The role of different hyaluronic acids in the articular cartilage of rabbit.
OBJECTIVE
To elucidate if the differences found in the physico-chemical and rheological behaviour of Hyaluronic Acids result in different in vivo activity. For this purpose two Hyaluronic Acids (HA), HA-1 and HA-2, with similar molecular weight but different percentage of concentration variation, were compared through an osteoarthritis model.


METHODS
Osteoarthritis was induced in white New Zealand rabbits by anterior cruciate ligament section. After the induction period, the animals were allocated to receive HA-1 or HA-2 intra-articularly in one knee whereas the contralateral knee was used as Operated Control. An additional group of non-operated animals was used as Healthy Controls. Samples of cartilage were taken for different measures: apoptosis, nitric oxide (nitrites) and hyaluronic acid in synovial fluid.


RESULTS
The administration of HA-1 had a significant inhibitor effect on apoptosis of the chondrocytes compared to operated untreated animals (p = 0.0089), whereas this difference was not observed in the HA-2 knees. Levels of nitrites determined by HPLC in the HA-1 knees were similar to those in the Healthy group (p = 0.6551) whereas they were significantly higher in Operated Control and HA-2 groups (p = 0.0001). The comparison between HA-1 and HA-2 also revealed significantly lower levels of nitrites in the HA-1 knees (p = 0.0001). Values of hyaluronic acid in synovial fluid did not show statistical differences between the different study groups.


CONCLUSIONS
HA-1 and HA-2 showed different physico-chemical characteristics and these differences have resulted in different in vivo behaviour. As a consequence, not all the HA with similar molecular weight can be considered as equivalent.
Departamento de Ciencias Biomédicas, Facultad de Veterinaria, University of León, Campus de Vegazana s/n, León 24071, León, Spain.
Jaime Antonio
JA
Sánchez Lázaro
Pilar Coronel
PC
Granado
Mercedes Gimeno
MG
Del Sol
Ana
A
González Medina
Luis
L
Díaz Gállego
Daniel
D
González-Arabio Sandoval
Julio Gabriel
JG
Prieto Fernández