Muse Bio is researching whether menstrual stem cells could one day be used in new therapies.
Our own work is at a very early stage.
Below are five areas we are exploring, each with a summary of the published, peer-reviewed research by independent scientists.
Spinal cord injury, stroke, multiple sclerosis and neurodegenerative disease
The brain and spinal cord have an extremely limited ability to recover after damage.2 In 2019 there were 12.2 million new strokes and 6.55 million deaths from stroke worldwide.16 Spinal cord injury led to 0.93 million new cases in 2016.17 An estimated 2.8 million people live with multiple sclerosis (MS), in which immune cells attack the myelin sheath that insulates nerve fibers.18, 3 Neurodegenerative diseases such as Alzheimer's and Parkinson's slowly destroy nerve cells. Today's treatments have clear limits: a 2024 review notes that no medication has yet been found that significantly halts the progression of these neurological diseases.19
In people. In 2009, researchers reported on four people with MS who had not responded to standard treatments and received donor cells grown from menstrual blood.1 The researchers reported no immunological reactions or treatment-related adverse effects. There was no control group, participants were also receiving other treatments, and the report assessed safety only.
In animals. In the most rigorous spinal cord study, 72 rats were randomly assigned to sham surgery, a partial spinal cord cut, or the cut plus human menstrual stem cells; treated rats walked better from day 7 to day 28.2 In mice with the standard animal model of MS, one dose of human donor menstrual stem cells reduced disease severity, and the cells performed about as well as umbilical cord stem cells.3 Other groups reported less damage in rats with experimental stroke.20 Others reported better memory-maze performance in Alzheimer's-model mice (15 per group) and better movement in Parkinson's-model rats (15 per group, randomized, blinded).21, 22
The limits of the evidence. The human evidence is a single uncontrolled report of four people that assessed safety only. All signs of benefit come from rodents, mostly in single-laboratory studies with follow-up of weeks. A November 2026 PubMed search found no controlled human trial of menstrual stem cells in these conditions.
The authors of the 2009 MS report concluded that their preliminary data “suggest feasibility” and support further studies, while stressing the small sample and limited number of injections. The authors of the 2018 rat study called the cells “quite fit” for spinal cord injury therapy, and added that their usefulness still has to be evaluated in clinical trials. The authors of the 2022 MS-model study concluded the cells “should be considered a candidate” for ready-to-use donor cell products.
J Transl Med · 2009
Human · donor (allogeneic) live cells · n = 4 · uncontrolled, safety only
Four people with multiple sclerosis who had not responded to standard treatments received donor cells grown from menstrual blood. Over 2 to 12 months, the researchers reported no immunological reactions or treatment-related adverse effects. There was no control group and participants were receiving other treatments, so only safety was assessed.
Cell Death Dis · 2018
Animal · rat · human menstrual stem cells (live), injected into the injury · n = 72 + 50 · randomized, blinded scoring
Rats with a partial spinal cord cut received human menstrual stem cells injected into the injury or a control injection. Treated rats walked better from day 7 to day 28, and at 28 days the lesion cavity took up 10.4% of the cord volume, against 21.4% in untreated injured rats.
Stem Cell Res Ther · 2022
Animal · mouse (MS model) · human donor menstrual stem cells (live) · 12 to 24 per group · blinded scoring, umbilical cord cell comparator
In mice with EAE, the standard animal model of MS, one dose of one million human donor menstrual stem cells reduced disease severity; in one experiment disease incidence fell from 93% to 62.5%. The cells worked about as well as umbilical cord stem cells. Cells given at the disease peak did not lower peak scores.
Acute respiratory distress syndrome, severe viral pneumonia and lung scarring
Acute respiratory distress syndrome (ARDS) is a sudden, severe lung injury: inflammatory fluid floods the air sacs, blood oxygen falls and patients need mechanical ventilation.23 Severe viral pneumonias, including H7N9 influenza and COVID-19, can progress to ARDS.5, 4 In a 2014 study across 459 intensive care units in 50 countries, hospital mortality was 34.9% in mild, 40.3% in moderate and 46.1% in severe ARDS.24 No specific drug therapy has been identified.23 Lung injury can also end in scarring: idiopathic pulmonary fibrosis is a chronic, progressive scarring disease, and the two approved drugs only slow its progression.25, 26
In people. Two studies, both controlled but not randomized and both from one research network in China, gave donor menstrual stem cells by intravenous infusion on top of standard care. In H7N9 influenza ARDS, researchers reported 17.6% mortality in 17 patients who volunteered for cells versus 54.5% in 44 treated at the same time without cells (P = 0.006).5 In severe and critical COVID-19, one-month mortality was 7.7% in 26 patients who received cells versus 33.3% in 18 who received standard care only (P = .048).4 Blood inflammatory markers did not change significantly.
In animals. The most rigorous animal study, from an independent team in Chile and Brazil, tested five doses in randomized mice (8–10 per group) with blinded tissue scoring. One dose improved survival and lung mechanics in mild to moderate injury; higher doses added no benefit.6 A head-to-head mouse study found that umbilical cord cells protected the injured lung better than menstrual stem cells.27
The limits of the evidence. All human data come from one research network, in two small studies where patients chose or volunteered for their group and received many other treatments. No randomized trial of live menstrual blood-derived cells in lung disease has been published (PubMed search, 10 November 2026). Most animal work is in mice, and the right dose for people is unknown.
The authors of the COVID-19 trial concluded that the treatment “significantly lowers the mortality” in their patients, while stressing that the research “is still in its infancy” and still lacks long-term data on possible side effects. The H7N9 team also called clinical work on these cells early-stage. The Chile–Brazil team concluded that turning a frozen, ready-to-use product into a clinical formulation “would have great potential”. Each team also set out the limits of its own work, from small numbers of patients to uncertain dosing.
Clin Transl Med · 2021
Human · donor (allogeneic) live cells · n = 44 · controlled, not randomized
One month after treatment, 2 of 26 patients (7.7%) who received the cells had died, against 6 of 18 (33.3%) in the comparison group (P = .048). Shortness of breath improved during the infusion days but not afterwards. Blood inflammatory markers did not change significantly. Patients chose their group.
Engineering (Beijing) · 2020
Human · donor (allogeneic) live cells · n = 61 · controlled, not randomized
3 of 17 patients (17.6%) who received the cells died, against 24 of 44 (54.5%) without cells (P = 0.006). The researchers reported no infusion-related toxicity or serious adverse events. Four treated patients were followed for five years. Patients volunteered for the cell group.
Front Cell Dev Biol · 2023
Mouse · human donor live cells (clinical-grade, cryopreserved) · n = 8–10 per group · randomized, controlled
In injured mice, one dose (about 4 million cells per kg) gave 0% mortality against 15% in untreated injured mice, and was the only dose that improved lung mechanics at both time points. Higher doses gave no extra benefit, and the model reflects mild to moderate ARDS.
Heart attack, heart failure and blocked blood flow to the limbs
A heart attack (myocardial infarction) happens when heart-muscle cells die because their blood supply is cut off.28 The dead muscle is replaced by scar tissue, which can eventually weaken the heart and end in heart failure.9 Heart failure affects more than 64 million people worldwide.29 Blocked arteries also starve the legs: about 202 million people were living with peripheral artery disease in 2010.30 Researchers note that the heart-muscle cells lost in a heart attack do not come back, and that the outlook in heart failure remains poor despite better treatment.9 Earlier stem cell trials, mostly using bone marrow cells, reported modest effects on heart function.7, 8
In people. No human results yet. A PubMed search (November 2026) found no published human outcome data for menstrual stem cells in heart attack, heart failure or limb ischemia.
In animals. In rats with normal immune systems, cells were injected around the injury 30 minutes after a heart attack (8–14 rats per group); treated rats kept more living muscle and pumped better at 7 and 28 days.7 Few cells survived, so the authors credited the benefit to factors the cells release. In the same group's randomized comparison (5 rats per group), scar covered 27% of the left ventricle at 28 days with these cells, against 50% with saline, 42% with bone marrow cells and 40% with fat cells.8 A separate group in Iran gave pre-treated menstrual blood cells or bone marrow cells into a vein one week after the heart attack (randomized, 8 per group); both improved heart function compared with no treatment, with no significant difference between them.9 For blocked leg arteries there is one pilot mouse experiment (8 treated, 8 untreated), without blood-flow imaging or statistics.31
The limits of the evidence. Every study was small, short (4–8 weeks) and in rodents. Most studies injected cells within minutes of permanently tying an artery; only one waited a week. No study tested doses systematically, and no large-animal study of the cells was found.
Jiang and colleagues noted that the cells can be collected without invasive procedures, concluded that menstrual blood offers “a potentially limitless source” of ready-to-use cells, and called for further investigation. Wang and colleagues reported that these cells outperformed bone marrow and fat-derived cells in their rat model, and added: “Further investigations and clinical trials are essential”. An independent group, Manshori and colleagues, called menstrual blood “a new and interesting source of stem cells”. The researchers frame these as grounds for further study, not as proof of benefit in people.
J Cell Mol Med · 2013
Rat · human live cells · n = 8–14 per group · controlled
In rats with normal immune systems, human menstrual blood-derived cells injected around a fresh heart attack preserved more living heart muscle and improved pumping at 7 and 28 days compared with saline. Few cells survived, so the authors concluded that the benefit came mainly from factors the cells release.
Stem Cells Transl Med · 2017
Rat · human live cells (exosome mechanism tested) · n = 5 per group · randomized, controlled
In a randomized rat study comparing three stem cell sources, these cells gave the smallest scars: 27% of the left ventricle at 28 days, compared with 50% for saline, 42% for bone marrow cells and 40% for fat cells. The paper's methods name only the cell supplier; its introduction says the cells come from menstrual blood.
BMC Cardiovasc Disord · 2022
Rat · human live cells (pre-treated, given in the medium they were grown in) · n = 8 per group · randomized, controlled
Rats received pre-treated menstrual blood cells or bone marrow cells into a vein one week after a heart attack. At day 35, scar covered 18% of the left ventricle with menstrual blood cells, compared with 47% with bone marrow cells and 53% untreated. The difference in heart function between the two cell types was not statistically significant.
Early loss of ovarian function, poor response to IVF stimulation, ovarian damage from chemotherapy, and menopause
Premature ovarian insufficiency (POI) is the loss of normal ovarian function before age 40, and a recognized cause of infertility.32 The 2024 international guideline puts its prevalence at 3.5% and notes that evidence for most management options is limited.33 Medical treatment is the most common identifiable cause, accounting for about half of all cases.34 Poor ovarian response, where the ovaries yield few eggs during IVF stimulation, accounts for 9–24% of IVF cycles.10 Menopause brings vasomotor, mood, sleep, urogenital and musculoskeletal symptoms; hormone replacement therapy is used, but some women avoid it over cancer-risk concerns.12
In people. Every published human study found (PubMed search, 10 November 2026) used the woman's own cells, and most of the data come from one research group in Tehran. In its non-randomized controlled trial of 180 poor responders, 22.5% of treated women conceived spontaneously within two months, compared with 7.4% of controls; live-birth differences were not statistically significant, and women chose (and paid for) their own group.10 In an earlier controlled trial of 31 women, four of 15 treated women conceived naturally within three months, against none of 16 controls (P = 0.04).11 An independent clinic in Japan gave 15 women with menopausal symptoms infusions of their own cells; symptom scores fell significantly, with no control group.12
In animals. In 48 rats with chemically induced POI, randomly assigned to four groups, researchers reported that exosomes from menstrual stem cells restored estrous cycling and hormone levels.35 In chemotherapy-sterilized mice, intravenous human menstrual stem cells improved estrous cycling.36
The limits of the evidence. The human evidence is small, mostly from a single center, non-randomized or uncontrolled, autologous only and largely short-term. The trial authors also call for rigorous randomized trials.10
The authors of the 180-woman trial concluded that the approach “may be a viable option” for women with poor ovarian response, adding that rigorous randomized trials are needed before wide clinical use. The authors of the earlier trial described the cell therapy as “a potential treatment”. Reporting on menopausal symptoms, Izawa and colleagues highlighted menstrual blood as a source that can be collected non-invasively, and called for larger trials to set dosing and confirm long-term efficacy and safety.
Stem Cell Res Ther · 2023
Human · autologous live cells · n = 180 · controlled, not randomized
Within two months of the injections, 22.5% of treated women conceived without IVF, against 7.4% of the untreated group. Differences in clinical pregnancy and live birth were not statistically significant, and the pregnancy benefit was seen only in women under 40. Women chose their own group.
Stem Cell Rev Rep · 2020
Human · autologous live cells · n = 31 · controlled phase I/II trial
Four of the 15 treated women became pregnant naturally within three months of the injection, against none of the 16 controls (P = 0.04). Overall, 7 of 15 treated women and 2 of 16 controls had a clinical pregnancy, leading to 5 and 1 live births. AMH did not change significantly.
Regen Ther · 2025
Human · autologous live cells (intravenous) · n = 15 · uncontrolled case series
Menopausal symptom scores fell within a month of the initial infusion and stayed low for about six months; some women's scores rose again by 12 months. Hormone changes are reported only as trends. No serious adverse events were seen. There was no control group.
Thin or scarred uterine lining, including intrauterine adhesions (Asherman syndrome)
The endometrium, the lining of the uterus, rebuilds itself every menstrual cycle.15 If its deeper layer is injured, most often by curettage of a recently pregnant uterus, scar tissue can form inside the uterus. These intrauterine adhesions are called Asherman syndrome when they cause symptoms such as scant periods or infertility.37 A related problem, thin endometrium, is linked to lower implantation and pregnancy rates in fertility treatment.38 Standard treatment is to cut the adhesions hysteroscopically.37 In 638 women treated at one specialist center, surgery restored a healthy cavity in 95%, yet adhesions came back in 27.3% of those women.39
In people. Two small single-arm studies used each woman's own cells, placed in the uterus and followed by hormone therapy. In seven women with severe Asherman syndrome, endometrial thickness rose significantly (P = 0.0002), reaching 7 mm in five.14 At a different center, 12 women with refractory adhesions saw mean thickness rise from 3.9 to 7.5 mm (P < 0.001).40 A 2025 meta-analysis of 12 before-and-after clinical studies (233 patients) of stem cells from several sources rated 75% of studies at high risk of bias; its menstrual-blood subgroup contained only the 12-patient study.13
In animals. In rodent injury models, menstrual stem cells have repeatedly been linked to a thicker lining, less scarring and better fertility measures.41 An independent group in Tokyo reported a thicker lining and less fibrosis in injured mice (4 per group); litter size rose from 7.2 to 9.1 pups, but not significantly.15
The limits of the evidence. The human evidence is 19 patients in two uncontrolled studies of autologous cells given with hormones, so the cells' own contribution cannot be separated. A PubMed search (November 2026) found no randomized or controlled trial of menstrual stem cells in this area. The animal studies are small, and the papers reviewed do not report blinding.
The authors of the seven-patient study concluded that transplanting a woman's own menstrual stem cells is “a potential option” for severe Asherman syndrome. The authors of the 2025 meta-analysis “cautiously recommended” local injection of the patient's own cells while calling for large randomized trials, and noted that their menstrual-blood estimate rested on a single study. The Tokyo group called transplanting a patient's own cells “a rational approach” for thin endometrium, while reporting only a partial fertility improvement in mice.
Front Bioeng Biotechnol · 2025
Human · meta-analysis of 12 uncontrolled studies (233 patients) · menstrual-blood subgroup: 1 study, autologous live cells, n = 12
Pooling 12 small before-and-after studies, the authors found that endometrial thickness rose by 2.28 mm on average after stem cell treatment. The menstrual-blood subgroup, a single 12-patient study, showed a 3.62 mm gain. Three in four included studies were at high risk of bias.
Hum Reprod · 2016
Human · autologous live cells · n = 7 · uncontrolled
Cells were grown from each woman's own menstrual blood and placed in her uterus, followed by hormone therapy. Endometrial thickness increased significantly (P = 0.0002) and reached 7 mm in five of the seven women. The authors name the small sample and the lack of rigorous controls as limitations.
Stem Cell Res Ther · 2023
Mouse · live cells from infertile patients' menstrual blood (human cells in immunodeficient mice) · n = 4 per group (fertility 5 to 10 per group)
The team grew cells from the menstrual blood of 10 of 16 infertile patients. In injured mouse uteri, the cells were linked to a thicker lining and less fibrosis at day 7, with no tumors. Litter size rose from 7.2 to 9.1 pups, a difference that was not statistically significant.