The stiffness of bone marrow cell-knit composites is increased during mechanical load

A novel device for mechanical stimulation of primary adult rat bone marrow cells cultured on three-dimensional knitted textiles has been prototyped. A method has been developed ensuring a well-defined, high-density, and repro ducible cell seeding on the knitted fabric. After culturing for 18-52 days the cell-knit composites were subjected to uniaxial 2% stretching and relax ation. The frequency was altered between 0.1 Hz (196 min, loading phase) an d 0.01 Hz (360 min, resting phase). Identically treated knits without cells exhibited a slight stiffness reduction, whereas the stiffness of knits wit h cells increased from cycle to cycle. The stiffness increase was found to depend on the duration of the culture period before mechanical loading. Our data suggest that the extracellular matrix deposited by the cells on the k nit and intact microtubuli of living cells cause the observed stiffness inc rease. In comparison to the unstrained static cell-knit composites cell pro liferation and bone cell differentiation were reduced by the mechanical loa d. (C) 2001 Elsevier Science Ltd. All rights reserved.