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 1 to 15 μm 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 μm for all polymers tested. For PET and PU, 75.0 and 71.4% respectively of the 1–5 μm fibers had no capsule, while for PE and PLA only 45.5 and 56.3% respectively had no capsule. For 1–5 μm fibers, PE had significantly thicker capsules than PET and PU. Reducing fiber diameters from 6–10 to 1–5 μm 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 μm fibers. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 222–227, 2002