ch.1 lec 3

• Biomaterials


  Developed to evaluate, treat, augment or replace human tissue, organ, or function
• Biocompatibility


  The main essential for the safe use of biomaterials as medical devices
• Biocompatibility evaluation


  1. In vitro tests

  2. In vivo tests (animal experiments)

  3. Clinical tests
• In vitro biocompatibility tests


  • Less expensive
  • Simulate biological reactions to materials
  • Performed in a test tube, cell-culture dish, or otherwise outside of a living organism
• Cell culture


  Process by which cells are grown under controlled conditions, usually outside their natural environment
• Types of cell cultures

  • Primary cells
  • Secondary cells
  • Cell lines
• Advantages of in vitro biocompatibility tests


  • Good experimental controllable
  • Repeatable
  • Fast
  • Inexpensive
  • More producible
  • Simpler
  • Avoid ethical and legal issues surrounding animal and human testing
• Disadvantages of in vitro biocompatibility tests

  • Uncertain clinical use (lack of relevance to clinical use)
• In vivo biocompatibility tests (animal experiments)

  • Necessary prior to human clinical testing
  • Determine biocompatibility or safety in a biological environment
  • Evaluate materials over long time durations and in different tissue qualities and ages
• Advantages of in vivo biocompatibility tests

  • Higher level of significance
  • Simulate real body conditions
  • Biological responses may be more relevant than in vitro tests
  • Less expensive than human clinical trials
  • Ability to test at many stages of life
• Disadvantages of in vivo biocompatibility tests

  • Expensive
  • Time consuming
  • Ethical/legal issues
  • Relevance to use of material questionable
  • Difficult to interpret, quantify and control
  • Material can be quite unclear, especially in estimating the suitability of an animal species to represent a human
  • Reading of response is complex
• Irritation and sensitization tests

  1. Determine if chemicals or compounds released from biomaterials cause sensitization reactions

  2. Skin irritation (skin-patch) test

  3. Ocular (eye) irritation test

  4. Mucosal irritation test
• Implantation tests


  1. Evaluate materials that will contact subcutaneous tissue or bone

  2. Short-term implantation (1-11 weeks)

  3. Long-term implantation (1-2 years)
• Clinical biocompatibility tests


  • Final step of the evaluation process
  • Material is placed into human volunteers for its final intended use
  • Biocompatibility data from clinical studies is of special interest for clinicians
• Advantages of clinical biocompatibility tests

  • Relevance to use of material is assured
• Disadvantages of clinical biocompatibility tests

  • Very expensive
  • Very time consuming
  • Major ethical/legal issues
  • Difficult to interpret, quantify and control