Tissue Engineering Higby - Lecture 1

• Any interdisciplinary field that applies the principles of engineering and life sciences for the development of therapeutic strategies aimed at the:
• Replacement
• Repair
• Maintenance
• Enhancement of tissue function for clinical use

Other uses include drug testing and toxicity. In vitro models and test systems are also important for future human uses.

From a cell to a tissue, to a organ, to a system.

"Form follows function" refers to the observations that systems are shaped in a manner to maximize their function.

For instance, the aveoli sacs within the lungs require high surface areas to keep the efficiency of the Oxygen/Cabon dioxide exchange as high as possible.

• Cell based therapeutics (drug delivery)
• In vitro tissue systems (toxicity/pharmacokinetics or disease mechanisms)
• Gene delivery systems
• Organ replacement
• Functional organ support
• Improved healing
• Tissue regeneration
• Limb re-growth
• Replace of missing parts and functionality

• Cells - building blocks
• Extracellular matrix - holds cells together (structure that may use scaffolds)
• Organization - architecture

Developmental biology's approach towards the replacement of damaged tissues involves the use of stem cells to repopulate damaged tissue or transplant of cells from a donor to a recipient.

• Stem cells to repopulate damaged tissue
• ECM to attract marrow stem cells
• Prepare an artificial matrix that contains
• differentiation factors
• stem cells
• directions for the architecture

The stem cells would expand in vivo to take on normal structure and function as directed by the local environment.

• It follows that stem cells and mature cells are harvested
• expanded in vitro (compared to in vivo)
• seeded on the scaffold
• forms the mature construct
• vascularize construct
• implant in paptient
• control immunogenicity
• return to function

The pancreas consists of several components including the signaling of tissues to absorb glucose from the blood stream and the release of glucose from the tissues.

It includes Beta cells and Alpha cells.

The scaffold would have to be constructed from a biocompatible material with the proper signaling proteins and chemicals, such as ligands and fibronectin.

• Leaky valves
• Increased cardiac demand
• Cardiac hypertrophy
• Hypertension
• Fibrotic valves
• Inconsistent with life

• Autologous cells - From same organism
• Allogeneic cells - From others of the same species
• Xenogeneic cells - From another species

Multipotent stem cells or stem cells that give rise to a limited number of lineages.

These cells can differentiate into a variety of cells including osteoblasts (bone cells), chrondocytes (cartilage), adipocytes (fat cells).

Multipotent stem cells or stem cells that give rise to a limited number of lineages.

These cells can differentiate into all the different types of blood cells.

Multipotent stem cells or stem cells that give rise to a limited number of lineages.

Undifferentiated cells, found throughout the body after embryonic development, that multiply by cell division to replenish dying cells and regenerate damaged tissues.

• Pluripotent stem cells or stem cells that have the potential to differentiate into any of the three germ layers:
• endoderm, mesoderm, ectoderm

These cells are found in the inner cell mass of the blastocyst of the embryo.

• Totipoent stem cells -
• Multipotent stem cells -
• Pluripotent stem cells -

All stem cells - regardless of their source - have three general properties:

• They are capable of dividing and renewing themselves for long periods
• They are unspecialized
• They can give rise to specialized cell types

Primary role: Provide a temporary substrate to which transplanted cells can adhere for cell adhesion, proliferation, differentiation and migration while allowing for cell communication.

Most synthetic polymer scaffolds do not possess the specific signals (ligands) that can be recognized by cell-surface receptors. It is preferable that the polymer chain have chemically modified functional groups or the ligand may be immobilized on the scaffold surface.

Most organ cell types are anchorage-dependent and require the presence of a suitable substrate in order to survive and retain their ability to proliferate, migrate, and differentiate.

There are several variations that are possible that are all interconnected:

• Material variations (material selection)
• Structural variations (mechanical properties and requirements such as porosity, pore size, and pore structure to create a scaffold with similar mechanical properties to the tissue or organ)
• Fabrication variation (various methods are available for the fabrication of tissue scaffolds)

An open, semi-open, semi-closed, or closed environment that promotes the survival of a limited and specified population of cells that may be outside of their usual environment, location, or physiology.

The bioreaction perofrms a metabolic task, facilitates a particular synthesis, and/or promotes (normal of some kind of) growth, differentiation, and function with dramatic reduction in the number of variables affecting the process.

• Unidifferentiated cells
• Differentiation cues
• Defined cell types
• Into recipient - takes function, no immune compromise, no cancer

A mass of undifferentiated cells that will re-develop lost organ or tissue.

True.

• Proper handling of animals and drug administration techniques
• Anesthetizing and ventilating animals
• Surgical procedures on small and large animals
• Post-operative pain control
• Use of imaging techniques with experimental animals

• Refine
• Reduce
• Replace