The total transforming growth factor (TGF) β₂ concentration in the anterior chamber aqueous humor of 96 cataract patients with ages ranging from 17 to 88 years was measured using ELISA to investigate the changes that occur with age, difference of axial length, difference of localization of opacification of the cataractous lens and complications with other eye diseases. It was found that the total TGF-β₂ concentration (1) decreases with age, (2) shows slight changes with axial length, (3) has slight changes with difference of localization of opacification, (4) is significantly high in patients with concurrent open-angle glaucoma (p < 0.05), (5) is high in patients with complicating diabetes who have undergone panretinal photocoagulation for diabetic retinopathy (p < 0.05) and (6) is low in patients with atopic cataracts. There have been several reports on point 4 above, but none to date of the other points. These findings provide useful information on the intraocular activity of TGF-β₂.

While epidermal growth factor (EGF) has been found to exist in the human aqueous humor, which is necessary for maintaining the physiological condition of the lens, our immunohistochemical study confirmed the presence of EGF receptors and EGF in human lens epithelial cells (LECs), with EGF promoting growth potential and morphological change of the cells. Based on these findings, we feel that the effect of EGF upon human LECs is related to the movement of the cells in vivo.

Using a newly established fixation method and immunohistochemical methods, we precisely described the regions of cells stained with various antibodies relating to cell proliferation; this method enabled us to make cellular-level diagrams of the epithelium in which the position of every lens epithelial cell (LEC) was determined in reference to the cell located at the top of the bow area. The proliferating activity of LECs of 4-week-old (4W) mice was examined either by labeling with 5-bromodeoxyuridine (BrdU) in vivo or by measuring the amount of mRNA prepared from LECs, which had been separated into the posterior part, containing the germinative zone, and the anterior part and then cultured. The epithelial region stained with antibody for proliferating cell nuclear antigen (PCNA) and cyclin D1 remained relatively constant during the study period, although the positive region was reduced a little from embryonic day 18 (E18) to 12W. This region at 4W overlapped well with the DNA synthesizing region. Therefore, we reasoned that this region would correspond to the germinative zone of the adult mouse. Considering together with results of the reactivation pattern of genes, we considered that the location of tissue-type stem cells in lens epithelium (LE) as immediately anterior to the germinative zone.

Fas, Caspase 3 and single-stranded (ss) DNA are indicators of cell apoptosis. In the present study, Fas, Caspase 3 and ssDNA were found in the pyramidal opaque portions of anterior polar cataracts and the opaque portions of the anterior capsulotomy margin following intraocular lens (IOL) implantation. It is thus possible that apoptosis occurs in the lens epithelial cells in these regions, and this finding may be related to the fact that the pyramidal opaque portion of anterior polar cataracts and the opaque portions of the anterior capsulotomy margin following IOL implantation do not spread beyond a given range.

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