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Tissue response to partially in vitro predegraded poly-L-lactide implants
Wim H De Jong1, J Eelco Bergsma, Joke E Robinson
1Laboratory for Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands. w.de.jong@rivm.nl
Biomaterials
|December 4, 2004
Summary
Pre-degrading poly-L-lactide (PLA96) in vitro simulates late tissue reactions, revealing macrophage infiltration and polymer degradation. Thicker implants (1.0-2.0 mm) provide more realistic resorption insights than thin ones.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Histopathology
Background:
- Poly-L-lactide (PLA96) is a biodegradable polymer used in medical implants.
- Understanding the in vivo tissue response to PLA degradation is crucial for clinical applications.
- Pre-degradation in vitro can simulate advanced degradation stages.
Purpose of the Study:
- To investigate the in vivo local tissue reaction to as-polymerized and pre-degraded PLA96.
- To compare the tissue response of pre-degraded PLA96 with polyethylene (PE) and non-degraded PLA96.
- To evaluate the influence of implant thickness on resorption characteristics.
Main Methods:
- Subcutaneous implantation of PLA96 and pre-degraded PLA96(168) samples in rats.
- Histological and immunohistochemical analysis at 2, 13, and 26 weeks post-implantation.
- In vitro pre-degradation of PLA96 to simulate advanced degradation.
Main Results:
- Non-degraded PLA96 and PE elicited mild local reactions with minimal inflammatory cells and connective tissue.
- Pre-degraded PLA96(168) showed pronounced macrophage infiltration, birefringent material, and polymer fragment encapsulation.
- Thinner pre-degraded PLA samples (0.5 mm) showed rapid resorption, while thicker samples (1.0-2.0 mm) exhibited more sustained degradation patterns.
Conclusions:
- In vitro pre-degradation is a valuable method for studying late-stage polymer tissue reactions.
- Implant thickness significantly influences the observed resorption rates and tissue responses.
- Thicker implants (1.0-2.0 mm) are recommended for accurately assessing the resorption characteristics of PLA for bone fixation applications.