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

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

Assistant Professor of Surgery
Division of General Surgery
Director, Chang Lab

Contact Information

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

Education

  • 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

Residencies

  • 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

Fellowships

  • 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

Board Certifications

  • American Board of Surgery

Program Affiliations

Clinical Expertise

  • Bariatric Surgery
  • General Surgery
  • Minimally Invasive Surgery

Research Interests

  • Liver Tissue Engineering

Biography

Dr. Tammy T. Chang is Assistant Professor of Surgery in the Division of General Surgery. 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 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.

She is currently on faculty as a member of the Surgical Hospitalist Program. She continues her laboratory investigations of 3D hepatocyte culture with long-term goals of tissue engineering a basic liver unit for therapeutic implantation.

Research Overview

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.

Dr. Chang's current research 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.

 

Publications

  1. Chang TT, Hughes-Fulford M. Molecular mechanisms underlying the enhanced functions of three-dimensional hepatocyte aggregates. Biomaterials. 2014 Feb; 35(7):2162-71. View in PubMed
  2. Chang TT, Walther I, Li CF, Boonyaratanakornkit J, Galleri G, Meloni MA, Pippia P, Cogoli A, Hughes-Fulford M. The Rel/NF-?B pathway and transcription of immediate early genes in T cell activation are inhibited by microgravity. J Leukoc Biol. 2012 Dec; 92(6):1133-45. View in PubMed
  3. Chang TT, Hughes-Fulford M. Monolayer and spheroid culture of human liver hepatocellular carcinoma cell line cells demonstrate distinct global gene expression patterns and functional phenotypes. Tissue Eng Part A. 2009 Mar; 15(3):559-67. View in PubMed
  4. Chang TT, Corvera CU. Caudate split for open and laparoscopic liver resections. J Am Coll Surg. 2008 Dec; 207(6):e7-9. View in PubMed
  5. Chang TT, Sawhney R, Monto A, Davoren JB, Kirkland JG, Stewart L, Corvera CU. Implementation of a multidisciplinary treatment team for hepatocellular cancer at a Veterans Affairs Medical Center improves survival. HPB (Oxford). 2008; 10(6):405-11. View in PubMed
  6. Chang TT, Schecter WP. Injury in the elderly and end-of-life decisions. Surg Clin North Am. 2007 Feb; 87(1):229-45, viii. View in PubMed
  7. Chang TT, Sobel RA, Wei T, Ransohoff RM, Kuchroo VK, Sharpe AH. Recovery from EAE is associated with decreased survival of encephalitogenic T cells in the CNS of B7-1/B7-2-deficient mice. Eur J Immunol. 2003 Jul; 33(7):2022-2032. View in PubMed
  8. Jabs C, Greve B, Chang TT, Sobel RA, Sharpe AH, Kuchroo VK. Genetic background determines the requirement for B7 costimulation in induction of autoimmunity. Eur J Immunol. 2002 Sep; 32(9):2687-97. View in PubMed
  9. Akbari O, Freeman GJ, Meyer EH, Greenfield EA, Chang TT, Sharpe AH, Berry G, DeKruyff RH, Umetsu DT. Antigen-specific regulatory T cells develop via the ICOS-ICOS-ligand pathway and inhibit allergen-induced airway hyperreactivity. Nat Med. 2002 Sep; 8(9):1024-32. View in PubMed
  10. Chang TT, Kuchroo VK, Sharpe AH. Role of the B7-CD28/CTLA-4 pathway in autoimmune disease. Curr Dir Autoimmun. 2002; 5:113-30. View in PubMed
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