Age-related Differences in Repair of Dermal Wounds and Myocardial Infarcts Attenuate During the Later Stages of Healing

Abstract

Background: It is unclear whether delays in wound repair due to the age of the host persist into the later stages of healing. Late stage healing of dermal wounds and myocardial infarcts in rodents was examined to determine if aged animals “catch up” to their younger counterparts. Materials and Methods: Excisional dermal wounds (5 mm) were made by punch biopsy and myocardial infarctions were produced by ligation of the left anterior descending coronary artery in young and aged mice and rats, respectively. Dermal wounds at day 11 and myocardial infarctions at day 14 were analyzed for wound area, angiogenesis, deposition of basement membrane proteins, and remodeling of collagen. Results: Analyses demonstrated that wound areas, the deposition of basement membrane proteins and angiogenic responses were similar in young and aged rodents at late stages of wound repair. The dermal wounds of young mice had larger quantities of mature, compacted collagen fibers relative to aged mice, but immature collagen fibers predominated in myocardial infarcts in both young and aged rats. Conclusion: These results show that, with the exception of dermal collagen remodeling, aged animals catch up to their young counterparts with respect to many features of tissue repair. Consequently, therapies that target age-related deficiencies in healing will be most effective when administered shortly after the initial insult.