 Clinical Relevance: Hair has feelings too
Even hair follicles want to ‘stay in touch’ with their roots. Research just published in Science Advances suggests that the structures that anchor individual strands of hair in place are capable of a sensory experience that was previously unknown to science. Beyond making sure that hair stays put, hair follicles also help regulate temperature and manage sweat. While humans don’t use whiskers to feel around the same way animals like cats and dogs do, our sense of touch is advanced enough to assist us in navigating the world and even process emotions. THE MANE RESULTS It works like this: special nerve cells in the skin send touch information to the brain. So do other skin cells. In the new study, Imperial College London explored the interaction between these nerve cells and human hair follicles to see what and how they experienced touch. The researchers started by collecting scalp skin samples from men aged 23 to 54 who were undergoing hair transplant surgeries and also gathering up leftover skin from abdominoplasties to establish keratinocyte cultures. A keratinocyte is a skin cell that produces keratin, the protein that makes up the outer layer of skin, hair, and nails. The researchers then processed the samples using various techniques. They used whole-mount immunolabeling to highlight specific tissue parts for microscopic viewing. Volumetric imaging captured detailed 3D tissue pictures. They also analyzed RNA extractions for gene expression. Additionally, they cultured different cell types and subjected them to a variety of treatments to observe the responses. This complex set of experimental methods helped demonstrate how the nerve cells sent signals to the brain that process touch sensitivity. Cells known as outer root sheath, or ORS, cells in the hair follicles interacted with these nerve cells. When something pressed against or moved the ORS cells, they released chemicals like serotonin and histamines to help modulate the response of the nerve cells. “This is a surprising finding as we don’t yet know why hair follicle cells have this role in processing light touch,” said lead author Claire Higgins, a professor at the Imperial College London’s department of bioengineering. “Since the follicle contains many sensory nerve endings, we now want to determine if the hair follicle is activating specific types of sensory nerves for an unknown but unique mechanism.”  A human hair follicle surrounded by nerve endings. Credit | Julia Agramunt EVEN MORE IN TOUCH Further testing showed just how sensitive the ORS cells were. The number of times something touched the hair follicle influenced the amount of serotonin and histamine released. More frequent brushups led to a greater chemical release. Compared to how skin cells react to contact, the researchers noted that while both types of cells respond to touch by releasing histamine, only the ORS cells released serotonin. This implies that hair follicles have a unique way of sensing and responding to touch compared to the rest of the skin. Interestingly, the researchers observed that ORS cells also had the ability to revert into regular skin cells when needed, like during wound healing, but still maintained their unique touch-sensing abilities. Previous research on ORS cells found that they emit ATP (Adenosine Triphosphate), a molecule that serves as a signaling agent to communicate with nerve cells. The new findings add complexity to this model by showing that the communication between ORS cells and nerve cells isn’t just a one-way street with ATP as the only traffic light. There might be other molecules or mechanisms involved, making the process more intricate than originally observed. SKIN DEEP SCIENCE These insights into the touchy feely powers of hair follicles could potentially lead to new treatments for conditions related to touch sensitivity or insensitivity. They might have implications for treating other types of skin problems as well. “This is interesting as histamine in the skin contributes to inflammatory skin conditions such as eczema, and it has always been presumed that immune cells release all the histamine. Our work uncovers a new role for skin cells in the release of histamine, with potential applications for eczema research,” Higgins said. The researchers say they need to conduct further experiments on living organisms to validate the study’s results. Since some nerve receptors exist only in hairy skin, the team will explore specialized signaling mechanisms within the hair follicle for these nerves. from Psychiatrist.com
 It’s official: Apple cider vinegar (ACV) is no longer a quaint ‘old wives remedy’ — It has surged in popularity, with the hashtag #applecidervinegar pulling in 210M views on TikTok in the past 2 months and 988M views overall. Many videos show users experimenting with using apple cider vinegar in their beauty routines, particularly focusing on how it can help to promote healthy hair. Experts at All Things Hair turned to Google data to find out the biggest hair concerns people are seeking to treat with apple cider vinegar and whether or not it does actually help to resolve them. Dandruff: 35,640 Google searches The greatest number of searches by far were asking if apple cider vinegar can help with dandruff. Milena Prinzi, hair expert at All Things Hair, sheds light on exactly how this fermented apple juice combats dandruff and answers Google users' questions: What causes dandruff and why is ACV a good treatment? "Dandruff happens when a yeast-like fungus called Malassezia gets out of control by feeding on oils on the scalp," Prinzi explains. "The excess of fungus unbalances the normal pH levels on the scalp and disrupts the cell regeneration process. As a result, white flakes, odor and itchiness appear on the scalp. Apple cider vinegar has natural antimicrobial and antioxidant properties and acetic acid, which helps regulate the scalp's pH levels and target dandruff." Which ACV is best for dandruff? "Many versions of ACV vinegar are available, but to tackle dandruff, you want to choose one with the highest concentration possible of acetic acid. Why? This acid will target the unprecedented production of Malassezia, the yeast-like fungus responsible for dandruff," Pinzi shares. "Furthermore, acetic acid will keep the scalp's pH levels in check to eliminate flakiness and itchiness. You also want to choose a version of the vinegar that is raw, unfiltered and unpasteurized, and if you can see the good bacteria floating on the bottom of the bottle, even better." How do you treat dandruff with ACV? "I'm a big fan of ACV as a scalp treatment and have used it for years. If your scalp can handle it straight up to target problematic areas, go for it. I usually dip a cotton ball and gently rub it on the scalp. However, this vinegar has a strong scent, so you should only apply it before washing your hair; 30 minutes to an hour before hitting the shower," Pinzi adds. "For my rinse, I purchase a spray bottle and mix 2 to 3 tablespoons of the vinegar in 8 to 10 ounces of water. Of course, you can adjust these measurements as you see fit and as your scalp's tolerance for the vinegar increases." Hair Growth: 16,920 searches Prinzi is not so convinced on the efficacy of ACV for this condition, saying: "This might be an unpopular opinion, but as far as I know, apple cider vinegar does not help with hair growth. However, apple cider vinegar is one of nature's greatest alkaline and aids the body to balance our pH levels, which means it helps eliminate free radicals in the organism." Prinzi continues adding, "Due to these redeeming qualities, apple cider vinegar is a fantastic scalp cleanser. People have used apple cider rinse to soothe scalp itchiness, remove product buildup, control the overproduction of Malassezia, the fungus responsible for dandruff, and eliminate scalp odor produced by bacteria developed by scalp dermatitis. A healthy scalp is necessary for hair growth, but the regular use of apple cider vinegar doesn't necessarily mean you'll grow long strands. Since hair is mostly protein, eating a high-protein diet might aid hair growth." Hair Loss: 4,800 searches Prinzi does not think ACV would make much difference: "As far as I know, there's no scientific proof that apple cider vinegar prevents hair loss or stimulates hair growth. Apple cider vinegar is best known for its antibacterial properties, which can be applied to treat scalp conditions such as dandruff and dermatitis." Greasy/Oily Hair: 4,320 searches Prinzi confirms that ACV could help with this condition: "There might be a precedent to support this claim due to apple cider vinegar’s natural cleansing properties. If used as a rinse or wash, ACV removes product buildup on the scalp. Since this vinegar is rich in antioxidants and balances the pH, it might control the overproduction of oil on the scalp and, therefore, less oily hair." Dry Hair: 960 searches Prinzi does not think ACV is the right treatment for dryness: "I don’t see how apple cider vinegar can hydrate dry hair because this vinegar has no moisturizing ingredients. Dry hair often needs the help of oils and vitamins to smooth its coarse texture and bring out the shine. If anything, I think apple cider vinegar will make dry hair drier." For more hair advice visit: https://www.allthingshair.com/en-us/ from BeautyLaunchPad
8/15/2023 Why does your hair curl in the summer? A chemist explains the science behind hair structure The three layers of hair If you have curly hair, you know that every day is a new adventure. What will my hair do today? Why does it curl better on some days than others? And even those without naturally curly hair might notice their hair curling—or, let's be honest, frizzing—a bit on humid summer days. As a person with curly hair, I'm always looking for the best way to care for and understand my hair. As a chemist, I'm interested in the science behind how my hair behaves at the molecular level. There are different hair types, from straight to curly, and they behave differently depending on their structure. But what hairs are made up of at the molecular level is the same. Hair structure Hair begins growing under the skin's surface, but it's what happens after it pokes through the skin that determines whether you have a good hair day or a bad one. Each hair can have three layers—the medulla, the cortex and the cuticle. You can think of each hair like a tiny tree trunk. The innermost, or core layer, is the medulla. This layer holds moisture, much like the pith in the center of a tree trunk. This layer is also very fragile, but only thick or coarse hairs contain this part—so those with thin or blond hair typically don't have the medulla layer in their hairs. Next is the cortex, which makes up most of a hair and is analogous to the wood of a tree. The cortex is made up of spring-shaped protein molecules that lie in parallel rows in a cylindrical bundle. The exact shape of that bundle is determined by the hair follicle, which is a pore on the skin from where the hair grows. How the hair grows out of the follicle influences the distribution of its proteins. So a straight follicle produces straight hair and a curved follicle produces curly hair. The less evenly distributed the squiggly proteins are, the curlier the hair. Your genetic code also plays a role in the shape of the cortex and, therefore, the shape and thickness of your hair.  A hair’s cuticle under a microscope. Lastly, the outermost layer of a hair is called the cuticle. The cuticle is like the bark of a tree—and it even looks like bark under a microscope. It's the cuticle's job to protect the cortex, but the cuticle is very easily damaged. Imagine lifting or removing the bark from a tree. Doing so would leave the wood inside susceptible to moisture loss, exposure to the environment and damage. The same is true for each hair. When the cuticle is damaged from brushing, chemicals, wind or heat, the proteins of the cortex have a much more difficult time lying smoothly together. This means they can lose moisture, gain moisture, fray like a rope—this causes split ends—and even break. All these factors can influence how your hair looks at any given moment. Hair in the summer So what does all of this have to do with humidity? Well, hair proteins contain many permanent chemical bonds. Only chemical treatments like perms or straightening can change these bonds. But there's another natural phenomenon that keeps the protein molecules in the cortex in line—something called hydrogen bonding. The long, stringy protein molecules in the cortex contain tiny positive and negative charges throughout their structure. Because opposite charges attract each other, entire rows of proteins can be attracted to each other like tiny, weak magnets. Heating or wetting your hair breaks the magnetlike attraction between these rows of proteins. So, heat and water can rearrange the proteins in your hair by breaking the hydrogen bonds that keep their structure together. Water is one of the best molecules at hydrogen bonding. So when a molecule of water has the opportunity to hydrogen bond with something, it will. In your hair, water can form hydrogen bonds between the rows of proteins in your hair's cortex. It is the extent to which this happens that determines your hair's fate. When just a little water enters the hair, like it might in lower humidity conditions or when the cuticle is healthy and able to keep too much water out of the cortex, your hair may curl. When humidity is high, or the cuticle is damaged, more water enters the hair. Too much water can swell and crack the cuticle, making hair look frizzy. Many people consider high humidity to be the problem behind frizzy hair, but styling your hair under high humidity and then entering a less humid environment can also be an issue. Water molecules leaving the hair's cortex can also lead to a change in hair behavior. Treating summer hair A damaged cuticle layer leaves the cortex more susceptible to water molecules creeping in or out and wreaking havoc on your hair. Anytime water molecules travel in or out, your hair's structure suffers and your hairstyle may be ruined. When the cuticle is healthy, it can protect the cortex, making your hair less susceptible to changes in the weather or environment. The bottom line is that a healthy hair cuticle helps keep proper moisture in the cortex. Heat from styling tools is the most common culprit behind damaged cuticles, but chemical treatments, brushing, sun and wind can also cause damage. Avoiding these activities can help, but some things, such as exposure to the sun, can't be avoided. You can also take care of your scalp—a clean, healthy scalp leads to healthy hair cuticles. Using moisturizing products on your hair can help maintain cuticle health as well. Oils and moisturizing treatments can even restore damaged cuticles. The good news is that by understanding your hair and treating it well, you can help prevent the undesired effects of humidity. from PHYS.org
Tightly curled scalp hair protected early humans from the sun’s radiative heat, allowing their brains to grow to sizes comparable to those of modern humans.  A graphic showing how scientists used a thermal manikin and human hair wigs to measure heat transfer from the scalp. Credit: Melisa Morales Garcia. All Rights Reserved. Curly hair does more than simply look good — it may explain how early humans stayed cool while conserving water, according to researchers who studied the role human hair textures play in regulating body temperature. The findings can shed light on an evolutionary adaptation that enabled the human brain to grow to modern-day sizes. “Humans evolved in equatorial Africa, where the sun is overhead for much of the day, year in and year out,” said Nina Jablonski, Evan Pugh University Professor of Anthropology at Penn State. “Here the scalp and top of the head receive far more constant levels of intense solar radiation as heat. We wanted to understand how that affected the evolution of our hair. We found that tightly curled hair allowed humans to stay cool and actually conserve water.” The researchers used a thermal manikin — a human-shaped model that uses electric power to simulate body heat and allows scientists to study heat transfer between human skin and the environment — and human-hair wigs to examine how diverse hair textures affect heat gain from solar radiation. The scientists programmed the manikin to maintain a constant surface temperature of 95 degrees Fahrenheit (35 degrees Celsius), similar to the average surface temperature of skin, and set it in a climate-controlled wind tunnel.  A thermal manikin wearing tightly curled (left) and straight (right) human hair wigs. The manikin uses electric power to simulate body heat and allows scientists to study heat transfer between human skin and the environment. A new study examining the role human hair textures play in regulating body temperature found that tightly curled hair provides the best protection from the sun’s radiative heat while minimizing the need to sweat to stay cool. Credit: George Havenith, Loughborough University. All Rights Reserved. The team took base measurements of body heat loss by monitoring the amount of electricity required by the manikin to maintain a constant temperature. Then they shined lamps on the manikin’s head to mimic solar radiation under four scalp hair conditions — none, straight, moderately curled and tightly curled. The scientists calculated the difference in total heat loss between the lamp measurements and the base measurements to determine the influx of solar radiation to the head, explained George Havenith, director of the Environmental Ergonomics Research Centre at Loughborough University, U.K., who led the manikin experiments. They also calculated heat loss at different windspeeds and after wetting the scalp to simulate sweating. They ran their results through a model to study how the diverse hair textures would affect heat gain in 86-degree Fahrenheit (30 degrees Celsius) heat and 60% relative humidity, like environments in equatorial Africa. The researchers found that all hair reduced solar radiation to the scalp, but tightly curled hair provided the best protection from the sun’s radiative heat while minimizing the need to sweat to stay cool. They reported their findings yesterday (June 6) in the Proceedings of the National Academy of Sciences. “Walking upright is the setup and brain growth is the payoff of scalp hair,” said Tina Lasisi, who conducted the study as part of her doctoral dissertation at Penn State. Lasisi will start as an assistant professor of anthropology at the University of Michigan in the fall. As early humans evolved to walk upright in equatorial Africa, the tops of their heads increasingly took the brunt of solar radiation, explained Lasisi. The brain is sensitive to heat, and it generates heat, especially the larger it grows. Too much heat can lead to dangerous conditions like heat stroke. As humans lost much of their body hair, they developed efficient sweat glands to keep cool, but sweating comes at a cost in lost water and electrolytes. Scalp hair likely evolved as a way to reduce the amount of heat gain from solar radiation, thereby keeping humans cool without the body having to expend extra resources, said Lasisi. “Around 2 million years ago we see Homo erectus, which had the same physical build as us but a smaller brain size,” she said. “And by 1 million years ago, we’re basically at modern-day brain sizes, give or take. Something released a physical constraint that allowed our brains to grow. We think scalp hair provided a passive mechanism to reduce the amount of heat gained from solar radiation that our sweat glands couldn’t.” The multidisciplinary research provides important preliminary results for bettering our understanding of how human hair evolved without putting humans in potentially dangerous situations, said Jablonski. The study also shows that evolutionary anthropologists have an extra tool in the thermal manikin – normally used for testing the functionality of protective clothing – for quantifying human data that is otherwise very difficult to capture, added Havenith. “The work that’s been done on skin color and how melanin protects us from solar radiation can shape some of the decisions that a person makes in terms of the amount of sunscreen needed in certain environments,” said Lasisi. “I imagine that similar decision making can occur with hair. When you think about the military or different athletes exercising in diverse environments, our findings give you a moment to reflect and think: is this hairstyle going to make me overheat more easily? Is this the way that I should optimally wear my hair?” Also contributing to the research were James Smallcombe, Loughborough University and the University of Australia; and from Penn State Larry Kenney, professor of physiology, kinesiology and Marie Underhill Noll Chair in Human Performance; Mark Shriver, professor of anthropology; and Benjamin Zydney, previously an undergraduate research assistant and now a Penn State alum. The National Science Foundation and the Wenner-Gren Foundation supported this work. from PennStateEdu
 A new study found that trapped stem cells may be the reason some aging hair turns gray. Ever wondered why your hair turns gray as you age? A team of researchers says it has identified the root cause as trapped stem cells — and that means new tips for naturally fending off grays from your mane could be coming soon. It all starts with a type of stem cell called melanocytes, also known as McSCs, says the study, which was published in the journal Nature this week. The research team from NYU Grossman School of Medicine was already familiar with melanocytes. They're the main mechanism that produces the pigment melanin, bringing color to your skin and eyes. That melanin is key to hair color. McSCs hang around in your hair follicles, where they receive a protein signal that tells them when to become mature cells. Mature cells release pigment and, voilà, you get your hair color. But over the course of this study, the researchers learned that McSCs actually move between microscopic compartments in your hair follicle. Each compartment might give the MsSC a slightly different protein signal, which allows the cell to oscillate between different levels of maturity. That's largely unlike how other stem cells operate — that is, maturing until they die. The unique maturity level of MsSCs gets more complicated the older you get. As your hair grows and sheds in cycles, the more McSCs get stuck in one particular compartment called the hair follicle bulge. The follicle bulge isn't giving those McSCs the signal to mature, and it's not sending the McSCs back to a compartment that would. The jammed cells allow the hair to keep growing, but the hair isn't given its dose of pigmentation. As a result, you go gray. To prove this concept, the research team produced salt-and-pepper-colored mice by physically plucking strands of their hair again and again over the course of two years. They found the number of McSCs lodged in the follicle bulge increased from 15 percent to nearly 50 percent. But in the younger hairs, which weren't plucked, the McSCs continued to move around the different compartments, picking up protein signals and producing a consistently rich brown pigment. To be clear, the McSCs aren't the sole factor in determining when your gray grows in. Dr. Jenna Lester, a dermatologist and professor at the University of California, San Francisco, told NPR's Short Wave podcast that there's a multitude of factors beyond aging that play a role. "Some people think sun exposure can damage their melanocytes more or less," she said. "And hormones also play into it as well." Then there's stress, genetics and certain medical conditions, which can all strip hair of its richer hues. Overall, 74% of people between the ages of 45 and 65 years of age have at least a few silver strands, according to research from the National Institutes of Health. If you're in that camp and resenting it, this new study could be a reason to rejoice: The researchers say that moving the McSCs to their proper location could prevent graying. And anyone scoffing at the vanity of stressing over silver strands can also rejoice: The researchers also say studies like this are putting us one step closer to curing cancer. (Seriously.) "We are interested in how stem cells residing in our body are regulated to properly maintain our body and how they can reform the tissues when they are lost by injuries," said Mayumi Ito, a professor at NYU Langone Health and a senior investigator on the study. "When the stem cell regulation goes awry, we will have multiple health problems including cancers," she told NPR. "The melanocyte stem cell system is advantageous to understand this broad issue in medical science, as the malfunction of the system is so visible." from NPR
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