To Save Lives, This Scientist Is Trying to Grow Human Organs Inside of Sheep
A lamb receiving a shot from medical personnel.
More than 114,000 men, women, and children are awaiting organ transplants in the United States. Each day, 22 of them die waiting. To address this shortage, researchers are working hard to grow organs on-demand, using the patient's own cells, to eliminate the need to find a perfectly matched donor.
"The next step is to transplant these cells into a larger animal that will produce an organ that is the right size for a human."
But creating full-size replacement organs in a lab is still decades away. So some scientists are experimenting with the boundaries of nature and life itself: using other mammals to grow human cells. Earlier this year, this line of investigation took a big step forward when scientists announced they had grown sheep embryos that contained human cells.
Dr. Pablo Ross, an associate professor at the University of California, Davis, along with a team of colleagues, introduced human stem cells into the sheep embryos at a very early stage of their development and found that one in every 10,000 cells in the embryo were human. It was an improvement over their prior experiment, using a pig embryo, when they found that one in every 100,000 cells in the pig were human. The resulting chimera, as the embryo is called, is only allowed to develop for 28 days. Leapsmag contributor Caren Chesler recently spoke with Ross about his research. Their interview has been edited and condensed for clarity.
Your goal is to one day grow human organs in animals, for organ transplantation. What does your research entail?
We're transplanting stem cells from a person into an animal embryo, at about day three to five of embryo development.
This concept has already been shown to work between mice and rats. You can grow a mouse pancreas inside a rat, or you can grow a rat pancreas inside a mouse.
For this approach to work for humans, the next step is to transplant these cells into a larger animal that will produce an organ that is the right size for a human. That's why we chose to start some of this preliminary work using pigs and sheep. Adult pigs and adult sheep have organs that are of similar size to an adult human. Pigs and sheep also grow really fast, so they can grow from a single cell at the time of fertilization to human adult size -- about 200 pounds -- in only nine to 10 months. That's better than the average waiting time for an organ transplant.
"You don't want the cells to confer any human characteristics in the animal....Too many cells, that may be a problem, because we do not know what that threshold is."
So how do you get the animal to grow the human organ you want?
First, we need to generate the animal without its own organ. We can generate sheep or pigs that will not grow their own pancreases. Those animals can then be used as hosts for human pancreas generation.
For the approach to work, we need the human stem cells to be able to integrate into the embryo and to contribute to its tissues. What we've been doing with pigs, and more recently, in sheep, is testing different types of stem cells, and introducing them into an early embryo between three to five days of development. We then transfer that embryo to a surrogate female and then harvest the embryos back at day 28 of development, at which point most of the organs are pre-formed.
The human cells will contribute to every organ. But in trying to do that, they will compete with the host organism. Since this is happening inside a pig embryo, which is inside a pig foster mother, the pig cells will win that competition for every organ.
Because you're not putting in enough human cells?
No, because it's a pig environment. Everything is pig. The host, basically, is in control. That's what we see when we do rat mice, or mouse rat: the host always wins the battle.
But we need human cells in the early development -- a few, but not too few -- so that when an organ needs to form, like a pancreas (which develops at around day 25), the pig cells will not respond to that, but if there are human cells in that location, [those human cells] can respond to pancreas formation.
From the work in mice and rats, we know we need some kind of global contribution across multiple tissues -- even a 1% contribution will be sufficient. But if the cells are not there, then they're not going to contribute to that organ. The way we target the specific organ is by removing the competition for that organ.
So if you want it to grow a pancreas, you use an embryo that is not going to grow a pancreas of its own. But you can't control where the other cells go. For instance, you don't want them going to the animal's brain – or its gonads –right?
You don't want the cells to confer any human characteristics in the animal. But even if cells go to the brain, it's not going to confer on the animal human characteristics. A few human cells, even if they're in the brain, won't make it a human brain. Too many cells, that may be a problem, because we do not know what that threshold is.
The objective of our research right now is to look at just 28 days of embryonic development and evaluate what's going on: Are the human cells there? How many? Do they go to the brain? If so, how many? Is this a problem, or is it not a problem? If we find that too many human cells go to the brain, that will probably mean that we wouldn't continue with this approach. At this point, we're not controlling it; we're analyzing it.
"By keeping our research in a very early stage of development, we're not creating a human or a humanoid or anything in between."
What other ethical concerns have arisen?
Conferring human properties to the organism, that is a major concern. I wouldn't like to be involved in that, and so that's what we're trying to assess. By keeping our research in a very early stage of development, we're not creating a human or a humanoid or anything in between.
What specifically sets off the ethical alarms? An animal developing human traits?
Animals developing human characteristics goes beyond what would be considered acceptable. I share that concern. But so far, what we have observed, primarily in rats and mice, is that the host animal dictates development. When you put mouse cells into a rat -- and they're so closely related, sometimes the mouse cells contribute to about 30 percent of the cells in the animal -- the outcome is still a rat. It's the size of a rat. It's the shape of the rat. It has the organ sizes of a rat. Even when the pancreas is fully made out of mouse cells, the pancreas is rat-sized because it grew inside the rat.
This happens even with an organ that is not shared, like a gallbladder, which mice have but rats do not. If you put cells from a mouse into a rat, it never grows a gallbladder. And if you put rat cells into the mouse, the rat cells can end up in the gallbladder even though those rat cells would never have made a gallbladder in a rat.
That means the cell structure is following the directions of the embryo, in terms of how they're going to form and what they're going to make. Based on those observations, if you put human cells into a sheep, we are going to get a sheep with human cells. The organs, the pancreas, in our case, will be the size and shape of the sheep pancreas, but it will be loaded with human cells identical to those of the patient that provided the cells used to generate the stem cells.
But, yeah, if by doing this, the animal acquires the functional or anatomical characteristics associated with a human, it would not be acceptable for me.
So you think these concerns are justified?
Absolutely. They need to be considered. But sometimes by raising these concerns, we prevent technologies from being developed. We need to consider the concerns, but we must evaluate them fully, to determine if they are scientifically justified. Because while we must consider the ethics of doing this, we also need to consider the ethics of not doing it. Every day, 22 people in the US die because they don't receive the organ they need to survive. This shortage is not going to be solved by donations, alone. That's clear. And when people die of old age, their organs are not good anymore.
Since organ transplantation has been so successful, the number of people needing organs has just been growing. The number of organs available has also grown but at a much slower pace. We need to find an alternative, and I think growing the organs in animals is one of those alternatives.
Right now, there's a moratorium on National Institutes of Health funding?
Yes. It's only one agency, but it happens to be the largest biomedical funding source. We have public funding for this work from the California Institute for Regenerative Medicine, and one of my colleagues has funding from the Department of Defense.
"I can say, without NIH funding, it's not going to happen here. It may happen in other places, like China."
Can we put the moratorium in context? How much research in the U.S. is funded by the NIH?
Probably more than 75 percent.
So what kind of impact would lifting that ban have on speeding up possible treatments for those who need a new organ?
Oh, I think it would have a huge impact. The moratorium not only prevents people from seeking funding to advance this area of research, it influences other sources of funding, who think, well, if the NIH isn't doing it, why are we going to do it? It hinders progress.
So with the ban, how long until we can really have organs growing in animals? I've heard five or 10 years.
With or without the ban, I don't think I can give you an accurate estimate.
What we know so far is that human cells don't contribute a lot to the animal embryo. We don't know exactly why. We have a lot of good ideas about things we can test, but we can't move forward right now because we don't have funding -- or we're moving forward but very slowly. We're really just scratching the surface in terms of developing these technologies.
We still need that one major leap in our understanding of how different species interact, and how human cells participate in the development of other species. I cannot predict when we're going to reach that point. I can say, without NIH funding, it's not going to happen here. It may happen in other places, like China, but without NIH funding, it's not going to happen in the U.S.
I think it's important to mention that this is in a very early stage of development and it should not be presented to people who need an organ as something that is possible right now. It's not fair to give false hope to people who are desperate.
So the five to 10 year figure is not realistic.
I think it will take longer than that. If we had a drug right now that we knew could stop heart attacks, it could take five to 10 years just to get it to market. With this, you're talking about a much more complex system. I would say 20 to 25 years. Maybe.
The Friday Five: Artificial DNA Could Give Cancer the Hook
In this week's Friday Five, artificial DNA could give cancer the hook. Plus, research suggests that this daily practice can improve relationships, social media could be good for finding factual information, injecting a gel may speed up recovery from injuries, and a blood pressure medicine is promising for a long healthy life.
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
Listen on Apple | Listen on Spotify | Listen on Stitcher | Listen on Amazon | Listen on Google
Here are the promising studies covered in this week's Friday Five:
- Artificial DNA gives cancer the hook
- This daily practice could improve relationships
- Can social media handle the truth?
- Injecting a gel could speed up recovery
- A blood pressure medicine for a long healthy life
9 Tips for Online Mental Health Therapy
Research shows that, for most patients, online therapy offers the same benefits as in-person therapy, yet many people still resist it. A behavioral scientist explains how you can use it to improve mental health.
Telehealth offers a vast improvement in access and convenience to all sorts of medical services, and online therapy for mental health is one of the most promising case studies for telehealth. With many online therapy options available, you can choose whatever works best for you. Yet many people are hesitant about using online therapy. Even if they do give it a try, they often don’t know how to make the most effective use of this treatment modality.
Why do so many feel uncertain about online therapy? A major reason stems from its novelty. Humans are creatures of habit, prone to falling for what behavioral scientists like myself call the status quo bias, a predisposition to stick to traditional practices and behaviors. Many people reject innovative solutions even when they would be helpful. Thus, while teletherapy was available long before the pandemic, and might have fit the needs of many potential clients, relatively few took advantage of this option.
Even when we do try new methodologies, we often don’t do so effectively, because we cling to the same approaches that worked in previous situations. Scientists call this behavior functional fixedness. It’s kind of like the saying about the hammer-nail syndrome: “when you have a hammer, everything looks like a nail.”
These two mental blindspots, the status quo bias and functional fixedness, impact decision making in many areas of life. Fortunately, recent research has shown effective and pragmatic strategies to defeat these dangerous errors in judgment. The nine tips below will help you make the best decisions to get effective online therapy, based on the latest research.
Trust the science of online therapy
Extensive research shows that, for most patients, online therapy offers the same benefits as in-person therapy.
For instance, a 2014 study in the Journal of Affective Disorders reported that online treatment proved just as effective as face-to-face treatment for depression. A 2018 study, published in Journal of Psychological Disorders, found that online cognitive behavioral therapy, or CBT, was just as effective as face-to-face treatment for major depression, panic disorder, social anxiety disorder, and generalized anxiety disorder. And a 2014 study in Behaviour Research and Therapy discovered that online CBT proved effective in treating anxiety disorders, and helped lower costs of treatment.
During the forced teletherapy of COVID, therapists worried that those with serious mental health conditions would be less likely to convert to teletherapy. Yet research published in Counselling Psychology Quarterly has helped to alleviate that concern. It found that those with schizophrenia, bipolar disorder, severe depression, PTSD, and even suicidality converted to teletherapy at about the same rate as those with less severe mental health challenges.
Yet teletherapy may not be for everyone. For example, adolescents had the most varied response to teletherapy, according to a 2020 study in Family Process. Some adapted quickly and easily, while others found it awkward and anxiety-inducing. On the whole, children with trauma respond worse to online therapy, per a 2020 study in Child Abuse & Neglect. The treatment of mental health issues can sometimes require in-person interactions, such as the use of eye movement desensitization and reprocessing to treat post-traumatic stress disorder. And according to a 2020 study from the Journal of Humanistic Psychology, online therapy may not be as effective for those suffering from loneliness.
Leverage the strengths of online therapy
Online therapy is much more accessible than in-person therapy for those with a decent internet connection, webcam, mic, and digital skills. You don’t have to commute to your therapist’s office, wasting money and time. You can take much less medical leave from work, saving you money and hassle with your boss. If you live in a sparsely populated area, online therapy could allow you to access many specialized kinds of therapy that isn’t accessible locally.
Online options are much quicker compared to the long waiting lines for in-person therapy. You also have much more convenient scheduling options. And you won’t have to worry about running into someone you know in the waiting room. Online therapy is easier to conceal from others and reduces stigma. Many patients may feel more comfortable and open to sharing in the privacy and comfort of their own home.
You can use a variety of communication tools suited to your needs at any given time. Video can be used to start a relationship with a therapist and have more intense and nuanced discussions, but can be draining, especially for those with social anxiety. Voice-only may work well for less intense discussions. Email offers a useful option for long-form, well-thought-out messages. Texting is useful for quick, real-time questions, answers, and reinforcement.
Plus, online therapy is often cheaper than in-person therapy. In the midst of COVID, many insurance providers have decided to cover online therapy.
Address the weaknesses
One weakness is the requirement for appropriate technology and skills to engage in online therapy. Another is the difficulty of forming a close therapeutic relationship with your therapist. You won’t be able to communicate non-verbals as fully and the therapist will not be able to read you as well, requiring you to be more deliberate in how you express yourself.
Another important issue is that online therapy is subject to less government oversight compared to the in-person approach, which is regulated in each state, providing a baseline of quality control. As a result, you have to do more research on the providers that offer online therapy to make sure they’re reputable, use only licensed therapists, and have a clear and transparent pay structure.
Be intentional about advocating for yourself
Figure out what kind of goals you want to achieve. Consider how, within the context of your goals, you can leverage the benefits of online therapy while addressing the weaknesses. Write down and commit to achieving your goals. Remember, you need to be your own advocate, especially in the less regulated space of online therapy, so focus on being proactive in achieving your goals.
Develop your Hero’s Journey
Because online therapy can occur at various times of day through videos calls, emails and text, it might feel more open-ended and less organized, which can have advantages and disadvantages. One way you can give it more structure is to ground these interactions in the story of your self-improvement. Our minds perceive the world through narratives. Create a story of how you’ll get from where you are to where you want to go, meaning your goals.
A good template to use is the Hero’s Journey. Start the narrative with where you are, and what caused you to seek therapy. Write about the obstacles you will need to overcome, and the kind of help from a therapist that you’ll need in the process. Then, describe the final end state: how will you be better off after this journey, including what you will have learned.
Especially in online therapy, you need to be on top of things. Too many people let the therapist manage the treatment plan. As you pursue your hero’s journey, another way to organize for success is to take notes on your progress, and reevaluate how you’re doing every month with your therapist.
Identify your ideal mentor
Since it’s more difficult to be confident about the quality of service providers in an online setting, you should identify in advance the traits of your desired therapist. Every Hero’s Journey involves a mentor figure who guides the protagonist through this journey. So who’s your ideal mentor? Write out their top 10 characteristics, from most to least important.
For example, you might want someone who is:
- Empathetic
- Caring
- Good listener
- Logical
- Direct
- Questioning
- Non-judgmental
- Organized
- Curious
- Flexible
That’s my list. Depending on what challenge you’re facing and your personality and preferences, you should make your own. Then, when you are matched with a therapist, evaluate how well they fit your ideal list.
Fail fast
When you first match with a therapist, try to fail fast. That means, instead of focusing on getting treatment, focus on figuring out if the therapist is a good match based on the traits you identified above. That will enable you to move on quickly if they’re not, and it’s very much worth it to figure that out early.
Tell them your goals, your story, and your vision of your ideal mentor. Ask them whether they think they are a match, and what kind of a treatment plan they would suggest based on the information you provided. And observe them yourself in your initial interactions, focusing on whether they’re a good match. Often, you’ll find that your initial vision of your ideal mentor is incomplete, and you’ll learn through doing therapy what kind of a therapist is the best fit for you.
Choose a small but meaningful subgoal to work on first
This small subgoal should be sufficient to be meaningful and impactful for improving your mental health, but not a big stretch for you to achieve. This subgoal should be a tool for you to use to evaluate whether the therapist is indeed a good fit for you. It will also help you evaluate whether the treatment plan makes sense, or whether it needs to be revised.
Know when to wrap things up
As you approach the end of your planned work and you see you’re reaching your goals, talk to the therapist about how to wrap up rather than letting things drag on for too long. You don’t want to become dependent on therapy: it’s meant to be a temporary intervention. Some less scrupulous therapists will insist that therapy should never end and we should all stay in therapy forever, and you want to avoid falling for this line. When you reach your goals, end your therapy, unless you discover a serious new reason to continue it. Still, it may be wise to set up occasional check-ins once every three to six months to make sure you’re staying on the right track.