Physical plugging does not account for attenuation of capillary leakage by hydroxyethyl starch 130/0.4: A synthetic gel layer model

Hydroxyethyl starch (HES) solutions, widely used plasma substitutes, reportedly attenuate capillary leakage via physical plugging of capillary defects. We investigated how 2% HES solutions of different molecular weights (HES 70 : 70 kDa, HES 130 : 130 kDa, HES 200 : 200 kDa, and HES 670 : 670 kDa) affect dye release from polyacrylamide gels (PAGs) as a model of endothelial glycocalyx. We assessed dye release from 4% PAG with varying concentrations of albumin [0, 1, 2, 4, and 8% (w/v)] by measuring the change in dye absorbance (ΔAbs) at 5 h for each HES solution. For PAG containing no albumin, ΔAbs for HES 130 was 30% lower than that for HES 70 and HES 200 , and 50% lower than that for HES 670 . At concentrations of 1–8% albumin, ΔAbs at 5 h with HES 70 , HES 130 , and HES 200 solutions were almost half that with the HES 670 solution, but no significant differences were noted in ΔAbs at 5 h among HES 70 , HES 130 , and HES 200 solutions. The inhibition of dye release by HES 670 is likely due to the hindering effect of HES molecules partitioned into gel pores. However, a unique property of HES 130 , including the heavy hydroxyethylation at the C 2 position, may promote specific interactions with PAG and thereby inhibit solute release. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 85–90, 2013.