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Principal Investigator

Marie Hollenhorst, MD, PhD

Dr. Hollenhorst is a physician and scientist with expertise in non-malignant hematology, transfusion medicine, and chemical biology. Dr. Hollenhorst values the one-on-one relationships that she forms with her patients, and strives to deliver the highest quality of care for individuals with blood diseases. Her experience caring for patients drives her to ask scientific questions in the laboratory, where she aims to bring a chemical approach to the study of non-malignant blood disease.

Dr. Hollenhorst pursued combined MD and PhD training at Harvard University, where she received a PhD in Chemical Biology under the mentorship of Professor Christopher T Walsh. She subsequently completed a residency in Internal Medicine at Brigham and Women’s Hospital, a fellowship in Transfusion Medicine at Harvard Medical School, and a fellowship in Hematology at Stanford.

Dr. Hollenhorst has an interest in the biology of platelets, which are cellular fragments that help the blood to maintain a healthy balance between bleeding and clotting. Working in the laboratory of Professor Carolyn Bertozzi of Stanford Chemistry, Dr. Hollenhorst is studying sugar molecules found on the surface of platelets that are important in controlling their function and lifespan.

Dr. Hollenhorst’s research is supported by an NIH K99 Career Pathway to Independence in Blood Science Award for Physician-Scientists, a Stanford Chemistry, Engineering & Medicine for Human Health Physician-Scientist Fellowship, and a National Blood Foundation Early-Career Scientific Research Grant.

Assistant Professor of Medicine, Harvard Medical School
Associate Physician, Brigham and Women’s Hospital, Department of Medicine, Division of Hematology
Faculty Affiliate, Dana Farber Cancer Institute
Associated Scientist, Broad Institute

Shaun Snyder

Shaun has been in academic research since 1987 and is involved in research management with an emphasis on efficient/effective workflow of laboratory leadership while advising, training, and facilitating tools and resources for the research and teaching members. Shaun is interested in translational biomedical research from bench to bedside, to benefit human health. Currently, Shaun is overseeing research laboratories within the Infectious Disease and Hematology divisions at BWH and HIM.

BS, Chemistry, University of Illinois, Urbana-Champaign

MA, Educational Leadership, Santa Clara University

MS, Mathematics, University of Illinois, Urbana-Champaign 

Joined March 2023


James grew up in the Boston area and completed his undergraduate at UMass Amherst with a degree in microbiology in 2023. As a pre-med with an interested in understanding disease pathology, he became a member of the Siegrist Lab in 2021. There, he conducted research on characterizing the response of the innate immune system to mycobacterial cell wall fragments through the usage of click chemistry and immunofluorescence. Due to an increasing interest in research, James joined the Hollenhorst Lab in 2023 with thoughts of pursuing a MSTP in the future. Outside of work, James enjoys playing the piano, swimming and going for very slow runs.

BS, Microbiology, University of Massachusetts Amherst

Joined September 2023

From New Bedford, MA, Kelsey (she/her) received her B.S. in Biology from the University of Massachusetts Amherst. During her time as an undergraduate, she conducted research in the Timme-Laragy Lab where she studied the effects of environmental toxicant exposure on pancreatic development and function. Interested in exploring a new area of research and set of skills, Kelsey joined the Hollenhorst Lab in 2024 excited to learn and with a desire to further her abilities as a researcher. In her free time, Kelsey enjoys reading, drinking coffee, hiking new trails, and going for long drives.

BS, Biology, University of Massachusetts Amherst

Joined June 2024

Born and raised in Miami, FL, Brett (they/he) is a junior at Harvard College on the premed track pursuing a double major in Human Developmental and Regenerative Biology and Psychology, along with a minor in Ethnicity, Migration, Rights. Before joining the Hollenhorst Lab in 2024, Brett spent their first two undergraduate summers with the Fortune Lab at HSPH and the Cardiovascular Biomechanics Computation Lab at Stanford CVI. Brett plans to write a senior honors thesis that combines his interests in biology and chemistry. Outside of academics, Brett enjoys biking, swimming, touring the city for new coffee shops, and fostering community for Latine/x students on campus through student leadership.

Joined February 2024.

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