Healing Her: Immunity, Menstruation and Medical Breakthroughs

Theme: Women and Medicine

Published: 27 April 2026

Summary
Mia Phillipson, Professor of Physiology at Uppsala University and Co‑Director of Science for Life Laboratory, explores novel roles of immune cells in tissue repair in this episode of SCAS Talks. Focusing on uterine wound healing during menstruation, Mia Phillipson describes how the uterus regenerates without scarring and how macrophages shift functions to promote restoration. Her team uses the spiny mouse, a mammal with exceptional scarless regeneration, to study mechanisms that could be applied to myocardial infarction and other fibrotic diseases. The episode also addresses endometriosis, challenges in diagnosis, and emerging immunotherapies that target restorative immune subsets. Mia Phillipson reflects on interdisciplinary research at SCAS and how language and metaphors shape immunology and may restrict knowledge seeking.

Keywords
Immunology, menstruation, women's health, wound healing, construction of knowledge

Suggested Link/s
About: Mia Phillipson External link, opens in new window.

Transcript of the Episode

Mia Phillipson 0:08
The immune system is extremely responsive and important when you become infected by bacteria or viruses. But before you were even born, I think they had other functions that perhaps are still there, but not utilised to the same extent because they shift and focus on the protection. And I'm interested in finding out what other things they are doing in order to wake those functions up to treat diseases.

Natalie von der Lehr 0:46
Welcome to SCAS Talks, a podcast by the Swedish Collegium for Advanced Study. My name is Natalie von der Lehr, and in this episode I talk to Mia Phillipson, Professor of Physiology at Uppsala University and Co-Director of the Science for Life Laboratory. She was a fellow at SCAS within the Natural Sciences Program during the spring of 2022. Mia Phillipson and her research group are investigating new functions of immune cells for different tissues and organs, contributing to a novel understanding of the immune system. We will hear more about some of her research in this episode, which is the fourth episode in our theme, Women and Medicine.

Natalie von der Lehr 1:27
Welcome to SCAS Talks, Mia, and the studio.

Mia Phillipson 1:30
Thank you.

Natalie von der Lehr 1:31
Could you tell us a little bit more about your research, a bit broadly? What are you studying?

Mia Phillipson 1:36
So we are studying what immune cells are doing in the body during homeostasis, meaning in between infections, in the healthy, growing body, but also when the body is struck by different diseases, including cardiovascular diseases, for instance, or cancer or inflammatory bowel disease, different autoimmune diseases. Because we believe or we have found, that immune cells do so much more than killing intruders, meaning bacteria or viruses.

Natalie von der Lehr 2:09
Yes, because that's what everybody knows.

Mia Phillipson 2:13
That's the classic view of the immune system, yeah. The traditional functions.

Natalie von der Lehr 2:17
How come you got interested in this area to start with, immunology and the immune system?

Mia Phillipson 2:22
Well, I'm a physiologist by training, and when studying different tissues, already when I was a PhD student, I saw that all tissues are filled with immune cells, even in healthy conditions. And we are using a lot of different transgenic mouse models in my lab where distinct immune cell populations are producing a fluorescent protein. So they really stand out from the black tissue. You see all these red or green cells. And then I started to wonder what they were doing in these healthy tissues. And I didn't believe that they were just laying around waiting for an infection to happen or a tumor cell to start growing. We started challenging the different organs and saw that they behaved differently than was reported, that they morphologically looked different. They ended up at different positions in the tissue and looked like other cell types. And a lot of our hypothesis comes from observing these tissues in the anesthetized animals using high-resolution microscopy. So we see what they're doing in the living tissue.

Natalie von der Lehr 3:33
That's fascinating.

Mia Phillipson 3:35
Yeah, it is.

Natalie von der Lehr 3:36
In a way, seeing is believing. So it's nice when you can see things and actually follow in a live animal, I guess.

Mia Phillipson 3:43
Yeah, so we are really coming from the physiological point of view, meaning like the healthy tissues. And then we try to understand how they alter their function when that specific tissue is hit by some kind of disorder

Natalie von der Lehr 3:57
I studied immunology when I was a student, an undergraduate. And I actually even did a short research project in immunology. And it really struck me then how complicated and intricate the whole system is and how many things can potentially go wrong. I also had long-covid and I was thinking a lot about what was happening in my body at the time and would I like to peek inside there and see the cells? How do you think about the immune system?

Mia Phillipson 4:23
Well I think that there are specific matters with the immune system that are completely unique compared to all other cells in the body. And one is their ability to mobilize themselves quickly to anywhere. I mean, they are transported in the bloodstream, they notice signals on the inside of the blood vessels that tell them that something is happening here. You should get out of the blood and into the tissue. And when they do that, they also have the ability to proliferate. So increase in numbers to a super great extent. And no other cells in the body can do that. I look at them as some fast responders but also a resource. Something that the body can use whenever in need. The immune system is extremely responsive and important when you become infected by bacteria or viruses. But before you were even born, I think they had other functions that perhaps are still there, but not utilised to the same extent because they shift and focus on the protection. And I'm interested in finding out what other things they are doing in order to wake those functions up to treat diseases.

Natalie von der Lehr 5:44
So they're there and they're doing things to keep us happy, keep the body happy. And then when a virus or bacteria or something else comes along, then they switch modus, so to say.

Mia Phillipson 5:57
Well, I can give a very, I can give a good example. And that is that if you do surgery on a fetus while in the womb, that fetus will not develop a scar. And that is due to immune cells that manage to heal this injury without scar formation. But when you're introduced into the exterior world and face all kind of bacteria and viruses, some of which we, you know, need for our wellbeing, but some that might be even lethal, then we lose this scar-free healing.

Natalie von der Lehr 6:32
That's fascinating.

Mia Phillipson 6:33
The immune system has then switched and forgotten or down-prioritised the scar-free healing while focusing on keeping that wound non-infected or, you know, fighting the bacteria that might be entering through the wounded tissue.

Natalie von der Lehr 6:50
Talking about scar-free tissue, you recently started a new project. You're looking at wound healing in the uterus, especially after menstruation, which every time causes a wound. Can you tell us more about this specific project

Mia Phillipson 7:05
I think this is an example of the optimal wound healing process. A woman during her fertile period in her life menstruates about 400 times without forming scars. Because if you would scar the inside of your uterus, you would not be able to become pregnant. So I'm fascinated by this and I would like to understand if there is something in this environment that prevents scars to be formed or fibrosis to be formed. And we have in different injured tissues, including injured skeletal muscle or heart tissues, we have found distinct immune cells that contribute a lot to the healing process. And they contribute by shifting fate even. So they down-regulate their immune cell properties while taking on properties from other cell types in order to make the blood flow come back or produce new blood vessels and so on that is needed in order for this tissue to get oxygen to heal and to maintain its function. So we started by just looking for these particular restorative immune cell subsets in the uterus and they were there, and they were there to a great extent. And now we would like to understand if there are other restorative non-fibrotic immune cells or the signals that prevents fibrosis or scars to form in this tissue. So the ultimate goal would be to understand how to induce that situation also in the healing myocardium, for instance, after an infarct. Because it's the fibrosis that limits function of the injured tissue. It's the fibrosis that kills you in the end in myocardial infarction or most conditions when the organ slowly loses its function.

Natalie von der Lehr 9:02
So a heart attack can be due to the scarred tissue?

Mia Phillipson 9:05
Yeah, the impaired function of the heart following the infarction is due to the scarring when the tissue loses its function. And the full muscle cannot be used to pump the blood in the body.

Natalie von der Lehr 9:18
But then back to your project, looking at the wound healing in the uterus, how are you going about to study that?

Mia Phillipson 9:25
So one of the problems with menstruation, or one of the reasons for our limited understanding of what's happening in the uterus during menstruation, is that very few mammals menstruate. Just higher primates, including humans, I think three species of bats, and then two rodents. One of which being the spiny mouse, which is not a mouse, but it's a rodent, and its natural habitat is in the African deserts. But they menstruate. I mean, that's another area that I think is super interesting. Why has this evolved at three different times in our history, that suddenly some mammals start menstruating? What's the cost-benefit? I have no idea. But we have at least now a colony of spiny mice in Uppsala, that we are going to investigate how the immune system in the uterus is behaving during the cycle, and how that is compared to the mouse. So all other mammals, they also have a cycle, a hormonal cycle, but they are absorbing their cells, or they are not excreting any blood. So they are cleaning up the growing mucosa by absorbing the cells, which perhaps might be more cost-efficient, if you would count the number of energy molecules that is needed, but there must be some reason for us not doing that.

Natalie von der Lehr 10:58
Yeah, because what happens in menstruation is that the mucus that has been built up...

Mia Phillipson 11:02
Yeah, the mucosa

Natalie von der Lehr 11:04
...is being excreted…

Mia Phillipson 11:06
Yeah

Natalie von der Lehr 11:07
…together with the blood.

Mia Phillipson 11:07
Yeah. I mean, it's a bleeding due to that the epithelial lining is, like, expelled. Thrown away, yeah. And then this healing starts, and the mucosa thickens and makes it prepared to accept a fetus. But if there's no implantation happening, then the mucosa is expelled again. 400 times, approximately.

Natalie von der Lehr 11:33
That's a lot. How often does this spiny mouse menstruate?

Mia Phillipson 11:38
We don't really know yet. They are, I mean, they are not well characterized, but they are thriving in Uppsala. So the first main goal was just to make sure that they were doing well. But they are interesting in another aspect also. They have extreme regenerative properties that we don't see in other mammals. They've been called the mammalian salamander due to this. I haven't seen this myself, but if you would grab one of these spiny mice over the back being the predator, trying to catch it, this mouse has the possibility to shed the entire skin, and thus can run away, whereas, I mean, the predator is stuck with this fluffy fur. And then it heals within a couple of days in a way you cannot tell that they just shed the skin.

Natalie von der Lehr 12:31
That's very smart.

Mia Phillipson 12:32
Super smart, but also not particularly cost-efficient. And also showing that they have an ability to heal without scarring also in their skin. And there's one paper on myocardial infarction so far that I have seen demonstrating that even the heart is healing better in this spiny mice compared to regular mice. So, of course, my hypothesis is that they have a shifted immune system that is accelerating the healing in some way. But it all remains to be determined.

Natalie von der Lehr 13:06
Sounds like the perfect animal model for wound healing in general.

Mia Phillipson 13:10
We have a lot of things that we would like to understand from these mice.

Natalie von der Lehr 13:15
But now the animals are thriving and happy, and you have them in place. So, once you get started now, for real, so to say, what are you going to do with them?

Mia Phillipson 13:25
Well, we are partly looking at their menstrual cycle to understand how the immune system is involved in the regeneration and the healing and the building up of the mucosa. But we are also inducing ischemic diseases in these mice in different way. Peripheral artery disease, for instance, looking at how the blood flow to the leg is restored. Following impairment, we have a lot of data in regular mice that we also are translating into the human situation. We would also like to induce myocardial infarctions. And the overall goal is to identify immune cell contributions to the healing process and to understand how those contributions could be regulated so that we can find a target for immunotherapy. So, when you have an infarct, for instance, that you can get a treatment that enhances your immune system capacity of healing this injury

Natalie von der Lehr 14:26
So, you can help the immune system, so to say, to do the right thing.

Mia Phillipson 14:30
We have done this already in skin wounds. So, we have a therapy now in clinical trials. It has been tested for the first time in humans here at Akademiska hospital, in wounds that were induced in these otherwise healthy individuals. And we could demonstrate that this treatment accelerated the wound healing with about 10 days. And, the mechanism of action is to target the macrophages, a specific immune cell within the wound, to make them more numerous and then increase their healing capacity. That skin wounds, that's the first like proof of principle, that we can actually target immune cells to improve healing.

Natalie von der Lehr 15:20
That's very fascinating. And at the moment, there is also, I mean, there are a lot of news about immunotherapy in different types of cancer and so on. So, the field is really moving, I feel.

Mia Phillipson 15:29
And those immunotherapies, I mean, they are enhancing the tumor-killing ability of the immune cells. So, that's the reason for why it's so important to define what immune cells are actually doing. Because then, you know, you could target the immunotherapy to do exactly what the immune cells are doing in different situations.

Natalie von der Lehr 15:50
You're looking now, first and foremost, at the healthy state in these spiny mice. But then, there are also diseases of the uterus, of course. And I'm thinking about endometriosis, when the lining, uterus lining grows a where it's not supposed to be. So, will you be looking at that also?

Mia Phillipson 16:07
Yeah, absolutely. It's... A very, one shouldn't say interesting disease, but it's interesting in the sense that we don't really understand the mechanism, how this uterine tissue starts to grow within your abdominal cavity. The mechanism of action is, is still unknown, and that's also why there is no efficient therapy, really, other than contraceptives and pain management. It's a very painful disorder and underdiagnosed.

Natalie von der Lehr 16:38
Exactly. Why is that? How can it be so underdiagnosed? You hear so many people saying, I had these extreme pains for years and years and years, and then it turned out it was endometriosis.

Mia Phillipson 16:50
Well, I don't know the answer to that, really. I guess there could be so many different reasons. But one, of course, is that having a menstruation is associated with pain in most individuals. And it's difficult to grade, because you only, you only live in your own body. So you don't know how it's supposed to feel. I collaborate with an endometriosis expert here at Akademiska, Mats Olavsson. And I know that he's really putting a lot of focus in identifying these individuals as early as possible. I don't want to speculate, but I don't want to speculate other than we have to improve here.

Natalie von der Lehr 17:29
Yeah, definitely. I mean, it's half of the population, right? In their fertile age that has menstruations and some are really bothered by pains.

Mia Phillipson 17:40
I mean, as many as 10% of all women during this period.

Natalie von der Lehr 17:44
Yeah, hopefully you will make progress there and other people as well. So we see some improvement in the future.

Mia Phillipson 17:51
Yeah, well, we have set up the mouse model of endometriosis and we can see that the immune cells that come with the endometrial tissue from the uterus is important for building new blood vessels. And, I mean, establishing this lesion at a new site. But the reason why the rest of the immune system doesn't recognize that this tissue should not be here is yet to be defined. It's the same thing with tumors, I guess, that they should not grow either. And yet they escape immune recognition. They have mechanisms of hiding from the immune system that could be true also for these endometriotic lesions. It will be exciting to see what's found here. But I think, I mean, when I started to think about this since then, perhaps three years ago, a lot of things has happened within the field. There has been a big shift in focus also to women's health issues, I would say.

Natalie von der Lehr 18:54
My feeling is that there is more awareness, at least.

Mia Phillipson 18:56
Yeah.

Natalie von der Lehr 18:57
And it's being more talked about. We started with talking off about the complexity of the immune system. You're going to look at the spiny mouse and what's during the menstrual cycle, how the immune system is contributing there. Do you have any hot candidates or favorite cells that you are going to look at, in particular, what they're doing?

Mia Phillipson 19:19
So we have been focusing on innate immune cells, which are the first responders during immunity. Meaning the neutrophils that are the most common immune cell in your circulation, for instance, or macrophages that are populating all tissues since birth. Well, so my favorite cell type at the moment are the different macrophage subtypes, because these cells are extremely plastic. They are early responders so that they notice if anything happens to the tissue. Then they react and they produce a lot of different molecules in order to call in other immune cells and regulate their function. They can also shift function during the different phases, for instance, during the different phases of healing. So they have some functions early on and then they take on other functions. And all of these different steps are important for restoring the tissue to what it was before the injury. And that's why they are so interesting in targeting, because if you can target them early on, you know, you could increase the entire cascade of functions that they are exhibiting during the different phases. So they are my favorite population at the moment. But that's just because I know more about them than the other cells

Natalie von der Lehr 20:44
Stupid question. How many different types of immune cells are there?

Mia Phillipson 20:49
I don't know. And I think - so this is something that I feel pretty strongly about within immunology, but, you know, within academia as a whole. That this way that we have constructed knowledge, the Linneaus' way of categorizing cells or species or whatever, it's beneficial for our understanding and how we remember the knowledge that we are building up. But biology doesn't care. It's a construction that we have made, it's man-made, man-made construction, because we need this in order to, you know, attach the different facts that we learn as we go along. But biology is so much uninterested or unaware of our categorization. So I think a cell could be many different things, depending on situation. Of course, there are characteristics, but they also seem to be able to do other things than what's classically associated with a different cell. And now I come to what I did during my SCAS project.

Natalie von der Lehr 21:56
Yes, please tell us about your SCAS project.

Mia Phillipson 21:58
Because I was so frustrated when it turned out that my bioinformatician had filtered away all the interesting data, because she had been reading up on what was expected from these cells that we were studying. And they were macrophages at the time. So she had removed the cells that no longer looked like these cells that the macrophage associated or the macrophage traditional markers. And since we were using many different methods in parallel, we could see that they were there, but she couldn't find them. And yet, the methods that she was using was an unbiased, large data set of cells based on single-cell sequencing. So you're sequencing all the cells in this tissue. And then, in order to understand anything from the data, you have to filter something out, or you have to categorize them in different ways. And by doing this, she removed the cell types that was something in between. So she removed the macrophages that behaved like neural cells or pericytes, which is a vascular cell, part of the blood vessel. And then we did the same experiment by marking all macrophages before we induced injury. So they were all red. And then she looked only at the red cells and found that some of the red cells are no longer macrophages. There are something in between. They have started to trans-differentiate into another cell fate. It was not known that they could do this in the adult tissue. And it's something that they are turning on as a response to this injury that we induced. And, well, I gave a talk at the Swedish Young Academy about these cells. And I challenged the view of immune cells being soldiers.

Natalie von der Lehr 23:52
Because that's how they're often described, right?

Mia Phillipson 23:54
Exactly. They are described as watching the borders of the human body. You know, they are guarding us. They are armed.

Natalie von der Lehr 24:01
They're killing.

Mia Phillipson 24:02
They have all different weapons. And when an intruder is entering, they do whatever they can to kill this. And I remember the last slide that I had during that presentation was something about, you know, the cleaning ladies. Or, you know, just starting another metaphor. The Swedish Young Academy is a great cohort of individuals from all different parts of the wide university. So extremely transdisciplinary or interdisciplinary individuals. And we started discussing, you know, what could one call these cells if one would leave the military narrative and try to find something else. And I discussed a lot with Ylva Söderfeldt, who is a researcher in history of science and ideas at Uppsala University. And she, I guess, gave me the confidence to also continue down this line, even though it was extremely outside of my medical comfort zone. The project was to try to understand how this military narrative has influenced the research that we are conducting within immunology. If it has restricted the free mind, in some sense, and shifted us towards only following up on this killing effects of the immune system. That they are absolutely doing. And it's such a strong metaphor also. You really understand their function and it sticks. So we wanted to understand if this is something that is impairing the field, actually. And today we have a joint PhD student that is now looking into this. She has access to all science journals and is utilizing large language models in order to understand how the military narrative has been developing or how it's been used during a specific time period in these journals. And if we are constructing these thought collectives, so that we are using the same language in order to make ourselves understood, but also in order to, you know, convince the reviewers and the editors that this is important.

Natalie von der Lehr 26:18
Now, that's very interesting. And I mean, words matter, right? Language matter, how we think, how we interpret the world, I guess.

Mia Phillipson 26:27
Absolutely. And the words are man-made. It's not biology. It's how we describe biology. Every time we do it, we are limiting biology as well. And I think that's so exciting to think about. What you choose to see, what you choose to talk about.

Natalie von der Lehr 26:53
And now we've already talked about your SCAS project. What was your experience of SCAS otherwise, this multi- and interdisciplinary environment that you were part of for one term?

Mia Phillipson 27:03
Too short period of time. I think for that project and for me also, it was perfect, a perfect surrounding. Well, I've learned a lot from all of the other fellows and also really needed their input on this line of thinking that, I mean, I really initiated here. And what the PhD student, Christina Humphrey, now is doing is so much. She has advanced those early thoughts a lot. But I was at that time more looking into how the field of immunology had developed, in order to understand why we are focusing so much on the immune cells. I read up a lot on the history of immunology, which I probably should have done before. But I try to keep myself on top of the recent papers within my field. What I tried to implement is really the seminar culture of SCAS, that you have a lot of time for discussions after the presentation. So it's so easy that you just, you know, stand up, thank you very much, and then leave. You go back to your computer. But it was amazing to follow the discussions at SCAS. First, the questions were always about directly, you know, the things that were presented to us. But after a while, another kind of discussion developed. That was just amazing to witness.

Natalie von der Lehr 28:30
And since you have scholars from so many different disciplines, I guess they also come in with different angles that you might have not thought about.

Mia Phillipson 28:37
Absolutely. And there must be a lot of trust, you know, to show your ignorance. That's one of the things that we as academics are not really good at. You have to be brave. And also, it has to be a very safe environment in order to expose that, I guess.

Natalie von der Lehr 28:56
Thank you very much for joining me here in the studio and our listeners, of course.

Mia Phillipson 29:00
Thank you.

Natalie von der Lehr 29:04
And thank you for listening to SCAS Talks, a podcast by the Swedish Collegium for advanced study. In this episode, I've talked to Mia Phillipson, Professor of Physiology at Uppsala University and co-director of the Science for Life Laboratory. She was a fellow at SCAS within the Natural Sciences Program during spring of 2022. We have talked about her research on wound healing in the uterus, and this was the fourth episode in our theme “Women and Medicine”. Earlier episodes in this series include episode 57 “Why do women go to the doctor twice as often as men”, with Anat Biegon. Episode number 59 “Self sampling for better screening and diagnosis of gynecological cancers”, with Stefan Enroth. And episode number 60 “Women's reproductive health in Ukraine”, with Irina Mogilevkina.

SCAS Talks covers a wide range of topics reflecting the Collegium's multi- and interdisciplinary research community. There is something for everyone. If you enjoyed this episode, please recommend SCAS Talks to colleagues and friends and subscribe so you don't miss any content. You can find us on Podbean, Apple Podcasts, Spotify and most podcast apps. Thanks again to Mia Phillipson for joining us and thank you for listening. Bye for now.

Transcribed by https://otter.ai