The findings are published in PNAS in an article titled, “Direct neuronal conversion of microglia/macrophages reinstates neurological function after stroke.”

“Although generating new neurons in the ischemic injured brain would be an ideal approach to replenish the lost neurons for repairing the damage, the adult mammalian brain retains only limited neurogenic capability,” wrote the scientists. “Here, we show that direct conversion of microglia/macrophages into neurons in the brain has great potential as a therapeutic strategy for ischemic brain injury.”

“When we get a cut or break a bone, our skin and bone cells can replicate to heal our body. But the neurons in our brain cannot easily regenerate, so the damage is often permanent,” explained Kinichi Nakashima, PhD, a professor at Kyushu University’s Graduate School of Medical Sciences. “We therefore need to find new ways to replace lost neurons.”

One possible strategy is to convert other cells in the brain into neurons. The researchers focused on microglia.

“Microglia are abundant and exactly in the place we need them, so they are an ideal target for conversion,” said first author, Takashi Irie, PhD, from Kyushu University Hospital.

In prior research, the scientists demonstrated that they could induce microglia to develop into neurons in the brains of healthy mice. In the current study, the scientists showed that this strategy of replacing neurons also works in injured brains and contributes to brain recovery.

The scientists caused a stroke-like injury in mice by temporarily blocking the right middle cerebral artery. A week later, the researchers examined the mice and found that they had difficulties in motor function and had a marked loss of neurons in a brain region known as the striatum.

The researchers then used a lentivirus to insert DNA into microglial cells at the site of the injury. The DNA held instructions for producing NeuroD1, a protein that induces neuronal conversion. By eight weeks, the new induced neurons had successfully integrated into the brain’s circuits.

At only three weeks post-infection, the mice showed improved motor function in behavioral tests. These improvements were lost when the researchers removed the new induced neurons.

“These results are very promising. The next step is to test whether NeuroD1 is also effective at converting human microglia into neurons and confirm that our method of inserting genes into the microglial cells is safe,” said Nakashima.

Furthermore, the treatment was conducted in mice in the acute phase after stroke, when microglia were migrating to and replicating at the site of injury. The scientists also plan to see if recovery is also possible in mice at a later, chronic phase.

The post Novel Approach Restores Brain Function after Stroke-Like Injury in Mice appeared first on GEN - Genetic Engineering and Biotechnology News.

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Reporting in ACS Central Science (“Deep Learning-Predicted Dihydroarteminsinin Rescues Osteoporosis by Maintaining Mesenchymal Stem Cell Stemness through Activating Histone 3 Lys 9 Acetylation,”) the team said their collective studies suggested that “… DHA could be a promising therapeutic agent for treating osteoporosis by maintaining BMMSC stemness.”

Osteoporosis is a degenerative disease that affects the skeletal system and is characterized by the loss of bone density and destruction of the bone microstructure. In healthy people, there is a balance between the osteoblasts that build new bone and osteoclasts that break it down. But when the “demolition crew” becomes overactive, it can result in bone loss and osteoporosis, which typically affects older adults. BMMSCs, which are the precursors of osteoblasts, play a crucial role in osteoporosis, the authors wrote. “BMMSCs maintain a constant flow of functional osteoblasts by committed differentiation and a local population through steady proliferation and refreshment, which together constitute the stemness of BMMSCs under physiological motion.” Maintaining the stemness of BMMSCs is thus “crucial for bone homeostasis and regeneration,” they continued.

However, during osteoporosis, these multipotent cells tend to turn into fat-creating adipocytes and have “diminished regenerative potential,” the authors continued. “Because BMMSCs provide a continuous supply of osteoblasts for bone repair, it is critical to find ways to restore their functions.”

Previously, Zhengwei Xie, PhD, at Peking University, and colleagues, trained a deep learning algorithm to predict cellular responses with drug treatment and eventually accurately predicted the efficacies of new drugs by comparing the changes in gene expression profiles of diseased and drug-treated cells. “This deep learning-based efficacy prediction system (DLEPS) has already been successful in discovering new drugs for a range of diseases, including obesity, hyperuricemia, and NASH.” For their newly reported study, the investigators, joined by Yan Liu, PhD, and Weiran Li, PhD, at Peking University School and Hospital for Stomatology, wanted to use the algorithm to find a new treatment strategy for osteoporosis that focused on BMMSCs.

The team ran the program on a profile of differently expressed genes (DEGs) in newborn and adult mice. One of the top-ranked compounds identified was DHA, a derivative of artemisinin and a key component of malaria treatments. “From the top-ranked candidates, we identified dihydroartemisinin (DHA), a traditional Chinese herbal extract that can promote BMMSC stemness, which is beneficial for establishing healthier bone homeostasis,” the investigators noted.

In vivo studies showed that administering DHA extract for six weeks to an ovariectomized (OVX) mouse model of osteoporosis significantly reduced bone loss in the animals’ femurs and nearly completely preserved bone structure. “In general, oral administration of DHA rescued endogenous mBMMSC stemness in OVX mice, while correcting the biased differentiation inclination from adipogenesis to osteogenesis,” the scientists explained.

“Taken together, the therapeutic effect of MSN-ALN@DHA on osteoporosis was mainly achieved by the protection effect of DHA on the stemness of BMMSCs, while both MSN-ALN and DHA also played a certain role in inhibiting osteoclastic activity,” they wrote. “The use of the bone-targeting carrier, MSN-ALN, has improved the therapeutic efficacy of DHA. Compared to oral administration of DHA, the application of MSN-ALN@DHA ensures treatment efficacy while reducing the frequency of drug administration.”

The researchers say that this work demonstrates that DHA is a promising therapeutic agent for osteoporosis. “These findings also demonstrate the potential of deep learning approaches to accelerate drug development and facilitate precision medicine,” they commented in their paper.

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Anurup Ganguli was finishing up his PhD at the University of Illinois at Urbana-Champaign, reading bioRxiv preprints on CRISPR-based molecular detection from the labs of Nobel laureate Jennifer Doudna, PhD, and the Broad Institute’s Feng Zhang, PhD, when he realized that every molecular detection platform has relied on DNA amplification since the advent of PCR in 1983.

“This is also true for the other CRISPR-based platforms developed by Sherlock and Mammoth Biosciences,” Ganguli told GEN Edge. “They are all doing a pre-amplification step, such as LAMP (Loop-Mediated Isothermal Amplification), before going to CRISPR.”

Ganguli argues that DNA amplification creates limitations, including the ability to massively multiplex and the time to result. He began looking for a solution that eliminates the need for a DNA amplification step typically required for molecular detection.

Today, VedaBio, co-founded by Ganguli, emerged from stealth mode and unveiled its Cascade molecular detection platform. Ganguli, who is CEO, said that this CRISPR-based technology has the best accuracy in its class, can detect molecules at room temperature, and gives results almost instantly without the need for target amplification. This is how Veda, which means “the creation of knowledge” in Sanskrit, was able to raise more than $40 million and get support from OMX Ventures, the company’s lead investor.

Ganguli’s work began in the lab of Rashid Bashir, PhD, professor of bioengineering, and currently Dean of the Grainger College of Engineering at the University of Illinois at Urbana-Champaign. Bashir is also a co-founder at VedaBio.

Creating a cascade of success

The Cascade platform is aptly named as it is essentially a positive feedback loop. It starts with a CRISPR complex called RNP1, which consists of an enzyme paired with a sequence that complements a target. When RNP1 binds to the target sequence, it cuts a reporter molecule, which sends out a fluorescent signal and gives RNP2 a place to go. RNP2 cuts the reporter molecule when it binds to this target sequence and turns on, just like RNP1. This releases a fluorophore and additional RNP2 target sequences, triggering an exponential cascade effect that creates a strong, easily detectable signal almost instantly.

Ganguli said that this approach has many advantages over DNA amplification systems, in part because of the use of primers and probes. Pooling of these primers results in false positives because the primers cross-react. But with the CRISPR-based approach, this cross-reactivity can be avoided because of the specificity of the guide RNA in RNP1, which cleaves different reporter molecules.

Cascade’s sensitivity is comparable to PCR, claimed Ganguli, going down to just a few copies of a target molecule.

“That’s the beauty of it—you can get rid of the amplification step while capturing state-of-the-art gold standard accuracy, and that’s what we will leverage for our first product and our application pipeline,” said Ganguli.

Behind this technology, Ganguli said that Veda is pursuing two core narratives. The first is to build and launch an initial flagship product, which he is still keeping under wraps. The second is to demonstrate the platform’s power in multiple application areas.

“We believe that, given the fundamental nature of the breakthrough, it can be applied to research use, industrial applications, diagnostics, and therapeutics,” said Ganguli. “We have solidified the core platform over the last two years. Being in stealth allowed us to focus a lot on our IP portfolio and strategy and to generate content and data for our publications.”

To do this, Ganguli moved the company and seven staff from Chicago to San Diego. In the past year, the company has grown to about 25 people. “We are growing quite quickly. San Diego has a lot to do with it, given the innovation hub here,” said Ganguli.

Although Cascade is amenable to most DNA purification methods, Ganguli said Veda’s growth will also support the development of its own proprietary sample prep methods that are catered toward its first product.

“For the first product, we are building a fit-for-purpose solution for a specific market,” said Ganguli. “If you look from an IP standpoint, [Veda has] a very broad portfolio. It goes beyond just CRISPR IP—we have engineering IP, and some of that ties back to sample prep.”

A league of their own

While CRISPR-based molecular detection platforms aren’t new, some prominent companies have yet to establish themselves with a commercial product.

The FDA gave Mammoth Biosciences, co-founded by Doudna, an early use authorization (EUA) in January 2022 for their CRISPR-based SARS-CoV-2 molecular assay. Since then, the company has expanded in other areas, including therapeutics and protein discovery. At ASGCT 2023, Janice Chen, PhD, co-founder and CTO, presented data showing that their ultra-compact NanoCas can perform robustly in vivo editing in mice, supporting one-and-done precision editing approaches to unlock new therapies.

Similarly, Sherlock Biosciences, co-founded by Zhang and others in 2018, announced in August that it had purchased a Cambridge-based manufacturing facility to support the production of five million diagnostic devices, with the capacity to grow as the company approaches commercialization. But to Ganguli’s point, even though Sherlock has gained U.S. rights to a patent for diagnostic use of a CRISPR system based on the smaller Cas12 enzyme, the CRISPR diagnostics developer marries amplification and detection through patents licensed to the company and the Broad Institute.

Then there’s Paragraf, which acquired Cardea Bio, a CRISPR-Chip company, earlier this year to pursue novel detection of both protein and RNA biosignals on a single graphene-based biosensor. Together with DARPA, the U.S. Army, and Siemens, Paragraf is creating a mass-market version of their SARS-CoV-2 RNA and protein detection platform.

It is not out of the question that Veda can make a splash in CRISPR-based molecular diagnostics. As the company provides updates in the coming months on its first product, we should get a better sense of whether they will be directly nipping at the heels of Mammoth and Sherlock or wading into uncharted territories.

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“Single-cell sequencing technology is helping us look at the biology of neurons in much more detail than has ever been possible, and this study really demonstrates that capability,” said senior author Binhai Zheng, PhD, professor in the Department of Neurosciences at UC San Diego School of Medicine. “What we’ve discovered here could be just the beginning of a new generation of sophisticated biomarkers based on single-cell data.” Zheng and colleagues reported on their findings in Neuron, in a paper titled “Deep scRNA sequencing reveals a broadly applicable Regeneration Classifier and implicates antioxidant response in corticospinal axon regeneration.” In their paper the team concluded, “Our data demonstrate a universal transcriptomic signature underlying the regenerative potential of vastly different neuronalpopulations and illustrate that deep sequencing of only hundreds of phenotypically identified neurons has the power to advance regenerative biology.”

Neurons are among the slowest cells to regenerate after an injury. While scientists have made progress in understanding neuronal regeneration, it remains unknown why some neurons regenerate and others do not.

For their study the researchers focused on neurons of the corticospinal tract, which is a critical part of the central nervous system that helps control movement. After injury, these neurons are among the least likely to regenerate axons—the long, thin structures that neurons use to communicate with one another. This is why injuries to the brain and spinal cord are so devastating. As the authors noted, “Despite substantial progress in understanding the biology of axon regeneration in the CNS, our ability to promote regeneration of the clinically important corticospinal tract (CST) after spinal cord injury remains limited.”

First author Hugo Kim, PhD, a postdoctoral fellow in the Zheng lab, added, “If you get an injury in your arm or your leg, those nerves can regenerate and it’s often possible to make a full functional recovery, but this isn’t the case for the central nervous system. It’s extremely difficult to recover from most brain and spinal cord injuries because those cells have very limited regenerative capacity. Once they’re gone, they’re gone.”

To carry out their investigations the researchers used Patch-based single-cell RNA sequencing to analyze gene expression in neurons from mice with spinal cord injuries. They encouraged these neurons to regenerate using established molecular techniques, but ultimately, this only worked for a portion of the cells. This experimental setup allowed the researchers to compare sequencing data from regenerating and non-regenerating neurons.

Further, by focusing on a relatively small number of cells—just over 300—the researchers were able to look extremely closely at each individual cell. “Just like how every person is different, every cell has its own unique biology,” said Zheng. “Exploring minute differences between cells can tell us a lot about how those cells work.”

Using a computer algorithm to analyze their sequencing data the researchers identified a unique pattern of gene expression that can predict whether or not an individual neuron will ultimately regenerate after an injury. The pattern also included some genes that had never been previously implicated in neuronal regeneration. “It’s like a molecular fingerprint for regenerating neurons,” commented Zheng.

To validate their findings the researchers tested this molecular fingerprint, which they named the Regeneration Classifier, on 26 published single-cell RNA sequencing datasets. These datasets included neurons from various parts of the nervous system and at different developmental stages.

The team found that with few exceptions, the Regeneration Classifier successfully predicted the regeneration potential of individual neurons and was able to reproduce known trends from previous research, such as a sharp decrease in neuronal regeneration just after birth.  “We found that our Regeneration Classifier can be applied in an unbiased manner to characterize any published scRNA-seq dataset,” the team commented. “This generated a pattern of regeneration classification for various neuronal populations that remarkably reflects prior knowledge on their regenerative potential based on the neuronal type and developmental stage.”

Zheng added, “Validating the results against many sets of data from completely different lines of research tells us that we’ve uncovered something fundamental about the underlying biology of neuronal regeneration,” said Zheng. “We need to do more work to refine our approach, but I think we’ve come across a pattern that could be universal to all regenerating neurons.” In their paper the investigators stated, “It has been extensively shown in the literature that neurons undergo a developmental stage-dependent decline in regenerative abilities. However, our data provide, for the first time to our knowledge, a transcriptomic basis for this phenomenon across vastly different neuronal types.”

A closer evaluation of differentially expressed genes, and gene network analyses, highlighted a gene called NFE2L2 (nuclear-factor-erythroid-derived-2-like 2) also known as NRF2 (nuclear-factor erythroid-2-related factor 2), as a potential regulator of differentially expressed genes in regenerating, compared with non-regenerating CST neurons. NFE2L2 encodes a transcription factor that activates antioxidant genes that are under oxidative stress in response to injury and inflammation. Tests in engineered mice indicated that NFE2L2 acted as a positive regulator of CST regeneration. The team said the findings “… validate our Patch-seq approach in discovering new regeneration regulators.”

Another top candidate PPARGC1A (or PGC-1α), encodes a master regulator of mitochondrial biogenesis, but the role of PGC-1α in CST regeneration has yet to be validated in vivo, the authors noted. Nevertheless, they stated, “… our observation that these two genes (NFE2L2 and PPARGC1A) sit at the top of the regulatory network in regenerating neurons highlights the importance of both antioxidative response and mitochondrial biogenesis.”

While the results in mice are promising, the researchers caution that at present, the Regeneration Classifier is a tool to help neuroscience researchers in the lab rather than a diagnostic test for patients in the clinic. “For preclinical studies, a Regeneration Classifier may serve as a biomarker to predict the likelihood of success for candidate regenerative therapies. In this regard, our approach will likely have broad applicability in studying many other neurological conditions,” the scientists stated.

“There are still a lot of barriers to using single-cell sequencing in clinical contexts, such as high cost, difficulty analyzing large amounts of data and, most importantly, accessibility to tissues of interest,” said Zheng. “For now, we’re interested in exploring how we can use the Regeneration Classifier in preclinical contexts to predict the effectiveness of new regenerative therapies and help move those treatments closer to clinical trials.”

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The findings are published in JCI Insight in an article titled, “A lipid-associated macrophage lineage rewires the spatial landscape of adipose tissue in early obesity.”

“Adipose tissue macrophage (ATM) infiltration is associated with adipose tissue dysfunction and insulin resistance in mice and humans,” wrote the researchers. “Recent single-cell data highlight increased ATM heterogeneity in obesity but do not provide a spatial context for ATM phenotype dynamics. We integrated single-cell RNA-Seq, spatial transcriptomics, and imaging of murine adipose tissue in a time course study of diet-induced obesity. Overall, proinflammatory immune cells were predominant in early obesity, whereas nonresident antiinflammatory ATMs predominated in chronic obesity.”

Studying fat is easier said than done. In tissues that are organized into defined layers for example the spinal cord or the brain “it’s easier to do sanity checks with your data and identify this or that layer as a particular cell type and know that it should be expressing genes X, Y, and Z,” said Lindsey Muir, PhD, a research assistant professor in the department of computational medicine and bioinformatics.

“With adipose, it’s a lot more challenging because the cell types are distributed evenly throughout the tissue, without defined cell layers.” In obesity, fat cells, or adipocytes, expand and can reach a limit that ultimately causes cell death and leads to inflammation.

The research team fed mice a high-fat diet over the course of 14 weeks, collected fat tissue, and then used single-cell and spatial analyses to produce a readout of all the mRNAs present in the sample. Using clustering in the single-cell data, they were able to group cells whose genetic makeup more closely resembled each other than other groups or the overall sample.

“We knew going in that macrophages would likely have multiple subtypes… what surprised us were the number that came out that were highly different from each other and coming up at different times and becoming more dominant over time.”

They identified five types, which they named Mac1, 2, 3, 4, and 5. Mac1 were resident to the tissue in both lean mice on a normal diet and obese mice. Mac2 and Mac3, which were identified by their pro-inflammatory genes, peaked after eight weeks of the high-fat diet.

However, as the high-fat diet progressed to 14 weeks, Mac4 and Mac5 cells, which had low pro-inflammatory gene expression, predominated, while pro-inflammatory Mac2 and Mac3 cells decreased.

“The thinking in the field has been that the type of macrophages that accumulate in obesity are promoting an inflammatory state. Based on these data there’s a lot more to the story,” said Muir.

Her hypothesis is that Mac4 and Mac5 are the lipid associated macrophages (LAMs) described in her own prior work and by other researchers and may be a sign of the body attempting to quell a damaging level of inflammation from pro-inflammatory macrophages and dying adipocytes.

Next, the researchers used spatial transcriptomics to analyze fat tissue. The study examined these images looking for tell-tale markers called crown-like structures—structures that are associated with insulin resistance.

“Once crown-like structures appear, it takes them a long time to go away and their appearance indicates tissue dysfunction,” noted Muir. “Using image processing, we identified based on the density of these regions what was likely to be a crown-like structure and then went in to verify that we could see them visually,” said Muir. These structures had gene expression indicating the presence of Mac4 and Mac5 LAMs.

With more insight into the cellular makeup and spatial organization of fat tissue in the context of obesity, the next step, Muir said, is to examine the signaling processes and proteins associated with the development of LAMs and metabolic disorders.

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IL-31 is found throughout the body, and findings from the newly reported study in mouse models represent what the researchers suggest is a breakthrough that could transform how doctors treat conditions from eczema, asthma, and allergies, as well as Crohn’s and other inflammatory diseases. The results could lay the groundwork for a new generation of drugs that interact more intelligently with the body’s innate ability to self-regulate.

“We tend to think that immune proteins like IL-31 help immune cells talk to one another, but here, when IL-31 talks to neurons, the neurons talk right back,” said Marlys Fassett, MD, PhD, UCSF professor of dermatology. “It’s the first time we’ve seen the nervous system directly tamp down an allergic response.” Added Mark Ansel, PhD, UCSF professor of immunology, “IL-31 causes itch in the skin, but it’s also in the lung and in the gut … We now have a new lead for fighting the many diseases involving both the immune and nervous systems.”  Fassett is lead author, and Ansel is senior author of the team’s published paper in Science Immunology, titled “IL-31–dependent neurogenic inflammation restrains cutaneous type 2 immune cell accumulation and cytokine production in allergic dermatitis.”

IL-31 is one of several “itch cytokines” that has the ability to instigate itch in animals and people. Administering IL-31 to animals triggers acute-onset itching, and mice engineered to overexpress the IL-31 gene in immune system T cells develop a serious spontaneous itch, the authors noted. “Transgenic mice that constitutively overexpress Il31 in T cells (IL31Tg) develop spontaneous itch so severe that they develop scratching-induced skin lesions …”

In contrast, scratching in animal models of induced dermatitis is ameliorated in individuals lacking the Il31 gene, “… confirming that IL31 is necessary for contact hypersensitivity-associated itch …” the team stated. However, they further noted, “Whereas IL-31–dependent itch-sensory pathways have been well characterized, the contributions of IL-31 to cutaneous inflammation remain unclear.”

For their reported study Fassett, a dermatologist and a researcher, teamed up with Ansel, a former colleague and asthma expert. The researchers removed the IL-31 gene from mice and exposed the animals to the house dust mite (HDM), a common, itchy allergen. “We wanted to mimic what was actually happening in people who are chronically exposed to environmental allergens,” Fassett said. “As we expected, the dust mite didn’t cause itching in the absence of IL-31, but we were surprised to see that inflammation went up.”

Why was there inflammation but no itching? Fassett and Ansel found that a cadre of immune cells had been called into action in the absence of the itch cytokine. Without IL-31, the body was effectively blindly waging an immunological war.

Ansel and Fassett then homed in on the nerve cells in the skin to which IL-31 signal and discovered that the same nerve cells that spurred a scratch also dampened any subsequent immune response. These nerve cells were integral to keeping inflammation in check, but without IL-31, they let the immune system run wild.

Fassett and Ansel also found that these neurons released a neuropeptide called calcitonin gene-related protein (CGRP), in response to the IL-31 itch signal, which could be responsible for dampening the immune response. The experiments in mice with chronic atopic dermatitis (AD)-like symptoms indicated that CGRP ultimately restrains the activity of T cells lurking in the skin that cause surface-level inflammation. Corroborating these results, the team demonstrated that mice without IL-31 receptors showed more severe type 2 immuno-inflammatory responses to allergen exposures. “ … we demonstrate that IL-31 activates sensory neuron–mediated pathways of dual purpose in allergic dermatitis: to induce itch and to stimulate neurogenic inflammation via CGRP release,” they wrote.

The findings match with what dermatologists were increasingly seeing with a new IL-31-blocking drug, nemolizumab, which has been developed to treat eczema. “Given the translational relevance of these conclusions to clinical dermatology, we note similar results from anti-IL31RA (nemolizumab) clinical trials for AD,” the authors pointed out. While clinical trial patients using the drug found that the dry, patchy skin of their eczema receded they also sometimes demonstrated flare-ups of other skin irritation, and even inflammation in the lungs. “Nemolizumab-treated AD patients experienced rapid improvement in pruritus but delayed improvements in dermatitis metrics, paradoxical dermatitis flares, and dose-dependent asthma exacerbations.”

Ansel commented, “When you give a drug that blocks the IL-31 receptor throughout the whole body, now you’re changing that feedback system, releasing the brakes on allergic reactions everywhere.” Fassett added, “The idea that our nerves contribute to allergy in different tissues is game changing … If we can develop drugs that work around these systems, we can really help those patients that get worse flares after treatment for itch.”

The team concluded, “Together, these results illustrate a previously unrecognized neuroimmune pathway that constrains type 2 tissue inflammation in the setting of chronic cutaneous allergen exposure, and may explain paradoxical dermatitis flares in atopic patients treated with anti-IL31RA therapy.”

Fassett recently founded her own lab at UCSF to tease apart these paradoxes in biology that complicate good outcomes in the clinic. And Ansel is now interested in what this itch cytokine is doing beyond the skin. “You don’t itch in your lungs, so the question is, what is IL-31 doing there, or in the gut?” Ansel asked. “But it does seem to have an effect on allergic inflammation in the lung. There’s a lot of science ahead for us, with immense potential to improve therapies.”

The post “Itch Cytokine” Contributes to Allergy via Neuroimmune Pathway appeared first on GEN - Genetic Engineering and Biotechnology News.

Carlsbad, CA—Durhane Wong-Rieger, PhD, president and CEO of the Canadian Organization for Rare Diseases and chair of a global alliance for patient organizations called Rare Diseases International, recalled a recent conference where he found himself speaking between panels with a patient advocate from Zimbabwe.

The woman, whom Wong-Rieger regards as one of the smartest and most involved patient advocates he knows, told him she would not go to any more sessions on cell and gene therapy because she didn’t want to hear about therapies that she or her patients would never get.

Wong-Rieger immediately realized the truth in her statement: many people who are in dire health conditions have no access to what may be a life-saving treatment.

“We really don’t have any rules for [cell and gene therapies] as we’re all saying this is the most amazing breakthrough in terms of therapies—truly lifesaving therapies,” said Wong-Rieger. “But the problem is we can’t give them to everybody. Unfortunately for us in this whole space, how do we get to doing what is the right thing?”

While Wong-Rieger doesn’t have the answer, he thinks that evolving ethics are at the heart of what will allow the field of cell and gene therapy get there.

A North Star

Ethics often gets a bad rap for being prohibitive, but for J. Benjamin Hurlbut, PhD, associate professor, School of Life Sciences, Arizona State University, that’s just plain wrong. Hurlbut believes that ethics is primarily about innovation and limits themselves can be sources of creativity and innovation.

“This is a domain where lives are at stake, and it makes this industry a different kind of industry than other industries because the stakes associated with the work, how the work is done, what the work means, and the name of the public goods the work has undertaken have a greater significance than in the automobile and smartphone industries,” said Hurlbut.

Tim Hunt, JD, CEO of the Alliance for Regenerative Medicine (ARM), has been mulling over the ethics of cell and gene therapy for months because, ultimately, this is the business of permanently altering people’s DNA or irreversibly transplanting cells.

“For too many of our patients—millions of people around the world—the status quo represents death or serious disability,” said Hunt. “No one runs out and takes gene therapy, a gene editing regimen, or cell therapy because they feel great and healthy. Patients are in difficult shape.”

Rob Perez, operating partner at the global growth equity firm General Atlantic, feels similarly about ethics, which he defines as a set of moral principles that helps one navigate challenging problems and situations.

“If we can have more conversations and come to more alignment on what an ethical code or ethical standards could be for the industry, it can help to be a north star on how we want to operate and how we want to make those very difficult decisions,” said Perez. “That’s always been a really important part of how I can deal with the most challenging questions, the most challenging decisions, and the most challenging complexities in operating a business.”

Value and accessibility

While the goal of many cell and gene therapies is to cure diseases and completely return a patient to full health, an incremental change in the patient’s health, which also can greatly affect a whole family, is understated. Somebody having to walk or sit for the rest of their time can be incredible in terms of that benefit.

Tay Salimullah, vice president, Global Head of Value and Access, Novartis Gene Therapies, was part of the team that led the first FDA-approved cell therapy, Kymriah, and is currently on a team working on a treatment for spinal muscular atrophy. He says defining patient success happens before one even begins to define value and economics.

“You have to actually understand the journey—the days, weeks, months, years—it takes families to try and get care,” said Salimullah. “It’s like a diagnostic odyssey where they can’t even actually then find out who’s going to treat them in what center. And that’s before even getting to the transaction of buying a gene therapy!”

For Salimullah, it’s all about democratizing access to gene therapies. Salimullah thinks carefully about how polarizing cell and gene therapy can be, especially regarding pricing.

“How can you have a $2-million gene therapy and leave babies to die?” asked Salimullah.

He believes in a self-imposed responsibility that looks for ways to find new opportunities where patients worldwide get access not only in the United States but in Europe and other environments. Salimullah thinks that the theme of democratizing access is dependent on finding the right people who can reinvent a playbook. But who is going to set that up? Will anyone take responsibility and apply it globally?

Janet Lambert, former CEO of ARM and now a consultant at The Densmore Group, believes the global democratization of cell and gene therapies will rely on public-private partnerships. That is a steep hill to climb.

“We’ve had such trouble successfully commercializing advanced therapies, and it is my view that getting it right and getting the economic base that’s necessary from the U.S. and Europe for these therapies is going to be absolutely essential to succeeding in global reach,” she said. “And we have a lot of work left to do there.”

The failed system of responsibility                             

Hurlbut thinks that it’s important to address whether the way of doing innovation in health for the public good is suited to the kind of innovation that is happening in cell and gene therapy. If it isn’t going to serve people as well as it can, then it’s no good.

“All the different stakeholders engage with the sector to ask pretty hard questions about whether the way business as usual is playing out is the best way for that business to play out,” said Hurlbut. “And if things change, some businesses may get broken. But that’s the way things should go if the question is about the broader purpose of this domain, which is to heal people, to treat people.”

According to Hurlbut, an obvious issue to address is pricing, because the sticker shock is so profound that it’s easy for people to protest such steep prices and blast the entire industry of cell and gene therapy as useless.

As he is not a health economist, Hurlbut doesn’t claim to have the answer. However, he said if the regimen is unsustainable for the long run such that society cannot benefit from the good things that its investments have produced, then it’s a failure. Hurlbut said that thinking about these kinds of questions—such as whether cell and gene therapy is economically sustainable—has ethical stakes.

“Is the right way to ask questions about that life in terms of healthcare costs saved, future economic productivity, or to count the various beings and pile them up and say, look, there’s value here?” said Hurlbut. “Maybe that’s the way that one has to convince some set of actors, but maybe that’s the wrong way to ask questions about children’s lives.”

Hurlbut goes one step further, suggesting that, depending on a particular society or government, the decision on whether to get treated or not could be taken completely out of the hands of the patient at the earliest of life stages, even before birth, for all sorts of reasons like cost-savings—the more people who are “cured,” the less of an economic burden on that society. Hurlbut brings up a situation for which he has unique insight—that of He Jankui and the IVF embryos that he gene-edited—noting that one of the central arguments for this infamous experiment that was undertaken in China a few years ago is that it’s a lot easier and a lot cheaper to do it in one cell than to do it in many.

Hurlbut thinks that thinking through this ethical problem highlights that with the system that gets put in place—the drug makers, the regulators, the insurance companies, the health systems—no singular actor is responsible, but instead, it’s the collective actions of the community put in place—and that’s where things can go wrong because it results in failures of responsibility, compassion, and recognition of what is at stake.

After all, there is a dark side to gene therapy, and not every company working on cell or gene therapy is thinking about how their technology may contribute to applications that they would never endorse and, even, abhor, such as genetic cleansing.

Changing the path of humanity 

Even in a world where accessibility and economics for cell and gene therapies get worked out ethically, there’s another set of questions lying in wait that are top of mind for Lambert. For example, if a person chooses to get treated with gene therapy and it reaches the germline, genetic changes will be made in the patient and possibly in their children and generations to come.

Similarly, who is responsible for whether a child with a disease will get gene therapy? Does it fall into the hands of the parents?

“One of the most profound conversations I had in my time at ARM was with a mom who had signed her child up for a safety study,” said Lambert. “And even though this was a very well-educated mom, she felt profound guilt about having done that and that her child was, therefore, ineligible to get a therapeutic dose, which in that particular case turned out to be different than the safety trial dose.”

When it comes to gene editing, Lambert thinks that a major challenge in deciding what is a disease, what’s worth preventing, and what needs to be prevented.

At the end of the day, cell and gene therapy is not about eliminating or customizing people—it’s about treating patients.

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Tal Danino, PhD, and Rosa L. Vincent, PhD, at Columbia University’s department of biomedical engineering, and colleagues, reported on their developments in Science, in a paper titled “Probiotic-guided CAR-T cells for solid tumor targeting,” in which they concluded, “These findings highlight the potential of the ProCAR platform to address the roadblock of identifying suitable CAR targets by providing an antigen that is orthogonal to both healthy tissue and tumor genetics … Overall, combining the advantages of tumor-homing bacteria and CAR-T cells provides a new strategy for tumor recognition and, in turn, builds the foundation for engineered communities of living therapies.”

Immunotherapies using CAR-T cells have proven successful in treating some types of blood cancers, but their efficacy against solid tumors remains elusive. A key challenge facing tumor-antigen targeting immunotherapies like CAR-T is the identification of suitable targets that are specifically and uniformly expressed on solid tumors, the authors noted. “A key challenge of antigen-targeted cell therapies relates to the expression patterns of the antigen itself, which makes the identification of optimal targets for solid tumor cell therapies an obstacle for the development of new CARs.” Solid tumors express heterogeneous and nonspecific antigens and are poorly infiltrated by T cells. As a result, the approach carries a high risk of fatal on-target, off-tumor toxicity, wherein CAR-T cells attack the targeted antigen on healthy vital tissues with potentially fatal effects. “Few tumor-associated antigens (TAAs) identified on solid tumors are tumor restricted, and thus, they carry a high risk of fatal on-target, off-tumor toxicity because of cross-reactivity against proteins found in vital tissues,” the team continued.

Previous studies have shown that, unlike CAR-T cells, which require “considerable engineering to target and infiltrate solid tumors,” some species of bacteria can selectively colonize and preferentially grow within the hostile tumor microenvironments (TMEs) of immune-privileged tumor cores, and can be engineered as antigen-independent platforms for therapeutic delivery.

In this study, Vincent, Candice Gurbatri, and colleagues combine probiotic therapy with CAR-T cell therapy to create a two-stage probiotic-guided CAR-T cell (ProCAR) platform, whereby T cells are engineered to sense and respond to synthetic CAR targets that are delivered by solid tumor-colonizing probiotic bacteria. “This approach leverages the antigen independence of tumor-seeking microbes to create a combined cell therapy platform that broadens the scope of CAR-T cell therapy to include difficult-to-target tumors,” the investigators explained.

Using synthetic gene circuit engineering on a well-characterized non-pathogenic strain of E. coli, Vincent et al. created a probiotic that could infiltrate and cyclically release synthetic CAR targets directly to the tumor core, effectively “tagging” the tumor tissue. “With this system, bacterial growth reaches a critical population density exclusively within the niche of the solid TME and subsequently triggers lysis events that cyclically release genetically encoded payloads in situ,” they further explained.

Then, CAR-T cells that were programmed to recognize the probiotic-delivered synthetic antigen tags could be generated that homed in on the tagged solid tumors, killing the tumor cells in situ. The scientists also engineered probiotics that co-released chemokines in addition to synthetic targets to further enhance CAR-T cell recruitment to the tumor, further boosting therapeutic response.

Vincent et al. tested the resulting probiotic-guided CAR-T cell platform in humanized and immunocompetent mouse models of leukemia, colorectal cancer, and breast cancer and showed that it resulted in the safe reduction of tumor volume. “Collectively, these mouse model data demonstrate the use of engineered probiotics to selectively grow within the TME niche and safely release combinations of CAR-T cell enhancing payloads in situ,” they wrote. The team acknowledged that further development of the system will be needed before it can be considered for clinical application. Nevertheless, they stated, “We have demonstrated an approach to engineering interactions between living therapies, in which tumor-colonizing probiotics have been repurposed to guide the cytotoxicity of engineered T cells.”

In a related Perspective, Eric Bressler, PhD, and Wilson Wong, PhD, at Boston University Biomedical Engineering and Biological Design Center, also noted, “Translation of the ProCAR system to the clinic will depend on scalability to larger tumors and attenuation of bacterial strains for safety.” However, they concluded, “The study of Vincent et al. is an important proof-of-concept for a potential approach to treating heterogeneous, immunologically cold, and poorly infiltrated solid tumors.”

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The new findings are published in Science Translational Medicine in an article titled, “Regeneration of Neuromuscular Synapses after Acute and Chronic Denervation by Inhibiting the Gerozyme 15-Prostaglandin Dehydrogenase.”

“To date, there are no approved treatments for the diminished strength and paralysis that result from the loss of peripheral nerve function due to trauma, heritable neuromuscular diseases, or aging,” wrote the researchers. “Here, we showed that denervation resulting from transection of the sciatic nerve triggered a marked increase in the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in skeletal muscle in mice, providing evidence that injury drives early expression of this aging-associated enzyme or gerozyme.”

“Our data suggests that inhibiting the function of this particular enzyme, called 15-hydroxyprostaglandin dehydrogenase or 15-PGDH, with a small molecule boosted a naturally occurring compound (prostaglandin E2 or PGE2) in muscle tissues that helps restore nerve connectivity, function, and strength,” said Yu Xin Wang, PhD, assistant professor in the development, aging, and regeneration program at Sanford Burnham Prebys.

“We wondered why this enzyme turns on with age if it has such a negative impact on muscle mass and strength,” said Wang.

The team studied young mice using surgical methods to model injuries to the sciatic nerve. Levels of 15-PGDH rose in the denervated muscles, but pharmacological inhibition of 15-PGDH promoted subsequent motor axon growth, neuromuscular connectivity, and faster recovery.

In studies of human tissues, the researchers detected aggregates of 15-PGDH in biopsies from a diverse range of human neuromuscular diseases, suggesting that inhibiting this enzyme could be beneficial.

“Restoring neuromuscular connectivity is a critical step in treating these debilitating disorders. This new approach is attractive because the treatment signals the nerve to grow back,” said Wang. “That’s why it has such a profound effect on the muscle and strength.”

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