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Lab-grown bones made from fat used to repair jaws

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Lab-grown bones made from fat used to repair jaws

Unread postby Wsj » Fri Jul 01, 2016 5:16 am

cientists have made giant strides in the quest to treat or eliminate any disease that is a threat to human existence with planned human trials for Zika vaccine and gene editing technology. They have also used lab-grown bones made from fat to repair jaws of pigs, which could also help reconstruct features of accident victims. CHUKWUMA MUANYA, Assistant Editor (Head Insight Team, Science and Technology) writes.

Scientists have closed in on effective vaccines for the dreaded Zika virus after preclinical study indicates jab to prevent the infection in humans is feasible even as they are moving quickly to test candidates.

They have also discovered that past exposure to dengue infection makes the virus more potent.

Clustered regularly interspaced short palindromic repeats (CRISPR), the genome-editing technology that has taken biomedical science by storm, is finally nearing human trials.

On June 21, an advisory committee at the United States (U.S.) National Institutes of Health (NIH) approved a proposal to use CRISPR–Cas9 to help augment cancer therapies that rely on enlisting a patient’s T cells, a type of immune cell.
The CRISPR interference technique has many potential applications, including altering the germline of humans, animals, and food crops. The use of CRISPR for genome editing was the American Association for the Advancement of Science (AAAS’s) choice for breakthrough of the year in 2015. Bioethical concerns have been expressed about the prospect of using this nascent biotechnology for editing the human germline.

Also, living bone grown from stem cells found in fat could soon be used to help reconstruct the faces of people injured in accidents or who have undergone cancer surgery.

Scientists have for the first time grown large sections of bone in the laboratory before implanting them into pigs to repair damage to their jaws.

The researchers say the implants can precisely replicate the original anatomical structure of the facial bone they are replacing, meaning facial features can be restored.

According to a study published in the journal Nature, the Walter Reed Army Institute of Research (WRAIR), US, and collaborators at the Beth Israel Deaconess Medical Center and Harvard Medical School, US, have completed a promising preclinical study of two Zika vaccine candidates that suggests that an effective human vaccine will be achievable.

In the preclinical study, WRAIR and the Beth Israel Deaconess Medical Center tested two Zika virus vaccine candidates: a DNA vaccine developed at Harvard based on a Zika virus strain isolated in Brazil, and a purified inactivated virus vaccine developed at WRAIR based on a Zika virus strain isolated in Puerto Rico.

The study showed that single shots of either vaccine candidate protected mice against subsequent Zika challenge. Both candidates were found to be safe and elicited an antibody response to Zika virus that correlated with protection. Further work with the DNA vaccine demonstrated that protection was solely due to antibodies raised by vaccination.

WRAIR is moving forward with the purified inactivated virus (PIV) vaccine, called ZPIV, because it builds on “a type of vaccine that has been licensed before,” said Col. Stephen Thomas, an infectious disease Army physician and a vaccinologist specializing in flaviviruses, and the WRAIR Zika programme lead. “It’s the same technology WRAIR has used to successfully develop other flavivirus vaccines.” Researchers are trying to mitigate risk by avoiding unproven technologies that could cause a licensing delay, he noted.

Also, British scientists have made a breakthrough. The study showed that the potentially fatal virus is being made worse by another infection that is spread by the same mosquito.

Being previously exposed to the dengue virus boosts the potency of Zika – explaining why cases in Brazil, where the former is rife, have soared.

It is believed prior infection with dengue is contributing to the spike in microcephaly where babies born to women infected with Zika are born with small heads.

Prof. Gavin Screaton, of Imperial College London, United Kingdom (U.K.), said: “Although this work is at a very early stage, it suggests previous exposure to dengue virus may enhance Zika infection.

“This may be why the current outbreak has been so severe, and why it has been in areas where dengue is prevalent.

“We now need further studies to confirm these findings, and to progress towards a vaccine.”

Dengue is also mainly spread by mosquitoes and is common in Brazil and other countries where Zika outbreaks have been occurring in the past couple of years.

The lab findings published in Nature Immunology suggest the recent explosive outbreak of Zika may have been driven by previous exposure to the dengue virus.

It uses the body’s own defences as a ‘Trojan horse’, allowing it to enter a human cell undetected. Once inside the cell, it replicates rapidly.

A second study by the same team, published in Nature, suggests an antibody that works against the dengue virus may also neutralise Zika – providing a potential target for a vaccine.

Dengue is not as severe as Zika, causing flu like symptoms, but cases have risen dramatically over recent decades. The virus is thought to cause around 390 million infections each year.

Each belongs to the same viral family, called the Flaviviridae, and the Aedes mosquito transmits both.

The researchers used antibodies that recognise the dengue virus collected from individuals who had been infected, and then added them to human cell cultures, together with the Zika virus.
Dengue is also mainly spread by mosquitoes and is common in Brazil and other countries where Zika outbreaks have been occurring in the past couple of years.

They showed dengue antibodies could recognise and bind to Zika, due to the similarities between the viruses.

Crucially, pre-existing dengue antibodies can amplify a Zika infection through a phenomenon called antibody-dependent enhancement (ADE).

Col. Nelson Michael, the WRAIR Zika programme co-lead, said, “This critical first step has informed our ongoing work in non-human primates and gives us early confidence that development of a protective Zika virus vaccine for humans is feasible.”

WRAIR scientists are moving rapidly to develop and test the ZPIV vaccine, and they plan to start human testing at their clinic in Silver Spring before the end of the year. Additional human trials are planned in the United States, supported by the National Institute of Allergy and Infectious Diseases (NIAID), through its Vaccine and Treatment Evaluation Units.

WRAIR has been researching flaviviruses, a family of viruses that includes Japanese encephalitis, dengue, West Nile and Zika viruses, for over half a century. “Our laboratory in Thailand has been conducting biosurveillance for Zika for the past three years, since we started to observe dengue-like illnesses in Thailand and the Philippines that were not dengue and did not test positive for other likely causes,” said Thomas. “These efforts gave us a head-start for our vaccine development efforts.”

Meanwhile, the Nature Immunology study’s co-author, Dr. Juthathip Mongkolsapaya said: “We now need to investigate whether the phenomenon of ADE may aid transfer of Zika across the placenta.”

The researchers also found a group of antibodies that bind to a certain site on the dengue virus – called EDE1 – were able to prevent the Zika virus from entering the immune cell.

The genome-editing technology study leader and physician at the University of Pennsylvania in Philadelphia, United States, Edward Stadtmauer, said: “Cell therapies (for cancer) are so promising but the majority of people who get these therapies have a disease that relapses. Gene editing could improve such treatments and eliminate some of their vulnerabilities to cancer and the body’s immune system.”

This first trial is small and designed to test whether CRISPR is safe for use in people, rather than whether it effectively treats cancer or not. It will be funded by a US$250-million immunotherapy foundation formed in April by former Facebook president Sean Parker. The trial itself does not yet have a budget. The University of Pennsylvania will manufacture the edited cells, and will recruit and treat patients alongside centres in California and Texas.

The researchers will remove T cells from 18 patients with several types of cancers and perform three CRISPR edits on them. One edit will insert a gene for a protein engineered to detect cancer cells and instruct the T cells to target them, and a second edit removes a natural T-cell protein that could interfere with this process. The third is defensive: it will remove the gene for a protein that identifies the T cells as immune cells and prevent the cancer cells from disabling them. The researchers will then infuse the edited cells back into the patient.
On the move
“Last year’s excitement over CRISPR was in anticipation of this,” says Dean Anthony Lee, an immunologist at MD Anderson Cancer Center in Houston, Texas, and a member of the NIH’s Recombinant DNA Research Advisory Committee (RAC), which reviewed the proposal. CRISPR, he says, makes genome engineering easy enough that such trials can move forward quickly.

The RAC reviews all proposals for human trials involving modified DNA that are conducted in the United States. Stadtmauer’s team will now have to convince US regulators and review boards at their own institutions to allow the trial. Immunologist Carl June at the University of Pennsylvania, who is a science adviser on the project, says that it could begin by the end of the year.

Other trials may not be far behind. Editas Biotechnologies in Cambridge, Massachusetts, for instance, has said that it wants to use CRISPR in a clinical trial for a rare form of blindness as soon as 2017. However, RAC members say that they have not yet been approached about reviewing the trial.
Other techniques

CRISPR has courted most attention because of its ease of use, however the T-cell trial will not be the first test of the efficacy of using gene editing to fight diseases. In 2014, June led a trial using a different gene-editing system called zinc-finger nuclease.

His group took blood from 12 people with Human Immuno-deficiency Virus (HIV) and removed the gene that encodes a protein on T cells that the virus targets. They hoped that this would prevent infection of the cells. The results were encouraging, and the technique is now being used in clinical trials for several other conditions.

And last week, researchers at Great Ormond Street Hospital for Children in London began a safety study with 10 children using a similar technique called TALENS. Instead of using a patient’s own cells, the system uses T cells from a donor that have been edited to remove genes that would cause the patient’s body to reject them. The gene editing then directs the T cells to attack the cancer and protects the cells from damage by other immunotherapy drugs.

Although CRISPR is easier to use than the other techniques, and better at editing multiple genes at once, June says that the main challenge will be overcoming CRISPR’s propensity for ‘off-target’ edits. These are instances in which the system cuts or mutates unintended parts of the genome. And despite precautions, the immune system could still attack the edited cells.

During the RAC meeting, one of the committee’s greatest concerns was a potential conflict of interest. Among other financial involvements, June has ties to the pharmaceutical company Novartis, holds patents on T-cell technologies, and could stand to benefit from the success of this trial. June declined to give details on the exact nature of his conflicts of interest, but says that his university is taking steps to manage it, such as preventing him from being involved in selecting patients.

Several RAC reviewers suggested that the University of Pennsylvania not be allowed to recruit patients at all and to leave it to other institutions: this language did not make it into their final approval.

However, the RAC members say they are being extra careful with this study. “Penn has a very extensive conflict and has a history,” says Laurie Zoloth, a bioethicist at Northwestern University in Evanston, Illinois. Looming over the discussion is the name Jesse Gelsinger, who died at age 18 while participating in an early gene-therapy trial conducted by researchers at the University of Pennsylvania in 1999.

A subsequent investigation found numerous problems with the study, including unreported animal data on the therapy’s ill effects and the fact that the investigators had a financial stake in the study’s outcome.

The incident is generally considered to have set gene therapy back by decades. “Any first use in humans we have to be extraordinarily careful,” Zoloth says. So a lot is riding on this trial.

But Mildred Cho, a bioethicist at Stanford University in California and an RAC member, says that safety work in animals for a new therapy will take researchers only so far. “Often we have to take the leap of faith.”

Meanwhile, the lab-grown bones made from fat used to repair jaws of pigs and could help reconstruct features of accident victims. The researchers initially create a 3D computer model of the facial bones they want to repair.

A robot is then used to carve a scaffold from a piece of cow bone that has had all the cells stripped from it.

Stem cells taken from the fat of the patient are then seeded on the scaffold before being placed in a bioreactor.

The stem cells were encouraged to grow into bone by a combination of nutrients and environmental changes over the course of three weeks.

The scaffold is subjected to mechanical strain to ensure the new bone and vascular systems grow in a way that mimics that seen in natural bone.

The technique can be used to grow relatively large pieces of bone.

It could mean that patients who have suffered damage to their face in an accident or have been born with defects could have their features reconstructed.

Dr. Gordana Vunjak-Novakovic, a biomedical engineer at Columbia University who led the work, said: “The need is huge, especially for congenital defects, trauma, and bone repair after cancer surgery.

“So this is a very exciting step forward in improving regenerative medicine options for patients with craniofacial defects, and we hope to start clinical trials within a few years.”

The researchers, whose work is published in the journal Science Translational Medicine, implanted bone grown in laboratory ‘bioreactors’ into 14 Yucatan mini-pigs.

They initially used CT scanners to create a 3D computer model of the animals’ jaws, allowing them to use this to shape a piece of cow bone from which the cells had been stripped.
This leaves just a scaffold into which the researchers placed stem cells taken from the pigs own fat.

This was then placed into a bioreactor where the stem cells were allowed to grow and repopulate the scaffold with bone and blood vessels.

Human clinical trials… The Walter Reed Army Institute of Research (WRAIR), US, and collaborators at the Beth Israel Deaconess Medical Center and Harvard Medical School, US, have completed a promising preclinical study of two Zika vaccine candidates that suggests that an effective human vaccine will be achievable. PHOTO CREDIT: google.com/search

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Re: Lab-grown bones made from fat used to repair jaws

Unread postby vanhealn » Sun Sep 16, 2018 9:37 pm


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