Could stem cell research spell the end of baldness?
“Baldness has plagued men for centuries, but the dreaded comb-over may soon be history,” The Times reports, somewhat prematurely.
This news comes from laboratory research in which human skin cells were injected into mice. No human has yet been treated for baldness using stem cells.
The researchers grew stem cells from human skin. They then converted these stem cells into epithelial stem cells – which can create the different types of cells that make up the varying levels of skin, such as the epidermis (the outer layer of skin).
They injected these cells into mice and were able to grow human hair-like structures and an outer layer of epidermal cells in the three-week study period. However, they were not able to grow the sebaceous cells also found in skin.
The researchers conclude that this discovery creates hope for new treatments for hair loss, wound healing and other degenerative skin disorders. However, the technique is in its early stages so will need refining and developing before any potential treatments could become a reality.
Also, longer studies will be needed to determine whether the stem cell derived hair follicles grow and regenerate in a normal way over time (for example, the stem cells were used to create hairy, bony tumours in the mice, which would be an unacceptable side-effect for a human baldness cure).
Whilst this is a promising piece of research, it is too early to suggest that it will be a cure for all types of hair loss. Until then, people worried about their baldness will have to stick to existing treatments for baldness.
Where did the story come from?
The study was carried out by researchers from the University of Pennsylvania and was funded by a grant from the US National Institutes of Health.
The study was published in the peer-reviewed science and medical journal Nature Communications.
Generally the media reported the story accurately, highlighting that further research is needed to find a way to encourage the epithelial stem cells to also create sebaceous skin cells and then to enable the technique to be used for humans. However, The Times claims that “the technique could provide a limitless supply of hair for balding men in the future” may have raised unrealistic expectations about the certainty of a possible baldness treatment based on this technology.
What kind of research was this?
This was laboratory research that aimed to transform mature human skin cells into skin stem cells capable of growing human hair and skin cells when transplanted into mice.
Epithelial stem cells are skin stem cells found in the bulge of a hair follicle (the skin structure that produces hair). Previous research has shown they are required for hair and skin growth and renewal. Despite many attempts, previous research has struggled to successfully take these skin stem cells and transplant them into other humans or animals to make new skin or hair. If this transplant technique was successful it would be useful for things such as skin grafts for burn victims, baldness, and a number of other medical conditions.
What did the research involve?
The researchers grew skin stem cells from mature human skin samples and conducted a variety of experiments in the laboratory to see if they could grow new hair and skin cells. This included transplanting the human stem cells into the skin of mice to see if anything grew. Any hair or skin grown was compared with human samples.
They collected the discarded samples of normal human skin from eight operations. From these samples they grew fibroblast cells – large flat cells that make the connective tissue such as skin.
The fibroblasts were infected with retroviruses in the laboratory in various feeding solutions and this created skin stem cells, called epithelial stem cells, after 45 days.
They grew the stem cells in different cultures to see if they would grow into three different skin cell types – keratin, epidermal cells and sebaceous cells.
They injected a mixture of the skin stem cells and mouse dermal (skin) cells into the flank of mice which grew into teratomas, a type of tumour containing hair or bone.
They then injected it subcutaneously (under the skin) into nude (hairless) mice and looked two and a half weeks later at whether the hair growths on the underside of the skin were similar to hair on normal human skin.
Lastly they also put a mixture of stem cells and mice dermal cells onto grafting chambers which were implanted on the back skins of nude mice. The grafting chambers were removed after one week and skin growth was assessed after three-four weeks.
What were the basic results?
The researchers were able to:
- Create human-induced pluripotent stem cells (hiPSCs) from normal human skin. These are stem cells capable of developing into many different cell types in the body.
- Create follicular human epithelial stem cells (hEpSCs) from the hiPSCs. These skin stem cells are capable of developing into the many different cell types that make up the skin.
- Use the hEpSCs to grow mature skin cells such as keratinocytes (cells present in skin and hair) in the laboratory setting.
- Inject the hiPSC mixed with mouse skin cells under the skin of mice to form cysts (balls of cells) containing keratinocytes and epidermal cells. Hair follicles also grew out of the cysts.
- Grow human like hair and human like skin on the backs of mice. The hiPSC-derived EpSCs, mixed with neonatal mouse dermal cells, grew into human-like hair follicles and human-like skin after three weeks on the backs of mice.
- The hiPSC-derived EpSCs did not grow into the sebaceous cells that are necessary for normal skin and growth of two proteins necessary for skin was not sustained over more than 25 days.
How did the researchers interpret the results?
“These results suggest an approach for generating large numbers of human EpSCs for tissue engineering and new treatments for hair loss, wound healing and other degenerative skin disorders”.
Conclusion
The researchers have developed a method of growing human stem cells from human skin samples. They have developed a technique to induce them into becoming epithelial (skin) stem cells and demonstrated they can produce some of the cells found in skin such as hair follicles, keratin and epithelial cells.
These techniques will be useful and encouraging to other researchers in this field who are looking into the regeneration of hair follicles and skin for humans. However, the research is in its early stages so we shouldn’t jump the gun and expect treatments based on it to arrive shortly.
There may be significant technological and biological challenges in developing these techniques to the point where they would be useful in developing treatments.
Currently the experiments have only been conducted in a laboratory setting using cell cultures, or transplanting cells on the back of mice for up to three weeks.
There is a big gap between these types of experiment and a fully developed, safe and effective treatment for people (and it’s worth noting that a stem cell treatment for baldness would likely be expensive compared to other options available, at least initially).
The researchers also point out that they were not able to do more lengthy studies because of ethical restrictions in animal experimentation. Therefore the study doesn't show whether the hair follicles would continue to regenerate over time, and the production of some of the proteins stopped after 25 days in the laboratory.
Some components of skin were grown, including hair follicles and skin epidermal cells, but they were not able to grow sebaceous cells which are needed to secrete oils onto the skin. This is an obstacle that will need to be overcome, as without working sebaceous cells the skin will become dry, cracked, damaged and vulnerable to infection.
There are many different causes of hair loss, and it is far too early to suggest that this could be a cure for all of them. Further research in the laboratory will be required before any human studies take place.
