DOS 2016

228

· DOS Abstracts

Proteomic analysis of early cartilage repair in a

chronic cartilage defect model in minipigs

Casper Bindzus Foldager, Morten Lykke Olesen, Bjørn Borsøe Christensen, Kris

Hede, Martin Lind, Johan Palmfeldt

Orthopaedic Research Laboratory, Aarhus University Hospital; Orthopaedic

Research Laboratory, Aarhus University Hospital; Orthopaedic Research

Laboratory, Aarhus University Hospital; Orthopaedic Research Laboratory,

Aarhus University Hospital; Sports Trauma Clinic, Aarhus University Hospital;

Research Unit for Molecular Medicine, Aarhus University

Background:

The early regenerative processes are believed to be important

determinants for cartilage repair outcome.

Purpose / Aim of Study:

The aim was to investigate the mechanisms in early

cartilage repair using microfracture with and without platelet-rich plasma (PRP)

in a chronic cartilage defect model in minipig knees.

Materials and Methods:

Six skeletally mature Göttingen minipigs received

two cylindrical full-thickness cartilage defects (Ø=6mm) in the trochlea in each

knee. The defects were allowed to become chronic for 5 weeks before they were

treated with microfracture with autologous 2mL PRP supplementation (Zimmer

Biomet) or saline. Animals were followed for 3 (n=3) and 12 (n=3) days. Normal

cartilage, debrided cartilage from chronic defects, and repair tissue at sacrifice

were collected for histological, immunohistochemical, and protein mass spec-

trometry (MS) analyses. Peptides were analyzed by liquid chromatography (LC)

tandem MS. Cluster 3.0, Java Tree View and Panther were used for clustering,

visualization and analysis.

Findings / Results:

Four days post-treatment a blood clot was formed with

red blood cells, loose matrix, and very few nucleated cells. Twelve days post-

treatment a vascularized, denser extracellular matrix with high cellularity had

replaced the blood clot. Of the 1213 proteins identified, 475 were expressed

in all samples. Protein clustering grouped samples from the same time-points

to highest degree (higher expression similarity). Proteins selectively expressed

in the PRP group were predominantly involved in metabolic processes. The col-

lagen composition in early cartilage repair (day 12) included types 1A1, 3A1,

6A1-3, 12A1 and 18A1 (endostatin) compared with types 2A1, 9A1 and 11A1

in normal cartilage.

Conclusions:

Complex processes in early cartilage repair can be identified and

visualized using repair tissue proteome analyses.

No conflicts of interest reported

179.