When Mackenzie Harrigan began her PhD at Harvard, she knew she loved science. What she didn’t yet know was how deeply she would come to value shaping how others learn it.
Now a fourth-year MCO PhD student in the lab of Ya-Chi Hsu in the Department of Stem Cell and Regenerative Biology, Harrigan studies skin regeneration and reproductive biology. At the same time, she serves as MCB’s Bok Fellow through the Derek Bok Center for Teaching and Learning—mentoring teaching fellows, coaching graduate student presenters, leading workshops on scientific illustration and communication, and helping faculty navigate the evolving role of AI in the classroom.
For Harrigan, the two worlds—research and teaching—are not separate spheres. “Teaching science is a way for me to share my passion for science,” she says. “It’s not completely separate from research. I really like how you can try to marry experiences in the classroom with bench science.”
Supporting the Teachers of LS1A and LS1B
Harrigan began her Bok Fellowship in August 2025. One of her central roles has been conducting teaching consultations for graduate student teaching fellows (TFs) in LS1A and LS1B, Harvard’s large introductory biology courses.
In the fall alone, she and another fellow conducted more than 20 consultations. The process involves recording TFs during section, reviewing the footage independently, and then meeting one-on-one to provide feedback grounded in Bok Center training and evidence-based teaching practices.
While some TFs approach the experience nervously—few people enjoy watching themselves on video—Harrigan sees the consultations as an opportunity to affirm strengths as much as to refine technique.
“I think the best part is being able to affirm what people are already doing well,” she says. “A lot of people come in feeling nervous about how their section went. Watching yourself on video is inherently awkward. It’s really rewarding to validate what’s working.”
Rather than focusing solely on areas for improvement, she highlights effective moments: a clear explanation, a well-designed activity, a stretch of genuine student engagement. “Even if the whole section wasn’t very strong, when you see a slice of the lesson that was working really well, you can encourage them to build on that,” she explains.
Coaching the Next Generation of Presenters
Harrigan also plays a central role in supporting the MCB graduate journal club, particularly first-year (G1) students. In a distinctive format revived this year, students present a paper of their choosing—but without digital slides. Instead, they use hand-drawn illustrations and an overhead camera.
The format pushes students beyond polished PowerPoints and into the fundamentals of visual thinking and scientific storytelling.
“Most of them are pretty comfortable with PowerPoint,” Harrigan says. “But taking complicated scientific data and communicating it more simply—especially with hand-drawn illustrations—is really challenging, but a really useful exercise.”
She meets with students in advance—sometimes multiple times—to coach them through distilling dense data into clear visuals and narrative structure. The one-on-one mentoring has become one of her favorite aspects of the fellowship.
“That sort of one-on-one coaching is really rewarding,” she says, particularly because it helps students develop skills they may not otherwise practice in graduate school.
Designing Visual Science
Beyond consultations and coaching, Harrigan has led hands-on workshops for MCB courses. In one session for MCB 197, she helped students design graphical abstracts and scientific posters. The workshop broke down principles of visual hierarchy, layout, and clarity, and introduced students to tools ranging from Canva to Adobe Illustrator.
“I love Illustrator—I use it for all my figures and posters in grad school,” she says. “But it has a steep learning curve. We wanted to equip students with tools that would set them up for success.”
She has also helped facilitate science communication workshops in multiple courses, including assignments in which students create explainer videos for general audiences. These sessions often intersect with broader pedagogical questions, including how instructors should approach artificial intelligence in the classroom.
Navigating AI in Education
One unexpected dimension of the fellowship has been grappling with the rapid rise of AI tools in undergraduate education.
“The surprising thing is how AI has come to affect the undergraduate education space,” Harrigan says. Some instructors are designing “AI-resilient” assignments; others are experimenting with thoughtfully incorporating AI into coursework.
In one course, students were permitted to use AI tools while creating science explainer videos. Afterward, many reported using AI to simplify jargon-heavy scientific language. While understandable, Harrigan reflects that the experience raised important pedagogical questions.
“For me, that was kind of the point of the assignment—learning to do that yourself,” she says. Still, she sees value in engaging with the reality of AI rather than ignoring it. “I think it can work well both ways,” she notes, depending on how instructors frame its use.
Science at the Bench
In Hsu’s lab, Harrigan investigates how sex hormones influence skin structure and regeneration. Her work, alongside Rebecca Freeman, another graduate student in the lab, has shown that the rise of androgens during puberty thickens the dermis and alters collagen composition, leading to functional differences in hair growth and wound healing between male and female mice.
More recently, she pivoted to a serendipitous discovery: a drug that delays puberty in mice for an extended period. Remarkably, mice whose puberty was suppressed retained healthier ovarian follicles later in life and exhibited improved fertility relative to age-matched controls.
“They weren’t completely as good as a prime breeding-age mouse,” Harrigan says, “but it sort of postponed their aging by about six months.” The team is now investigating the mechanisms behind follicle preservation and whether the biology might inform future studies of human reproductive health.
Hsu notes that Harrigan’s strengths in the classroom mirror her approach to research. “Mackenzie has a rare gift for explaining complex ideas with clarity, making difficult concepts interesting and accessible,” she says. “She is courageous and creative in her scientific work, pushing into new areas our lab hasn’t explored before. She is also a generous collaborator, always offering thoughtful input or practical help, whether for someone’s project or for the everyday needs of the lab. It is truly a pleasure to have her with us.”
A Midwestern Heart in a Boston Hub
A proud Minnesotan, Harrigan came to New England after working as a research assistant at Boston Children’s Hospital. She describes arriving in Boston as “a little starstruck,” immersed in what she calls an extraordinary density of scientific institutions.
Yet her long-term goal is clear: to become a professor at a small liberal arts college or primarily undergraduate institution, where teaching and mentoring take center stage.
“I always knew I liked teaching,” she says, recalling early jobs as a tennis coach and YMCA science instructor. “For me, it’s about sharing excitement—and helping students learn how to think critically.”
