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How gene editing a person’s brain cells could be used to curb the opioid epidemic
Is CRISPR the solution?
Even as the COVID-19 pandemic cripples the economy and kills hundreds of people each day, there is another epidemic that continues to kill tens of thousands of people each year through opioid drug overdose.
Opioid analgesic drugs, like morphine and oxycodone, are the classic double-edged swords. They are the very best drugs to stop severe pain but also the class of drugs most likely to kill the person taking them. In a recent journal article, I outlined how a combination of state-of-the-art molecular techniques, such as CRISPR gene editing and brain microinjection methods, could be used to blunt one edge of the sword and make opioid drugs safer.
I am a pharmacologist interested in the way opioid drugs such as morphine and fentanyl can blunt pain. I became fascinated in biology at the time when endorphins – natural opioids made by our bodies – were discovered. I have been intrigued by the way opioid drugs work and their targets in the brain, the opioid receptors, for the last 30 years. In my paper, I propose a way to prevent opioid overdoses by modifying an opioid user's brain cells using advanced technology.
Opioid receptors stop breathing
Opioids kill by stopping a person from breathing (respiratory depression). They do so by acting on a specific set of respiratory nerves, or neurons, found in the lower part of the brain that contain opioid receptors. Opioid receptors are proteins that bind morphine, heroin and other opioid drugs. The binding of an opioid to its receptor triggers a reaction in neurons that reduces their activity. Opioid receptors on pain neurons mediate the pain-killing, or analgesic, effects of opioids. When opioids bind to opioid receptors on respiratory neurons, they slow breathing or, in the case of an opioid overdose, stop it entirely.
Respiratory neurons are located in the brainstem, the tail-end part of the brain that continues into the spine as the spinal cord. Animal studies show that opioid receptors on respiratory neurons are responsible for opioid-induced respiratory depression – the cause of opioid overdose. Genetically altered mice born without opioid receptors do not die from large doses of morphine unlike mice with these receptors present.
Unlike laboratory mice, humans cannot be altered when embryos to remove all opioid receptors from the brain and elsewhere. Nor would it be a good idea. Humans need opioid receptors to serve as the targets for our natural opioid substances, the endorphins, which are released into the brain during times of high stress and pain.
Also, a total opioid receptor knockout in humans would leave that person unresponsive to the beneficial pain-killing effects of opioids. In my journal article, I argue that what is needed is a selective receptor removal of the opioid receptors on respiratory neurons. Having reviewed the available technology, I believe this can be done by combining CRISPR gene editing and a new neurosurgical microinjection technique.
CRISPR to the rescue: Destroying opioid receptors
CRISPR, which is an acronym for clustered regularly interspaced short palindromic repeats, is a gene editing method that was discovered in the genome of bacteria. Bacteria get infected by viruses too and CRISPR is a strategy that bacteria evolved to cut-up the viral genes and kill invading pathogens.
The CRISPR method allows researchers to target specific genes expressed in cell lines, tissues, or whole organisms, to be cut-up and removed – knocked out – or otherwise altered. There is a commercially available CRISPR kit which knocks out human opioid receptors produced in cells that are grown in cell cultures in the lab. While this CRISPR kit is formulated for in vitro use, similar conditional opioid receptor knock-out techniques have been demonstrated in live mice.
To knockout opioid receptors in human respiratory neurons, a sterile solution containing CRISPR gene-editing molecules would be prepared in the laboratory. Besides the gene-editing components, the solution contains chemical reagents that allow the gene-editing machinery to enter the respiratory neurons and make their way into the nucleus and into the neuron's genome.
How does one get the CRISPR opioid receptor knockout solution into a person's respiratory neurons?
Enter the intracranial microinjection instrument (IMI) developed by Miles Cunningham and his colleagues at Harvard. The IMI allows for computer-controlled delivery of small volumes of solution at specific places in the brain by using an extremely thin tube – about twice the diameter of a human hair – that can enter the brain at the base of the skull and thread through brain tissue without damage.
The computer can direct the robotic placement of the tube as it is fed images of the brain taken before the procedure using MRI. But even better, the IMI also has a recording wire embedded in the tube that allows measurement of neuronal activity to identify the right group of nerve cells.
Because the brain itself feels no pain, the procedure could be done in a conscious patient using only local anesthetics to numb the skin. Respiratory neurons drive the breathing muscles by firing action potentials which are measured by the recording wire in the tube. When the activity of the respiratory neurons matches the breathing movements by the patients, the proper location of the tube is confirmed and the CRISPR solution injected.
The call for drastic action
Opioid receptors on neurons in the brain have a half-life of about 45 minutes. Over a period of several hours, the opioid receptors on respiratory neurons would degrade and the CRISPR gene-editing machinery embedded in the genome would prevent new opioid receptors from appearing. If this works, the patient would be protected from opioid overdose within 24 hours. Because the respiratory neurons do not replenish, the CRISPR opioid receptor knockout should last for life.
With no opioid receptors on respiratory neurons, the opioid user cannot die from opioid overdose. After proper backing from National Institute on Drug Abuse and leading research and health care institutions, I believe CRISPR treatment could enter clinical trials in between five to 10 years. The total cost of opioid-involved overdose deaths is about US$430 billion per year. CRISPR treatment of only 10% of high-risk opioid users in one year would save thousands of lives and $43 billion.
Intracranial microinjection of CRISPR solutions might seem drastic. But drastic actions that are needed to save human lives from opioid overdoses. A large segment of the opioid overdose victims are chronic pain patients. It may be possible that chronic pain patients in a terminal phase of their lives and in hospice care would volunteer in phase I clinical trials for the CRISPR opioid receptor knockout treatment I propose here.
Making the opioid user impervious to death by opioids is a permanent solution to a horrendous problem that has resisted efforts by prevention, treatment and pharmacological means. Steady and well-funded work to prove the CRISPR method, first with preclinical animal models then in clinical trials, is a moonshot for the present generation of biomedical scientists.
- 5 ways CRISPR will reshape humanity and the world - Big Think ›
- Opioids: Things your doctor should tell you before prescribing - Big ... ›
Astronomers find these five chapters to be a handy way of conceiving the universe's incredibly long lifespan.
- We're in the middle, or thereabouts, of the universe's Stelliferous era.
- If you think there's a lot going on out there now, the first era's drama makes things these days look pretty calm.
- Scientists attempt to understand the past and present by bringing together the last couple of centuries' major schools of thought.
The 5 eras of the universe<p>There are many ways to consider and discuss the past, present, and future of the universe, but one in particular has caught the fancy of many astronomers. First published in 1999 in their book <a href="https://amzn.to/2wFQLiL" target="_blank"><em>The Five Ages of the Universe: Inside the Physics of Eternity</em></a>, <a href="https://en.wikipedia.org/wiki/Fred_Adams" target="_blank">Fred Adams</a> and <a href="https://en.wikipedia.org/wiki/Gregory_P._Laughlin" target="_blank">Gregory Laughlin</a> divided the universe's life story into five eras:</p><ul><li>Primordial era</li><li>Stellferous era</li><li>Degenerate era</li><li>Black Hole Era</li><li>Dark era</li></ul><p>The book was last updated according to current scientific understandings in 2013.</p><p>It's worth noting that not everyone is a subscriber to the book's structure. Popular astrophysics writer <a href="https://www.forbes.com/sites/ethansiegel/#30921c93683e" target="_blank">Ethan C. Siegel</a>, for example, published an article on <a href="https://www.forbes.com/sites/startswithabang/2019/07/26/we-have-already-entered-the-sixth-and-final-era-of-our-universe/#7072d52d4e5d" target="_blank"><em>Medium</em></a> last June called "We Have Already Entered The Sixth And Final Era Of Our Universe." Nonetheless, many astronomers find the quintet a useful way of discuss such an extraordinarily vast amount of time.</p>
The Primordial era<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTEyMi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNjEzMjY1OX0.PRpvAoa99qwsDNprDme9tBWDim6mS7Mjx6IwF60fSN8/img.jpg?width=980" id="db4eb" class="rm-shortcode" data-rm-shortcode-id="0e568b0cc12ed624bb8d7e5ff45882bd" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="1049" />
Image source: Sagittarius Production/Shutterstock<p> This is where the universe begins, though what came before it and where it came from are certainly still up for discussion. It begins at the Big Bang about 13.8 billion years ago. </p><p> For the first little, and we mean <em>very</em> little, bit of time, spacetime and the laws of physics are thought not yet to have existed. That weird, unknowable interval is the <a href="https://www.universeadventure.org/eras/era1-plankepoch.htm" target="_blank">Planck Epoch</a> that lasted for 10<sup>-44</sup> seconds, or 10 million of a trillion of a trillion of a trillionth of a second. Much of what we currently believe about the Planck Epoch eras is theoretical, based largely on a hybrid of general-relativity and quantum theories called quantum gravity. And it's all subject to revision. </p><p> That having been said, within a second after the Big Bang finished Big Banging, inflation began, a sudden ballooning of the universe into 100 trillion trillion times its original size. </p><p> Within minutes, the plasma began cooling, and subatomic particles began to form and stick together. In the 20 minutes after the Big Bang, atoms started forming in the super-hot, fusion-fired universe. Cooling proceeded apace, leaving us with a universe containing mostly 75% hydrogen and 25% helium, similar to that we see in the Sun today. Electrons gobbled up photons, leaving the universe opaque. </p><p> About 380,000 years after the Big Bang, the universe had cooled enough that the first stable atoms capable of surviving began forming. With electrons thus occupied in atoms, photons were released as the background glow that astronomers detect today as cosmic background radiation. </p><p> Inflation is believed to have happened due to the remarkable overall consistency astronomers measure in cosmic background radiation. Astronomer <a href="https://www.youtube.com/watch?v=IGCVTSQw7WU" target="_blank">Phil Plait</a> suggests that inflation was like pulling on a bedsheet, suddenly pulling the universe's energy smooth. The smaller irregularities that survived eventually enlarged, pooling in denser areas of energy that served as seeds for star formation—their gravity pulled in dark matter and matter that eventually coalesced into the first stars. </p>
The Stelliferous era<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTEzNy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMjA0OTcwMn0.GVCCFbBSsPdA1kciHivFfWlegOfKfXUfEtFKEF3otQg/img.jpg?width=980" id="bc650" class="rm-shortcode" data-rm-shortcode-id="c8f86bf160ecdea6b330f818447393cd" data-rm-shortcode-name="rebelmouse-image" data-width="481" data-height="720" />
Image source: Casey Horner/unsplash<p>The era we know, the age of stars, in which most matter existing in the universe takes the form of stars and galaxies during this active period. </p><p>A star is formed when a gas pocket becomes denser and denser until it, and matter nearby, collapse in on itself, producing enough heat to trigger nuclear fusion in its core, the source of most of the universe's energy now. The first stars were immense, eventually exploding as supernovas, forming many more, smaller stars. These coalesced, thanks to gravity, into galaxies.</p><p>One axiom of the Stelliferous era is that the bigger the star, the more quickly it burns through its energy, and then dies, typically in just a couple of million years. Smaller stars that consume energy more slowly stay active longer. In any event, stars — and galaxies — are coming and going all the time in this era, burning out and colliding.</p><p>Scientists predict that our Milky Way galaxy, for example, will crash into and combine with the neighboring Andromeda galaxy in about 4 billion years to form a new one astronomers are calling the Milkomeda galaxy.</p><p>Our solar system may actually survive that merger, amazingly, but don't get too complacent. About a billion years later, the Sun will start running out of hydrogen and begin enlarging into its red giant phase, eventually subsuming Earth and its companions, before shrining down to a white dwarf star.</p>
The Degenerate era<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNTk3NDQyN30.gy4__ALBQrdbdm-byW5gQoaGNvFTuxP5KLYxEMBImNc/img.jpg?width=980" id="77f72" class="rm-shortcode" data-rm-shortcode-id="08bb56ea9fde2cee02d63ed472d79ca3" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="810" />
Image source: Diego Barucco/Shutterstock/Big Think<p>Next up is the Degenerate era, which will begin about 1 quintillion years after the Big Bang, and last until 1 duodecillion after it. This is the period during which the remains of stars we see today will dominate the universe. Were we to look up — we'll assuredly be outta here long before then — we'd see a much darker sky with just a handful of dim pinpoints of light remaining: <a href="https://earthsky.org/space/evaporating-giant-exoplanet-white-dwarf-star" target="_blank">white dwarfs</a>, <a href="https://earthsky.org/space/new-observations-where-stars-end-and-brown-dwarfs-begin" target="_blank">brown dwarfs</a>, and <a href="https://earthsky.org/astronomy-essentials/definition-what-is-a-neutron-star" target="_blank">neutron stars</a>. These"degenerate stars" are much cooler and less light-emitting than what we see up there now. Occasionally, star corpses will pair off into orbital death spirals that result in a brief flash of energy as they collide, and their combined mass may become low-wattage stars that will last for a little while in cosmic-timescale terms. But mostly the skies will be be bereft of light in the visible spectrum.</p><p>During this era, small brown dwarfs will wind up holding most of the available hydrogen, and black holes will grow and grow and grow, fed on stellar remains. With so little hydrogen around for the formation of new stars, the universe will grow duller and duller, colder and colder.</p><p>And then the protons, having been around since the beginning of the universe will start dying off, dissolving matter, leaving behind a universe of subatomic particles, unclaimed radiation…and black holes.</p>
The Black Hole era<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE2MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMjE0OTQ2MX0.ifwOQJgU0uItiSRg9z8IxFD9jmfXlfrw6Jc1y-22FuQ/img.jpg?width=980" id="103ea" class="rm-shortcode" data-rm-shortcode-id="f0e6a71dacf95ee780dd7a1eadde288d" data-rm-shortcode-name="rebelmouse-image" data-width="1400" data-height="787" />
Image source: Vadim Sadovski/Shutterstock/Big Think<p> For a considerable length of time, black holes will dominate the universe, pulling in what mass and energy still remain. </p><p> Eventually, though, black holes evaporate, albeit super-slowly, leaking small bits of their contents as they do. Plait estimates that a small black hole 50 times the mass of the sun would take about 10<sup>68</sup> years to dissipate. A massive one? A 1 followed by 92 zeros. </p><p> When a black hole finally drips to its last drop, a small pop of light occurs letting out some of the only remaining energy in the universe. At that point, at 10<sup>92</sup>, the universe will be pretty much history, containing only low-energy, very weak subatomic particles and photons. </p>
The Dark Era<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMTE5NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Mzg5OTEyMH0.AwiPRGJlGIcQjjSoRLi6V3g5klRYtxQJIpHFgZdZkuo/img.jpg?width=980" id="60c77" class="rm-shortcode" data-rm-shortcode-id="7a857fb7f0d85cf4a248dbb3350a6e1c" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="810" />
Image source: Big Think<p>We can sum this up pretty easily. Lights out. Forever.</p>
Dr. Katie Mack explains what dark energy is and two ways it could one day destroy the universe.
- The universe is expanding faster and faster. Whether this acceleration will end in a Big Rip or will reverse and contract into a Big Crunch is not yet understood, and neither is the invisible force causing that expansion: dark energy.
- Physicist Dr. Katie Mack explains the difference between dark matter, dark energy, and phantom dark energy, and shares what scientists think the mysterious force is, its effect on space, and how, billions of years from now, it could cause peak cosmic destruction.
- The Big Rip seems more probable than a Big Crunch at this point in time, but scientists still have much to learn before they can determine the ultimate fate of the universe. "If we figure out what [dark energy is] doing, if we figure out what it's made of, how it's going to change in the future, then we will have a much better idea for how the universe will end," says Mack.
A unique exoplanet without clouds or haze was found by astrophysicists from Harvard and Smithsonian.
- Astronomers from Harvard and Smithsonian find a very rare "hot Jupiter" exoplanet without clouds or haze.
- Such planets were formed differently from others and offer unique research opportunities.
- Only one other such exoplanet was found previously.
Munazza Alam – a graduate student at the Center for Astrophysics | Harvard & Smithsonian.
Credit: Jackie Faherty