ab22306

The biological action of hyaluronan on human osteoartriticarticular chondrocytes: The importance of molecular weight

E. Maneiro¹, M.C. de Andres¹, J.L. Fernández-Sueiro¹, F. Galdo^1,2, F.J. Blanco¹

¹Laboratory of Investigation, Rheumatology Division, CHU Juan Canalejo, A Coruña; ²Department of Medicine. University of A Coruña, A Coruña, Spain.

ABSTRACT
Objectives
The intra-articular injection of hyaluronan (HA) was originally used in the treatment of osteoarthritis (OA) to increase the viscosity of synovial fluid. However, some findings suggest that the activity of HA cannot be solely explained by its biomechanical properties. The aim of this study was to analyze the in vitro biological effects of HA on human OA chondrocytes and the impact of its molecular weight (MW) on those effects.

Methods
Cells were isolated from cartilage obtained during joint replacement surgery in OA patients. The chondrocytes were cultured for 24 hours to detect prostaglandin E2 (PGE2) and for 48 hours to measure nitric oxide (NO), after which they were pre-incubated with HA and stimulated with interleukin-1 (IL-1) at 5 ng/ml. Two commercial HA preparations with different MWs were used: Hyalgan® (500-730 kDa, HA, Bioibérica S.A.) and Synvisc® (hylan of 6,000 kDa, Biomatrix Inc). NO was detected by the Greiss reaction and PGE2 was quantified by a commercial EIA in the supernatant. Apoptosis was induced by an NO donor (sodium nitroprusside, SNP) and the effect of HA on apoptosis was quantified by flow cytometry.

Results
Neither HA preparation studied had any effect on the basal production of NO or PGE2. However, the 500-730 kDa HA at 200 mg/ml reduced the synthesis of both IL-1-induced NO and PGE2 by 70% and 45% respectively. Furthermore both HA preparations at 200 mg/ml decreased the apoptosis induced by SNP, 500-730 kDa to 40% and 6,000 kDa to 36%.

Conclusion
HA may induce biological effects in addition to acting as a viscoelastic substance. This study suggests that HA preparations are different due to differences in biological activity resulting from MW.

Key words
Chondrocytes, nitric oxide, apoptosis, hyaluronan, osteoarthritis, molecular weight.

Presented in part at the 2001 OARSI World Congress, Washington DC, October 2001.
This study was supported by grants from Fondo de Investigacion Sanitaria, Spain (expediente 02/1700), Bioiberica S.A. Barcelona-Spain, and Secretar’a Xeral de I+D, Xunta de Galicia (expediente: PGIDIT02SAN91603PR). E. Maneiro was supported by FIS, Programa Investigadores del SNS. M.C. de Andres's work was supported by FIS-Spain: BEFI 02/9012.
Please address correspondence to: Dr. Francisco J. Blanco, Laboratorio de Investigación, Servicio de Reumatología, C.H. Universitario Juan Canalejo, C/ Xubias, 84, 15006 A Coruña, Spain.
E-mail: fblagar@canalejo.org