Measuring tiny forces in nM: human cell level interactions

Tendons connect muscles to bones. They undergo some of the strongest forces in human body.

Made up of collagen fibres,tendons sit in a matrix of connective tissue. Tendon cells influence the development of the matrix, and the rigidity of the matrix in turn affects the tendon cell behaviour. But it is not well understood in what way. Scientists in Denmark have been investigating the interactions between the cells and the matrix, with the help of a Microlink 751 data acquisition device. Their findings have been published in the Journal of the Mechanical Behavior of Biomedical Materials.

Accumulation of collagen cross-links and stiffening of the matrix occur in diabetes, cancer and ageing. The researchers, led by Antonios Giannopoulos of the Institute of Sports Medicine Copenhagen, have measured the cell-matrix interactions.

To do this they made 3D engineered tendon constructs using human tendon fibroblasts. They also made their own force monitor to non-destructively measure cellular and matrix forces.

The force monitor comprised force transducers, stepper motors with a motor controller, culture wells and a Microlink 751 PC data collection system running Windmill software. The Microlink collected data at 1 sample per second. The sensitivity of the force monitor to detect low scale forces could reveal tiny differences.

Tendon force graph
Force vs Time Data Measurement, Giannopoulos et al

Silk suture loops at the end of each construct were used to attach the force monitor. The tendon constructs were subjected to three unloading/loading cycles. The data from the Microlink was fed into GraphPad software for comparison test analysis.

The authors confirmed the strong correlation between cross-links and matrix properties.

The model provides a useful tool to evaluate tissue's local environment and provides a quantifiable measure of cell-matrix interactions.

Reference and Further Reading

Microlink 751: Multi-Function USB Unit: Voltage, Temperature, Strain, pH, Current, Counting, Control

Journal of the Mechanical Behavior of Biomedical Materials A. Giannopoulos et al, Effects of genipin crosslinking on mechanical cell-matrix interaction in 3D engineered tendon constructs, Journal of the Mechanical Behavior of Biomedical Materials, Volume 119, 2021.