Lesson Summary:

Tissue Engineering- The use of a combination of cells, engineering and materials methods, suitable biochemical and physicochemical factors to improve or replace biological tissues.

Types of Engineering:
- Generating whole tissue in-vitro and replacing damaged tissues in patients
- Generating part tissue in-vitro and replacing damaged portions of the tissues in patients
- Putting in scaffolds to regenerate damaged part of the tissue in-vivo
- Adding support/filler material to support the function of damaged tissue

Most widely used tissue replacement method of whole tissue replacement is decellularization of tissue from cadavers and animals.
Regenerating part of a tissue
This is more successful
Two approaches: - material + cells in-vitro followed by implantation - material implantation for scaffolding
The ultimate goal is to get the tissue back to its native state
Applications: 1) cartilage defects 2) vascular grafts 3) heart patch



Foreign Body Response
Proteins in the plasma can adsorb on the surface of an implant
These proteins can attract cells of the immune system like macrophages and monocytes
These cells launch an immune response that leads to bone resorption and ultimately loss of fixation
This response of the body to an implant is called foreign body response
Implant-Associated Infections:
Biofouling- The phenomenon of protein, cellular, and bacterial, attachment to material surfaces that leads to loss of device function, infection and implant failure

Biofilms- Microorganisms in colonies on the surface for layers which are composed of organism, cellular material, extracellular polysaccharides, environmental adsorbates and debris.
Road to infection:
Material Implant- tissue injury and inflammation, blood interaction, bacterial interaction during surgery
Race to the surface - proteins, bacteria, cells
Bacterial adherence to the material surface - all about cell adhesion
Bacterial colonization - aggregation of bacterial mass
Biofilm formation - formation of matrix layer, resistance to antibiotics
Device failure - infection, loss of function, device removal