Senescence and the healing rates of venous ulcers

Premature cellular senescence has been linked to venous hypertension and may contribute to delayed healing of venous ulcers. We hypothesized that the percentage of senescent cells in in vitro populations of fibroblasts isolated from venous ulcers is directly related to the clinical time-to-healing.

Biopsy specimens were obtained from ulcer margins and unaffected dermal tissue of the ipsilateral thigh of seven patients with active venous ulcers. Using explant culture techniques, we obtained populations of wound fibroblasts and normal fibroblasts. The percentage of senescence in these cell populations was determined with X-Gal (5-bromo-4-chloro-3-indolyl beta-D-galactoside), which was used as a stain for B-galactosidase, a biomarker for senescent dermal fibroblasts. The X-Gal stain is a peroxidase stain for B-galactosidase. All patients in the study were treated with compression dressings. On a weekly basis, digital images were taken until ulcers healed. Planimetric healing rates were calculated from these images, and an overall time-to-healing was recorded. All cytologic investigations were performed on first passage cells.

The average starting ulcer size was 4.2 cm2. Five of the data points represented healed ulcers. The two remaining patients withdrew from the study to pursue other therapies after having been treated with compression dressings for a long time. Linear regression analysis of healed ulcers identified a relationship between percent of senescence and time-to-healing, which was statistically significant (R2 = 0.81, P =.037). High percentages of senescent cells also had a correlation with slowed planimetric healing, which was not statistically significant.

This study demonstrates a clinical correlation between quantitative in vitro senescence and time-to-healing. A percentage of senescence that is greater than 15% in populations of cells isolated from venous ulcers may identify a "difficult to heal" ulcer. There is no good clinical indicator for determining the likelihood of ulcer healing, but these results indicate that senescence percentage may have potential in this regard.