Basics

Basics
Some tissues can regenerate themselves like skin, while some cannot like the heart. Most tissues cannot regenerate when injured or diseased, but even tissues that can regenerate, cannot always do so effectively. Regeneration can take a long time, or form scar tissue in the process of healing. As such, the body needs help from an outside source to aid in the healing process.

Autograft

 * Tissue harvested from one location of the patient's body and transplanted into another part of the body
 * Common practice that creates a new wound area, which makes it difficult to get enough material
 * In bypass surgeries, the saphenous vein is harvested for transplant, however, multiple surgeries are sometimes needed, so more vasculature is needed to be sacrificed

Allograft

 * Tissue or organ harvested from a donor and then transplanted into the patient

Xenograft

 * Tissue or organs harvested from an animal for transplantation into a human recipient

Synthetic Grafts

 * Replacement of tissue with implants to replicate, augment, and extend functions performed by biological systems

Tissue Engineering Elements

 * 1) Scaffold
 * 2) * Inorganic Materials
 * 3) ** Ceramics and Bioglass
 * 4) ** Primarily used in bone tissue engineering
 * 5) * Synthetic Polymers
 * 6) ** Can customize the mechanical properties and biodegradability
 * 7) ** Primarily used in soft tissue regeneration and drug release
 * 8) * Natural Polymers
 * 9) ** Naturally occurring polymers proteins that comprise the native extracellular matrix like chitosan and collagen
 * 10) Cells
 * 11) * Specialized Cells
 * 12) ** Differentiated cells of the same type as the tissue
 * 13) ** Ex. smooth muscle cells from smooth muscle
 * 14) * Cell Types
 * 15) Regulators
 * 16) * Growth Factors
 * 17) * Bioreactor
 * 18) * Mechanical Loading

Roles of Scaffolds in Tissue Engineering

 * 1) Serve as a matrix for cell adhesion to facilitate or regulate cell processes such as growth and migration
 * 2) Maintain the shape of the defect and prevent distortion of surrounding tissue
 * 3) Serve as a barrier to the surrounding tissue that may impede the process of regeneration
 * 4) Serve as a delivery vehicle for cells, growth factors, and genes
 * 5) Facilitate cell-matrix interactions that are involved with tissue regeneration by providing the appropriate sites for cell interaction