Nadja Nijenhuis, Daisuke Mizuno, Jos A. E. Spaan, and Christoph F. Schmidt
“Viscoelastic Response of a Model Endothelial Glycocalyx”
PHYSICAL BIOLOGY , Vol. 6, 25014-25014 (2009)
【概要】Many cells cover themselves with a multifunctional polymer coat, the pericellular matrix (PCM), to mediate mechanical interactions with the environment. A particular PCM, the endothelial glycocalyx (EG), is formed by vascular endothelial cells at their luminal side, forming a mechanical interface between the flowing blood and the endothelial cell layer. The glycosaminoglycan (GAG) hyaluronan (HA) is involved in the main functions of the EG, mechanotransduction of fluid shear stress and molecular sieving. HA, due to its length, is the only GAG in the EG or any other PCM able to form an entangled network. The mechanical functions of the EG are, however, impaired when any one of its components is removed. We here used microrheology to measure the effect of the EG constituents heparan sulfate, chondroitin sulfate, whole blood plasma and albumin on the high-bandwidth mechanical properties of a HA solution. Furthermore, we probed the effect of the hyaldherin aggrecan, a constituent of the PCM of chondrocytes, and very similar to versican (present in the PCM of various cells, and possibly in the EG). We show that components directly interacting with HA (chondroitin sulfate and aggrecan) can increase the viscoelastic shear modulus of the polymer composite.

Daisuke Mizuno, Rommel Bacabac, Catherine Tardin, david Head, and Christoph Schmidt
“High-Resolution Probing of Cellular Force Transmission”
Phys. Rev. Lett., Vol. 102, 168102-1 – 168102-4 (2009)
【概要】細胞は自ら生み出した力を外部環境に印加することでその力学物性を検出している。我々は光トラップを利用して細胞が生み出す全ての力とそのうち細胞外物質に伝播した成分の両方を計測した。細胞外物質の力学強度に相当する光トラップ強度を系統的に変化させて実験を行うことで、力の伝達は外部環境の力学応答に強く依存することを見出した。この結果に基づき我々は細胞の力学知覚の物理メカニズムを提案する。