Could stem cells help reverse hair loss?

I thought that headline would grab your attention. The idea behind it grabbed my attention when I read about a new study in the journal Cell Metabolism that explored that idea and came away with a rather encouraging verdict of “perhaps”.

The research team from the University of Helsinki say that on average people lose 1.5 grams of hair every day, which over the course of a year adds up to more than 12 pounds (I think, sadly, this is the one area where I’m above average.) Normally all that falling hair is replaced by stem cells, which generate new hair follicles. However, as we get older, those stem cells don’t work as efficiently which explains why so many men go bald.

In a news release, lead author Sara Wickstrom says this was the starting point for their study.

“Although the critical role of stem cells in ageing is established, little is known about the mechanisms that regulate the long-term maintenance of these important cells. The hair follicle with its well understood functions and clearly identifiable stem cells was a perfect model system to study this important question.”

Previous studies have shown that after stem cells create new hair follicles they essentially take a nap (resume a quiescent state in more scientific parlance) until they are needed again. This latest study found that in order to do that the stem cells have to change their metabolism, reducing their energy use in response to the lower oxygen tissue around them. The team identified a protein called Rictor that appears to be the key in this process. Cells with low levels of Rictor were less able to wake up when needed and generate more hair follicles. Fewer replacements, bigger gaps in the scalp.

The team then created a mouse model to test their theory. Sure enough, mice with low or no Rictor levels were less able to regenerate hair follicles. Not surprisingly this was most apparent in older mice, who showed lower Rictor levels, decreased stem cell activity and greater hair loss.

Sara Wickstrom says this could point to new approaches to reversing the process.

“We are particularly excited about the observation that the application of a glutaminase inhibitor was able to restore stem cell function in the Rictor-deficient mice, proving the principle that modifying metabolic pathways could be a powerful way to boost the regenerative capacity of our tissues,”

It’s early days in the research so don’t expect them to be able to put the Hair Club for Men out of business any time soon. But a follicle-challenged chap can dream can’t he.

For the first time, scientists entirely reprogram human skin cells to iPSCs using CRISPR

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CRISPR iPSC colony of human skin cells showing expression of SOX2 and TRA-1-60, markers of human embryonic pluripotent stem cells

Back in 2012, Shinya Yamanaka was awarded the Nobel Prize in Physiology or Medicine for his group’s identification of “Yamanaka Factors,” a group of genes that are capable of turning ordinary skin cells into induced pluripotentent stem cells (iPSCs) which have the ability to become any type of cell within the body. Discovery of iPSCs was, and has been, groundbreaking because it not only allows for unprecedented avenues to study human disease, but also has implications for using a patient’s own cells to treat a wide variety of diseases.

Recently, Timo Otonkoski’s group at the University of Helsinki along with Juha Kere’s group at the Karolinska Institutet and King’s College, London have found a way to program iPSCs from skin cells using CRISPR, a gene editing technology. Their approach allows for the induction, or turning on of iPSCs using the cells own DNA, instead of introducing the previously identified Yamanka Factors into cells of interest.

As detailed in their study, published in the journal Nature Communications, this is the first instance of mature human cells being completely reprogrammed into pluripotent cells using only CRISPR. Instead of using the canonical CRISPR system that allows the CAS9 protein (an enzyme that is able to cut DNA, thus rendering a gene of interest dysfunctional) to mutate any gene of interest, this group used a modified version of the CAS9 protein, which allows them to turn on or off the gene that CAS9 is targeted to.

The robustness of their approach lies in the researcher’s identification of a DNA sequence that is commonly found near genes involved in embryonic development. As CAS9 needs to be guided to genes of interest to do its job, identification of this common motif allows multiple genes associated with pluripotency to be activated in mature human skin cells, and greatly increased the efficiency and effectiveness of this approach.

In a press release, Dr. Otonkoski further highlights the novelty and viability of this approach:

“…Reprogramming based on activation of endogenous genes rather than overexpression of transgenes is…theoretically a more physiological way of controlling cell fate and may result in more normal cells…”