INTERACTION OF MACROPHAGES WITH FIBROUS MATERIALS IN-VITRO

Fibrous materials have the potential of being used for tissue scaffold ing. The interaction of macrophages with fibres of various composition s and sizes was observed in vitro. The following materials were tested : individual gold fibres; woven fibres of polyester and nylon; non-wov en fibres of polybutylene/polypropylene 80:20 and polyester. All fibre s had diameters between 2 and 40 mu m. At the end of the 24 h incubati on time, culture media were retrieved for the assay of tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6), two cytokines secr eted by activated macrophages. Fibre samples were processed for scanni ng electron microscopy (SEM), or for immunofluorescence labelling of t he MAC-1 and ICAM-1 cell surface markers. Confocal microscopy was used for the latter, which was performed with the woven and non-woven samp les. None of the fibre samples induced significant amounts of TNF-alph a or IL-6 secretion in the culture medium, suggesting that the cells d id not activate this pathway. SEM on individual gold fibres showed tha t the fibre diameter had an effect on the morphology of the cells, nam ely on their extent of spreading. Larger fibres had a higher number of cells, which tended to cluster together without spreading extensively . When comparing woven and non-woven fibres, SEM showed that cells spr ead extensively on the woven fibres, whereas they tended to maintain t heir spherical shape on the non-woven fibres. Confocal microscopy demo nstrated a difference between materials in the number of MAC-1 and ICA M-1 positive cells. These results demonstrate that a combination of mo rphological, immune and biochemical markers can be used to distinguish the response of elicited macrophages to various materials. The cells appeared to be only moderately activated on all materials tested, with changes in their morphology but without increased secretion of cytoki nes. The measured responses imply interactions between nominal fibre c omposition and fibre diameter. (C) 1996 Elsevier Science Limited