Injectable Gels Could Repair Disc Degeneration

Nanoscopic polymer particles with unique swelling and mechanical properties that can transform into a gel could help restore the mechanical properties of damaged intervertebral discs (IVDs).

Researchers at the University of Manchester (United Kingdom) have succeeded in developing doubly crosslinked (DX) microgels, a new type of hydrogel that are constructed from covalently linked, singly crosslinked (SX) microgels. Linking the microgel particles together--using covalent linking of physically gelled dispersions of interpenetrating, vinyl-functionalized microgels--formed durable, elastic gels capable of sustaining large permanent changes in shape without breaking. These improved injectable gels have much better mechanical properties than the first generation SX microgels, and the researchers say they now display the necessary long-term durability required for an implanted device.

The relationships between DX microgel composition and mechanical properties were investigated using dynamic rheology and swelling experiments; yield strains could be varied between 5-65%. The ability to tune the mechanical properties of the DX microgels and control of intra- and inter-particle crosslinking is achieved using preparation conditions, including Ph regulation, resulting in microgels that have the potential to be used as injectable gels for soft and load-bearing tissue repair. The study describing the development and properties of the new microgels was published in the May 15, 2011, issue of the journal Soft Matter.

"Degeneration of the intervertebral disc results in chronic back pain which costs the country billions of pounds per annum and causes untold misery for sufferers and their families," said study coauthor Prof. Tony Freemont, PhD, head of research in the school of biomedicine. "We have been working for 25 years to identify methods for treating degeneration of the intervertebral disc."

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