Protective effect of pyrroloquinoline quinine on cartilage in rabbit osteoarthritis models

Abstract

Objective To study the protective effect of pyrroloquinoline quinone (PQQ) on cartilate in rabbit osteoarthritis models.Methods Thirty-six 6-month-old Japanese white rabbits were randomly divided into experimental group,control group and sham-operation group ( 12 rabbits in each group).The osteoarthritis models at the right knee in experimental group and control group were established followed by the Huhh method.Animals in the experimental group were given intra-articular injection of 1 × 104 μmol/L PQQ (0.2 ml/kg body weight),3 days a week for 6 weeks.The same volume of saline was delivered in the control group.There was no special treatment on animals in the sham-operation group.Animals were sacrificed 6 weeks after anteroposterior X-ray evaluation.HE staining,type Ⅱ collagen immunohistochemical staining,chondrocyte apoptosis [TdT-mediated dUTP nick end labeling (TUNEL)] detection,and electron microscopy observation of mitochondrion changes in cartilage were done.Results Kellgren-Lawrance score in experimental group,control group and sham-operation group was 1.49 ±0.45,5.69 ± 1.08,and 0.28 ± 0.06,respectively,P ＜ 0.05.Degeneration changes of femoral condyle were alleviated by PQQ (JP score 1.46 ± 0.42,2.75 ± 0.60,0.08 ± 0.04,P ＜0.05 ).Mankin scores were 2.68 ± 0.86,6.95 ±1.46 and 0.25 ± 0.06,P ＜ 0.05 ; and number of apoptotic chondrocytes was ( 5.60 ± 1.20) ％,( 35.30 ±4.90) ％,(0.70 ± 0.30 ) ％,P ＜ 0.05.More mitochondrials were observed under an electron microscope (3.40 ± 0.68,1.24 ± 0.45,and 6.40 ± 1.20,P＜0.05 ).Well structured type Ⅱ collagen fibers were observed in the experimental group.Conclusion Intra-articular injection of PQQ can protect the cartilage during osteoarthritis development by alleviating the structure and function damage of the cartilage and promoting its metabolism and self-repair capacity.PQQ may take the function by protecting mitochondria in chondrocytes. Key words: Osteoarthritis; Pyrrololine quinone; Chondrocyte