Wound healing in the corneal epithelium in diabetic and normal rats

Morphometric analysis of the surface cells of rabbit corneal epithelium by scanning electron microscopy

The corneal surface of female New Zealand white rabbits (1.9-2.6 kg) was examined at x500 magnification by scanning electron microscopy. A total of 112 micrographs, taken as sequential sets from the center to the edge of the corneal surface from 8 different animals, was analyzed using a digitizer pad. Each cell was identified by the number of immediately bordering cells and by the nature of its electron reflex (light, medium, dark). Analysis of areas of the cells by number of bordering cells (number of cell sides) reveals a wide range of areas and skewed distributions especially when the number of sides is 5 or less. Overall, the cell-surface area increases as the number of cell sides increases. However, analyses of the mean surface areas for cells with different numbers of sides and additionally grouped by electron reflex suggests the existence of three separate populations of cells at the corneal surface. The possible etiology and dynamics of this complex cell mosaic are discussed in relation to circadian rhythms and to resurfacing of the cornea following mechanical trauma, ultraviolet radiation, and toxic chemical exposure.

Time-course and rate of healing after wounding the avascular mesentery in diabetic rats

The effects of inflicting trauma on the mesentery of diabetic and control rats by perforation with a scalpel were studied with regard to time-course of healing and rate of healing by closure. In this tissue, which is virtually free from blood vessels and nerves, healing precedes vascularization of the wound area. Insulin-deficient rats with streptozotocin diabetes of 4 weeks' duration were used. Non-specific histamine release and cell proliferation (expressed as specific DNA activity) lasting 30 h took place after opening the abdomen and handling the mesentery. Wounding caused further histamine release and cell proliferation. These variables were the same in diabetic and control rats. The time-course of healing was significantly delayed in diabetes, whereas the rate of healing (number of wound closures per day) during the phase of rapid healing was not. Because the rate of healing was normal in diabetic rats the impairment of healing in diabetes can be ascribed to pre-healing reparative events unrelated not only to vascular and neural factors but apparently also to the amount of histamine released and to the cell proliferation elicited by wounding. The delayed healing thus seems to be related to some cellular or metabolic feature of diabetes as yet unknown.

Wound healing with diabetes mellitus. Better glucose control for better wound healing in diabetes

Wound healing is impaired in diabetic patients with infection or hyperglycemia. Several approaches to glucose management are discussed for patients whose diabetic history has been stable and also for those whose diabetic condition is labile or poorly controlled.

Quantitative studies of corneal epithelial wound healing in rabbits

Corneal epithelial defects are covered rapidly by the movement of adjacent epithelium. However, the mechanism of this tissue movement is poorly understood. In this study, the quantity or cell water, protein, and DNA were determined in healing epithelium to test the hypothesis that cell enlargement contributes to the rapid coverage of the defect. In addition, light and transmission electron microscopy and [3H] thymidine incorporation into epithelial cells were used to determine whether the healing tissue moves as a unit or as individual cells. The quantitative determinations lead us to conclude that healing begins with a dramatic rise in cell water, followed by an increase in cell protein and finally by a gradual increase in DNA. The morphologic and autoradiographic evidence strongly suggests that large corneal epithelial defects in rabbits are covered by the movement of adjacent tissue as a unified, multilayered sheet of cells. Furthermore, the cells appear large than normal with minimal changes in intercellular spaces. We suggest that the increase in cell volume is due to water uptake, which plays an important role in covering the defect by increasing the cells' surface area. Protein is then accumulated, followed by cell proliferation.