Issue 29

23 July - 27 August 1996

Science insight

The growing powers of Bioglass®

In the '60s, driven by a commitment to make a contribution to the prosthetic treatment of his countrymen in Vietnam, Professor Hench developed the first man-made material to bond to living tissue in a single attempt. Bioglass®, as it later became known, demolished the centuries-old assumption that human tissue would not accept a foreign replacement substance. It essentially ignited the field of bioceramics research which is now developing internationally to revolutionise prosthetics and aid bone regeneration in medicine and dentistry.

As an undergraduate at the Ohio State University, Larry Hench was drawn into ceramic engineering by the anthropological significance of ceramics, and by the "fiery furnace effect", the "primal turn-on" he experienced seeing the raw incandescent heat and light of ceramic furnaces.

His glass material exploited an under-explored melting point based on a low silica content with a sodium flux, and it carried the calcium to phosphorous ratio of hydroxyapatite, the essence of bone. Bioglass® provides a compatible chemical, mechanical and stereological environment for bone tissue attachment, and it genetically stimulates the differentiation and immigration of the stem cells which precede bone growth.

The more recent discovery that powdered Bioglass® can induce bone to generate faster than its natural rate caused another major shift in thinking, and opened up a wealth of new research opportunities. There is now the possibility that the body could be encouraged to regrow tissues like cartilage, and "maybe then a whole limb."

His current and future research projects stand to extend the impact of his work on both medical and materials science, and particularly on the invaluable clinical application of bioactive materials to the repair of bones, joints and teeth.

Professor Hench is coordinating an inter-institutional effort to establish "in numbers" the speed and nature of tissue growth in Bioglass®. He is also working with immunologists at the Royal Postgraduate Medical School on quantum-mechanical molecular orbital modelling of t-cell receptor interactions with proteins which cause immune disease. The work will help determine the reaction pathways of interactions between amino acids and the inorganic constituents of Bioglass®, and may have implications for the treatment of rheumatoid arthritis and AIDS.

Professor Hench's development of bioactive glass, and his parallel work on both the mechanisms of glass surface reactions and the chemical processing of materials, has led to many international awards, the publication of nearly 370 research papers, 21 books and 23 patents. Many of these successes were achieved jointly with his scientific colleague of some 20 years - his wife June Wilson, herself an outstanding biologist, physiologist, histopathologist and toxicologist.

When asked why he had decided to come to Imperial he replied, "I came for the excitement of working with some of the best students in the world, in some of the best faculties in the world, in a location that has the best hospitals in the world. Get those all working together and you can accomplish things that would be inconceivable in an isolated unit!"

Photography by Neville Miles.

Interview by James Porteous, an MSc Science Communication student.