REATTACHMENT OF CULTURED HUMAN RETINAL-PIGMENT EPITHELIUM TO EXTRACELLULAR-MATRIX AND HUMAN BRUCHS MEMBRANE

Purpose. To determine the mechanism of reattachment of harvested human retinal pigment epithelium (RPE) to RPE-derived extracellular matrix and Bruch's membrane. Methods. Confluent first- to third-passage human RPE were harvested from tissue culture and plated onto RPE-derived ex tracellular matrix or human Bruch's membrane exoplants denuded of cell s by treatment with 0.02 N ammonium hydroxide. The authors measured RP E reattachment to uncoated surfaces or surfaces precoated with extrace llular matrix proteins (fibronectin, laminin, vitronectin, or type IV collagen), antibodies to extracellular matrix proteins, or the synthet ic peptide RGDS (arginine-glycine-aspartate-serine). Some RPE were pre treated with anti-Pi integrin antibodies before plating onto either su bstrate. Results. Coating the surface of either RPE-derived extracellu lar matrix or Bruch's membrane with fibronectin, laminin, vitronectin, or type ni collagen increased the RPE attachment rate. Exposing RPE t o anti-pi integrin antibodies or RGDS or precoating the surface with a ntibodies to fibronectin, laminin, vitronectin, or type IV collagen de creased the RPE attachment rate to both surfaces. The RPE attachment r ate to Bruch's membrane was lower when the exoplants were harvested fr om the macula of older (age, 70 to 90 years) versus younger (age, 30 t o 40 years) persons (52.4 +/- 3.6% versus 64.3 +/- 3.5%, respectively; P < 0.05). Conclusions. The attachment of cultured human RPE cells to human Bruch's membrane or to RPE-derived extracellular matrix is medi ated by an interaction between the beta(1)-subunit of integrin on the RPE surface and ligands in the extracellular matrix that include lamin in, fibronectin, vitronectin, and type IV collagen. The lower rate of RPE reattachment to the macula from older human cadaveric eyes may hav e implications for studies aimed at RPE transplantation in elderly per sons.