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Surgical Sciences

Transplant Research Group

  • Transplant Research Group
  • Transplant Research Group
  • Transplant Research Group

What we do:
Fundamental and translational research to learn how cells/tissues/organs maintain their unique and homeostatic gene expression signatures, and what we can do to return them to this state during degenerative or disease conditions.

How we do it:
We use genomic, proteomic, molecular genetics, cell biological, and biochemical approaches to learn about these systems, and have a particular interest in how regulation of RNA processing fits into the picture.

Active Projects:
  • Preventing and reversing liver (and other types of) fibrosis
  • Determining how RNA binding proteins (RBPs) influence early cell fate decisions
  • Testing how alternative splicing leads to changes in transcript abundance and localization
  • Exploring embryonic-, amniotic-, and adult stem cell-based regenerative medicine options


Sam Fagg, PhD, MS (Assistant Professor)

Sam Fagg PhD, MS

John L. Hearn Endowed University Chair of Transplant Surgery
Faculty Member of Graduate School of Biomedical Services, Human Pathophysiology and Translational Medicine (HPTM)
My true passion in research lies at the intersection of discovery and “the next step.” When we make one significant finding the immediately emerging question is “what is the next step?” This can be as challenging as making a discovery, but often is more important. I also thoroughly enjoy being engaged in training the next generation of scientists and physician-scientists, and so I like to discuss science with the folks in my lab and elsewhere. I am especially interested in how competition between RBPs and regulatory or substrate RNAs influences the overall gene expression process and as a result, cell fate. I also enjoy spending time with my family, surfing, fishing, and traveling.

I got my Bachelor of Science degree at Lees McRae College in Banner Elk NC, then my Master’s at East Carolina University with Mary Farwell, unofficial embryonic stem cell and molecular genetics training at Cedars Sinai Medical Center in Los Angeles CA with Seigo Hatada and Jeff Fair, and did my PhD and a brief postdoc with Manny Ares Jr at UC-Santa Cruz in Santa Cruz, CA.
Contact: wsfagg [at] utmb [dot] edu
PubMed papers
Google Scholar page

Mike Kueht, MD (Transplant Surgeon)

Mike Kueht, MD (Transplant Surgeon)
As an active transplant surgeon and scientist, my research revolves around important factors contributing to pre- and post-transplant outcomes. Our studies range from epidemiological-scale projects to ex-vivo studies of the human immune system. Importantly, with our collaborators, we have laid the groundwork for measuring phenomena within the transplant operation as a tool to help manage the post-transplant setting. We are focused on exploring the interplay between donor and recipient factors, organ preservation, operative kinetics, and immunosuppression and its effects on graft function and recipient health.

Karen Pereira Larissa de Castro, PhD (Postdoctoral Associate)

Karen Pereira Larissa de Castro, PhD (Postdoctoral Associate)
My research focuses on understanding the regulation of gene expression by studying post-transcriptional regulation by the RNA-binding protein Quaking. I received my Master's degree in Neuroscience from the Universidade Federal de Minas Gerais, Brazil, studying snake neurotoxins, under the supervision of Dr. Carlos Chavez Olortegui; and my PhD degree from the Biochemistry and Molecular Department from the University of Texas Medical Branch where I studied protein-protein interactions of the transcription factor AhR and its regulation of gene expression under the supervision of Dr. Cornelis Elferink. These interdisciplinary research experiences have contributed to my development as a scientist and sparked my interest in regulated gene expression. I am currently a Postdoctoral fellow in the laboratory of Dr. Fagg studying the molecular mechanisms of pre-mRNA alternative splicing by using molecular, cell biology, and biochemical approaches to uncover how the Quaking RBP regulates RNA processing.

Naiyou Liu, PhD (Project Scientist)

Naiyou Liu, PhD (Project Scientist)
Naiyou obtained his PhD from the Chinese Academy of Sciences in 2008. In his current role as Project Research Manager, he is interested in how RBPs and alternative splicing can influence stem cell biology including plasticity between cell fates/lineages. He also has interests in determining how specific RBPs function mechanistically and is working to understand how splicing can influence additional steps in the RNA processing cascade. Naiyou also supports other projects in the lab including those studying applied and fundamental regenerative medicine.

Chase Bowen, MS2

Chase Bowen, MS3
I am a third-year medical student at UTMB and a mentee of Dr. Sam Fagg in the Department of Surgery. In the Fagg Lab, we are interested in novel therapeutics that can be utilized in the clinic to broadly reduce inflammation in various diseases. For my project, we are specifically pursuing these in the context of reversing and repairing liver damage by suppressing fibrosis and promoting tissue regeneration. While durable treatments for liver disease remain a dire unmet clinical need, we have devoted a significant amount of energy in studying the use of amniotic fluid in hopes of developing a therapeutic to intercept or prevent chronic liver damage. I am currently working toward completing this project.

As an aspiring physician-scientist with interests in transplant surgery, I recognize the present need for training as a physician-scientist situated at the interface of basic-science research and clinical medicine. With my formal training under the guidance of Dr. Fagg, in my future career, I aspire to treat patients with complex maladies, expand the body of knowledge in the diseases that compel me, and educate our next generation of physicians and scientists.

 Erick Ditmars, MS2

Erick Ditmars, MS4
Following my training in Dr. Sclonzewski’s molecular evolutionary genetics lab at Kenyon College, I’ve worked to focus my passion for molecular biology and direct it toward issues of human health. Currently, my research interests focus on molecular pathways of disease, in particular the motifs of wound healing and sclerosis across tissue types. Moreover, I am interested in the usage of 3D tissue culture as a way to model human organ systems.

For the last four years, I’ve tried to combine these interests with Dr. Fagg and the rest of the transplant team. My current project focuses on using human multi-lineage hepatic spheroids to model liver fibrosis, and on amniotic fluid as an anti-inflammatory/anti-fibrotic therapy. As a future physician, I hope to continue doing translational research and improving care for patients with treatment-resistant conditions.

 Emmanuel Nyong, MD/ PhDEmmanuel Nyong, MD/ PhD
I'm currently a first-year Ph.D. student in the Human Pathophysiology and Translational Medicine program at the University of Texas Medical Branch (UTMB), where I'm part of Dr. Sam Fag's research group. My research focuses on understanding how posttranscriptional regulation of gene expression by RNA binding proteins (RBPs) influences early cell fate decisions. I aim to explore the role of the RBPs CELF2 and QKI in developmentally regulated splicing patterns using various molecular, cell biology, and biochemical approaches. Before embarking on my PhD journey at UTMB, I completed my undergraduate studies at the University of Texas at San Antonio, engaging in research under Dr. Mark Eppinger.

With a career vision as a physician-scientist, I am dedicated to forging a path that connects fundamental scientific research with its practical clinical applications.

 Brian Amburn, MD/ PhDBrian Amburn, MD/ PhD
"I have always been interested in the improvement of human medicine and the expansion of our reach. I’m a fourth-year MD-PhD student (second-year graduate student) at UTMB in Dr. Sam Fagg’s lab, currently studying how non-coding RNAs can interfere with RNA processing exacerbating disease states in the heart. Not only may this identify a new drug target for heart disease but may illuminate novel mechanisms through which non-coding RNAs disrupt RNA processing machinery.

As I grow in my training my goals develop and currently have landed on a long-time dream of mine. To medically treat and support people in the most extreme situations possible, particularly spaceflight. The training under Dr. Fagg will afford me the knowledge and skills necessary to perform research relevant to what happens in the extremes, in disease and space.

 Jose Abril, MS2Jose Abril, MS2
I am a second-year medical student with a deep interest in leveraging computational approaches to address complex biological challenges. My research is focused on developing and implementing computational solutions to understand and tackle various aspects of human health and disease. Currently, I am part of Dr. Sam Fagg's group, where I aim to contribute to the lab's projects through bioinformatic approaches, data pipelines, and dataset analyses.

Before joining UTMB, I completed my undergraduate studies in Biomedical Sciences at Sam Houston State University. Under the guidance of Dr. James Harper and Dr. Anne Gaillard, I gained a solid foundation in molecular biology and physiology. As an avid technology enthusiast, I am always excited to incorporate the latest technological advances into my medical training and research endeavors. I am grateful for the opportunity to blend my dual passions for biology and technology under Dr. Fagg's mentorship.

My ultimate goal is to become a physician who can seamlessly integrate the fast-paced technological advances into medical research and clinical practice. I aspire to instill in my two young children a love for medicine, research, and technology, nurturing a future generation that shares this enthusiasm.