have all the right pieces in all the right places. And we know that although we continue to grow, develop and mature as we age, these changes are nothing compared to the growth, development and maturation that occurs before birth. Today, we will discuss why that is true.

Here we will discuss Embryonic Stem Cells- we will consider what they are, how they are different from adult stem cells (discussed in the earlier post: Stem Cells - what are they and why do i care?), and why they are a source of much contention.

Early cell divisions following fertilization generate a mass
of embryonic stem cells that continue to divide and
differentiate into all the tissues of an adult human being

I think the best way to discuss this topic is to start at the beginning, the very beginning, and then finish somewhere around the end.

So, how do we begin? Well... with the miraculous act of conception, right? Right! When the sperm (containing your Dad's DNA) and the egg (which contains your Mom's DNA) come together for the very first time a complex chemical reaction starts the process of creating a human being. This process begins with cell divisions- lots and lots and lots of divisions that transform that single cell into many, many cells. These very first cells are the embryonic stem cells, and these cells are able to make all the different tissues, organs, and systems of a functioning human being.

A single embryonic stem cell can make ANY cell type in our entire body!

Let me repeat that, just to make sure you realize how important that really is. Embryonic stem cells can make any cell- this includes a blood cell, a bone cell, a liver cell, an eye cell, a skin cell, or even a brain cell. They are completely undetermined and have tonnes of potential! All they need is a little direction, or the right nudge, to 'differentiate' and become a specific cell type.

Image via Wikipedia

One might say that embryonic stem cells are like a fresh mound of rainbow-coloured Playdoh that can be transformed into any shape or form with the right kind of manipulation. Embryonic stem cells have virtually unlimited potential.

And this fact is why embryonic stem cells are different from adult stem cells. If you recall from the previous post, adult stem cells are present in the adult body and are present in many different tissues. These stem cells are also capable of generating many cell types, but adult stem cells have restricted potential and can only make specific cells for a specific tissue. For instance skin has skin stem cells and blood has blood stem cells and the brain has brain stem cells, and each of these stem cell will only make cells for that specific type of adult tissue. A skin stem cell maintains our skin but not our blood because a skin stem cell is specific and restricted to only skin. Adult stem cells are specific to only one kind of adult tissue.

Adult stem cells are required to maintain and repair our body as we age, and although adult stem cells have very important uses (ex. using skin stem cells to generate new skin for burn victims), their use in research and medicine is much more limited than their embryonic counterparts. And this is solely due to the fact that the potential of adult stem cells is limited, while embryonic stem cell potential is unlimited.

Return to our Playdoh analogy. While an embryonic stem cell is like fresh, rainbow-coloured Playdoh capable of forming anything, an adult stem cell is more like stiff, green Playdoh that is more difficult to manipulate and resistant to new shapes; it's potential is more restricted.

Although we have a rough understanding of the different
developmental stages a human embryo progresses through,
the details of this development remains very poorly defined.

The fact that embryonic stem cells can make any cell type in the human body means they have many important uses in research and medicine. For instance, embryonic stem cells can help us study human development. We currently have very little knowledge of how groups of cells in an embryo are able to become functioning organs in the adult. By studying embryonic stem cells we can better understand how humans transform from a single cell into a complex, multicelled organism. And by understanding how humans develop normally we will be able to identify when this development goes wrong. Imagine, one day we might actually be able to stop birth defects and disabilities before they even happen.

Stem cells are also very important in medicine since they can be used to repair injuries and cure diseases. For instance, a patient with leukemia (blood cancer) can be given healthy, undiseased blood stem cells that will generate healthy, undiseased blood and this will cure the cancer. Also, a patient with a paralyzing spinal cord injury can regain movement if brain stem cells are used to grow new, uninjured neurons. These examples use adult stem cells, but imagine if we had a cell type that could create both new blood cells for a leukemia patient and a new spinal cord for a car crash victim. But... wait a minute.... we do have that kind of cell type! We have embryonic stem cells!

In theory, a single embryonic stem cell can be used to repair and cure any injury or disease that a person may encounter. In theory, that single embryonic stem cell can even be used to regrow an entire organ (such as new eyes for the blind) or an entire appendage (like a new leg for an amputee)! All we have to do is learn how to manipulate these cells and learn how to mould them into these different forms or tissues.

Image via Wikipedia

As you can imagine, while embryonic stem cells have amazing potential for health, they also have amazing potential for harm.  And this is why the ethical debates surrounding these cells are ongoing.

Because a single embryonic stem cell can be used to grow an entire human being there are many concerns about human cloning. Some say that if research using full-grown humans is illegal and unethical so is research using human embryonic stem cells. This relates to the question: 'When does an embryo, a cluster of cells, become a human being with thoughts and rights?' There are also issues of accessibility. Who will benefit from the medicines and therapies developed from embryonic stem cell research? And who will regulate this research? Will only the rich few that have enough money to pay for the treatment be allowed to access the technology? And who will ensure that everyone, including the poorest people in the poorest countries, benefits from these medicines?


Here is a discussion on the history of stem cell research. This 'fire-side chat' is between leading scientists James Till and Janet Rossant who helped found the stem cell field.



StemCellTalks Fireside Chat with Jim Till and Janet Rossant from Stem Cell Network on Vimeo.



Related articles

• Stem Cell Biology- the Basics (stemcells.nih.gov)
• Stem Cell Research (als.ca)
• The Controversy of Stem Cell Research (wikipedia.org)
• Stem Cell Therapies (utah.edu)
• Canadian Guidelines for Human Embryonic Stem Cell research (cihr-irsc.gc.ca)
• Canadian Network for Stem Cell Scientists (stemcellnetwork.ca)
• Cell Stem Cell: A Scientific Journal on Latest Stem Cell Research (cell.com)