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Department of Surgery »  Faculty »  General Surgery »  Tammy T. Chang, M.D., Ph.D.
Tammy T. Chang, M.D., Ph.D.

Tammy T. Chang, M.D., Ph.D.

Associate Professor of Surgery
Division of General Surgery

Contact Information

University of California, San Francisco
521 Parnassus Ave., C341
San Francisco, CA 94143-0790
Tel: (415) 476-0762
Fax: (415) 476-8694

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  • 1990-1992, California State University, Los Angeles, Early Entrance Program
  • 1992-1994, University of California, Los Angeles, Bachelor of Science, Biology
  • 1994-2003, Harvard Medical School and Harvard Graduate School of Arts and Sciences, M.D., Ph.D. Combined Degree
  • 2003-2004 University of California, San Francisco, Surgery, Intern
  • 2004-2009 University of California, San Francisco, Surgery, Resident
  • 2009-2010 University of California, San Francisco, Surgery, Chief Resident
  • 2006-2008 University of California, San Francisco and Veterans Affairs Medical Center, San Francisco, Liver Tissue Engineering, American College of Surgeons Research Scholarship, Research Fellow
  • 2010-2011  University of California, San Francisco, Minimally Invasive Surgery and Bariatric Surgery, Clinical Fellow
  • American Board of Surgery
  • Complex Abdominal Surgery
  • Enterocutaneous Fistula
  • Gastrointestinal Cancer
  • Hernia Repair
  • Intra-abdominal Sepsis
  • Laparoscopic Inguinal Hernia Repair
  • Pancreas Surgery
  • Recurrent Hernia
  • Soft Tissue Infections
  • Liver Tissue Engineering

Tammy T. Chang, M.D., Ph.D. is a gastrointestinal and acute care surgeon in the Division of General Surgery.

Her clinical training includes internship, residency, and chief residency in Surgery at the University of California, San Francisco.  In addition, she has completed a clinical fellowship in Minimally Invasive Surgery and Bariatric Surgery at the same institution.  Her research experience includes a post-doctoral fellowship investigating three-dimensional (3D) organization of hepatocytes in rotational bioreactors funded by the American College of Surgeons Research Scholarship.

Her background demonstrates her strong commitment to facilitate transfer of advances in laboratory research into clinical applications that benefit patients. Dr. Chang holds an M.D., Ph.D. combined degree from Harvard Medical School through the Medical Scientist Training Program. Her Ph.D. degree is in the field of immunology with specific focus on immunoregulation in autoimmune disease.

Her research includes the study of 3D hepatocyte culture with long-term goals of tissue engineering a basic liver unit for therapeutic implantation.

Liver transplantation is currently the only treatment for patients with end-stage liver disease (ESLD), which is the 12th leading cause of death by disease in the U.S.  The shortage of donor organs remains a major treatment limitation.  Alternatives such as hepatocyte transplantation have shown promise in treating metabolic liver disorders, but low engraftment efficiency and poor long-term efficacy are barriers to broader clinical application.

Another strategy that holds great promise is ex vivo tissue engineering of a functional liver unit that can be implanted and then induced to further expand by host factors after incorporation.  Progress towards building three-dimensional (3D) tissue structure with biocompatible scaffolds has been hindered because these materials prevent normal cell-cell and cell-to-extracellular matrix (ECM) interactions.

The slow scaffold degradation rates also prevent remodeling and vascularization of the implant by the local host milieu. Moreover, it is increasingly clear that the surrounding environment is critically important for the durable function of hepatocytes. In particular, evidence shows that three factors independently improve and prolong primary hepatocyte differentiated functions ex vivo: 1) contact with ECM, 2) interaction with stromal cells (fibroblasts and endothelium), and 3) 3D cell-cell contact.

Dr. Chang's previous work showed that hepatocytes cultured in solid-body rotational bioreactors, which provide minimal shear stress with maximal 3D spatial freedom, produced self-aggregated spheroids with optimal metabolic and synthetic gene expression and function as compared to those cultured in two-dimensional (2D) monolayers.

Research in the The Chang Laboratory for Liver Tissue Engineering builds upon those observations and aims to generate "micro-liver-tissues" with endogenous ECM scaffolds and built-in microvascular networks through co-culture of hepatocytes with stromal cells within solid-body rotational bioreactors. Findings from this research are expected advance the field of tissue engineering by increasing our understanding of hepatocyte cellular response to matrix composition and heterotypic 3D cell contact. It will form the basis for the long-term goal of creating ex vivo engineered liver tissue for therapeutic implantation in patients with ESLD.

From a total of 27 publications
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