Connect with us

Health

Growing eggs and sperm to treat infertility – News-Medical.net

Published

 on


Scientists at the University of California, Los Angeles, have reported, in the journal Cell Reports, the mechanism of how the very early precursor or stem cells which eventually give rise to the germ cells, eggs and sperm, are formed over the course of development. This could help create eggs and sperms under laboratory conditions to help infertile people who don’t have sperms, or eggs, for instance.

UCLA Broad Stem Cell Research Center/Cell Reports – Differentiating human pluripotent stem cells (blue) turning into human germ cells (pink and white).

The problem

Infertility is a problem for 1 in 10 of the population in the US, and shows an increasing trend over the last few decades because of the later time of first pregnancy. In many of these cases, in vitro fertilization (IVF), and more advanced techniques like intracytoplasmic sperm injection (ICSI) are successfully used to begin a pregnancy. In IVF, the male and female germ cells are joined outside the body and the resulting conceptus is later inserted back into the uterus. With ICSI, the sperm nucleus is injected directly into the egg cell.

However, both of these techniques require sperm and eggs to be present. When it comes to people who lack these germ cells, other therapies must be looked for. The lack of sperm or eggs could be a result of genetic abnormalities, chemotherapy or radiation, or sometimes unknown causes.

One option is to use donor eggs or sperm, or both. However, as researcher Amander Clark says, “With donated eggs and sperm, the child is not genetically related to one or both parents. What we want to do is use stem cells to be able to generate germ cells outside the human body so that this kind of infertility can be overcome.”

The beginning

All embryos develop from a set of undifferentiated cells are present that is capable of developing in many different directions to make almost any kind of cell in the body. These are the pluripotent stem cells, the cells that can also give rise to sperms and eggs.

Scientists have already discovered how to make cells very similar to these from already differentiated adult skin or blood cells, by reversing the developmental timetable and un-differentiating them. These are called induced pluripotent stem cells (iPSCs).

The process

The current study made use of technology to measure the genes that were active in over 100,000 embryonic stem cells and iPSCs as they gave rise to sperm and egg cells. This huge amount of information was then analyzed, using newly developed algorithms from their colleagues at the Massachusetts Institute of Technology, to discern the pattern of development.

The scientists were thus able to come up with a high-definition picture of the process by which germ cells are formed. The first step occurred at 24-48 hours, when the stem cells begin to differentiate into the different types of cells that continue to develop into all the distinctive and highly specialized cells of the adult human body.

At the 12th day after fertilization, around the time of implantation but before the earliest formation of embryonic parts like the primitive streak or the gastrula, it is possible to recognize the earliest stem cells that are differentiating into the germ cell production line, called the human primordial germ cells (hPGCs). At this point the hPGC-like cells (hPGCLCs) are specified, or set apart, by a change in their gene expression towards a transitional state. At this point they share the characteristics of the pre-implantation stem cell as well as the post-implantation embryonic stem cell, which is described as naïve and primed, respectively. They then turn into the pathway to become germ cell progenitors, by the regulation of the sex-determining chromosome area SOX17 that is responsible for hPGCLC specification.

At this point, the hPGCLCs can no longer differentiate into somatic cells – this is called crossing Weismann’s barrier, after the legendary German biologist who proposed the existence of the hereditary factor within germ cells, today known to be DNA. This is the key point in achieving the in vitro production of gametes, or sex cells (eggs and sperms).

Implications

In the current experiment, the primed hPGCLCs are turned back to become transitional germinal pluripotent cells and thus begin to differentiate into germ cells. The researchers now know when to intervene so that they can maximize the number of germ cells formed by diverting more of the differentiation process into this stream.

Another interesting finding was that germ cells arise from stem cells originating in the amnion, the thin translucent membrane containing the fluid surrounding the embryo, as well as the gastrula-forming cells that belong to the baby proper.

Finally, they found that the gene activation patterns leading to germ cell formation are nearly the same, whether it is an embryonic stem cell or an iPSC. This proves they are using the right technique to form the germ cells.

Clark says, “Now we’re poised to take the next step of combining these cells with ovary or testis cells.” These germ cells are not yet decided on whether to develop into sperm or egg cells, and this depends on the molecular signals they receive, whether from the ovary or the testis.

The researchers say, “Through this work, we uncovered the human germline trajectory and discovered the identity of potential peri-implantation progenitors for hPGCs.”

The researchers hope they will eventually be able to coax the iPSCs formed from the patient’s own skin cells to differentiate into germ cells and into ovarian or testicular tissue. This could be used to let each person have his or her germ cells created in the laboratory. The process, however, is a long-drawn-out one and will require intensive research and work.

A step too far?

These techniques have been restricted to laboratory use, and are not approved by the US Food and Drug Administration for use in humans, nor have they undergone human testing.

It is obvious that such experiments involve the abundant use of human pre-implantation embryos. Though ethical approval norms are fulfilled, such testing nonetheless raises numerous other ethical issues. Again, the true motivation of the research remains in doubt since the lack of value for potential human life shown by such experiments makes it difficult to believe that making it possible for infertile couples to have babies is the real incentive.

Finally, the potential for misapplication of this technology is obvious, just one example being its use to allow both sperm and egg cells to be created from the same patient, nurtured by both ovarian and testicular tissue derived from that patient, and eventually giving rise to a single-parent zygote. One hopes that scientists will not allow their curiosity to run rampant but rein it in within appropriate bounds rather than ruin human life with unnecessary technology -simply because they can.

UCLA research could be step toward lab-grown eggs and sperm to treat infertility – http://newsroom.ucla.edu/releases/lab-grown-eggs-and-sperm-step-toward-infertility-treatment

Journal reference:

Human Primordial Germ Cells Are Specified from Lineage-Primed Progenitors Chen, Di et al. Cell Reports, Volume 29, Issue 13, 4568 – 4582.e5, https://www.cell.com/cell-reports/fulltext/S2211-1247(19)31574-8

Let’s block ads! (Why?)



Source link

Continue Reading

Health

Ontario confident in monkeypox vaccine strategy, Moore says, but some seek expansion – Cornwall Seaway News

Published

 on


TORONTO — Ontario’s top doctor says the province’s current monkeypox vaccination strategy is working and cases of the virus appear to be levelling off, but some who work with people in shelters say the immunization program should be expanded to better serve those communities.

Chief Medical Officer of Health Dr. Kieran Moore said the province has vaccinated more than 20,000 people against monkeypox so far, with the priority group being gay, bisexual and other men who have sex with men that meet certain criteria.

“We have been able to get the vaccines that we need from our federal partners, we’ve been able to staff our immunization clinics to meet the needs of our population, we have the funding necessary and the partnerships to ensure that our health system protects those at risk from this virus,” Moore said in a recent interview.

“Our response in Ontario has been quite robust. We’ve got a long ways to go still, but it appears that our total number of (monkeypox) cases is plateauing.”

But for some, the province’s vaccination strategy doesn’t do enough to protect those living in high-risk settings like homeless shelters, noting a recent confirmed monkeypox case in a person who attended a Toronto shelter.

Diana Chan McNally, a community worker at a Toronto centre for people in need, said she believes monkeypox vaccines should be broadly available to those living in shelters given the congregate nature of the settings and the fact those who live there might share belongings.

“This kind of laissez-faire attitude towards the vaccine is part and parcel of the fact that we don’t seem to prioritize creating special protocols or really taking into account the unique conditions that can lead to monkeypox infection in the shelter system,” said Chan McNally.

She also said the current monkeypox vaccine strategy doesn’t account for intersections between people who live in shelters and those who might be eligible for the shot, such as sex workers and people in the LGBTQ community experiencing homelessness, who may not have access to city-run immunization clinics.

“Why we can’t bring, even in small amounts, dedicated amounts of the vaccine to the priority groups within the shelter system, I don’t know,” she said. “I think that’s something that could potentially help mitigate any potential for spread.”

Chan McNally also said she wants to see the shot offered to shelter workers. “If we protect their health, we can protect other people in the shelter system,” she said.

Toronto Public Health held pop-up monkeypox vaccine clinics at the shelter where a case was recently reported, which Moore says is part of Ontario’s “ring immunization” strategy targeting those who may have been exposed to a known case.

Patricia Mueller, CEO of Homes First, the company that oversees the shelter where the case was confirmed, said there have been no further cases of monkeypox linked to that one. She said their staff, the city and Toronto Public Health acted quickly to move the infected individual to an isolation and recovery site and set up a vaccination clinic.

Mueller added that shelter workers are considered low risk for monkeypox infection.

Rita Shahin, associate medical officer of health at Toronto Public Health, said the city is not currently planning a larger monkeypox vaccine program for all shelter residents, though those who meet the criteria are eligible for the shot.

“We need to watch where the disease is, who’s most at risk, and if we see additional cases or spread in the shelter system, that’s certainly something we would look at,” Shahin said.

Shahin also said the city’s monkeypox vaccine supply is “fairly limited,” though Moore said the province has a “significant reserve” of doses ready for emergency situations.

Thomas Tenkate, a professor at the School of Occupational and Public Health at Toronto Metropolitan University, said he agrees men who have sex with men should remain the primary group targeted for monkeypox vaccination based on transmission trends, but added that pop-up clinics in shelters could be a way to proactively curb spread of the virus.

“If you’re going to vaccinate people who are in shelters, the strategies have to be different than the general community,” Tenkate said. “People who use shelters or are homeless, you really have to go to them.”

He said another challenge to vaccinating those in shelter settings is understanding their health history to flag any possible complications from getting the shot. “That might be a limiting factor to implementing it as well,” he said.

Public Health Ontario reported a total of 449 confirmed cases of monkeypox in the province as of Thursday, up from 423 on Tuesday. The agency’s latest report said the majority of cases — more than 77 per cent — were reported in Toronto.

It also said almost all the people infected are male, with only two reported in female patients. The virus generally doesn’t spread easily and is transmitted through prolonged close contact via respiratory droplets, direct contact with skin lesions or bodily fluids, or through contaminated clothes or bedding.

— With files from Allison Jones.

This report by The Canadian Press was first published Aug. 8, 2022.

Adblock test (Why?)



Source link

Continue Reading

Health

Major test of 1st potential Lyme disease vaccine in 20 years begins in U.S., Europe – CBC.ca

Published

 on


Researchers are seeking thousands of volunteers in the U.S. and Europe to test the first potential vaccine against Lyme disease in 20 years in hopes of finding a better way to fight the tick-borne threat.

Lyme disease, caused by bacteria entering the body through the bite of an infected tick, is a growing problem, with reports of case numbers rising and warming weather helping ticks expand their habitat

While a vaccine for dogs has long been available, the only Lyme disease vaccine for humans was pulled from the U.S. market in 2002 due to lack of demand, leaving people to rely on bug spray and tick checks.

“There’s currently no Lyme disease vaccine available for humans,” according to Health Canada. “However, there are clinical trials taking place in Europe and the U.S.”

Those trials involve Pfizer and French biotech company Valneva. They are aiming to avoid previous pitfalls in developing a new vaccine to protect both adults and kids as young as five from the most common Lyme strains on two continents.

When the last vaccine was pulled from the market, Pfizer vaccine chief Annaliesa Anderson told the Associated Press that “there wasn’t such a recognition, I think, of the severity of Lyme disease.”

Robert Terwilliger, an avid hunter and hiker, was first in line Friday when the study opened in central Pennsylvania. He’s seen lots of friends get Lyme and is tired of wondering if his next tick bite will make him sick.

“It’s always a worry, you know? Especially when you’re sitting in a tree stand hunting and you feel something crawling on you,” said Terwilliger, 60, of Williamsburg, Pa. “You’ve got to be very, very cautious.”

Canadian cases under-reported

Exactly how often Lyme disease strikes isn’t clear.

The U.S. Centers for Disease Control and Prevention cites insurance records suggesting 476,000 people are treated for Lyme in the U.S. each year. Pfizer’s Anderson put Europe’s yearly infections at about 130,000. 

In Canada, provincial public health units have reported 14,616 human cases of Lyme disease between 2009 and 2021. But the federal government says on its website the numbers are like under-reported “because some cases are undetected or unreported.”

Black-legged ticks, also called deer ticks, carry bacteria that cause Lyme disease. The infection initially causes fatigue, fever and joint pain. Often — but not always — the first sign is a circular red rash around the spot of the tick bite.

Registered nurse Janae Roland, prepares either the vaccine or a placebo in Duncansville, Pa. The clinical trial will test the safety and efficacy of the vaccine, called VLA15. (Gary M. Baranec/The Associated Press)

Early antibiotic treatment is crucial, but it can be hard for people to tell if they have been bitten, since some ticks are as small as a pin.

Untreated Lyme disease can cause severe arthritis and damage the heart and nervous system. Some people have lingering symptoms even after treatment.

How the vaccine works

Most vaccines against other diseases work after people are exposed to a germ. The Lyme vaccine offers a different strategy — working a step earlier to block a tick bite from transmitting the infection, according to Dr. Gary Wormser, a Lyme expert at New York Medical College who isn’t involved with the new research.

It does this by targeting an “outer surface protein” of the Lyme bacterium called OspA that’s present in the tick’s gut.

It’s estimated a tick must feed on someone for about 36 hours before the bacteria spreads to its victim. That delay provides time for the antibodies the tick ingests from a vaccinated person’s blood to attack the germs right at the source.

In small, early-stage studies, Pfizer and Valneva reported no safety problems and a good immune response.

The newest study will test the safety and efficacy of the new vaccine, called VLA15. The companies aim to recruit at least 6,000 people in Lyme-prone areas including the Northeast U.S. plus Finland, Germany, the Netherlands, Poland and Sweden.

Roland begins the process of preparing refrigerated doses of the new Lyme disease vaccine at the Altoona Center for Clinical Research in Duncansville, Pa. (Gary M. Baranec/The Associated Press)

Subjects will receive three shots of either the vaccine or a placebo between now and next spring’s tick season. A year later, they’ll get a single booster dose.

“We’re really looking at something that’s a seasonal vaccine,” Anderson said, so people have high antibody levels during the months when ticks are most active.

Volunteers for the study can be as young as five and should be at high risk because they spend a lot of time in tick-infested areas, such as hikers, campers and hunters, said Dr. Alan Kivitz, who heads one of the study sites at Altoona Center for Clinical Research in Duncansville, Pa.

In his own practice, Kivitz said “not a single day goes by that someone either has a concern about Lyme disease, could possibly have Lyme disease.”

Tick-bite prevention vaccine

The new Pfizer-Valneva vaccine is engineered somewhat differently than its predecessor and also targets six Lyme strains in the U.S. and Europe instead of just one. 

The Pfizer study will span two tick seasons to get answers — but it’s not the only research into new ways to prevent Lyme.

The University of Massachusetts scientists are working on a vaccine alternative, shots of pre-made Lyme-fighting antibodies. And Yale University researchers are in the early stages of designing a vaccine that recognizes a tick’s saliva — which in animal testing sparked a skin reaction that made it harder for ticks to hang on and feed.

Since different tick species carry many diseases other than Lyme, ultimately “we’re all hoping for a tick-bite prevention vaccine,” Wormser said.

Adblock test (Why?)



Source link

Continue Reading

Health

Climate hazards make 58% of infections diseases in people worse, study shows – Global News

Published

 on


Climate hazards such as flooding, heat waves and drought have worsened more than half of the hundreds of known infectious diseases in people, including malaria, hantavirus, cholera and anthrax, a study says.

Researchers looked through the medical literature of established cases of illnesses and found that 218 out of the known 375 human infectious diseases, or 58%, seemed to be made worse by one of 10 types of extreme weather connected to climate change, according to a study in Monday’s journal Nature Climate Change.

The study mapped out 1,006 pathways from the climate hazards to sick people. In some cases, downpours and flooding sicken people through disease-carrying mosquitos, rats and deer. There are warming oceans and heat waves that taint seafood and other things we eat and droughts that bring bats carrying viral infections to people.

Read more:

Joe Biden surveys Kentucky flood damage as more storms move in

Doctors, going back to Hippocrates, have long connected disease to weather, but this study shows how widespread the influence of climate is on human health.

“If climate is changing, the risk of these diseases are changing,” said study co-author Dr. Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison.

Doctors, such as Patz, said they need to think of the diseases as symptoms of a sick Earth.

“The findings of this study are terrifying and illustrate well the enormous consequences of climate change on human pathogens,” said Dr. Carlos del Rio, an Emory University infectious disease specialist, who was not part of the study. “Those of us in infectious diseases and microbiology need to make climate change one of our priorities, and we need to all work together to prevent what will be without doubt a catastrophe as a result of climate change.”

In addition to looking at infectious diseases, the researchers expanded their search to look at all type of human illnesses, including non-infectious sicknesses such as asthma, allergies and even animal bites to see how many maladies they could connect to climate hazards in some way, including infectious diseases. They found a total of 286 unique sicknesses and of those 223 of them seemed to be worsened by climate hazards, nine were diminished by climate hazards and 54 had cases of both aggravated and minimized, the study found.


Click to play video: 'Glaciers melting at alarming rate due to summer heatwaves, scientists warn'



2:17
Glaciers melting at alarming rate due to summer heatwaves, scientists warn


Glaciers melting at alarming rate due to summer heatwaves, scientists warn – Jul 30, 2022

The new study doesn’t do the calculations to attribute specific disease changes, odds or magnitude to climate change, but finds cases where extreme weather was a likely factor among many.

Study lead author Camilo Mora, a climate data analyst at the University of Hawaii, said what is important to note is that the study isn’t about predicting future cases.

“There is no speculation here whatsoever,” Mora said. “These are things that have already happened.”

One example Mora knows firsthand. About five years ago, Mora’s home in rural Colombia was flooded _ for the first time in his memory water was in his living room, creating an ideal breeding ground for mosquitoes — and Mora contracted Chikungunya, a nasty virus spread by mosquito bites. And even though he survived, he still feels joint pain years later.

Sometimes climate change acts in odd ways. Mora includes the 2016 case in Siberia when a decades-old reindeer carcass, dead from anthrax, was unearthed when the permafrost thawed from warming. A child touched it, got anthrax and started an outbreak.

Read more:

More mosquitoes? Why Canadians could be seeing an uptick this summer and beyond

Mora originally wanted to search medical cases to see how COVID-19 intersected with climate hazards, if at all. He found cases where extreme weather both exacerbated and diminished chances of COVID-19. In some cases, extreme heat in poor areas had people congregate together to cool off and get exposed to the disease, but in other situations, heavy downpours reduced COVID spread because people stayed home and indoors, away from others.

Longtime climate and public health expert Kristie Ebi at the University of Washington cautioned that she had concerns with how the conclusions were drawn and some of the methods in the study. It is an established fact that the burning of coal, oil and natural gas has led to more frequent and intense extreme weather, and research has shown that weather patterns are associated with many health issues, she said.

“However, correlation is not causation,” Ebi said in an email. “The authors did not discuss the extent to which the climate hazards reviewed changed over the time period of the study and the extent to which any changes have been attributed to climate change.”

But Dr. Aaron Bernstein, interim director of the Center for Climate, Health, and the Global Environment at Harvard School of Public Health, Emory’s del Rio and three other outside experts said the study is a good warning about climate and health for now and the future. Especially as global warming and habitat loss push animals and their diseases closer to humans, Bernstein said.

“This study underscores how climate change may load the dice to favor unwelcome infectious surprises,” Bernstein said in an email. “But of course it only reports on what we already know and what’s yet unknown about pathogens may be yet more compelling about how preventing further climate change may prevent future disasters like COVID-19.”

© 2022 The Canadian Press

Adblock test (Why?)



Source link

Continue Reading

Trending