Menstrual blood has historically been overlooked in research - considered only to be a waste product .
Author
- April Rees
Lecturer, Biochemistry & Immunology, Swansea University
But menstrual blood actually has a rich cellular and molecular makeup . It contains immune cells, stems cells and endometrial cells - as well as metabolites such as proteins and lipids (fat). This makes menstrual blood a potential goldmine for insights into many different health conditions. It can also be a less invasive way for researchers to access important biological material without the need for surgical biopsies or other invasive techniques.
Given its important composition, researchers are now using menstrual blood to investigate whether it can be used to uncover the causes of a disease, identify signs of a health condition and develop personalised treatments.
One area where menstrual blood could be integral is research investigating endometriosis. This condition causes endometrial tissue (which normally lines the uterus) to grow outside of the womb and on other organs, such as the bowel and ovaries.
Research into endometriosis is severely underfunded , despite it affecting 10% of women . It's also difficult to understand the mechanisms behind the disease without using invasive procedures. As a result, current treatment options - which include surgical lesion removal, hormonal contraceptives and pain relief - fail to address the root cause or associated complications (such as infertility).
But some researchers have managed to develop organoids using the endometrial cells from menstrual blood . Organoids are miniature, lab-grown 3D models of organs derived from the stem cells found in the blood. These organoids can mimic what happens in the actual endometrium (the innermost lining of the uterus). This gives researchers a non-invasive way to investigate the health status of the endometrium.
By developing organoids from the menstrual blood of those suffering with endometriosis, researchers are able to model the disease in the lab. This may one day lead the way to better understanding the underlying mechanisms of the condition.
Endometriosis is also considered to be an inflammatory condition . This is because there's an over-activation of the immune system seen in people with endometriosis, which worsens symptoms. As such, an area of high interest for research into endometriosis is the study of the immune system.
Menstrual blood contains live immune cells which have come from the reproductive tract. These immune cells offer insight into the inflammation that's occurring in the womb. This may help researchers better understand and develop treatments for painful sex, a common symptom for people with endometriosis which is linked to inflammation .
While the presence of endometrial cells makes it an ideal tool for studying endometriosis, menstrual blood is also being used to offer insights into other reproductive diseases. For example, it has unveiled immune differences in patients with recurrent pregnancy loss that was not previously detectable using blood from the vein.
Stem cell research
Menstrual blood also contains stem cells , which makes it an important resource for research into a variety of other health conditions - including those involved in critical processes such as cardiovascular function, respiration and nervous system function .
Stem cells are defined by their naive status and ability to become a new, specialised type of cell under the right conditions. Adult stem cells are usually taken from umbilical cord blood, amniotic fluid, bone marrow or fat tissue. However, it requires invasive techniques to extract a stem cell sample from these areas - and only small amounts can be acquired.
But menstrual blood, a fluid which is typically produced monthly, has been found to contain stem cells that are also capable of differentiating into various other cell types. This is particularly exciting as menstrual blood is readily available, naturally regenerates and collecting it does not require any surgical procedures or discomfort. This makes it a convenient and ethical option for stem cell research and potential therapies.
Aside from using these menstrual blood-derived stem cells to investigate reproductive diseases such as endometriosis , there are also several studies looking at using these cells in other applications. For example, researchers have used them to investigate techniques for promoting wound healing and improving blood sugar levels in diabetes patients.
On the topic of diabetes, menstrual blood is also being used for a proof-of-concept study to monitor glycaemic control . This offers alternatives to traditional blood tests - such as the Q pad , a pad which contains a removable collection strip for blood testing.
Other diseases which are showing promising results in being diagnosed through menstrual blood include cervical cancer , chlamydia and diseases associated with lipid levels - such as atherosclerosis and coronary artery disease.
The new normal?
Menstrual blood is gaining traction in research due to its novelty and because it's a less invasive way to collect different cells and molecules for testing. It's easily accessible as a monthly "waste" product, and allows women to collect samples themselves. This could bypass the need for doctors and nurses and the inconvenience of appointments if it becomes a more reliable diagnostic tool.
But despite its promise, there are practical challenges that researchers face. Discussion around menstrual blood is still sometimes seen as taboo . Some women may not feel comfortable handling their own blood.
There are also inconsistencies with how menstrual blood is collected between studies. For example, studies which only required a smaller volume of menstrual blood have been able to make use of sanitary pads and tampons to collect samples. However, those which require a larger sample used menstrual cups. The first issue with this is that the products used have different compositions, which can interfere with the reliability of the results. Another issue lies predominantly with menstrual cups and the lack of knowledge surrounding their proper use.
As such, addressing stigma and promoting awareness around menstrual blood research is vital. While it has historically been overlooked, menstrual blood must now be recognised as a powerful, non-invasive tool in advancing research.
April Rees receives funding from Royal Society.
