Publisher Health

Independent teams from Texas Biomedical Research Institute and the Medical College of Wisconsin have published two papers in Science Translational Medicine identifying how the only approved drug to treat schistosomiasis, a widespread parasitic worm infection, works on the molecular level.
The insights lay the groundwork for diagnostic tests to help identify specific patients and regions with drug-resistant parasites, as well as for developing treatments that can overcome this challenge.
“We have two independent papers using completely different methods coming to the exact same conclusions,” says Texas Biomed Professor Tim Anderson, PhD, senior author of one of the papers. “Because the papers are being published back-to-back, I think they will be taken very seriously.”
Schistosomiasis is a parasitic disease, caused by tiny flatworms called schistosomes. More than 200 million people across a large part of the globe are infected, and thousands die each year. Praziquantel is the only approved drug to treat schistosomiasis, and more than 250 million doses are distributed each year as part of an international campaign to try to eliminate the disease. However, about 30% of people are still infected after treatment.
“We have one drug to treat this huge population of parasites, and it works, but it is not perfect,” says Winka Le Clec’h, PhD, a staff scientist at Texas Biomed and first author. “We didn’t know how it was working, what is the precise mechanism of action. Now, for the first time we have a better idea about the target of praziquantel.”
The drug binds to a specific type of channel in the cell membrane, called a transient receptor potential (TRP) channel. When the channel is open, there is a massive influx of calcium ions into the cells, which results in worm paralysis and death.

Not too long ago the idea of taking, for instance a skin cell and transforming it into a muscle cell was unthinkable. About 10 years ago, however, revolutionary research showed that it is indeed possible to reprogram differentiated adult cells into other types fully capable of conducting new functions.
Cell reprogramming is a main interest of the lab of Dr. Todd Rosengart, chair and professor of the Michael E. DeBakey Department of Surgery at Baylor College of Medicine, whose research focuses on finding innovative therapeutic approaches for heart failure.
“Heart failure remains the leading cause of death from heart disease,” said Rosengart, DeBakey-Bard Chair in Surgery and professor of molecular and cellular biology at Baylor. “Nearly 5 million Americans can be expected to develop advanced congestive heart failure, and heart transplant or mechanical circulatory support implantation currently are the only options for patients with end-stage heart disease. However, these options are limited. We need to improve how to treat this devastating condition.”
After a heart attack, the parts of the heart muscle that die do not regenerate into new heart tissue; instead, they are replaced by a scar that does not help the heart to beat. “The idea behind cell reprograming is to coach the heart to heal itself by inducing the scar tissue, which is made mostly of fibroblasts, to change into functional heart muscle,” said Rosengart, professor of heart and vascular disease at the Texas Heart Institute.
Researchers have succeeded at reprograming fibroblasts from small animals to become heart muscle, with dramatic improvements in heart function. The challenge has been to apply this technology to human cells — human fibroblasts are more resistant to reprograming. In this study, Rosengart and his colleagues explored a novel strategy to enhance the reprogramming efficiency of human fibroblasts.
“While human fibroblasts resist being reprogramed, endothelial cells, those that line the blood vessels, are known to be more flexible — they have the capacity to naturally transdifferentiate or change into other cells,” said co-first author Dr. Megumi Mathison, associate professor of surgery at Baylor. “This gave us the idea of using this endothelial cell plasticity to improve the reprograming efficiency.”
The researchers’ idea was to first induce fibroblasts to transition into an endothelial cell-like state and then treat these cells with their reprograming cocktail that directs them to change into cardiomyocytes. The expectation was that transitioning into endothelial cell-like cells, a cell type more open to reprogramming than fibroblasts, would facilitate the desired change into heart muscle.

In Down syndrome, the third copy of chromosome 21 causes a reorganization of the 3D configuration of the entire genome in a key cell type of the developing brain, a new study shows. The resulting disruption of gene transcription and cell function are so similar to those seen in cellular aging, or senescence, that the scientists leading the study found they could use anti-senescence drugs to correct them in cell cultures.
The study published in Cell Stem Cell therefore establishes senescence as a potentially targetable mechanism for future treatment of Down syndrome, said Hiruy Meharena, a new assistant professor at the University of California San Diego who led the work as a Senior Alana Fellow in the Alana Down Syndrome Center at MIT.
“There is a cell-type specific genome-wide disruption that is independent of the gene dosage response,” Meharena said. “It’s a very similar phenomenon to what’s observed in senescence. This suggests that excessive senescence in the developing brain induced by the third copy of chromosome 21 could be a key reason for the neurodevelopmental abnormalities seen in Down syndrome.”
The study’s finding that neural progenitor cells (NPCs), which develop into major cells in the brain including neurons, have a senescent character is remarkable and novel, said senior author Li-Huei Tsai, but it is substantiated by the team’s extensive work to elucidate the underlying mechanism of the effects of abnormal chromosome number, or aneupoloidy, within the nucleus of the cells.
“This study illustrates the importance of asking fundamental questions about the underlying mechanisms of neurological disorders,” said Tsai, Picower Professor of Neuroscience, director of the Alana Center, and of The Picower Institute for Learning and Memory at MIT. “We didn’t begin this work expecting to see senescence as a translationally relevant feature of Down syndrome, but the data emerged from asking how the presence of an extra chromosome affects the architecture of all of a cell’s chromosomes during development.”
Genomewide changes
Meharena and co-authors spent years measuring distinctions between human cell cultures that differed only by whether they had a third copy of chromosome 21. Stem cells derived from volunteers were cultured to turn into NPCs. In both the stem cells and the NPCs, the team examined 3D chromosome architecture, several metrics of DNA structure and interaction, gene accessibility and transcription, and gene expression. They also looked at the consequences of the gene expression differences on important functions of these developmental cells, such as how well they proliferated and migrated in 3D brain tissue cultures. Stem cells were not particularly different, but NPCs were substantially affected by the third copy of chromosome 21.

In the most comprehensive analysis to date, researchers found that the shapes of fingerprints — whether they are circular, wavy, or winding — are influenced by the genes responsible for limb development instead of skin patterning. The study, presented January 6 in the journal Cell, could help scientists better understand the association between genes and phenotypical traits in humans.
“People may wonder why our team is working on fingerprints,” says Sijia Wang, a geneticist at the Shanghai Institute of Nutrition and Health, of Chinese Academy of Sciences, and co-senior author on the paper. “We started the work purely out of curiosity. But later it turns out fingerprint pattern is associated with genes for limb growth, which are critical for fetal development. This provides another classic example of pleiotropy, when multiple phenotypes are interrelated to each other and are affected by the same genes.”
While fingerprints are unique to individuals, they are generally categorized into three types: arch, loop, and whorl. These furrows and ridges begin to form on a fetus’ fingers and toes after the third month of pregnancy. Scientists have suspected that fingerprints have potentially evolved to help grab objects and sense their textures, but exactly how these patterns are formed remains unknown.
Wang and colleagues scanned the DNA of more than 23,000 people across ethnic groups and found that at least 43 regions on the genome are associated with fingerprint patterns. One of the most influential regions appeared to be regulating the expression of a gene called EVI1, which is known for its role in embryonic limb development.
To test their finding, the team modified the DNA of mice so their expression of EVI1 was turned down. They found that mice with downregulated EVI1 developed abnormal skin patterns on their digits compared with wild-type mice.
Analysis of human data revealed that fingerprint patterns are genetically correlated with finger length. For example, people with whorl-shaped fingerprints on both of their little fingers tend to have longer little fingers than those who do not, and this correlation is strongly linked to genes involved ini limb development.
“We don’t know exactly how the genes shape fingerprint patterns, but it could be determined by the amount of strength from growth that’s put on an embryonic tissue called volar pads that plays an important role in the formation of different patterns of fingerprint,” says Jinxi Li, a geneticist at the Human Phenome Institute at Fudan University in Shanghai, and a co-first author on the paper. She explains that as a fetus’ hands grow, the palms and fingers would stretch and elongate. These forces could turn a whorl into a loop, for example.
Notably, previous research has suggested that EVI1 is linked to risk of leukemia, and some studies have observed that people with more whorl patterns are more susceptible to the disease,” Wang says.
“Many congenital genetic disorders are related to different dermatoglyphic patterns, such as fingerprints,” he says. For example, children with Down’s syndrome are more likely to have a single crease running across the palm of their hands. “Our study suggests that dermatoglyphic patterns are affected by crucial development genes, which provides a strong theoretical basis for this kind of pleiotropy.”
The research is part of the International Human Phenome Project led by Fudan University in Shanghai that aims to map how the human phenotypical traits are correlated with each other. Next, the team plans to conduct more research on how dermatoglyphic patterns are related to diseases and the underlying pleiotropic mechanism.
Story Source:
Materials provided by Cell Press. Note: Content may be edited for style and length.

Certain subtle differences in DNA sequences are known to raise the chances a person may develop Alzheimer’s or Parkinson’s disease. Some of these differences may work by altering the genetic activity of microglia, the brain’s immune cells. Those are just a few of the findings from a study led by scientists at the Icahn School of Medicine at Mount Sinai.
The researchers analyzed thousands of microglia from different brain regions of deceased patients who had been diagnosed with a variety of neuropsychiatric and neurodegenerative disorders. Their results, published in Nature Genetics, support the idea that microglia may play critical roles in some cases of brain disease while also providing a potentially valuable guide for future studies.
The study was led by Katia de Paiva Lopes, PhD, Gijsje Snijders, MD, PhD, and Jack Humphrey, PhD, working in the laboratories of Towfique Raj, PhD, Associate Professor of Neuroscience, and Lotje D. De Witte, MD, PhD, Assistant Professor of Psychiatry at Icahn Mount Sinai.
Shaped like octopi, microglia can be found sprinkled throughout the brain. For nearly a century after they were first spotted, scientists thought that these cells served as both the brain’s infection-fighting immune system and clean-up crew. They also thought that microglia strictly played a reactive, rather than causative, role in brain disorders.
Recently this view has started to change. For instance, experiments in rodents have shown that microglia may actively shape how the brain is wired. Meanwhile, genomic studies identified potential links between microglia and the risk that certain DNA sequences are associated with developing several brain disorders, including Alzheimer’s disease and multiple sclerosis. However, tying these results to specific genes has proved elusive.
In this study, scientists used advanced genomic techniques to take an in-depth look at the many roles that microglia may play in the brain. To do this, they created the largest and most thorough high-resolution microglial genomic atlas of its kind. Microglia were extracted from samples of human brain tissue and then underwent a series of gene activity experiments. A total of 255 samples representing four different brain regions were obtained from 100 donors, who were part of the Netherlands Brain Bank and the Neuropathology Brain Bank Research CoRE at The Mount Sinai Hospital. The average donor was about 73 years old, spanning a range of 21 to 103 years of age. Ninety-six samples came from control donors whereas the rest came from donors who had been diagnosed with a neurological or psychiatric disorder.
Overall, the results both supported previous findings and made new discoveries. For example, microglia gene activity changed with age or in different brain regions, reinforcing the idea that the roles microglia play can vary throughout the brain and at different stages of life. Moreover, aging appeared to alter primarily the activity of genes associated with the immune system.
The results strengthened the evidence that microglia may be linked to some cases of Alzheimer’s and Parkinson’s diseases while also finding links to other disorders, including multiple sclerosis, schizophrenia, and bipolar disorder. Finally, the researchers identified two new genes that may be associated with brain disorders. One gene, called USP6NL, was associated with Alzheimer’s disease while the other one, called P2RY12, was associated with Parkinson’s disease. According to the authors, these results support the idea that the atlas provides the kind of comprehensive guide needed to fully understand the roles microglia may play under healthy and disease states.

Using data from over 300 patient tumors, researchers have described 12 classes of ‘immune archetypes’ to classify cancer tumors. Their findings reveal that cancers from different parts of the body are immunologically similar to one another. These classifications provide unique strategies for enhancing each patient’s choice of cancer immunotherapies.
The UCSF researchers, led by first co-authors Alexis Combes, PhD, and Bushra Samad, MS, and senior author, Max Krummel, PhD, obtained tumor specimens from 78 UCSF clinicians, and surveyed 364 tumors biopsies from patients and categorized them into groups based on their immune microenvironment. Their findings offer a new way of looking at cancer immunotherapy that matches the immune environment around the tumor and points the way to personalized immunotherapies.
“This is a new framework for how to look at cancer patients,” said Combes, director of the D2B CoLab and incoming assistant professor in the Department of pathology at UCSF. “This work will help clinicians find the right biology to target and avoid targeting cells that aren’t present in the tumor.”
Immunotherapy for cancer treatment harnesses the body’s immune system to fight cancer. It has held great promise since it was first developed as a biological therapy used to treat a variety of cancers. While it has proven successful for some patients, immunotherapy does not work for all patients.
“We were driven by this question of why immunotherapies work for some people and not others,” said Krummel, Robert E. Smith Endowed Chair in Experimental Pathology and director of the Krummel Lab at UCSF. “It’s more complex than responders and non-responders. Our goal was to discern how many responses there are to these targeted therapies.”
Tumors have microenvironments
Tumors are more than just out-of-control cells. They are also filled with immune cells which are supposed to kill the cancer cells. But in cancer, malignant cells are able to overcome the body’s immune response and continue to multiply.

Scarce supplies and surging Covid cases have caused health officials, hospitals, doctors and patients to scramble for pills and infusions.At the onset of the coronavirus pandemic in 2020, scarce ventilators and protective equipment faced strict rationing. Today, as the pandemic rages into its third year, another precious category of products is coming under tight controls: treatments to stave off severe Covid-19.There is a greater menu of Covid pills and infusions now than at any point in the pandemic. The problem is that the supplies of those that work against the Omicron variant are extremely limited.That has forced state health officials and doctors nationwide into the fraught position of deciding which patients get potentially lifesaving treatments and which don’t. Some people at high risk of severe Covid are being turned away because they are vaccinated.Some hospitals have run out of certain drugs; others report having only a few dozen treatment courses on hand. Staff are dispensing vitamins in lieu of authorized drugs. Others are scrambling to develop algorithms to decide who gets treatments.“There is simply not enough to meet the needs of everyone who is going to have Covid in the upcoming weeks and be at risk of severe complications,” said Dr. Natasha Bagdasarian, Michigan’s chief medical executive. “I don’t think there is a way to make sure it gets to all the right people right now.”At Family Health Centers of San Diego, a network of clinics for low-income patients, staff have had to turn away about 90 percent of the hundreds of people who are calling daily and are eligible for Covid treatments.“It makes me nauseous going home at night because it makes me feel like I’m deciding, with this limited resource, who should get it,” said Dr. Christian Ramers, an infectious disease specialist there.A plentiful supply of effective treatments would be a powerful weapon as the virus again surges across the United States. Fueled by the highly contagious Omicron variant, Covid cases have soared to record highs, and the number of hospitalized patients also has increased sharply, though Omicron tends to cause milder illness than other variants.For most of the pandemic, monoclonal antibodies — a treatment generally administered intravenously at hospitals or clinics — have been the primary option for recently infected patients. But the two most common types of the antibodies don’t appear to work against the Omicron variant, which is quickly becoming the world’s dominant version of the coronavirus.There is a third antibody treatment, made by GlaxoSmithKline and Vir Biotechnology, that is potent against Omicron. But the federal government has ordered only about 450,000 treatment courses, many of which have already been used or have not yet been delivered by Glaxo.The Food and Drug Administration two weeks ago authorized the use of a new antiviral pill, developed by Pfizer, that shows great promise at fighting Covid in general and Omicron cases in particular.A shipment of Pfizer’s Covid pill, Paxlovid, arriving in Israel last week.Maya Alleruzzo/Associated PressThe federal government is providing the pill, known as Paxlovid, to states, whose health officials decide where to send the pills and how to advise doctors to use them.Supplies are already being depleted. New York City, for example, received about 1,300 treatment courses of Paxlovid in late December, which it used up within a week, according to a spokesman for Alto Pharmacy, which is distributing the city’s supply. New York City currently does not have any Paxlovid in stock.On Tuesday, the U.S. government doubled its order for Paxlovid, though supplies won’t be plentiful until April.State and local officials say the goal is to get Paxlovid to as many of the most vulnerable people as possible, with a particular focus on those with weakened immune systems or who are unvaccinated.Unvaccinated people are at far greater risk of hospitalization or death from Covid. But giving them priority access to treatments leaves people feeling “like you are rewarding intransigence,” said Dr. Matthew K. Wynia, the director of the Center for Bioethics and Humanities at the University of Colorado, who has advised the state on how to ration Covid treatments.Only some states, like Ohio and Nevada, have sent Paxlovid to pharmacies that serve nursing homes, whose residents are especially vulnerable to Covid. Many states, including Virginia, Pennsylvania and Arizona, have sent most or all of their initial Paxlovid supplies to pharmacy chains like Walgreens and Rite Aid.That was meant to make the pills as widely accessible as possible. But the system rewards patients who have the time, energy and savvy to chase down treatments.Patrick Creighton, 48, a sports radio host in Katy, Texas, woke up on New Year’s Eve with his throat burning. He was vaccinated but tested positive later that day. Concerned that his diabetes elevated his risk of becoming seriously ill, he decided to seek out Paxlovid, which he had been reading up on.A telemedicine doctor wrote him a prescription the next day. Now he needed to find a pharmacy with Paxlovid in stock. He said he called 18 pharmacies within driving distance: one Brookshire Brothers, four Krogers, four H-E-Bs, three Walgreens, three CVS stores and three Walmarts. None had the pills.His 19th call was a winner: A nearby Walmart had Paxlovid in stock. The ordeal still wasn’t over. He was incorrectly told that he might have to pay $500 for the free treatment. Then he had to see a second telemedicine doctor because of a problem with the way his prescription was sent. Then his wife had to make a second trip to Walmart to pick up the pills. But on the evening of Jan. 2, he finally took the first three tablets of the 30-pill regimen.Mr. Creighton said he worried about patients who aren’t able to navigate the obstacles like he could. “It should be easily obtainable for everybody.”The GlaxoSmithKline antibody treatment is similarly hard to come by.At the University of Pittsburgh Medical Center, the staff is now giving out 400 to 800 antibody treatments each week, down from 2,000 to 3,000 before Omicron rendered two of the products useless. Demand has rocketed higher, but the hospital no longer has enough supply.“It is devastating to tell these patients, ‘Sorry, we can’t do anything for you, we have to save this drug only for our most severely immunocompromised,’” said Erin McCreary, an infectious diseases pharmacist at the hospital.On Tuesday, the U.S. government doubled its order for Paxlovid.Thomas Hansmann/PfizerLouis Shantzek, a Miami retiree, tried unsuccessfully to get an antibody infusion last week after he tested positive for the virus. He is 72 and has diabetes and a heart condition — all factors that would normally make him eligible to get an antibody treatment.The Coronavirus Pandemic: Key Things to KnowCard 1 of 6The global surge.

Large wildfires and severe heat events are happening more often at the same time, worsening air pollution across the western United States, a study led by Washington State University researchers has found. In 2020, more than 68% of the western U.S. — representing about 43 million people — were affected in one day by the resulting harmful-levels of air pollution, the highest number in 20 years.
The study, published in Science Advances, found that such widespread air pollution events are not only increasing in frequency but also persisting longer and affecting a larger geographic extent across the region. They have become so bad that they have reversed many gains of the Clean Air Act. The conditions that create these episodes are also expected to continue to increase, along with their threats to human health.
“We have seen an increasing trend in the past 20 years of days when high-levels of both particulate matter and ozone are occurring simultaneously,” said lead author Dmitri Kalashnikov, a WSU doctoral student. “This is tied to two things: more wildfires and increases in the types of weather patterns that cause both wildfires and hot weather.”
When wildfires and extreme heat occur at the same time, they magnify air pollution: wildfire smoke increases fine particulate matter in the air and the heat combines the smoke and other pollutants to create more ground-level ozone. While in the stratosphere ozone is protective, ozone that forms at the ground level has long been recognized as harmful to human health. It’s a major component of smog, and reducing it was a major goal of clean air policies in the twentieth century. Simultaneous exposure of millions of people to high levels of both pollutants, ground-level ozone and particulate matter, poses a substantial public health burden.
Weather patterns called high-pressure ridging, more commonly known as heat domes, occur when an area of high-pressure air lingers over a region trapping warm stagnant air and its pollutants on the ground. These conditions typically lead to higher levels of harmful ground-level ozone during summer months. Particulate matter affecting air quality used to be more common in the winter in the western United States, but wildfires have flipped that dynamic, bringing the dangers of both particulate matter and ground-level ozone together at the same time in the summer.
For this study, the researchers tracked air quality by using all available monitoring station data from 2001-2020 from across the western states as well as parts of Canada. They combined this data with wildfire information derived from NASA satellites along with ERA5 weather data produced by the European Center for Medium-Range Weather Forecasts.
The co-occurring events were defined as days that registered in both the top 10% in particulate matter levels and top 10% in ozone. The researchers found that annual population exposure to these extreme combined episodes is increasing by approximately 25 millionperson-days a year- a figure that counts the number of people affected as well as the number of days they were impacted by the air pollution.
“From every indication we have, the hotter, drier conditions projected for this region are likely to increase wildfire activity and contribute to more widespread, severe heat, which means we can expect to see these conditions happen more often in the future,” said co-author Deepti Singh, a WSU assistant professor. “Preparing for these events is really important. We need to think about who is exposed, what capacity there is to minimize that exposure, and how we can protect the most vulnerable people.”
These events could potentially be mitigated by taking measures to slow the temperature rise caused by climate change as well as better managing wildfires, such as through prescribed burns. Aside from those efforts, Kalashnikov and Singh suggested treating these air pollution events like a severe snowstorm or heatwave by making sure people have shelters with air quality filters where they can go to get out of polluted air. They also recommended adopting policies that minimize workplace exposure for people who typically work outside.
The size of the simultaneous air pollution events will make it difficult for many people to avoid their impacts, Singh said.
“If there’s such a large region that’s being affected by this air pollution, it really limits where people can go to escape those conditions,” she said. “You could travel a hundred miles and still not find air quality that is any better.”
Other co-authors on this study include Jordan Schnell of the University of Colorado, Boulder; John Abatzoglou of University of California, Merced; and Daniel Swain of the University of California, Los Angeles, the National Center for Atmospheric Research and The Nature Conservancy of California.
Story Source:
Materials provided by Washington State University. Original written by Sara Zaske. Note: Content may be edited for style and length.

The bacterium Vibrio cholerae is the causative agent of the diarrheal disease cholera and is responsible for seven known pandemics. The seventh cholera pandemic began in 1961 and is still active. Unlike previous pandemics, it is caused by cholera strains of a slightly different type. How did the modified cholera strains develop and spread, and what might have contributed to their success? Scientists from the Max Planck Institute for Evolutionary Biology in Plön, Germany, and CAU Kiel, in an international team with colleagues from City College New York and the University of Texas Rio Grande Valley, have now gained new insights into a molecular mechanism that provides insight into the interactions between cholera bacteria and may have played a role in the emergence of the seventh pandemic.
In their natural environment, bacteria are subject to competition with other bacteria for space and nutrients. In this process, molecular mechanisms help them to hold their own. One such mechanism is the so-called “type 6 secretion system” (T6SS), with which a bacterium transports toxic proteins into a neighboring bacterium and thereby kills it. Thus, cholera bacteria of the seventh pandemic use their T6SS to keep other bacteria in check and presumably more easily cause infection.
Researchers now had the special opportunity to study the T6SS of cholera bacteria from previous pandemics. For this purpose, among other things, the T6SS genome sequence of cholera bacteria from the 2nd pandemic was reconstructed from a museum specimen from the 19th century in a complex procedure and recreated in the laboratory.
In the process, the scientists were able to show that 2nd and 6th pandemic cholera bacteria lack a functional T6SS. As a result, the bacteria of earlier pandemics not only lack the ability to attack other bacteria, they are themselves killed by bacterial strains of the seventh pandemic. This may have been one of the reasons that older cholera strains were displaced by modified cholera strains of the seventh pandemic and are now hard to find.
Data from new lab
Daniel Unterweger, one of the study’s authors and a group leader at the Max Planck Institute in Plön, Germany, says: “With these findings, we support the theory that microbial competition between bacteria is very important for understanding pathogens and bacterial pandemics. Our research on the cholera bacterium was made possible by an S2 laboratory newly established at the institute. Here, we can conduct experiments with bacterial pathogens under the necessary safety precautions. The study contains some of the first data from the new laboratory.”
Story Source:
Materials provided by Max-Planck-Gesellschaft. Note: Content may be edited for style and length.

The correct functioning of our cells rests upon the precise orchestration of many complex processes and organelles. Lysosomes — vital cell organelles — are enzyme-filled subunits found within many animal cells that help break down and reuse macromolecules, such as proteins, lipids, and nucleotides. Besides their function in cellular digestion and waste management, lysosomes also participate in amino acid signaling, which stimulates protein synthesis alongside other effects.
Given that a lot of diseases are caused by defects in lysosome function, it is no surprise that researchers have been actively trying to understand these organelles for decades. But there are only a few techniques that allow the extraction of lysosomes from within a cell. The most common method is called “density gradient ultracentrifugation.” It involves gently breaking the cell membrane and applying a centrifugal force to the cell’s contents. This separates the cell components by density. Unfortunately, some other organelles have the same density as lysosomes, resulting in samples with impurities. Moreover, the process takes so long that by the time it finishes, many lysosomal proteins have already been lost and/or degraded.
A more advanced technique, called “immunoprecipitation,” relies on modifying the surface proteins of lysosomes so that they can be captured by magnetic beads covered in specially tailored antibodies. While this approach produces purer results, the protein composition of the extracted lysosomes is modified by the procedure and, thus, subsequent protein analyses can be compromised. It is clear, then, that we need to find a better way to extract lysosomes from cells.
Fortunately, a team of scientists led by Prof. Shinya Maenosono from the Japan Advanced Institute of Science and Technology (JAIST) has stepped up to the plate and developed a novel strategy to quickly separate intact lysosomes with high purity. This study was published in ACS Nano and also included Prof. Kazuaki Matsumura and Associate Prof. Yuichi Hiratsuka from JAIST, and Prof. Tomohiko Taguchi of Tohoku University, Japan.
Their strategy is centered around the use of magnetic-plasmonic hybrid nanoparticles (MPNPs) made of silver and an iron-cobalt alloy and covered in a compound called amino dextran (aDxt). The basis for this approach is that the aDxt-covered MPNPs are naturally ingested by the cells through “endocytosis,” which culminates inside lysosomes. Once enough MPNPs have accumulated inside the lysosomes, the cells can be gently “crushed,” and the lysosomes retrieved using magnets.
For this method to work, it is essential that MPNPs are located only within lysosomes and not in other organelles. This is where plasmon imaging comes in handy, as the distinct way plasmonic nanoparticles interact with light makes them easy to visualize with an optical microscope. By coloring each type of organelle in the endocytic pathway differently using immunostaining and checking how the location of MPNPs overlaps with them, the researchers determined the precise time it takes most MPNPs to reach the lysosomes. In turn, this ensures that the separation process yields lysosome samples with high purity.
Afterwards, the team analyzed the effects of temperature and magnetic separation time on the protein composition of the extracted lysosomes. Their results showed that protein loss was remarkably quick, even at temperatures as low as 4°C. Fortunately, their approach was fast enough to extract intact lysosomes, as Prof. Maenosono highlights: “We found that the maximum time required to isolate lysosomes after cell rupture was 30 minutes, which is substantially shorter than the time required using centrifugation-based techniques, which typical require a minimum separation time of several hours.”
Overall, this new technique will help researchers explore the fragile metabolites of lysosomes and how they change in response to stimuli. In turn, this shall pave the way to new insights into disorders related to lysosomal dysfunction. In this regard, Prof. Maenosono remarks: “Given the profound relation of lysosomes with many cellular metabolites, a deeper understanding of lysosomal function is necessary to determine its regulation in different cell states. Therefore, our technique can contribute to better understanding and treatment of lysosomal diseases in the future.” Moreover, this new approach could be modified to extract other organelles besides lysosomes. Hopefully, this study will put us closer to understanding the contents of cells to a much higher degree.