Tissue engineering involves the use of living cells to develop biological substitutes for tissue replacements

TISSUE ENGINEERING

Introduction

Chemical Engineering and Tissue Engineering

Current Research and Future Advancements

Introduction

Tissue engineering involves the use of living cells to develop biological substitutes for tissue replacements. These can be utilized as opposed to the traditional synthetic implants. Loss of human tissue or organ is a devastating problem for a patient and family. Half of the annual health care cost in the United States is related to tissue or organ loss. Therefore, the goal is to design and grow new tissue outside the body that could then be transplanted into the body. Transplanting body parts has been medically used for quite some time, i.e., kidney transplants, but tissue engineering involves growing a tissue and than aiding in transplant. Using this technology, it will one day be possible to regenerate or replace damaged tissues with laboratory-grown parts such as bone, cartilage, blood vessels, and skin.

The tissue engineering field is barely a decade old. Thus far in its development there has been one form of man-made skin which is already on the market in the U.S. Tiny tubes containing cells that secrete painkilling substances have been implanted into the spinal columns of people with chronic pain. And tissue-engineered cartilage is in clinical tests and is expected to be commercially available within the next few years. Scientists have learned how to cultivate human embryonic stem cells that might allow researchers to build custom-made organs on demand.

The term ‘tissue engineering’ was officially coined at a National Science Foundation workshop in 1988 to mean the application of principles and methods of engineering and life sciences toward fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and the development of biological substitutes to restore, maintain or improve tissue function. Although cells have been cultured outside the body for many years, research has recently begun to develop complex three-dimensional tissue constructs that will ideally mature into fully functional tissues and organs.¹

There are now several products that are commercially available and some of the products are seen here:²

Product	Distributor / Manufacturer	Details
Apligraf	Novartis / Organogenesis	Approved by the FDA on May 26, 1998. This product has both a dermal and epidermal layer. Initial USA indication is venous stasis ulcers. For more information, visit http://www.organogenesis.com
Dermagraft	Smith & Nephew / ATS	Dermal tissue layer. Initial USA indication applied for is full thickness diabetic foot ulcers.
Dermagraft TC	Smith & Nephew / ATS	This product is approved for sale in the USA for burn wounds. You would not substitute Dermagraft TC for Dermagraft. They are two very different products with distinct indications.

Skin is the most commonly produced in Tissue Engineering:

The sequence of cell seeding and growth can be seen in these drawings. Scaffolds are designed for specific tissues; this one is for skin.

Millions of living skin cells, called fibroblasts, are seeded within the scaffold. The cells multiply on the scaffold, which is contained and nourished within a device called a bioreactor.

In the bioreactor, the cells grow and multiply. As they organize themselves into three-dimensional layers of skin, the scaffold material slowly degrades and disappears.

Over a period of a few weeks, human skin tissue is formed, ready to treat victims of serious burns.

This photograph shows skin cells that have multiplied. The cells have been tricked into thinking they are in their natural environment instead of an engineered structure. Several days after seeding, they completely fill in the space of the scaffold. A few weeks of further growth will produce a piece of artificial skin large enough to be used for healing burns or replacing diseased tissue. Courtesy of Advanced Tissue Sciences, Inc.³

There are several tissue engineering companies that have emerged recently including Sulzer Medica, Life Cell, Advanced Tissue Sciences, Organogenesis, Genzyme Tissue Repair, and Integra Life Sciences.⁴

References:

http://biomed.tamu.edu/biomaterials/TissueEngineering.htm

http://www.medicaledu.com/tissue%20engineering.htm

Taken from http://www.eweek.org/2000/nbm/connect/index.htm

www.che.utexas.edu/~schmidt/links/eng.html

Created by Christine Brown and Jessica Laclair for Biochemical Engineering Fall 2000