Tissue response to microfibers of different polymers: Polyester, polyethylene, polylactic acid, and polyurethane

Tissue response to single polymer microfibers of polyester (PET), polyethylene (PE), poly(L-lactic acid) (PLA), and polyurethane (PU) was assessed using a rat subcutaneous model. Fibers of diameters ranging from I to 15 mum were aligned parallel to each other on polycarbonate frames and implanted in the subcutaneous dorsum in the subscapular region. After 5 weeks of implantation, fibrous capsule thickness was significantly less for fibers of diameters 1-5 than for those of 11-15 mum for all polymers tested. For PET and PU, 75.0 and 71.4% respectively of the 1-5 mum fibers had no capsule, while for PE and PLA only 45.5 and 56.3% respectively had no capsule. For 1-5 mum fibers, PE had significantly thicker capsules than PET and PU. Reducing fiber diameters from 6-10 to 1-5 mum induced a greater reduction in capsule thickness than changing polymers among PET, PE, and PLA. PU showed the least encapsulation of all polymers, demonstrating significantly thinner capsules than PET, PE, and PLA for 6-10 and 11-15 mum fibers. (C) 2002 Wiley Periodicals, Inc.