Hydrodynamics of cryogelation

Cryogel, prevalent in the plasma of rheumatoid arthritis patients, is a plasma fibronectin (pFN)-extra domain A containing FN [EDA(+)FN]-fibrinogen (Fbg) aggregate formed by the addition of heparin (Hep) at low temperature. Although EDA(+)FN is not usually present in normal plasma, its prevalence in rheumatic patients induces cryogelation. In this study, we determined the hydrodynamic radius (R(h)) ratio (R(h)/R(h30)) of the cryogel component by dynamic light scattering in vitro. R(h)/R(h30) was normalized to R(h) at 30 degrees C (R(h30)) at several temperatures. The R(h)/R(h30) of Fbg was found to increase only by self-aggregation, whereas the R(h)/R(h30) of FNs does not increase in response to temperature changes. The R(h)/R(h30) of the Fbg/FN aggregate is increased by the addition of Hep, and the R(h)/R(h30) (12.5) of the Hep-induced EDA(+)FN/Fbg aggregate is greater than that (2.5) of the pFN/Fbg aggregate. These results suggest that cryogelation requires Fbg self-aggregation and the interaction between EDA(+)FN and Hep.