Research Project
3497091
Currently, the vitreous compartment of owl monkeys (Aotus trivirgatus) is used to evaluate viscoelastic hyaluronan ophthalmic medical devices before use in humans. More than one million patients per year receive HA during ophthalmic surgical procedures (intraocular lens implantation, intra and extra capsular lens extraction, penetrating keratoplasty, retinal detachment and glaucoma surgery). It is imperative that the HA substances used in these procedures be purified and noninflammatory. To date, no test other than the monkey vitreus test (MVT) has been able to predict, with the required consistency, the inflammatory/noninflammatory nature of HA materials. For several reasons, it would be advantageous to have a reliable alternative which could predict with reasonable certainty the nature of the substance. These reasons include the desire to reduce the frequency of testing involving primates and the desire to eliminate pain and injury to monkey eyes which may be caused by injection of an inflammatory substance. In addition, owl monkeys represent an expensive, limited, and ever decreasing resource. The mouse chemotaxis assay was developed as a potential substitute for the MVT. Preliminary testing with HA samples demonstrates that MVT results correlate with mouse chemotaxis results, and that inflammatory and noninflammatory HA can be distinguished by the mouse chemotaxis assay. In the mouse assay, test material in injected intraperitoneally (IP); after 24 hours the IP fluid is harvested and placed in the lower compartment of a chemotaxis chamber. The upper compartment contains fresh human leucocytes and the compartments are separated by a 2 um and a 5 um membrane. After 1.5 hours, the membranes are harvested and evaluated (cell number). Inflammatory HA has been found to produce chemotactic IP fluid (and elevated cell counts) while noninflammatory HA does not. Further, the potential exists for the development of a totally in vitro assay not requiring mice. The development of this assay may serve to greatly reduce the use of primates for this purpose, to a marked decrease in the cost of testing, and to an increased use of lower animals and tissue culture for sample evaluation.
