A model to predict the permeation kinetics of dimethyl sulfoxide in articular cartilage

Cryopreservation of articular cartilage (AC) has excited great interest due to the practical surgical importance of this tissue. Characterization of permeation kinetics of cryoprotective agents (CPA) in AC is important for designing optimal CPA addition/removal protocols to achieve successful cryopreservation. Permeation is predominantly a mass diffusion process. Since the diffusivity is a function of temperature and concentration, analysis of the permeation problem would be greatly facilitated if a predictive method were available. This article describes, a model that was developed to predict the permeation kinetics of dimethyl sulfoxide (DMSO) in AC. The cartilage was assumed as a porous medium, and the effect(s) of composition and thermodynamic nonideality of the DMSO solution were considered in model development. The diffusion coefficient was correlated to the infinite dilution coefficients through a binary diffusion thermodynamic model. The UNIFAC model was used to evaluate the activity coefficient, the Vignes equation was employed to estimate the composition dependence of the diffusion coefficient, and the Siddiqi-Lucas correlation was applied to determine the diffusion coefficients at infinite dilution. Comparisons of the predicted overall DMSO uptake by AC with the experimental data over wide temperature and concentration ranges [1~37°C, 10~47% (w/w)] show that the model can accurately describe the permeation kinetics of DMSO in AC [coefficient of determination (R(2)): 0.961~0.996, mean relative error (MRE): 2.2~9.1%].