Posted on by Dr. Francis Collins
Gene editing has shown great promise as a non-heritable way to treat a wide range of conditions, including many genetic diseases and more recently, even COVID-19. But could a version of the CRISPR gene-editing tool also help deliver long-lasting pain relief without the risk of addiction associated with prescription opioid drugs?
In work recently published in the journal Science Translational Medicine, researchers demonstrated in mice that a modified version of the CRISPR system can be used to “turn off” a gene in critical neurons to block the transmission of pain signals . While much more study is needed and the approach is still far from being tested in people, the findings suggest that this new CRISPR-based strategy could form the basis for a whole new way to manage chronic pain.
This novel approach to treating chronic pain occurred to Ana Moreno, the study’s first author, when she was a Ph.D. student in the NIH-supported lab of Prashant Mali, University of California, San Diego. Mali had been studying a wide range of novel gene- and cell-based therapeutics. While reading up on both, Moreno landed on a paper about a mutation in a gene that encodes a pain-enhancing protein in spinal neurons called NaV1.7.
Moreno read that kids born with a loss-of-function mutation in this gene have a rare condition known as congenital insensitivity to pain (CIP). They literally don’t sense and respond to pain. Although these children often fail to recognize serious injuries because of the absence of pain to alert them, they have no other noticeable physical effects of the condition.
For Moreno, something clicked. What if it were possible to engineer a new kind of treatment—one designed to turn this gene down or fully off and stop people from feeling chronic pain?
Moreno also had an idea about how to do it. She’d been working on repressing or “turning off” genes using a version of CRISPR known as “dead” Cas9 . In CRISPR systems designed to edit DNA, the Cas9 enzyme is often likened to a pair of scissors. Its job is to cut DNA in just the right spot with the help of an RNA guide. However, CRISPR-dead Cas9 no longer has any ability to cut DNA. It simply sticks to its gene target and blocks its expression. Another advantage is that the system won’t lead to any permanent DNA changes, since any treatment based on CRISPR-dead Cas9 might be safely reversed.
After establishing that the technique worked in cells, Moreno and colleagues moved to studies of laboratory mice. They injected viral vectors carrying the CRISPR treatment into mice with different types of chronic pain, including inflammatory and chemotherapy-induced pain.
Moreno and colleagues determined that all the mice showed evidence of durable pain relief. Remarkably, the treatment also lasted for three months or more and, importantly, without any signs of side effects. The researchers are also exploring another approach to do the same thing using a different set of editing tools called zinc finger nucleases (ZFNs).
The researchers say that one of these approaches might one day work for people with a large number of chronic pain conditions that involve transmission of the pain signal through NaV1.7. That includes diabetic polyneuropathy, sciatica, and osteoarthritis. It also could provide relief for patients undergoing chemotherapy, along with those suffering from many other conditions. Moreno and Mali have co-founded the spinoff company Navega Therapeutics, San Diego, CA, to work on the preclinical steps necessary to help move their approach closer to the clinic.
Chronic pain is a devastating public health problem. While opioids are effective for acute pain, they can do more harm than good for many chronic pain conditions, and they are responsible for a nationwide crisis of addiction and drug overdose deaths . We cannot solve any of these problems without finding new ways to treat chronic pain. As we look to the future, it’s hopeful that innovative new therapeutics such as this gene-editing system could one day help to bring much needed relief.
 Long-lasting analgesia via targeted in situ repression of NaV1.7 in mice. Moreno AM, Alemán F, Catroli GF, Hunt M, Hu M, Dailamy A, Pla A, Woller SA, Palmer N, Parekh U, McDonald D, Roberts AJ, Goodwill V, Dryden I, Hevner RF, Delay L, Gonçalves Dos Santos G, Yaksh TL, Mali P. Sci Transl Med. 2021 Mar 10;13(584):eaay9056.
 Nuclease dead Cas9 is a programmable roadblock for DNA replication. Whinn KS, Kaur G, Lewis JS, Schauer GD, Mueller SH, Jergic S, Maynard H, Gan ZY, Naganbabu M, Bruchez MP, O’Donnell ME, Dixon NE, van Oijen AM, Ghodke H. Sci Rep. 2019 Sep 16;9(1):13292.
 Drug Overdose Deaths. Centers for Disease Control and Prevention.
Congenital insensitivity to pain (National Center for Advancing Translational Sciences/NIH)
Opioids (National Institute on Drug Abuse/NIH)
Mali Lab (University of California, San Diego)
Navega Therapeutics (San Diego, CA)
NIH Support: National Human Genome Research Institute; National Cancer Institute; National Institute of General Medical Sciences; National Institute of Neurological Disorders and Stroke
Posted on by Dr. Francis Collins
If laughter really is the best medicine, wouldn’t it be great if we could learn more about what goes on in the brain when we laugh? Neuroscientists recently made some major progress on this front by pinpointing a part of the brain that, when stimulated, never fails to induce smiles and laughter.
In their study conducted in three patients undergoing electrical stimulation brain mapping as part of epilepsy treatment, the NIH-funded team found that stimulation of a specific tract of neural fibers, called the cingulum bundle, triggered laughter, smiles, and a sense of calm. Not only do the findings shed new light on the biology of laughter, researchers hope they may also lead to new strategies for treating a range of conditions, including anxiety, depression, and chronic pain.
In people with epilepsy whose seizures are poorly controlled with medication, surgery to remove seizure-inducing brain tissue sometimes helps. People awaiting such surgeries must first undergo a procedure known as intracranial electroencephalography (iEEG). This involves temporarily placing 10 to 20 arrays of tiny electrodes in the brain for up to several weeks, in order to pinpoint the source of a patient’s seizures in the brain. With the patient’s permission, those electrodes can also enable physician-researchers to stimulate various regions of the patient’s brain to map their functions and make potentially new and unexpected discoveries.
In the new study, published in The Journal of Clinical Investigation, Jon T. Willie, Kelly Bijanki, and their colleagues at Emory University School of Medicine, Atlanta, looked at a 23-year-old undergoing iEEG for 8 weeks in preparation for surgery to treat her uncontrolled epilepsy . One of the electrodes implanted in her brain was located within the cingulum bundle and, when that area was stimulated for research purposes, the woman experienced an uncontrollable urge to laugh. Not only was the woman given to smiles and giggles, she also reported feeling relaxed and calm.
As a further and more objective test of her mood, the researchers asked the woman to interpret the expression of faces on a computer screen as happy, sad, or neutral. Electrical stimulation to the cingulum bundle led her to see those faces as happier, a sign of a generally more positive mood. A full evaluation of her mental state also showed she was fully aware and alert.
To confirm the findings, the researchers looked to two other patients, a 40-year-old man and a 28-year-old woman, both undergoing iEEG in the course of epilepsy treatment. In those two volunteers, stimulation of the cingulum bundle also triggered laughter and reduced anxiety with otherwise normal cognition.
Willie notes that the cingulum bundle links many brain areas together. He likens it to a super highway with lots of on and off ramps. He suspects the spot they’ve uncovered lies at a key intersection, providing access to various brain networks regulating mood, emotion, and social interaction.
Previous research has shown that stimulation of other parts of the brain can also prompt patients to laugh. However, what makes stimulation of the cingulum bundle a particularly promising approach is that it not only triggers laughter, but also reduces anxiety.
The new findings suggest that stimulation of the cingulum bundle may be useful for calming patients’ anxieties during neurosurgeries in which they must remain awake. In fact, Willie’s team did so during their 23-year-old woman’s subsequent epilepsy surgery. Each time she became distressed, the stimulation provided immediate relief. Also, if traditional deep brain stimulation or less invasive means of brain stimulation can be developed and found to be safe for long-term use, they may offer new ways to treat depression, anxiety disorders, and/or chronic pain.
Meanwhile, Willie’s team is hard at work using similar approaches to map brain areas involved in other aspects of mood, including fear, sadness, and anxiety. Together with the multidisciplinary work being mounted by the NIH-led BRAIN Initiative, these kinds of studies promise to reveal functionalities of the human brain that have previously been out of reach, with profound consequences for neuroscience and human medicine.
 Cingulum stimulation enhances positive affect and anxiolysis to facilitate awake craniotomy. Bijanki KR, Manns JR, Inman CS, Choi KS, Harati S, Pedersen NP, Drane DL, Waters AC, Fasano RE, Mayberg HS, Willie JT. J Clin Invest. 2018 Dec 27.
Video: Patient’s Response (Bijanki et al. The Journal of Clinical Investigation)
Epilepsy Information Page (National Institute of Neurological Disease and Stroke/NIH)
Jon T. Willie (Emory University, Atlanta, GA)
NIH Support: National Institute of Neurological Disease and Stroke; National Center for Advancing Translational Sciences
Posted on by Dr. Francis Collins
For most people, pain eventually fades away as an injury heals. But for others, the pain persists beyond the initial healing and becomes chronic, hanging on for weeks, months, or even years. Now, we may have uncovered an answer to help explain why: subtle differences in a gene that controls how the body responds to stress.
In a recent study of more than 1,600 people injured in traffic accidents, researchers discovered that individuals with a certain variant in a stress-controlling gene, called FKBP5, were more likely to develop chronic pain than those with other variants . These findings may point to new non-addictive strategies for preventing or controlling chronic pain, and underscore the importance of NIH-funded research for tackling our nation’s opioid overuse crisis.