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Open Access Research article

Decrease in the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes in animals with osteoarthritis

Christoph Becher1, Thomas Szuwart2, Philipp Ronstedt2, Sven Ostermeier1, Adrian Skwara3, Susanne Fuchs-Winkelmann3 and Carsten O Tibesku4*

Author Affiliations

1 Orthopaedic Department, Hannover Medical School, 30625 Hannover, Germany

2 Institute of Anatomy, Westfalian Wilhelms University, 48149 Muenster, Germany

3 Department of Orthopaedics and Rheumatology, Philipps University Marburg 35043 Marburg, Germany

4 Sporthopaedicum Straubing, 94315 Straubing, Germany

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Journal of Orthopaedic Surgery and Research 2010, 5:28  doi:10.1186/1749-799X-5-28

Published: 26 April 2010

Abstract

Background

To evaluate the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA).

Methods

In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed. Four animals from each group were killed at 3, 6, and 12 weeks. After opening the knee joint, OA was macroscopically graded and hyaline cartilage of the load-bearing area was evaluated histologically according to the Mankin scale and by immunostaining for PTH1R.

Results

There was a positive linear correlation between the time after surgery and the macroscopic and histologic OA scores. The scores in the control group were constant over the time course. Immunostaining showed significantly less expression of PTH1R in the experimental compared to the control group after 6 (P < 0.05) and 12 weeks (P < 0.01). In the experimental group, a negative linear correlation between PTH1R expression and macroscopic and histologic grades was found.

Conclusions

The results show an in vivo decrease in the expression of PTH1R on chondrocytes over the time course of OA. Further studies are needed to evaluate whether new treatment approaches could evolve from this knowledge.