What if the secret to healthier, longer lives is quietly discarded in hospital operating rooms every day?

Stem cells offer enormous promise, but the search for the right type—biologically active, ethically sourced, and scalable—has left researchers walking a tightrope for decades. Few realize the story begins in one of medicine’s routine, overlooked byproducts: tissue from ectopic pregnancies.

David Brühlmann welcomes Yuta Lee, founder and CEO of Accelerated Bio, a pioneering biotech company at the forefront of regenerative medicine and longevity.

Key Topics Discussed

• Bioprocess development in biotech is inherently unpredictable, even under tightly controlled manufacturing conditions.
• Stem cell manufacturing requires deep understanding of biological complexity, scalability, and regulatory risk.
• Early-stage stem cells offer far greater expansion potential and potency compared to adult-derived stem cells.
• Immortal or highly proliferative stem cells raise major regulatory concerns due to potential cancer-like behavior.
• Population doubling capacity is a critical metric determining commercial scalability of cell therapies.
• Placental and trophoblast stem cells exhibit immune-privileged properties, enabling potential universal donor therapies.
• The industry is shifting from personalized autologous therapies toward scalable allogeneic “off-the-shelf” treatments.
• Strong intellectual property strategy, ethical compliance, and long-term funding are essential for successful biotech platform development.

Episode Highlights

• Common misconceptions and challenges in bioprocess development for biological therapeutics [02:45]
• The origin story behind Yuta Lee's interest in stem cells, including his father’s surgical discovery [04:15]
• A look at the intellectual property strategy that protected and enabled Yuta Lee's company to develop its platform [07:26]
• A clear explanation of different stem cell types (embryonic, trophoblast, mesenchymal, adult, and induced pluripotent) and their sources [09:37]
• Ethical and regulatory issues involved in sourcing stem cells, and how trophoblast cells offer a unique alternative [10:59]
• Discussion of stem cell differentiation, population doubling, and scalability for manufacturing purposes [17:03]
• Importance of immune privilege and HLA-G expression in pre-placental cells for off-the-shelf therapies [20:20]
• Shifts in the industry from autologous to allogeneic therapies, and the role trophoblast cells may play in future treatments [22:00]

In Their Words

He was performing surgery on an ectopic pregnancy and he took the mass out. And I was thinking to himself, why are we throwing this away? There's got to be amazing stem cells in here. But to avoid all of the ethical issues that human embryonic stem cells went through, what he ended up doing was scraping off the pre-placental tissue from the outside of it. He handed the rest of the tissue back to the pathologist. And the reason why they can discard it is because in this type of pregnancy, OB-GYNs understand it to be non-viable. Well, my father, having taken the pre-placental tissue from the outside of the embryo, now has the earliest stem cells that you could possibly source without the same ethical concerns.

How to Source, Manufacture, and Scale the Earliest Stem Cells for Allogeneic Cell Therapy Without Ethical Barriers - Part 1

David Brühlmann [00:00:44]:
What if the key to reversing biological aging was hiding in tissue that medicine routinely discards? My guest today has spent more than two decades pursuing exactly that question. Yuta Lee is the founder and CEO of Accelerated Bio, and he's built a platform around human trophoblast stem cells, the earliest ethically sourced cells from the embryonic stage. Today we explore the biology, the ethics, and the manufacturing logic behind a cell therapy platform targeting age-related decline.

Welcome, Yuta. It's good to have you on today.

Yuta Lee [00:02:36]:
David, happy to be here.

David Brühlmann [00:02:38]:
Share something that you believe about bioprocess development that most people disagree with.

Yuta Lee [00:02:45]:
Ooh, that's a good one—already hitting with the hard questions. Most people disagree with… I think that only people in the industry know how difficult it is to manufacture biological systems. And even if you set all the conditions in the most ideal setting—the ideal SOPs, the ideal parameters—things will still go wrong.

And I think it's almost a myth that a lot of people who are not in manufacturing, processing, or process development believe that once you set the process, it's done and not much can go wrong. But a lot of things can go wrong.

I think the devil really is in the details. And it would be great to have everybody who's not in the manufacturing world, the CMC world, or the process development world understand that this is a really difficult job—because we barely understand biology, and we're trying to control it. And so it's very, very hard to do.

David Brühlmann [00:03:41]:
You're making a great point, and thank you for the reminder. This is something I try to repeat as much as possible to all the people I speak to—manufacturing and development are hard, very difficult.

And it's actually surprising that you are making this statement because you came into biotech with a business background.So tell us your story—what sparked your interest in stem cells, and what were the pivotal and defining moments along the way that led you to becoming a CEO?

Yuta Lee [00:04:15]
Okay, I'm going to start with the story. Actually, the story starts with my father, who is an MD, PhD. His name is Professor Jau-Nan Lee, and he got his MD from Tohoku University in Sendai, Japan, and his PhD at Barts and The London School of Medicine and Dentistry at the University of London. So I actually spent four years of my childhood in London, which was a lot of fun. Then he went back to Taiwan to practice, and he became a key opinion leader in OB-GYN. He sent us off to Los Angeles, and that's why I have this very American accent.

But what happened was, in 2003, he was performing a procedure called a salpingectomy for an ectopic pregnancy. And an ectopic pregnancy happens when the embryo is traveling down the fallopian tube, and sometimes—usually about 1 to 2% of the time—that embryo may become implanted there. And if it implants there, it will grow until it ruptures the tube. And with rupture of the tube, the mother may die from internal bleeding. So it's actually one of the leading causes of death in first-trimester pregnancies.

So to make a long story very short, he was performing surgery—a salpingectomy—for an ectopic pregnancy. And he removed the tissue and was thinking to himself, why are we throwing this away? There's got to be valuable stem cells in here.

But to avoid all of the ethical issues that human embryonic stem cells went through, what he ended up doing was scraping off the pre-placental trophoblast tissue from the outside of it. He handed the rest of the tissue back to the pathologist to confirm the diagnosis—yes, it's an ectopic pregnancy—and then it could be discarded.

And the reason why it can be discarded is because in a normal pregnancy, the embryo needs to implant into the uterine lining, typically by day 7 or day 8. But an ectopic pregnancy is usually not discovered until about 4 to 8 weeks. So there are many weeks in between where that embryo is not properly connected to the uterine environment—there is inadequate support and nutrient exchange. So OB-GYNs understand it to be non-viable. That is the reason why, when you perform this surgery, all you have to do is remove the tissue, send it to a pathologist to confirm, and then it can be discarded.

Well, my father, having taken the pre-placental trophoblast tissue from the outside of the embryo, now has the earliest stem cells that you could possibly source without the same ethical concerns.

And he comes to me two years later—so he discovers this in 2003, and in 2005 he comes to me and goes, “Yuta, you're the business guy. Do something with this.”

To which I respond, “Hey dad, I went to Berkeley for economics and law—what do you want me to do?”

That was pretty hilarious. But as the oldest son, I said, all right, challenge accepted. I’ll take it on and see what I can do with it. Luckily, my brother-in-law was an investment banker at Morgan Stanley in San Francisco, covering healthcare. So I called him up and said, “Bob, who is your go-to IP lawyer for this kind of work?” And he said, “You’ve got to go to Wilson Sonsini in Palo Alto, right next to Stanford—probably the best lawyers for this.”

So we went, found a partner, and filed the first patent. That was the beginning of it all. And five years later, we obtained our first composition of matter patent. And it was so strong that one of the top attorneys called me and said, “Yuta, your patent portfolio—this first composition patent—is very powerful, because you sit between embryonic stem cells and induced pluripotent stem cells, and the non-scalable mesenchymal stromal cells. You have advantages from both sides.” He said, “Keep building out the portfolio. Don’t tell anybody you have this—you’re too early.”

This was 2010, and at that time, no one wanted to invest in stem cells. VCs were not interested. He said, “Keep building the portfolio, but most importantly, do not give this to academic researchers. Because once they publish on it, everything becomes public. And if institutions like Stanford or Harvard file patents, you’ll end up with a patent thicket—and if you ever want to commercialize, you’ll have to license everything back.”

I thought, wow, that is incredible advice. So we went back, I spoke with my parents, and we decided to fund the first 10 years of patent prosecution ourselves as a family. And that’s the reason why we now have access to these early-stage stem cells without the same ethical concerns.

And not only that—we’ve already taken them into Good Manufacturing Practice (GMP) manufacturing, which I’ll talk about in a bit. They also have some very interesting biological characteristics, which I’ll go into as well. But that’s really the beginning of the story. That was 2005 to 2010, and we’ve been working on it ever since. I formed the company Accelerated Biosciences in 2013, and only in 2020—when the topic of allogeneic cell therapy became more prominent—did I start sharing this more publicly. So that's the origin story in a very, very long format.

David Brühlmann [00:09:16]:
What a fascinating story. And it's definitely a non-linear story—really great. Tell us, Yuta, a bit more about stem cells. You mentioned different stem cell types and different stages. Let's start very simple: what are the different types of stem cells, and what is important to watch out for?

Yuta Lee [00:09:37]:
I love that question because this is what most people want to know, right? So I usually explain stem cells in the context of fetal development.

First of all, let’s take it one step back—what is a stem cell? A stem cell is an undifferentiated cell from which all specialized cells originate. Every cell in our body ultimately came from a single original cell. You may already know that every cell in your body contains your DNA within the nucleus.

A stem cell is defined as a cell that can both self-renew—meaning it can generate another identical stem cell—and also differentiate into specialized cells. So it has multiple functional capacities and serves as the origin of all cell types.

Now, relative to where stem cells come from, I usually use a timeline of fetal development. The first eight weeks of our development is the embryonic period. That’s when the sperm and egg fuse, forming a zygote, which then divides and develops. After about eight weeks, development transitions into the fetal period, where organs continue to form and mature. And then, on average, birth occurs around the 38th week. Anything after that is considered adult.

Where do stem cells come from? The earliest stem cells are human embryonic stem cells, typically derived from embryos created via in vitro fertilization (IVF). In IVF, sperm and egg are combined in a dish to create embryos, which are then implanted into the mother. Often, multiple embryos are created, and unused ones may be stored.

In 1998, James Thomson at the University of Wisconsin published the first paper on human embryonic stem cells. He obtained consent to use a donated embryo for research. However, this led to significant ethical concerns, as many people believe embryos represent potential human life. This triggered regulatory restrictions on embryonic stem cell research in many countries. These cells are typically derived at around the blastocyst stage, about five days after fertilization.

Next are human trophoblast stem cells, which are associated with pre-placental trophoblast tissue. These arise during early development and contribute to the formation of the placenta. In our case, these cells are sourced between roughly 4 to 8 weeks post-fertilization—still within the embryonic period.

If you recall my earlier story, in ectopic pregnancies, the tissue is surgically removed. We isolate the trophoblast tissue and return the rest for pathological confirmation and disposal. This is why we describe them as early-stage cells obtained without the same ethical concerns.

After that, during the fetal period (8 to 38 weeks), cells could theoretically be sourced—but this would involve fetal tissue, typically from elective termination, which raises ethical and regulatory challenges, so it is rarely used.

At birth, around 38 weeks, additional biological materials become available: placenta, umbilical cord, cord blood, and amniotic fluid. These are rich in stem cells, particularly mesenchymal stromal cells (MSCs), which are more differentiated and have more limited potential compared to embryonic stem cells.

After birth, in adulthood, stem cells still exist throughout the body. For example, when you cut yourself, stem cells help regenerate tissue. These are adult stem cells, found in various tissues. However, they are harder to isolate. Common sources include adipose (fat) tissue and bone marrow. Bone marrow extraction, for example, requires an invasive procedure.

The last type I want to mention is induced pluripotent stem cells (iPSCs). For those familiar with longevity research, these are very important. They were first described by Shinya Yamanaka at Kyoto University in 2006.

What he showed was that by introducing specific transcription factors (often referred to as the Yamanaka factors) into an adult somatic cell—using methods such as viral vectors like Sendai virus—you can reprogram that cell back into a pluripotent stem cell state. He received the Nobel Prize in 2012 for this work.

This has major implications for longevity and healthspan. If you can reprogram an adult cell back to a more primitive, pluripotent state—essentially a “reset”—then, in theory, cellular aging could be reversed. That’s why many researchers see aging, at least partially, as a biological engineering problem. There are companies like Life Biosciences and Retro Biosciences exploring these reprogramming approaches.

So to recap:

• Human embryonic stem cells: earliest and pluripotent, but ethically controversial.
• Trophoblast stem cells: early-stage, placenta-associated.
• Fetal-derived cells: rarely used due to ethical concerns.
• Birth-associated cells: rich in MSCs.
• Adult stem cells: tissue-specific and harder to isolate.
• iPSCs: reprogrammed adult cells with pluripotent potential.

I hope that helps.

David Brühlmann [00:16:19]:
So that means that today, most of the stem cells that are being used clinically are from adult sources, right? That's the large majority today.

Yuta Lee [00:16:31]:
That's right. Most of the research is either using mesenchymal stromal cells (MSCs) or induced pluripotent stem cells (iPSCs). With iPSCs, you reset the cell back to a pluripotent stem cell state, and then you have to differentiate it forward into specific cell types—like neurons, kidney cells, or liver cells.

David Brühlmann [00:16:54]:
Tell us, Yuta, why you are focusing on much earlier cells. What are the advantages of these cells?

Yuta Lee [00:17:01]:
Right—based on that timeline I just mapped out, the general rule is that the earlier you find the cells, the more biologically active they tend to be.

For example, embryonic stem cells can proliferate indefinitely under the right conditions—they are often described as having unlimited self-renewal capacity. You can keep expanding them, although over time they may accumulate genetic changes.

Our cells are also very early, but they are not immortal. They are replicatively senescent, meaning that after a certain number of divisions, they stop proliferating. But because we derive them from such an early developmental stage, we can expand them to about 85 population doublings.

Now, let me explain that. A population doubling is when a cell divides and doubles—so 1 to 2, 2 to 4, 4 to 8, and so on, repeated multiple times. At around 85 doublings, you reach an extremely large number of cells. If you can imagine the number 8 and 25 zeros behind it, that's how many cells you can get from one.

David Brühlmann [00:18:06]:
That’s a lot of cells. So tell us how many that is.

Yuta Lee [00:18:12]:
It’s an enormous number. To give context, the human body has roughly 37 trillion cells. If you expand cells across that many doublings, in theory you could generate enough cells for trillions of individuals from a single donor. So from a manufacturing perspective, scale is effectively addressed. That’s one of the reasons to use earlier-stage cells.

However, even with early cells like embryonic stem cells, regulatory agencies such as the U.S. Food and Drug Administration are cautious. Beyond ethical concerns, there is concern about uncontrolled proliferation.

If you think about it, what other cells proliferate indefinitely? Cancer cells. So introducing cells with high proliferative capacity requires careful control during manufacturing and clinical use. Our cells don’t have that same concern—they undergo cellular senescence, meaning they will eventually stop dividing. But they still offer a high expansion potential, giving you both scalability and a built-in biological limit.

In contrast, MSCs derived at birth—such as from umbilical cord or placenta—typically achieve around 25 to 30 population doublings under standard conditions. That limits scalability.

Another issue is donor variability. If you go back to collect cells from a new donor, you are working with a different genetic background. From a regulatory perspective, that can require additional validation, because it is essentially a new biological starting material.

So this is where earlier-stage cells offer advantages in consistency and scale.

Now, another major advantage of pre-placental trophoblast-derived cells is related to immune interaction. These cells express HLA-G, which is a non-classical major histocompatibility complex molecule involved in immune modulation.

Let me explain it more simply. An embryo contains genetic material from both the mother and the father, so it is partially foreign to the mother’s immune system. Normally, the immune system would recognize and reject foreign tissue.

However, the placenta acts as an interface between the mother and the embryo, and molecules like HLA-G help suppress immune responses locally—essentially signaling immune tolerance.

This mechanism is what allows an embryo to implant and develop. It also enables situations like surrogacy, where a genetically unrelated woman can carry a pregnancy to term.

Because our cells originate from trophoblast-related tissue, they retain some of these immune-modulatory properties.

So if you combine these characteristics:

1. High expansion potential with natural replicative limits
2. Immune-modulatory properties

You get a strong foundation for scalable and potentially broadly applicable cell therapies.

David Brühlmann [00:21:53]:
And I think this also opens the way to allogeneic, off-the-shelf cell therapy treatments, correct?

Yuta Lee [00:22:00]:
That’s right. That’s exactly what we’re aiming for—allogeneic cell therapy. This is also why, even though I founded the company in 2013, I didn’t really talk about it publicly until around 2020. Before that, most of the industry focus—especially with things like CAR-T—was on autologous cell therapy, where you use the patient’s own cells. But now that allogeneic approaches are gaining traction, we have a more complete platform and are ready to share it more broadly. So if you're a researcher or a company thinking about developing an allogeneic therapy, we’d be happy to talk.

David Brühlmann [00:22:34]:
We’ve covered a lot of ground today—from the biology of trophoblast stem cells to the IP fundamentals that underpin Accelerated Bio’s platform.

In part two, we’ll go further into the science of aging itself and what a therapeutic approach to healthspan extension might look like in practice. If this episode added value, please leave a review on Apple Podcasts or your preferred platform. Thank you so much for tuning in—I’ll see you next time.

Disclaimer: This transcript was generated with the assistance of artificial intelligence. While efforts have been made to ensure accuracy, it may contain errors, omissions, or misinterpretations. The text has been lightly edited and optimized for readability and flow. Please do not rely on it as a verbatim record.

Next Step

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Thanks for tuning in to the Smart Biotech Scientist podcast and being part of this journey toward bioprocess mastery. For more insights and practical tips, visit www.smartbiotechscientist.com.

About Yuta Lee

Yuta Lee is the Founder and CEO of Accelerated Bio, a regenerative medicine company pioneering the use of human Trophoblast Stem Cells (hTSCs) to advance longevity and age-reversal therapies. For more than 20 years, he has focused on developing scalable, ethically sourced cell technologies designed to extend human healthspan and accelerate the future of allogeneic cell and gene therapies.

Under Yuta’s leadership, Accelerated Bio has built a robust intellectual property portfolio with 53 patents supporting commercialization pathways for partners and researchers worldwide. His work is driven by a belief that regenerative medicine should move beyond symptom management toward restoring youthful biological function and making cutting-edge longevity science more accessible to people globally.

Connect with Yuta Lee on LinkedIn.

Further Listening

If you’re interested in exploring further the concepts we touched on—such as cell therapy manufacturing, process control, and scaling living therapies—take a look at these related discussions:

Episodes 105 - 106: From Proteins to Cell Therapy: Why ATMPs Aren’t Just Complex Biologics with Oliver Kraemer

Episodes 147 - 148: Lab-Grown Blood: How Stem Cells Transform Transfusions with Ari Gargir

Episodes 179 - 180: How Mesenchymal Stromal Cells Are Transforming Care for Diabetes and Autoimmune Diseases with Lindsay Davies

Episodes 211 - 212: When the Innovator Becomes the Patient: Manufacturing Reality vs. Patient Urgency with Jesús Zurdo

He is also a biotech technology innovation coach, technology transfer leader, and host of the Smart Biotech Scientist podcast—the go-to podcast for biotech scientists who want to master biopharma CMC development and biomanufacturing.  

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