Diane Blake, Ph.D.

The Blake Laboratory has for several years focused their research efforts on the interactions of cells with their surrounding extracellular matrix. In the human cornea, they are studying the effects of extracellular matrix proteins on the proliferative capacity of human corneal endothelial cells. The corneal endothelium is essential to the maintenance of normal corneal hydration, thickness and transparency. Despite the critical importance of this cell layer in pumping water and salts out of the cornea, many investigators have shown that human corneal endothelial cells in vivo do not divide after an individual has reached approximately 10 years of age. Corneal endothelial cell density therefore decreases with increasing age and after ocular insults, and cells respond to this cell loss of injury by migrating into a wound site, restoring partial tight junctions, and reestablishing pump function. Although corneal endothelial cells have receptors for many growth factors, addition of growth factors will not induce these cells to proliferate. We have discovered that, in addition to signals from growth factors, human corneal endothelial cells required signals from the extracellular matrix before they would proliferate (Blake et al, (1997) IOVS 38:1119-1129). More recent (unpublished) studies have indicated that specific extracellular matrix receptors called integrins must be activated and ligated before cells can enter the cell cycle. Studies are underway in the laboratory to 1) determine the profile of extracellular matrix proteins synthesized by human corneal endothelial cells; 2) study the signal transduction pathways that lead to cell proliferation when cells are presented simultaneously with growth factors and extracellular matrix molecules; 3) determine the effects of extracellular matrix molecules on human corneal endothelial cell migration.

In the course of our studies with corneal endothelial cells, the laboratory has also discovered that an extracellular matrix molecule called thrombospondin-1 did not stimulate, but rather inhibited endothelial cell proliferation (Guo et al, (1992) PNAS 89:3040-3044, Vogel et al (1993) J. Cell. Biochem. 53:74-84). Peptide fragments derived from thrombospondin-1 have subsequently been shown to inhibit retinal angiogenesis in a retinal explant assay and a rat model of retinopathy of prematurity (Shafiee et al (2000) IOVS, in press). Studies are in progress to 1) test these peptide fragments in a primate model of ocular angiogenesis in order to bring them out of the laboratory and into the clinic; 2) use the technique of phage display to optimize the potency of these peptides; 3) devise constructs that could be used in a gene therapy approach to deliver the active peptides when a the retina becomes hypoxic.
Because this laboratory has developed a number of assays that test for the activity of angiogenic and anti-angiogenic compounds, they have also collaborated with other laboratories at Tulane to study the activity of such compounds. Such a collaborative study was just completed on an ascorbate derivative from green tea. This low molecular weight compound inhibited endothelial cell migration and proliferation, angiogenesis in a corneal pocket assay, and growth of C6 glioma cells implanted into the caudate/putamen of rats (Arimura et al (2000) Nature Medicine, submitted). The plan is to conduct Phase I clinical trials of this compound at the General Clinical Research Center of Tulane University.

To see Dr. Blake's curriculum vitae, click here.