The intra-articular injection of a new chitosan biomaterial prevents the progression of osteoarthritis in ACLT rabbit model

Purpose
To evaluate the effects of a single intra-articular injection of a new biomaterial consisting in a mix of alginate-chitosan (AC) beads and a viscous thermogelling chitosan-based (H) hydrogel on cartilage lesion in osteoarthritis (OA) rabbit model. These effects were compared to those obtained with the intra-articular injection of either chitosan-based (H) hydrogel without the AC bead or saline solution.
Methods
OA was surgically induced by the transection of the anterior cruciate ligament (ACLT) in HYLA albino rabbits. One week after surgery, animals were randomly divided into 3 groups: group I (n=7): mix of AC beads and H hydrogel; group II (n=7): H hydrogel alone; group III (n=7): saline solution (control). The treatments (900 µl) were injected intra-articularly. X-rays from the right knee were performed before surgery, at the time of injection and at sacrifice. The standard radiographs were acquired in extension and scored by the Kellgren and Lawrence (K&L) scale. After 6 weeks, animals were euthanized and the right joint was dissected. The macroscopic evaluation of cartilage from femoral condyles and tibial plateaus stained with India ink was done. Histological sections stained with Safranine-O/fast green from bearing areas of each compartment were evaluated according to the OARSI histological score. Briefly, the evaluation considered: staining of the cartilage matrix (0-6), cartilage structure (0-11), chondrocyte density (0-4) and cluster formation (0-3), where 0 represented a normal situation and 24 points the maximum severity score. Blood samples were collected the day of injection and prior the sacrifice. Prostaglandin E2 (PGE2) and C-reactive protein (CRP) were measured in serum using immunoassays.

Results
The X-rays analysis showed a significant decrease (p <0.05) of the K&L score in group I (AC beads and H hydrogel; 1.5 ± 0.2) compared with group II (H hydrogel; 2.2 ± 0.5) and group III (saline solution; 3.0 ± 0.4). The size and the severity of the macroscopic OA cartilage lesion tended to decrease in group I compared to the other groups. The histological global score that refers to all compartments of the knee joint was significantly decreased in group I (11.0 ± 0.7) compared to group II (14.4 ± 0.6, p <0.01) and group III (14.8 ± 0.6, p <0.001). No significant variation of PGE2 and CRP serum levels were observed in each after 6 weeks follow-up whatever the treatment injected.
Conclusions
This study showed that a biphasic hydrogel composed by AC beads and H hydrogel prevented OA in rabbit with ACL transection. This effect was not observed with the hydrogel alone, suggesting that AC beads play a role in joint protection. The preventive effect was observed in all joint compartments indicating a global protective effect of this new viscosupplementation.