Reduction of protein adsorption and macrophage and astrocyte adhesion on ventricular catheters by polyethylene glycol and N‐acetyl‐L‐cysteine

Cellular obstruction of poly(dimethyl)siloxane (PDMS) catheters is one of the most prevalent causes of shunt failure in the treatment of hydrocephalus. By modifying PDMS using short- and long-chain mono-functional polyeth- ylene glycol (PEG604 and PEG5K, respectively) and N-acetyl- L-cysteine via adsorption and covalent binding (NAC and NAC/EDC/NHS, respectively), we increased surface wettabil- ity. We hypothesized that these surface modifications would inhibit protein adsorption and decrease host macrophage and astrocyte adhesion. Tested in a bioreactor set to mimic physiological flow, all modified surfaces significantly decreased albumin adsorption compared with PDMS (p < 0.05) except for PEG604-modified PDMS (p ¼ 0.14). All four modification strategies significantly reduced (p < 0.01) fibro- nectin adsorption. PEG604, PEG5K, NAC, and NAC/EDC/NHS reduced the average level of macrophage adhesion by 53%, 63%, 40%, and 58% (p <.0.05 except when comparing PDMS with NAC) and astrocyte adhesion by 47%, 83%, 91%, and 72% (p < 0.05 except when comparing PDMS with PEG604), respectively. Combined with saline soak results which sug- gest that the surface wettability is stable over 30 days for each modification, our results are consistent with the hypoth- esis that these modifications decrease cell adhesion on cathe- ters in vitro for the treatment of hydrocephalus. V C 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 98A: 425-433, 2011.