Retinal pigment epithelium resurfacing of aged submacular human Bruch's membrane

To determine whether cultured fetal human retinal pigment epithelium (RPE) cells can attach and differentiate on submacular Bruch's membrane from donors over age 55.

Differential debridements of Bruch's membrane were performed to expose three different surfaces: the RPE basement membrane, the superficial inner collagenous layer (ICL) directly below the RPE basement membrane, and the deeper ICL. Approximately 3,146 cells/mm2 were seeded onto these Bruch's membrane explants and cultured for 1 or 7 days. Explants were bisected and examined histologically or analyzed with scanning electron microscopy. Nuclear density counts were performed on stained sections. Morphology and cell density were compared to those of cells seeded onto bovine corneal endothelial cell-extracellular matrix (BCE-ECM).

Compared to cells seeded onto BCE-ECM at similar density, cell coverage and cellular morphology were poor at both time points. Unlike cells on BCE-ECM, cell density remained the same or decreased with time. In general, cell morphology on all surfaces worsened by day 7 compared to day 1. Although cells were more pigmented on RPE basement membrane and deep ICL at day 7, poor cellular morphology indicated the remaining cells were not well differentiated. An explant from a donor with large soft drusen showed the poorest resurfacing at day 7 in organ culture.

These data indicate that aged submacular human Bruch's membrane does not support transplanted RPE survival and differentiation. The formation of localized RPE defects, cell death, and worsening cellular morphology on aged Bruch's membrane suggest that modification of Bruch's membrane may be necessary in patients with age-related macular degeneration receiving RPE transplants to prevent graft failure.