Alginate as a novel material for duraplasty: Investigation of the material properties, in vivo stability, and sealing capabilities.
Nunamaker, Elizabeth Anne
2006
Abstract
Investigations for an ideal duraplasty material have been underway since 1890 to accommodate the 100,000 dural graft procedures that are performed annually in the United States alone. Currently, all clinically used materials bear risk of graft failure due to leakage, inflammatory response, infection, or seizure. The mild reaction conditions, manipulable material properties, and long-term biocompatibility make alginate a strong candidate for this application. Previous studies have demonstrated the feasibility of utilizing alginate for duraplasty; however many aspects of its development require further investigation and optimization before being clinically available. The research presented describes investigations of three vital aspects in the development of a duraplasty material: (1) investigate the material properties of alginate and trade-offs due to gelation mechanism; (2) identify the <italic>in vivo</italic> stability of the hydrogel; and (3) determine the optimal properties in order to establish a watertight seal in the rabbit duraplasty model. First, both diffusion and <italic>in situ</italic> gelation of alginate yielded hydrogels with material properties similar to brain tissue; however, both methods demonstrated unique advantages. Diffusion gelled alginate reacted quickly (< 10 minutes) while <italic>in situ</italic> gelled alginate formed hydrogels that exhibited lower levels of shrinkage (< 5%). These results suggested further investigation of 1.95 wt% 43 mPas alginate with either 200 mM CaCl<sub>2</sub> (diffusion) or 100 mM CaCO<sub>3</sub> and 80 mM gluco-delta-lactone (<italic>in situ</italic>). Second, <italic>in vivo</italic> stability investigations revealed the superior stability of <italic> in situ</italic> gelled alginate. <italic>In situ</italic> gelled alginate remained in the biologically relevant complex modulus range for up to 3 months indicating its candidacy in the development of the duraplasty material. Lastly, application of <italic>in situ</italic> gelled alginate to a dural defect resulted in a watertight seal at time points of 3 days, 3 weeks, and 3 months, withstanding pressures greater than 5 times normal human intracranial pressure. This result was repeatable in the presence of an intracortical electrode, suggesting its superior sealing capabilities and utility. These results detail the successful development of alginate for duraplasty. Alginate's watertight sealing capabilities and unique utility make it an invaluable neurosurgical tool. Further, these results support continued development toward a multifunctional duraplasty material.Subjects
Alginate Capabilities Duraplasty Hydrogel Investigation Material Novel Properties Sealing Stability Vivo
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