Every month, your body builds one of its most sophisticated tissues from scratch, sheds it, and rebuilds it again.
Without scarring.
Without intervention.
Without fail.
Roughly 400 times before menopause.
And every month, the stem cells that make that possible get flushed away.
One of my Girls Into VC alums introduced me to Dr. Michele Ferguson, CMO of Muse Bio.
And here's what you need to know about Michele.
She spent years in the ICU. Then primary care. Then longevity and women's reproductive health.
And that whole time she was watching the same failure, on repeat: a woman walks in with fatigue, mood swings, weight changes, hormonal chaos, cycle disruption.
A constellation of symptoms that any physician who's paying attention would read as connected.
And she gets seven minutes. Maybe ten.
One symptom is addressed.
She’s given a prescription (usually the pill).
And off she goes…
Every visit was about managing a single complaint instead of understanding the whole picture.
But Michele wanted to “actually move the needle”, not just treat the symptom closest to the surface.
She wasn't necessarily looking for a startup.
Sure, her dad and both brothers are serial entrepreneurs, so she knew it was just a matter of time before she crossed over.
But one day she met Juliette Humer (Muse Bio's founder) at a longevity event in SF.
They ended up co-running an event on the frontiers of reproductive health tech.
By the time Michele sat down with the exec team, alignment was obvious.
The science was foundational. The mission was real. She joined as Chief Medical Officer.
So what is Muse Bio actually doing?
Juliette founded the company after doctors quoted her $250,000 for stem cell therapy to treat her degenerating spine. At 23.
She spent a year on a cane.
While doing some research, she surfaced something that had been sitting in the scientific literature since 2007, largely ignored: menstrual fluid contains a highly scalable source of mesenchymal stem cells.
Easier to collect, faster to grow, and more practical than bone marrow.
And unlike bone marrow, collecting them doesn't require needles, surgery, or a medical professional!
It requires a menstrual cup, a prepaid shipping label, and fifteen minutes of your time.
The endometrium is one of the most regenerative tissues in the entire human body.
Its anti-fibrotic remodeling is rare.
Most tissues scar when they repair.
The endometrium doesn't.
That property makes the stem cells it produces potentially valuable in research on conditions where scar (fibrotic) tissue is the problem: infertility, cardiac disease, liver fibrosis, lung injury, neurological damage.
"Nature designed something remarkable," Michele said. "The endometrium has had millions of years to perfect regeneration. It remodels itself, every single month. And we've just been flushing it away."
And we really have been…
As of 2020, menstrual stem cell research was 0.25% of all mesenchymal stem cell research.
Bone marrow: 47.7%.
It's the same reason women wait an average of seven years to be diagnosed with endometriosis.
Not because the biology is too complex… but because no one thought it was worth funding.
And because there's certainly an ick factor.
But when you look at what these cells can actually do… the immunomodulatory properties, the anti-inflammatory activity, the regenerative potential in preclinical models… the ick evaporates pretty fast.
Their first commercial product leans into exactly that: a skin serum made from growth factors secreted by cultured menstrual stem cells.
Applied topically.
Launching this year, with 700 medspa and surgical office agreements already signed.
As a topical cosmetic, it follows the established regulatory pathway for cosmetic products, an entirely separate track from the company's therapeutic pipeline, which will pursue full FDA regulatory pathways.
It's a smart commercial entry point that generates the revenue funding the actual roadmap: fertility treatments for uterine-caused infertility, ovarian rejuvenation research, and cell therapies for acute respiratory distress already in clinical trials elsewhere.
Michele's day right now is what she calls “translation”.
In the morning she might be in the weeds with their CTO and scientists, designing experimental protocols, defining clinical trial endpoints, mapping FDA regulatory pathways.
By afternoon she's on calls with skincare partners.
In between: donor safety, eligibility criteria, making sure every sample meets the bar for eventual cell therapy use.
"I'm constantly moving between the science, the data, the literature, and the business model," she said. "My job is to make sure they all flow together… that we're not building something scientifically brilliant that no one can use."
When it comes to pitching investors, Michele goes emotional first, data second. Though you obviously need both :)
Muse Bio has 350+ active donors in San Francisco, $1.1M raised, and is targeting $6M to scale.
Bottom line: Your period has power! It's not waste. It can help develop life-changing medicines.
Menstrual blood under a microscope 🩸
