Abstract
Purpose :
The Schwalbe’s line region of Human Trabecular Meshwork (TM) has been demonstrated by us to harbour stem-like cells having high expression of ATP binding cassette protein G2 (ABCG2) and neural growth factor receptor (p75). In continuation, this study aims to elucidate whether the age related loss in TM cells is associated with loss of stem-like cells in the Schwalbe’s line region.
Methods :
Anterior segment with intact iris and ciliary body were dissected from human donor tissues (age group- <30 years, 30-60 years and >60 years, n=3 each) into 4 quadrants. Radial paraffin sections of minimum two quadrants were immunostained for ABCG2 and p75. Images were acquired using Leica SP8 confocal microscope. A minimum of 3 sections per quadrant were analysed in ImageJ. The total number of cells in the TM (including the filtering and the non- filtering region but excluding the Schlemm’s canal endothelial cells) and the cells positive for ABCG2 and p75 in each section were counted. Spearman rank order correlation was used to determine the correlation between age and the cell counts using Stata 14.0. P-value less than 0.05 was considered statistically significant.
Results :
The total TM cell count (Mean ± SD) from 18 sections per age group decreased significantly (Rho= -0.92; p=0.0004) with increase in age: 134±30 in <30 years; 93±16 in 30-60 years and 80 ±17 in >60 years. In younger donors (<30 years) 9±3% and 11±4% of TM cells had high positivity to ABCG2 and p75 respectively. These positive cells were restricted to the Schwalbe’s line region. The percentage of ABCG2 and p75 positive cells decreased significantly (Rho= -0.95; p= 0.0001 and Rho= -0.90; p= 0.0010 respectively) in higher age groups (30-60 years- ABCG2- 7±4%; p75- 7±6% and >60 years- ABCG2- 5±4%; p75- 0±1%).
Conclusions :
Presence of stem-like cells in the Schwalbe’s line region were observed to be significantly reduced with ageing and this reduction is associated with the loss in TM cells. Further studies are essential to understand the nature of these stem-like cells in glaucomatous condition.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.