Individual inflammatory response of human blood monocytes to mesh biomaterials

Background: Alloplastic implants such as those employed in hernia repair induce distinct local inflammation and seroma production. As monocytes take a key position in the inflammatory foreign body reaction, their specific release of cytokines was investigated in vitro after incubation with alloplastic materials. Methods: Human blood monocytes were isolated from huffy coats of 42 healthy blood donors. Cells were cultivated in polystyrene culture wells (4 x 10(6) cells/well) on polypropylene-polyglactin mesh, on polytetrafluoroethylene, in control wells with the addition of 1 mug lipopolysaccharide (LPS) and on pure polystyrene. Supernatant was taken after 1 h and 5 days, and concentrations of tumour necrosis factor (TNF) alpha, interleukin (IL) 6 and IL-10 were determined. Donors were defined as 'high' or 'low' responders when concentrations of TNF-alpha were above the 75th or below the 25th percentiles, respectively. Results: In contact with biomaterials, the monocytes liberated TNF-alpha, IL-6 and IL-10, similar to levels observed after stimulation with LPS. Median cytokine concentrations were not normally distributed and were influenced by donor, timepoint and applied stimulus. One donor matched the criteria for low responder and three for high responder. Conclusion: The individual was identified as an independent factor for the inflammatory response of monocytes to biomaterials. Moreover, high and low responders could be identified. The variability of cytokine release and the lack of a normal distribution suggest that a larger sample size should be used in future studies of cellular response.