When Karen Davis attended a presentation at a dental conference in 2013, she unexpectedly discovered a service that could help her daughter, Madeline: storing stem cells derived from her teeth that potentially could be used in the future to treat her Crohn's disease.
"Even though this isn't a viable option today, I know how rapidly things can change."
Throughout high school, Madeline suffered from the painful autoimmune disorder, which wreaks havoc on the gastrointestinal system and can lead to life-threatening complications.
"I leave no stone unturned when it comes to medical care and this resonated with me," says Davis, a Dallas-based dental hygienist who was encouraged by advances in stem cell research. Later that year, when Madeline got her wisdom teeth extracted, Davis shipped them off to the Store-A-Tooth company in Massachusetts, where they will be kept frozen until needed. "Even though this isn't a viable option today, I know how rapidly things can change," says Davis. "To me, this was a worthwhile investment—I didn't want to miss out on an opportunity that would provide a pathway to a cure."
Karen Davis pictured with her daughter Madeline.
(Courtesy of Karen Davis)
The process itself was straightforward. Madeline's newly extracted wisdom teeth--baby teeth can be saved, too—were bathed in a special solution, loaded into a Styrofoam container lined with cold packs and sent to the stem cell company. There, a team harvested the dental stem cells from the pulp, then grew them in culture and cryogenically preserved them. Store-A-Tooth charges $1500-1749 for tooth collection and $120 per year for storage, while other dental pulp stem cell tissue banks cost $500-$600 upfront and in the $120 range annually for storage.
The rationale here is that if you missed out on banking your baby's umbilical cord blood, this gives you another chance to harvest their stem cells. "If their child later develops an illness that could be managed or even cured with stem cell therapy, this is an insurance policy," says Amr Moursi, DDS, PhD, chair of the department of pediatric dentistry at New York University College of Dentistry.
But is there a genuine potential here for some effective treatments in the relatively near future—or is this just another trendy fad? Scientific opinion is decidedly mixed. Stem cells have been heralded as the next frontier in medicine because of their versatility: with a little chemical coaxing, they can be transformed into different cell types, such as heart, blood or brain cells, to create tissue that can mend damaged body parts. Because they're taken from your own body, there's little chance of rejection, which means patients don't have to take strong antirejection drugs that can have all sorts of unpleasant side effects for the rest of their lives.
However, while stem cells are immature cells found in different tissues, ranging from abdominal fat to bone marrow, there is a vast difference between the stem cells found in cord blood and in teeth. Cord blood, which is culled from the umbilical cord when a baby is born, contains what are called hematopoietic stem cells (HSCs), which can mature into other blood cells. These type of stem cells have already been approved by the U.S. Food and Drug Administration to treat patients—especially children--with blood cancers, such as leukemias and lymphomas, and certain blood disorders like sickle cell anemia.
In contrast, stem cells in teeth are called mesenchymal stem cells (MSCs), which are found in dental pulp, the tissue in the center of the tooth that's filled with nerves and blood vessels. MSCs are adult stem cells normally found in the bone marrow that can transform into bone, fat, and cartilage cells, and also aid in the formation of blood stem cells.
"Right now we just don't have rigorous evidence that they can be used in that fashion and have real benefit."
Small studies on lab animals suggest that MSCs secrete growth factors—hormonal steroids or proteins—that can nurture ailing cells, act as powerful anti-inflammatory agents that could tame autoimmune disorders like the one that plagues Karen Davis's daughter, and may even generate new nerve and muscle tissue. Preliminary research suggests they potentially could treat medical conditions as varied as heart disease, spinal cord injury and type 1 diabetes by generating new cells, which can replace damaged or dead cells.
But this is all very early research and there's a vast difference between how cells behave in the tightly controlled environment of a lab versus the real world in a diverse population of human patients. "Right now we just don't have rigorous evidence that they can be used in that fashion and have real benefit," says Pamela G. Robey, PhD, chief of the skeletal biology section at the National Institute of Dental and Craniofacial Research at the National Institutes of Health.
Robey should know—she headed the research team that discovered stem cells in human baby teeth and in wisdom teeth more than fifteen years ago. She believes prospects are better using these stem cells for tooth repair: research suggests they may be able to fix cracked teeth, repair bone defects caused by gum disease, or in root canal therapy, where they can be used to replace infected tissue with regenerated healthy pulp.
In the meantime, though, there are no clinical applications for MSCs. "These tooth banking companies aren't doing their own research," says Leigh Turner, a bioethicist at the University of Minnesota who monitors stem cell clinics. "They cobble together reports of early research in humans or from animal studies in an effort to provide a narrative to make it seem like it is evidence based."
Still, in all fairness, tooth banking companies aren't making the kind of extravagant claims made by stem cell clinics, which operate in a gray area of the law and purport to treat everything from chronic lung disease to Alzheimer's. "We don't know when therapies will be available using these cells because the pace of research is hard to predict," says Peter Verlander, PhD, a molecular geneticist and chief scientific officer of Provia Laboratories, the parent company of Store-A-Tooth. "But for parents who regretted not banking their child's cord blood, especially if they later develop a disease like diabetes, this is another opportunity."
But the jury is still out if this is truly a good investment. Moursi, a national spokesperson for the American Academy of Pediatric Dentistry who fields queries about this practice from a dozen or so families a year, concludes: "If you could afford it, and know the risks, benefits and current limitations, then it is something to consider."
Declining numbers of insects, coupled with climate change, can have devastating effects for people in more ways than one. But clever use of technologies like AI could keep them buzzing.
And because many insects serve as food for other species—bats, birds and freshwater fish—they’re an integral part of the ecosystem’s food chain. “If you like to eat good food, you should thank an insect,” says Scott Hoffman Black, an ecologist and executive director of the Xerces Society for Invertebrate Conservation in Portland, Oregon. “And if you like birds in your trees and fish in your streams, you should be concerned with insect conservation.”
Deforestation, urbanization, and agricultural spread have eaten away at large swaths of insect habitat. The increasingly poorly controlled use of insecticides, which harms unintended species, and the proliferation of invasive insect species that disrupt native ecosystems compound the problem.
“There is not a single reason why insects are in decline,” says Jessica L. Ware, associate curator in the Division of Invertebrate Zoology at the American Museum of Natural History in New York, and president of the Entomological Society of America. “There are over one million described insect species, occupying different niches and responding to environmental stressors in different ways.”
Jessica Ware, an entomologist at the American Museum of Natural History, is using DNA methods to monitor insects.
Credit:D.Finnin/AMNH
In addition to habitat loss fueling the decline in insect populations, the other “major drivers” Ware identified are invasive species, climate change, pollution, and fluctuating levels of nitrogen, which play a major role in the lifecycle of plants, some of which serve as insect habitants and others as their food. “The causes of world insect population declines are, unfortunately, very easy to link to human activities,” Lehmann says.
Climate change will undoubtedly make the problem worse. “As temperatures start to rise, it can essentially make it too hot for some insects to survive,” says Emily McDermott, an assistant professor in the Department of Entomology and Plant Pathology at the University of Arkansas. “Conversely in other areas, it could potentially also allow other insects to expand their ranges.”
Without Pollinators Humans Will Starve
We may not think much of our planet’s getting warmer by only one degree Celsius, but it can spell catastrophe for many insects, plants, and animals, because it’s often accompanied by less rainfall. “Changes in precipitation patterns will have cascading consequences across the tree of life,” says David Wagner, a professor of ecology and evolutionary biology at the University of Connecticut. Insects, in particular, are “very vulnerable” because “they’re small and susceptible to drying.”
For instance, droughts have put the monarch butterfly at risk of being unable to find nectar to “recharge its engine” as it migrates from Canada and New England to Mexico for winter, where it enters a hibernation state until it journeys back in the spring. “The monarch is an iconic and a much-loved insect,” whose migration “is imperiled by climate change,” Wagner says.
Warming and drying trends in the Western United States are perhaps having an even more severe impact on insects than in the eastern region. As a result, “we are seeing fewer individual butterflies per year,” says Matt Forister, a professor of insect ecology at the University of Nevada, Reno.
There are hundreds of butterfly species in the United States and thousands in the world. They are pollinators and can serve as good indicators of other species’ health. “Although butterflies are only one group among many important pollinators, in general we assume that what’s bad for butterflies is probably bad for other insects,” says Forister, whose research focuses on butterflies. Climate change and habitat destruction are wreaking havoc on butterflies as well as plants, leading to a further indirect effect on caterpillars and butterflies.
Different insect species have different levels of sensitivity to environmental changes. For example, one-half of the bumblebee species in the United States are showing declines, whereas the other half are not, says Christina Grozinger, a professor of entomology at the Pennsylvania State University. Some species of bumble bees are even increasing in their range, seemingly resilient to environmental changes. But other pollinators are dwindling to the point that farmers have to buy from the rearing facilities, which is the case for the California almond industry. “This is a massive cost to the farmer, which could be provided for free, in case the local habitats supported these pollinators,” Lehmann says.
For bees and other insects, climate change can harm the plants they depend on for survival or have a negative impact on the insects directly. Overly rainy and hot conditions may limit flowering in plants or reduce the ability of a pollinator to forage and feed, which then decreases their reproductive success, resulting in dwindling populations, Grozinger explains.
“Nutritional deprivation can also make pollinators more sensitive to viruses and parasites and therefore cause disease spread,” she says. “There are many ways that climate change can reduce our pollinator populations and make it more difficult to grow the many fruit, vegetable and nut crops that depend on pollinators.”
Disease-Causing Insects Can Bring More Outbreaks
While some much-needed insects are declining, certain disease-causing species may be spreading and proliferating, which is another reason for human concern. Many mosquito types spread malaria, Zika virus, West Nile virus, and a brain infection called equine encephalitis, along with other diseases as well as heartworms in dogs, says Michael Sabourin, president of the Vermont Entomological Society. An animal health specialist for the state, Sabourin conducts vector surveys that identify ticks and mosquitoes.
Scientists refer to disease-carrying insects as vector species and, while there’s a limited number of them, many of these infections can be deadly. Fleas were a well-known vector for the bubonic plague, while kissing bugs are a vector for Chagas disease, a potentially life-threatening parasitic illness in humans, dogs, and other mammals, Sabourin says.
As the planet heats up, some of the creepy crawlers are able to survive milder winters or move up north. Warmer temperatures and a shorter snow season have spawned an increasing abundance of ticks in Maine, including the blacklegged tick (Ixodes scapularis), known to transmit Lyme disease, says Sean Birkel, an assistant professor in the Climate Change Institute and Cooperative Extension at the University of Maine.
Coupled with more frequent and heavier precipitation, rising temperatures bring a longer warm season that can also lead to a longer period of mosquito activity. “While other factors may be at play, climate change affects important underlying conditions that can, in turn, facilitate the spread of vector-borne disease,” Birkel says.
For example, if mosquitoes are finding fewer of their preferred food sources, they may bite humans more. Both male and female mosquitoes feed on sugar as part of their normal behavior, but if they aren’t eating their fill, they may become more bloodthirsty. One recent paper found that sugar-deprived Anopheles gambiae females go for larger blood meals to stay in good health and lay eggs. “More blood meals equals more chances to pick up and transmit a pathogen,” McDermott says, He adds that climate change could reduce the number of available plants to feed on. And while most mosquitoes are “generalist sugar-feeders” meaning that they will likely find alternatives, losing their favorite plants can make them hungrier for blood
Similar to the effect of losing plants, mosquitoes may get turned onto people if they lose their favorite animal species. For example, some studies found that Culex pipiens mosquitoes that transmit the West Nile virus feed primarily on birds in summer. But that changes in the fall, at least in some places. Because there are fewer birds around, C. pipiens switch to mammals, including humans. And if some disease-carrying insect species proliferate or increase their ranges, that increases chances for human infection, says McDermott. “A larger concern is that climate change could increase vector population sizes, making it more likely that people or animals would be bitten by an infected insect.”
Science Can Help Bring Back the Buzz
To help friendly insects thrive and keep the foes in check, scientists need better ways of trapping, counting, and monitoring insects. It’s not an easy job, but artificial intelligence and molecular methods can help. Ware’s lab uses various environmental DNA methods to monitor freshwater habitats. Molecular technologies hold much promise. The so-called DNA barcodes, in which species are identified using a short string of their genes, can now be used to identify birds, bees, moths and other creatures, and should be used on a larger scale, says Wagner, the University of Connecticut professor. “One day, something akin to Star Trek’s tricorder will soon be on sale down at the local science store.”
Scientists are also deploying artificial intelligence, or AI, to identify insects in agricultural systems and north latitudes where there are fewer bugs, Wagner says. For instance, some automated traps already use the wingbeat frequencies of mosquitoes to distinguish the harmless ones from the disease-carriers. But new technology and software are needed to further expand detection based on vision, sound, and odors.
“Because of their ubiquity, enormity of numbers, and seemingly boundless diversity, we desperately need to develop molecular and AI technologies that will allow us to automate sampling and identification,” says Wagner. “That would accelerate our ability to track insect populations, alert us to the presence of new disease vectors, exotic pest introductions, and unexpected declines.”