Department of Restorative Dentistry and Biomaterials Houston Biomaterials Research Center 6516 M.D. Anderson Blvd., DBB 4.133 Houston, Texas 77030 (713)500-4083 (713)500-4372 FAX yunzhi.yang@uth.tmc.edu

Yunzhi Yang

Dr. Yang is an Assistant Professor for the Dental Branch Department of Restorative Dentistry and Biomaterials and the Houston Biomaterials Research Center. Dr. Yang is also an Adjunct Assistant Professor with the Department of Bioengineering at Rice University, and an Adjunct Assistant Professor with the School of Biomedical Engineering and Imaging at the University of Tennessee Health Science Center. He is also a Program Faculty Member of Department of Biomedical Engineering at the University of Texas at Austin and a GSBS faculty member at UTHSC-H.

Education

Professional Experience:

• Jan 2009 – Present Assistant Professor (Tenure track), Department of Restorative Dentistry and Biomaterials, University TexasHealth Science Center at Houston, Houston, TX
• October 2009 - Present Regular Faculty member, Graduate School of Biomedical Science, The University of Texas Health Science Center at Houston, Houston, TX
• August 2009 - Present Program Faculty member, Department of Biomedical Engineering, The University of Texas, Austin, TX
• Jan 2009 – Present Adjunct Assistant Professor, Department of Bioengineering, Rice University, Houston, TX
• Jan 2009 – Present Adjunct Assistant Professor, School of Biomedical Engineering and Imaging, University Tennessee, Memphis, TN
• June 2006-Dec 2008 Assistant Professor (Tenure track), Department of Biomedical Engineering and Imaging, University Tennessee, Memphis, TN
• Jan 2004-May 2006 Res. Assist. Professor, Department of Biomedical Engineering, University Tennessee, Memphis, TN
• Nov 1999-Oct 2001 Associate Professor, Beijing Fine Ceramic lab, Tsinghau University, Beijing, China
• 1991-1997 Research Assistant I, Sichuan University, Chengdu, China

Interests:

The research interest of our laboratory is designing and developing bio-inspired biomaterials for implant devices, tissue regeneration, and cancer treatment. Our research lies at the interfaces of fundamental material science, biology, clinical applications at the macro-, micro- and nano- scale level, where basic understanding of biology inspires the development of novel biomaterials for medical applications. We believe quality work depends on idea, passion and perseverance. The students and postdoc fellows who join our group will have opportunities to learn from and work with engineers, biologists and clinicians.

• Enabling technology for tissue engineering
  • Tissue engineering consists of three categories: scaffolds, cells and signals. In our lab, we developed different novel technologies to manipulate scaffolds, cells and signals to mimic the in vivo natural environment, to aid and induce tissue regeneration. More specifically, our research is integrating bottom-up with top-down approaches, achieving controlled signals that regulate tissue regeneration, and revascularizing tissue at larger scale, leading to a functional tissue regeneration with biomimetic complexity and enhanced functionality. In addition, we are interested in applying the developing biomaterials for specific diseases such as bony birth defects, large load-bearing defects, and cancer therapy.
  • A. Biomaterial design, fabrication and characterization

    In our lab, biomaterials are designed and fabricated on basis of the application. The chemical and physical properties of the developed biomaterials are characterized using all kinds of facilities. Figure 1 is an example of a three dimensional calcium phosphate scaffold.

    Figure 1 Representative Micro CT images of porous calcium phosphate scaffolds. Left figure is with 3-dimension reconstruction and right figure is with 2-dimension section. Figure 1 shows the interconnective macroporous structure which assembles the trabecular bone. The porous structure and chemistry of calcium phosphate scaffold are very critical to help bone tissue regeneration as a template.

  • B. Biological evaluation by in vitro cell culture and in vivo animal study

    Biological evaluation is very critical to biomaterial research and development. In our lab, we use in vitro cell culture to screen the formula and geometry of the developed biomaterial and then we use animal model to evaluate the biomaterial - tissue response in vivo. Figure 2 is an example of the osteoblast precursor cell responses to different composition of calcium phosphate scaffold. Figure 3 is an example of calcium phosphate scaffold as a carrier for growth factor delivery in vivo.

    

    Figure 2 Alkaline phosphatase specific activity of osteoblast precursor cells in calcium phosphate scaffolds. Alkaline phosphatase production is an indicator of osteoblast differentiation. Beta-tricalcium phosphate scaffolds significantly enhanced osteoblast differentiation compared to hydroxyapatite scaffolds during a 3-week incubation.

    
    
    
    
    
    
    

    Figure 3 Histology of bone formation with rhBMP-2 loaded β-tricalcium phosphate scaffold in implanted muscle of mice at 14 days after implantation. The specimen is stained with HE stain (original magnification X 25). WB = woven bone, MA = bone marrow, M = muscle. At 14 days after implantation, woven bone and immature marrow was observed in the rhBMP-2 loaded beta-tricalcium phosphate scaffold.

    
    
    
    
    
    
    
• Surface nanotechnology for implant devices
  • Surface engineering

    Surface engineering focuses on implant surface chemistry, texture and mechanical properties to improve performance of dental and orthopedic implant devices. In clinical, osseointegration, which is defined as the direct bone-implant contact, is critical for initial fixation and long-term success of endosseous dental and orthopedic implants. The initial host response after implantation is similar to a common bone wound modified by the presence of the implant. The new bone formation in the gap between the implant surface and host bone consists of three categories: osteogenesis at the implant surface (contact osteogenesis), within the surgical microgap at sites of neovasculization, and the surgical host bone margin (distance osteogenesis). As such, surface features that may influence any or all of these rates of bone formation will have the potential to enhance osseointegration. In our lab, the implant surface chemistry, texture and mechanical properties have been modified via plasma spraying, sputtering, ion implantation and chemical treatment. The chemistry include titanium, hydroxyapatite, zirconia, titania, and biomolecule and growth factor. The enhancement of osseointegraion has been evidenced by in vitro cell culture and in vivo animal study. We give some examples in the implant surface modification, characterization, and biological evaluation in the following.

    		Figure 4 Scanning electron micrographs of plasma sprayed hydroxyapatite coating (a) and plasma sprayed titanium coating (b). The plasma sprayed coatings roughen the surface texture which helps with osseointegration.
    Nano Grains	Nano Pores	Nano Rods
    Figure 5 Scanning electron micrographs of nanoscale implant surfaces. Using different techniques, we can fabricate different nanoscale morphologies. For example, we can use vapor based deposition to make dense surface with different nanosize grains. We can use solution based deposition to produce porous surfaces with different nanosize pores. Also, we can use solid based deposition to prepare nano rods with different nanosize diameters. The amazing thing is the different nano patterns have different effects on cell responses, which may allow us to manipulate the cell response as we expect.

    

    Figure 6 Osteoblast cells adhere, migrate and grow into the plasma sprayed titanium porous coating, suggesting excellent biocompatibility of the implant surface.
    
    
    
    
    
    
    
    
    

    

    Figure 7 Osseointegration of new bone-titanium interface with fluorescent microscopy (original X100). Yellow indicates new bone; black indicates titanium. The plasma sprayed functionally porous graded titanium coated samples were placed into dog femur. At 8 weeks after implantation, the new bone not only directly contacted with the implant, but also grew into the interconnective pores and formed mechanical interlocking, thereby enhancing the fixation of implants with bone.
    

    
    
    
    
    
    

    Figure 8 Osseointegration of new bone-titanium interface by scanning electron microscopy (original X 500). Yellow arrows indicate holes within coating; white arrows indicate line analysis. The plasma sprayed functionally porous graded titanium coated samples were placed into dog femur. At 8 weeks after implantation, a lot of pores were observed within the porous coatings and these pores were rich in calcium and phosphorus elements with the Ca/P ratio of 1.14 to 1.88, indicating that the new bone does grow into the pores and form mechanical interlocking, which helps with the implant fixation.

    
    
    
    
    
    
    
    
    
    
    
    
• Naturally based novel biomaterials for cancer treatment
  • We are interested in developing naturally based novel biomaterials for improving efficacy of cancer treatment and reducing side effects. Glioblastoma is the most common malignant tumor of the nervous system in adult humans. The survival rates of the patients have not changed in the past 30 years because high grade gliomas mostly recur locally. Therefore, local therapies combined with surgical intervention are an ideal approach to improve the efficacy of treatments. These methods administer drugs directly into the brain, bypass the blood brain barrier (BBB), and deliver the drugs in a concentration-dependent manner. Some clinical studies have demonstrated that local chemotherapy delivered by polymer carrier significantly prolongs the survival time of patients. Currently we are developing a novel local chemotherapy using a naturally based ellagic acid - chitosan composite that are safe and highly efficacious to optimize the treatment of glioblastoma.

    Figure 9 Fluorescence images of nude mice with GFP (green fluorescent protein) tagged rat C6 glioma in each right flank on the 5th and 21st days after tumor inoculation. The chitosan-ellagic acid composite significantly inhibit the tumor growth in a mice flank model. (A) untreated tumor-bearing group; (B) chitosan carrier control group; (C) Ch-ellagic acid experimental group. The arrows indicate the tumors.

Inventions and patents:

• Y. Yang, Y Liu. Method for increasing the strength and controlling composition and architecture of ceramic articles.
• Y. Yang, Y Liu. Method for making ceramic articles, including ceramic scaffolds for bone repair.

Scholarship And Research

Selected peer-reviewed journal publications
(total 56 publications and > 100 abstracts):

Lab Members - 2009

Principal Investigator
	Yunzhi "Peter" Yang, Ph.D. Assistant Professor Department of Restorative Dentistry and Biomaterials Yunzhi.yang@uth.tmc.edu Tel: 713-500 4083 Fax: 713 500 4372
Post-doctoral Fellows
	Joong-Hyun Kim, Ph.D. Post-doctoral Fellow Joong-hyun.kim@uth.tmc.edu Tel: 713-500 4083
	Yunqing Kang, Ph.D. yunqingkang@hotmail.com Tel: 713-500 4083
Graduate Students
	Sungwoo Kim School of Biomedical Engineering and Imaging College of Medicine University of Tennessee Health Science Center, Memphis, TN skim45@utmem.edu Tel: 713-500 4083
	Daniel Young School of Biomedical Engineering and Imaging College of Medicine University of Tennessee Health Science Center, Memphis, TN danielyoung@gmail.com Tel: 713-500 4083
Dental Students
	Brian Case University of Texas Dental Branch at Houston brcase800@gmail.com
	Joi Stallworth College of Dentistry University of Tennessee Health Science Center, Memphis, TN jstallwo@utmem.edu
	Whittaker Moss College of Dentistry University of Tennessee Health Science Center, Memphis, TN wmoss@utmem.edu
Undergraduate Students
	Barrett Steinberg BME Program Boston University barretts@bu.edu

News

• Congratulations to Dr. Sungwoo Kim. Dr. Kim successfully defended his Ph.D. dissertation on Nov 18, 2009. He will receive his Ph.D. in Biomedical Engineering from the Joint Graduate Program of the University of Tennessee and University of Memphis.
• Dr. Yang received a Young Investigator Award in the University of Texas Health Science Center at Houston on October 20, 2009 (http://www.db.uth.tmc.edu/webnews/default.htm#Award).
• Dr. Yang received a Wallace H. Coulter Foundation Early Career Award Phase II in August 2009. His clinical collaborator is Dr. Milan Sen, assistant Professor with the Department of Orthopedic Surgery.
• Welcome, Dr. Yunqing Kang. He will be joining my lab as a postdoctoral fellow in August 2009.
• Congratulations to Ms. Joi Stallworth! She won the Dentsply Award for Best Student Clinician at Dental Research Day. She will be representing her school and presenting her research at the American Dental Association meeting in Hawaii in 2009 and receiving a plaque at the Board of Trustees meeting of the University of Tennessee.
• Congratulations to Mr. Benjamin Reves! He received the Student Award for Outstanding Research in the Masters Degree category from the Society For Biomaterials in April 2009.