α2-macroglobulin-rich serum as a master inhibitor of inflammatory factors attenuates cartilage degeneration in a mini pig model of osteoarthritis induced by “idealized” anterior cruciate ligament reconstruction

Use of quantitative mass spectrometry-based proteomics and ELISA to compare the alpha 2 macroglobulin concentration in equine blood-based products processed by three different orthobiologic devices

Introduction

Alpha 2 macroglobulin (A2M), a multi-functional protein in the plasma protease inhibitor class, regulates proinflammatory cytokines and the clearance of chondrodestructive enzymes in cases of joint injury and osteoarthritis (OA). The purpose of this study was to compare A2M concentrations in equine plasma samples processed by three commercial devices developed for stall-side regenerative joint therapy.

Methods

Plasma samples were obtained from healthy adult horses (N = 13). Mass spectrometry analysis was used to determine the concentration of protein analytes in each sample. Selected reaction monitoring measured a specific A2M peptide as a surrogate of the whole A2M protein. A2M concentrations produced by each test device were compared for two sample types: a pre-concentrate or platelet-poor (PP) component and a final component for use in the horse.

Results

There was no significant difference (p > 0.05) in the geometric mean (GM) concentration of A2M in the final concentration samples produced by the Alpha2EQ® device (N horses = 13) and the single-centrifugation PP samples produced by the Pro-Stride® APS (autologous protein solution) device (N = 13) and the Restigen® PRP (platelet-rich plasma) device (N = 11). When A2M content in final concentration samples produced by each device was compared, the Pro-Stride APS and Restigen PRP samples had significantly greater GM A2M content (p < 0.0001) compared to the Alpha2EQ samples, and the Pro-Stride APS final concentration samples had significantly greater GM A2M concentration (p < 0.0001) versus that for the Restigen PRP final samples.

Discussion

This comparison demonstrated that the volume and A2M concentration of an Alpha2EQ final concentrate are no different than the volume and concentration of A2M in the PP from Pro-Stride or Restigen devices.

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation

BACKGROUND

Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery.

OBJECTIVE

Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation.

METHODS

Seventeen male Sprague-Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread.

RESULTS

Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes.

CONCLUSIONS

The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery.

Molecular Mechanisms of Cartilage Repair and Their Possible Clinical Uses: A Review of Recent Developments

Articular cartilage (AC) defects are frequent but hard to manage. Osteoarthritis (OA) is a musculoskeletal illness that afflicts between 250 and 500 million people in the world. Even though traditional OA drugs can partly alleviate pain, these drugs cannot entirely cure OA. Since cartilaginous tissue of the joints has a poor self-repair capacity and very poor proliferative ability, the healing of injured cartilaginous tissue of the joint has not been accomplished so far. Consequently, the discovery of efficacious mediations and regenerative treatments for OA is needed. This manuscript reviews the basic concepts and the recent developments on the molecular mechanisms of cartilage repair and their potential clinical applications. For this purpose, a literature exploration was carried out in PubMed for the years 2020, 2021, and 2022. On 31 October 2022 and using "cartilage repair molecular mechanisms" as keywords, 41 articles were found in 2020, 42 in 2021, and 36 in 2022. Of the total of 119 articles, 80 were excluded as they were not directly related to the title of this manuscript. Of particular note are the advances concerning the mechanisms of action of hyaluronic acid, mesenchymal stem cells (MSCs), nanotechnology, enhancer of zeste 2 polycomb repressive complex 2 subunit (EHZ2), hesperetin, high mobility group box 2 (HMGB2), α2-macroglobulin (α2M), proteoglycan 4 (Prg4)/lubricin, and peptides related to cartilage repair and treatment of OA. Despite the progress made, current science has not yet achieved a definitive solution for healing AC lesions or repairing cartilage in the case of OA. Therefore, further research into the molecular mechanisms of AC damage is needed in the coming decades.