Abstract
Sepsis is characterized by a systemic inflammatory response caused by infection, and can result in organ failure and death. Removal of inflammatory mediators such as cytokines from the circulating blood is a promising treatment for severe sepsis. We are developing an extracorporeal hemoadsorption device to remove cytokines from the blood using biocompatible, polymer sorbent beads. In this study, we used confocal laser scanning microscopy (CLSM) to directly examine adsorption dynamics of a cytokine (ILโ6) within hemoadsorption beads. Fluorescently labeled ILโ6 was incubated with sorbent particles, and CLSM was used to quantify spatial adsorption profiles of ILโ6 within the sorbent matrix. ILโ6 adsorption was limited to the outer 15 ฮผm of the sorbent particle over a relevant clinical time period, and intraparticle adsorption dynamics was modeled using classical adsorption/diffusion mechanisms. A single model parameter, ฮฑ = q^max^
K/D, was estimated by fitting CLSM intensity profiles to our mathematical model, where q^max^ and K are Langmuir adsorption isotherm parameters, and D is the effective diffusion coefficient of ILโ6 within the sorbent matrix. Given the large diameter of our sorbent beads (450 ฮผm), less than 20% of available sorbent surface area participates in cytokine adsorption. Development of smaller beads may accelerate cytokine adsorption by maximizing available surface area per bead mass. ยฉ 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010