The living shunt: A tissue engineering approach in the treatment of hydrocephalus

Tissue engineering is the use of cultured cells seeded into biodegradable p olymers to create custom designed, living implantable devices. As a first a pproach to the use of this technique in the treatment of hydrocephalus, we have prepared chondrocyte-seeded polyglycolic acid (PGA) tubes coated with polylactic glycolic acid (PGLA), implanted initially with thin silastic ste nts removed four weeks after shunt insertion. The use of bovine xenograft c ells in athymic (nude) rats resulted in more efficient seeding with chondro cytes, stiffer tube walls, and better patency. When implanted in 6-week-old rats made hydrocephalic by cisternal injection of kaolin at 4 weeks of age , six of eight 'living shunts' remained patent to radio-opaque contrast inj ection at two weeks after stent removal. At four weeks after stent removal, all four of the shunts had occluded at the ventricular end, three of the f our apparently due to growth of the animal. We conclude that polymer type, cell type, and cell density will require considerable optimization, but a w orking tissue engineered shunt is feasible and may one day address some pro blems of interactions of living tissue and inert polymer.