Polyacrylamide hydrogel lubricates cartilage after biochemical degradation and mechanical injury

Abstract

Intra-articular injections of hyaluronic acid have been a mainstay of osteoarthritis treatment for decades. However, controversy surrounds the mechanism of action and efficacy of this therapy. As such, there has been recent interest in developing synthetic lubricants that lubricate cartilage. Recently, a synthetic 4 wt% polyacrylamide (pAAm) hydrogel was shown to effectively decrease lameness in horses.However, its mechanism of action and ability to lubricate cartilage is unknown. The goal of this study was to characterize the lubricating ability of this hydrogel and determine its efficacy for healthy and degraded cartilage. The study utilized previously established IL-1β-induced biochemical degradation and mechanical impact injury models to degrade cartilage. The lubricating ability of the hydrogel was then characterized using a custom-built tribometer using a glass counterface and friction was evaluated using the Stribeck framework for articular cartilage. pAAm hydrogel was shown to significantly lower the friction coefficient of cartilage explants from both degradation models (30%-40% reduction in friction relative to controls). A striking finding from this study was the aggregation of the pAAm hydrogel at the articulating surface. The surface aggregation was observed in the histological sections of explants from all treatment groups after tribological evaluation. Using the Stribeck framework, the hydrogel was mapped to higher Sommerfeld numbers and was characterized as a viscous lubricant predominantly in the minimum friction mode. In summary, this study revealed that pAAm hydrogel lubricates native and degraded cartilage explants effectively and may have an affinity for the articulating surface of the cartilage.

Loss of effective lubricating viscosity is the primary mechanical marker of joint inflammation in equine synovitis

“…This lack of stratification into distinct lubrication modes can be attributed to the fact that the average measured viscosities of all samples were within the same order of magnitude (10–90 mPa∙s, Table ). It is well established that the measured viscosity alters the Stribeck curve where higher viscosity lubricants shift the curve to the right 28,31 . Notably the use of the measured viscosity did not shift the Stribeck curve sufficiently to identify distinct modes of lubrication.…”

“…It is well established that the measured viscosity alters the Stribeck curve where higher viscosity lubricants shift the curve to the right. 28,31 Notably the use of the measured viscosity did not shift the Stribeck curve sufficiently to identify distinct modes of lubrication.…”

Application of 3D Bioprinting in Urology

“…Its 3D structure and biophysical properties (shape, mechanical strength and permeability) are similar to naturally sourced ECM [ 47 ]. It is currently extensively used in the medical field with 3D bioprinting, including the repair of skin wounds [ 48 , 49 , 50 ], bone damage [ 51 , 52 , 53 ], cartilage injury [ 54 , 55 , 56 ] and cardiac rehabilitation [ 57 , 58 , 59 , 60 ].…”

Highlights of recent clinically relevant papers

“…The aim of this study by Karan Vishwanath and co‐workers in the USA was to characterise the lubricating ability of polyacrylamide hydrogel and determine its efficacy for healthy and degraded cartilage…”