Guillermo’s journey into biotech entrepreneurship started a world away—literally. “I was born in Mexico City and received a scholarship from the Mexican government to pursue my PhD in the UK,” he explains. “They covered tuition and living expenses, and I enrolled at the University of York to study prostate cancer and molecular biology.”
After earning his doctorate, Guillermo moved to the U.S. for a postdoctoral fellowship at Yale University with Dr. Valerie Horsley, whose lab focused on skin biology. He stayed there for about six years. “I became really interested in stem cells within tissues, and was looking for someone who shared this focus.”
That search led him to a talk by Dr. Samantha Morris, a rising star in single-cell and lineage tracing tools. “She gave this talk—I still remember it—and later she joined Washington University in St. Louis. I reached out with a project idea, and she invited me to present. We had great synergy, and I joined her lab.”
But something was still missing. “I wanted more than the next research paper,” he reflects. He wanted to see his science make a tangible difference in people’s lives.
Guillermo still remembers the moment a mentor slipped a crisp white business card across a lab bench and said, “You belong on both sides of this.” Until then, Guillermo’s world had been beakers and bench notebooks. Finance decks and market sizing felt galaxies away from the work he was doing in the lab. Yet that single gesture planted a seed—one that grew into a realization: he wanted something more.
That desire eventually led him to BioSTL and BioGenerator’s Venture Fellows Program, a transformative experience that helped him grow from scientist to startup founder while building a life for his young family in St. Louis.
The fellowship bridges the gap between science and business, providing scientists like Guillermo with real-world skills in company formation, capitalization, and investor engagement. “It’s intense, but that’s how you learn,” he says.
“I had no business background when I started,” Guillermo admits. “Suddenly, I was talking about investor decks, due diligence, and term sheets.” Each week felt like a new adventure. Monday might bring a deep-dive on term sheets with a seasoned venture capitalist; Tuesday could whisk the fellows to a St. Louis startup where a founder recounted the white-knuckle night, she nearly missed payroll. Guillermo cherished those site visits most. For Guillermo, the Venture Fellows Program isn’t merely an education—it was an invitation to belong in every room where science meets possibility.
At home, Guillermo’s evenings were a different balancing act. He and his wife, Nallely, a pre-k teacher by day, tag-teamed family responsibilities of raising two young children, Mateo, 9, and Leonora, 4. The fellowship’s built-in flexibility was a saving grace: webinars were recorded, mentors were willing to meet after 8 p.m., and no one blinked when a toddler toddled across a Zoom screen. “If we can’t make room for real life,” the program coordinator often said, “we aren’t training real leaders.”
The program has given Guillermo the opportunity to actively help build a company—Capybio—based on technology he helped develop. From pitching funders to understanding the business regulatory landscape, he’s experiencing the full range of entrepreneurial demands. “It’s a crash course in running a startup,” he says. “You learn by doing, by failing, and by trying again the next day.”
“St. Louis has the research and the funding—but it still lacks experienced startup leaders in the life sciences,” Guillermo says. The fellowship addresses this gap by developing leadership-ready talent. “I want to help fill that gap,” he says. “And I want to see more scientists step up and realize they can lead, too.”
Guillermo sees promise in St. Louis’ evolving innovation ecosystem. “Compared to other Midwestern cities, St. Louis is getting close to a critical mass in biotech,” he says. With strong research institutions like Washington University and dedicated early-stage support from BioGenerator, the ingredients are coming together. What the region needs now, he adds, is more operators who can translate scientific breakthroughs into thriving companies—exactly the kind of leadership the fellowship aims to cultivate.
From the lab to the startup trenches, from Mexico City to St. Louis via England, Guillermo is living proof of what happens when promising science meets practical training—and when a city invests in the people behind the next big idea.
