These therapeutic effects appear to be independent of the polymeric structure of HA, since the work described here was done with a cross-linked bacterial HA, whereas in other studies [ 8- 10] non-cross-linked, high-molecular-weight preparations were found to be effective.
We therefore investigated whether different molecular weight HA preparations can affect proinflammatory cytokine (IL1β and TNFα) or chemokine (IL8, MCP-1 and RANTES) expression in human chondrocytes and synoviocytes isolated from OA patients.
It was demonstrated that the treatment of fibrosarcoma (HT1080) cells with various molecular weight hyaluronan preparations resulted in regulation of their migration capacity in a manner strictly dependent on HA size [ 34].
These are rare, particularly when using low molecular weight dextran preparations, 53, 54 but are serious events and have led to recommendations that i.v. iron dextran should be avoided.
Seven genomic DNA samples came from the UCLA international KIR exchange programme [ 37] and these were selected because they were recently extracted, high molecular weight DNA preparations from bulk cultures.
Of these studies, one investigated unfractionated heparin thromboprophylaxis, (Bozzetti et al, 1983) while another three studied the efficacy of different low molecular weight heparin preparations (dalteparin, nadroparin and enoxaparin, respectively) (Monreal et al, 1996; Mismetti et al, 2003; Verso et al, 2005).
Lang and colleagues demonstrated that a high molecular weight HES preparation (6% HES 670 kD) has no intrinsic non-thiol-dependent anti-inflammatory properties in vitro indicating that HES preparations may have pro-inflammatory effects.
Recently Tolouian et al. reported extensive deposits of iron in the mesangium and in the interstitial histiocytes in a patient with advanced diabetic nephropathy treated with ferumoxytol, another high molecular weight iron preparation, whereas renal iron deposition was not observed in another patient receiving IV iron dextran [ 33].
High molecular weight hyaluronic acid preparations are highly effective in relieving pain and have greater anti-inflammatory activity in vivo [ 35], while low molecular weight HA is similar to native hyaluronic acid.
