Observation of Solute Transport between Articular Cartilage and Subchondral Bone in Live Mice

Abstract

Objective To establish a method for investigating the permeability of calcified cartilage zone (CCZ) and to observe solute transport between articular cartilage (AC) and subchondral bone (SB) through intact CCZ in vivo. Design We developed a novel fixing device combined with un-decalcified fluorescence observation method to address the permeability of CCZ in live mice. Twenty-four Balb/c female mice aged 1 to 8 months were used to observe the development of CCZ. Eighty-four Balb/c female mice (aged 1 or 6 months) with mature or immature CCZ of distal femur were used to investigate the permeability of intact CCZ in vivo. Diffusivity of rhodamine B (476 Da) and tetramethyl-rhodamine isothicyanate-dextran (TRITC-Dextran, 20 kDa) was tested from AC to SB in 0 minutes, 1 minute, 15 minutes, 30 minutes, 1 hour, and 2 hours. None diffused knee joints (0 minutes) served as blank control, while in vitro immersion of distal femurs in rhodamine B or TRITC-Dextran for 72 hours served as positive control. Results CCZ was well developed in 6-month mice. Both tracers penetrated immature CCZ down to SB in less than 1 hour in live mice, while the diffusion of both tracers decreased rapidly at tidemark in all testing time points. Conclusion Current study provided direct evidence of blocking effect of CCZ in solute transportation during short diffusion period in live animal, indicating the important role of CCZ in joint development and microenvironment maintenance.

Identification of an Ultrathin Osteochondral Interface Tissue with Specific Nanostructure at the Human Knee Joint

“…Previous studies have shown that the porous layer may facilitate transportation of mineral ions and precursors to form isolated mineral particles . Conversely, the densely packed structures have been implicated in blocking solute diffusion, which subsequently prevented vascular invasion from SB into AC, thereby enhancing pressurization of AC to resist load. , …”

“…26 Conversely, the densely packed structures have been implicated in blocking solute diffusion, which subsequently prevented vascular invasion from SB into AC, thereby enhancing pressurization of AC to resist load. 27,28 This distinct mineral distributions at the osteochondral interface played a major role in tissue adhesion, 6 owing to the fact that removal of minerals from the interface initiated separation of AC and SB (Figure S6a−c). To affirm this phenomenon, we prepared nanoparticle glues using 10% HAp (20 nm) in PBS (wt/v) solution to adhere to the tissues.…”

High Resolution Nanostructure with Two-stages of Exponential Energy Dissipation at the Ultrathin Osteochondral Interface Tissue of Human Knee Joint

“…The copyright holder for this this version posted October 19, 2021. ; https://doi.org/10.1101/2021.10.18.464899 doi: bioRxiv preprint solute diffusion, thus preventing the vascular invasion from SB into AC and helping pressurization of AC to resist load. 20,21 This characteristic microstructure due to distinct mineral distributions at osteochondral interface contributed a lot to tissue functions.…”

“…SEM and EDX Analyses. 200-um-thick cryo-cut samples were thawed at room temperature and washed with DI water for several times, followed by dehydrated through a graded ethanol treatments (20,30,40,50,70,80,90,95, 100 and 100 % (v/v)) for 30 min in each solution and air dried. Then, the samples were gold sputtered and imaging was performed (Hitachi SU-70) at 3 kV accelerating voltage to observe the morphology of osteochondral interface.…”

Scaffold With Natural Calcified Cartilage Zone for Osteochondral Defect Repair in Minipigs

“…41 The reason may be that the permeability in natural CCZ is far less than that in adjacent tissues 3,32 because of its highly calcified status, leading to difficulties in substance exchange. 19 As a result, cartilage and subchondral bone were separated into relatively independent physiological environments by this thin structure. These independent environments that are different from the subchondral bone might help to maintain the phenotype of cartilage from degeneration, 2,42 and may provide an explanation for why the cartilage tissue in the non-CCZ group was ultimately replaced by fibrocartilage.…”