A study of the cellular response to orientated fibronectin material in healing extensor rat tendon.

3D orientated fibronectin (Fn) mats have been used as biocompatible and biodegradeable scaffolds to provide orientated cues using contact guidance for cell migration/adhesion and deposition of extracellular matrix. We have implanted Fn scaffolds in an established rat tendon(partial tenotomy) injury model to test its efficacy and monitor the early cellular and inflammatory response. Tendons were harvested at 0, 6 h, 1, 3, 5, 7 and 14 days for H&E, immunohistochemistry and TEM. Total cell counts within the window increased progressively with time with no significant differences between the Fn scaffolds and controls. CD45 (pan leukocyte) positive cell numbers peaked at 6 h and when expressed as a percentage of total cell counts as determined by H&E staining constituted 20% of the total cell number at 6 h but decreased to 5% of total number by 72 h. There were no significant differences in the inflammatory response between the control and implanted groups. Few CD44 (mesenchymal stem cell) positive cells identified had a surface location. A novel cell with long exaggerated cytoplasmic processes was identified by TEM. Our results show that the Fn scaffold did not degrade or elicit any untoward inflammatory response at the time points tested and has potential use in guiding the repair process. Copyright 2001 Kluwer Academic Publishers