Osmotic Swelling Responses Are Conserved Across Cartilaginous Tissues With Varied Sulfated‐Glycosaminoglycan Contents

Abstract

Determining the influence of tissue composition on the osmotic swelling stress of articular cartilage and meniscus fibrocartilage is important to enhance our understanding of physiology and disease. This osmotic swelling stress is critical for the load‐bearing capability of both tissues and results in part due to the interactions between the negatively charged sulfated glycosaminoglycan (sGAG) chains and the ionic interstitial fluid. Changes in sGAG content, as those occurring during the progression of degenerative joint disease, alter such interactions. Here, we compare the time‐varying effects of altered osmotic environments on the confined compression swelling behavior of bovine tissues spanning a range of sGAG concentrations: juvenile articular cartilage, juvenile and adult meniscus, and juvenile cartilage enzymatically degraded to reduce its sGAG content. The transient response to changes in bath conditions was evaluated for explants assigned to one of three compressive offsets (5%, 10%, or 15% strain) and one of three bath conditions (0.1X, 1X, or 10X phosphate‐buffered saline). Our results show that relative responses to alterations to the osmotic environment are consistent across native tissues but differ for degraded juvenile cartilage, demonstrating that changes in sGAG do not completely recapitulate the native swelling behaviors. Further, we found a strong correlation between aggregate modulus and sGAG/collagen, as well as between sGAG and collagen contents across native tissue types, suggesting some conservation of composition–function relationships across a range of tissue types with varying sGAG concentrations. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:785‐792, 2020

A Mathematical Model for Transport in Poroelastic Materials with Variable Volume:Derivation, Lie Symmetry Analysis, and Examples

“…Its specific extension includes internal sources inside the tissue as the capillary and lymphatic beds in the muscle [4, 8-10, 13, 14]. However, most biological models neglect the elastic characteristics of the tissue and focus on the transport of fluid and solute inside and out of the tissue, as in peritoneal dialysis [19], whereas for the non-perfused tissues the poroelastic description may include both phenomena: transport processes and elastic changes of the tissue volume [4,15,[20][21][22]. Beside the hydrostatic pressure of fluid also the osmotic pressure of dissolved solutes may be of importance, especially in biological applications [9,14,[21][22][23][24].…”

“…However, most biological models neglect the elastic characteristics of the tissue and focus on the transport of fluid and solute inside and out of the tissue, as in peritoneal dialysis [19], whereas for the non-perfused tissues the poroelastic description may include both phenomena: transport processes and elastic changes of the tissue volume [4,15,[20][21][22]. Beside the hydrostatic pressure of fluid also the osmotic pressure of dissolved solutes may be of importance, especially in biological applications [9,14,[21][22][23][24]. The poroelastic theory considers the system formed by a solid, elastic matrix with pores that can be penetrated by a fluid and dissolved solutes.…”

“…The relationship between stress and strain is usually assumed to be linear, but we discuss a simple generalization to nonlinear relationship. The flux of fluid depends on the hydrostatic pressure and solute concentration gradients (osmotic pressure), whereas the fluxes of solutes include diffusive and convective transport mechanisms [9,12,21,22,27].…”

3D Printing for Cartilage Replacement: A Preliminary Study to Explore New Polymers

“…72.6% and 79.6%, respectively. Such difference can be related to the increased amount of porous and consequent free space in the structure of wFOMM, which favors water penetration into the polymeric network [52].…”

Non-ionic CT contrast solutions rapidly alter bovine cartilage and meniscus mechanics

“…These large variations in contrast solution properties are concerning given the known sensitivity of proteoglycan-rich tissues, such as cartilage, to the osmotic environment. Alterations to bath ion concentrations affect the osmotic swelling stress in cartilaginous tissues produced by interactions between the negatively charged sulfated GAGs and the ions in the interstitial fluid [21][22][23][24][25][26][27][28] . These interactions are functionally important and contribute to both the equilibrium and dynamic stiffness of these tissues.…”