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 bio degradeable scaffolds to provide orientated cues using contact guidance for cell migration/adhesion and deposition of extracellular matrix. We have im planted 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 increase d progressively with time with no significant differences between the Fn sc affolds and controls. CD45 (pan leukocyte) positive cell numbers peaked at 6 h and when expressed as a percentage of total cell counts as determined b y H&E staining constituted 20% of the total cell number at 6 h but decrease d to 5% of total number by 72 h. There were no significant differences in t he 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 un toward inflammatory response at the time points tested and has potential us e in guiding the repair process. (C) 2001 Kluwer Academic Publishers.