To evaluate the effect of adding exogenous extracellular matrix (ECM) proteins on the reattachment of retinal pigment epithelium (RPE) to the damaged surface of Bruch's membrane (BM).

Porcine BM explants were divided into six groups: BMs with an intact basal lamina (bl-BM) and five damaged BMs (d-BM: bare & four ECM-coated). The d-BM was coated with ECM proteins (either fibronectin, laminin, collagen IV, or all). Primary RPE sheets were plated and cultured for each group of BM explants. The attached live cells were counted and examined with a scanning electron microscope after three days, as well as at 1, 2 and 4 weeks.

The RPE reattachment rate was highest in bl-BM and lowest in uncoated d-BM. ECM-coated groups showed a lower reattachment rate than bl-BM, but when compared with the uncoated group, the reattachment rate was significantly increased (p<0.05). ECM-exposure time did not influence the reattachment rate of any of the groups. RPE cells plated on bl-BMs and ECM-coated d-BMs attached and proliferated well and achieved confluence over time. Even though most cells were flat and large in shape, some cells revealed a good morphology with microvilli on their surface. On the other hand, only some of the RPE sheets plated on the uncoated d-BM attached loosely and most cells remained round and clumped.

These results show that the addition of ECM proteins may increase the ability of RPE cells to reattach to the damaged BM surface, which would likely create a good morphology.