Stimulatory effects of ascorbic acid on hyaluronic acid synthesis of in vitro cultured normal and glaucomatous trabecular meshwork cells of the human eye.

The outflow of aqueous humor of the primate eye occurs across the filter system of the trabecular meshwork (TM) into Schlemm's canal. Cells of TM derived from a normal (TM-N-cells) and a glaucomatous human eye (TM-G-cells) were established in monolayer culture. The present comparative experiments were performed with cells kept in a defined serum-free medium (the aqueous humor is nearly protein-free!).

Aging of trabecular meshwork cells of the human eye in vitro.

A monolayer cell line established from the trabecular meshwork of a human eye exhibited a limited proliferation potential with about 18 population doublings (PD). There was a gradual increase of the average PD time with increasing PD level. Finally, there was complete growth cessation.

In vitro cultures of trabecular meshwork cells of the human eye as a model system for the study of cellular aging.

Cells from the human trabecular meshwork providing a drainage system for the outflow of aqueous humour in the eye were isolated and propagated in monolayer culture. Following serial subcultivation of the primary cultures, there was a gradual decline in the fraction of dividing cells with increasing population doubling level (PDL) resulting finally in growth cessation and disintegration of these 'senescent' cultures. The number of population doublings was at most 20.

Exogenous glycosaminoglycans stimulate hyaluronic acid synthesis by cultured human trabecular-meshwork cells.

Addition of hyaluronic acid (50-200 micrograms ml-1) to the defined, serum-free media of cultured human trabecular-meshwork cells resulted in an increase of glycosaminoglycan (GAG) synthesis as measured by the incorporation of [14C]glucosamine. Lesser stimulatory effects were exerted by dermatan sulfate and chondroitin-4- or -6-sulfate. Nearly 90% of the labeled GAGs were found to be exerted into the medium and ea.

Hydrolysis of FMN and FAD by alkaline phosphatase of the intestinal brush-border membrane.

Both FMN and FAD were found to be hydrolysed with saturation kinetics by purified alkaline phosphatase (aPase E.C. 3.