Age-related changes in the extracellular matrix contribute to delayed wound repair

Age-related changes in the extracellular matrix contribute to delayed wound repair in aging. over wounds that received carrier (water) alone. Treatment with HA250 was associated with increased expression of transcripts for the hyaluronan receptors CD44 Canertinib (CI-1033) and RHAMM as well as collagens III and I. Analyses of dermal protein content by mass spectrometry and Western blotting confirmed significantly increased expression of collagen III in wounds treated with HA250 relative to control wounds. In summary we find that HA250 improves Canertinib (CI-1033) wound repair and increases the synthesis of collagen III in aged dermal wounds. Aging is associated with deficits in many stages of cutaneous wound repair including granulation tissue formation fibroblast proliferation and extracellular matrix (ECM) synthesis.1 One important but understudied component of dermal ECM is hyaluronan (HA). HA is a linear disaccharide polymer that can range from 2 to 25 0 disaccharides with molecular masses up to 2 × 102 kDa. HA is the most abundant nonproteinaceous component of dermis and is necessary for the organization assembly and homeostasis of wound ECM including dermal collagens.2-4 HA size (i.e. its molecular weight) determines its biological properties: higher molecular weight (HMW) forms of HA inhibit proliferation and migration of most cells whereas lower molecular weight (LMW) forms (ranging from oligosaccharides to polymers of 300 kDa) typically promote cell proliferation and angiogenesis.5-8 Although HA is associated with many cell types resident fibroblasts are primarily responsible for HA secretion in the dermis. HA in wound dermis largely reflects the activity of HA synthases 2 and 3. 9-11 Once secreted HA size is regulated primarily by cleavage via hyaluronidases.12 Although it is generally accepted that HMW-HA can inhibit processes necessary for wound repair and LMW-HA promotes inflammation angiogenesis and proliferation the size of HA and its subsequent effects are tissue specific.13 14 Fetal skin contains high levels of HMW-HA which is thought to induce healing without fibrosis and scar formation.15 It has been proposed that HMW-HA is critical to the scarless healing observed in fetal wounds by inhibiting myofibroblast differentiation and the subsequent expression of the fibrogenic transforming growth factor (TGF)-β1.16 In Rabbit polyclonal to ZNF276. contrast to the body of literature describing the involvement of HA in fetal wound repair the influence of aging on HA content and MW in normal Canertinib (CI-1033) tissues remains incompletely characterized.7 17 There is evidence that in normal tissues cleavage of HA into lower MW forms is altered by aging.7 17 We have found that in mice age-related impairments in dermal wound repair are correlated with a deficit in the production of LMW-HA.21 In the nervous system there is evidence that the presence of LMW-HA can block inflammatory signals that potentiate encephalitis. Moreover HA oligomers are implicated in toll-like receptor signaling mechanisms that affect oligodendrocyte maturation and remyelination during inflammation of the central nervous system.22 23 Regardless of the tissue Canertinib (CI-1033) studied Canertinib (CI-1033) it is generally accepted that cells can sense differences in HA size which makes a compelling argument for testing the effects of different HA sizes in accessible locations such as the dermis.24 We have recently found that aged wound dermis is less able to generate smaller forms of HA than young wound dermis.21 The present set of experiments was designed to determine the effect of HA of distinct sizes on dermal wound repair in aged mice. MATERIALS AND METHODS Animals Male C57/BL6 mice of 24 months of age were obtained from the NIA Aged Rodent Colony ( The Office of Animal Welfare at the University of Canertinib (CI-1033) Washington approved the care of mice and all procedures. Dermal wound model Aged (24 months old) mice received two dorsal 6 full-thickness dermal wounds as previously described.21 25 Wounds were covered with Tegaderm (3M St. Paul MN) to delay wound contraction a prominent feature of skin wound healing in rodents. Wounds were treated every 48 hours (beginning with day 0) with 100 μL of endotoxin-free water containing 10 ng HA/μL (the optimal concentration based on studies by others and our pilot studies of dermal fibroblast responses in vitro).13 We evaluated HA of specific MWs of 2 kDa (HA2) (= 8) 250 kDa (HA250) (= 11) and 1.