Electromechanical properties of dried tendon and isoelectrically focused collagen hydrogels

Abstract

Assembling artificial collagenous tissues with structural, functional, and mechanical properties, which mimic natural tissues, is of vital importance for many tissue engineering applications. While the electromechanical properties of collagen are thought to play a role in, e.g., bone formation and remodeling, this functional property has not been adequately addressed in engineered tissues. Here, the electromechanical properties of rat tail tendon are compared with those of dried iso-electrically focused collagen hydrogels using piezoresponse force microscopy in ambient conditions. In both the natural tissue and the engineered hydrogel, D-periodic, type I collagen fibrils are observed, which exhibit shear piezoelectricity. While both tissues also exhibit fibrils with parallel orientation, Fourier transform analysis has revealed that the degree of parallel alignment of the fibrils in the tendon is three times that of the dried hydrogel. The results obtained demonstrate that iso-electrically focused collagen has similar structural and electromechanical properties to that of tendon, which is relevant for tissue engineering applications.

The past, present and future in scaffold-based tendon treatments

“…Further, preclinical experimentation in peripheral nerve repair and in tendon small and large animal models enhanced the clinical potential of these fibres, as judged by improved structural alignment and biomechanics [361][362][363]. Using an isoelectric focusing setup, aligned collagen fibres have been produced with ultrastructural characteristics and physical properties similar to native tendon [364,365]. Of significant importance are in vitro data that have been obtained using these materials.…”

Tendon injury and repair – A perspective on the basic mechanisms of tendon disease and future clinical therapy

“…Tendon cells from the intrinsic compartment, as well as migrated progenitors from the extrinsic compartment show poorer tenogenic expression when exposed to a randomly organized niche, compared to an aligned niche [224][225][226][227][228][229]306]. A promising development therefore is the fabrication of aligned collagen constructs [230], which recently have been produced with properties that resemble native tendon tissue [231,232]. A potentially promising future direction may be to engineer injectable gels that adopt an aligned configuration upon administration, providing a tissue template for re-establishing a native tissue multi-scale architecture.…”

Piezoelectric Tensor of Collagen Fibrils Determined at the Nanoscale

“…With the advent of piezoresponse force microscopy (PFM), it is now possible to probe piezoelectricity in biosystems, including collagen, [18][19][20][21] with nanoscale resolution. The longitudinal piezoelectric response of adult humerus and tibia bone under both dry and wet conditions was reported to be nonzero for transverse cuts and zero for longitudinal cuts, perpendicular and parallel to the diaphysial axis, respectively.…”