Human Adipose-Derived Stem Cell Conditioned Media and Exosomes Containing MALAT1 Promote Human Dermal Fibroblast Migration and Ischemic Wound Healing.

Objective: Chronically ill patients heal recalcitrant ulcerative wounds more slowly. Human adipose-derived stem cells (hADSCs) play an important role in tissue regeneration and exosomes secreted by hADSC contribute to their paracrine signaling. In addition to cytokines, lipids and growth factors, hADSC secrete mRNA, miRNA, and long noncoding (lnc) RNA into exosomes. In this study we examined the role of lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), an abundant lncRNA in exosomes from conditioned media (CM), on cell migration and ischemic wound healing. Approach: CM and isolated exosomes from hADSC were applied to human dermal fibroblast (HDF) in scratch assays and electric cell-substrate impedance sensing (ECIS) assays. CM was also applied to a rat model of ischemic wound healing and wound closure was followed. Results: CM stimulated cell migration of HDFs in vitro by 48%. CM stimulated the closure of ischemic wounds in a rat model 50% faster than unconditioned media. The depletion of MALAT1 in adipose-derived stem cell (ADSC) CM significantly reduced cell migration. Since MALAT1 is secreted into exosomes, a purified population of exosomes was applied to HDF where they enhanced cell migration in a similar manner to FGF-2 or basic fibroblast growth factor (bFGF) in ECIS wound healing assays. The uptake of exosomes by HDF was shown using dynasore, an inhibitor that blocks clathrin- and caveolin-dependent endocytosis. Depletion of MALAT1 in hADSC with antisense oligonucleotides resulted in exosomes without MALAT1. These exosomes had an effect similar to the unconditioned, control media in ECIS assays. Innovation: Exosomes contain lncRNA MALAT1 and other factors that have the potential to stimulate HDF cell migration and angiogenesis involved in wound healing without applying stem cells to wounds. Conclusion: Our results show the potential of using topically applied ADSC-derived exosomes containing MALAT1 for treating ischemic wounds. This allows for harnessing the power of stem cell paracrine signaling capabilities without applying the cells.

Prospective Randomized Controlled Trial Comparing the Effects of Noncontact Low-Frequency Ultrasound with Standard Care in Healing Split-Thickness Donor Sites.

BACKGROUND: Skin graft donor sites are notoriously painful, with potential complications of fluid loss, delayed healing, infection, and hypertrophic scarring, particularly in patients with burns or traumatic injury. In this population, rapid epithelialization is critical to reducing morbidity and cost. STUDY DESIGN: This prospective, randomized controlled trial compared the effects of 40-kHz noncontact low-frequency ultrasound (NLFU) in addition to standard care (SC) with SC alone in subjects with split-thickness donor sites of 20 to 200 cm(2). Standard care consisted of cleansing and moist wound dressings. Outcomes measured were time to healing, defined as absence of drainage and full epithelialization; pain and itching scores; and recidivism rates. RESULTS: Of 33 patients enrolled; 27 were randomized and received a minimum of 4 study treatments. Median age was 49 years, 69% were male, and 84% were burn patients. Comorbidities included hypertension (31%), coronary artery disease (22%), pulmonary disease (38%), anemia (31%), and diabetes (16%). Median donor site area was 136.0 cm(2). Noncontact low-frequency ultrasound and SC compared with SC demonstrated a mean time to heal of 12.1 days vs 21.3 days (p = 0.04). All NLFU+SC subjects had epithelialized by 4 weeks compared with only 71% in SC. Recidivism rates were 8% for NLFU+SC compared with 45% for SC. Pain scores were reduced and significant differences in itching were observed. CONCLUSIONS: Noncontact low-frequency ultrasound and SC compared with SC alone in the treatment of split-thickness donor sites demonstrated significant accelerated healing and reduced pain and itching. Noncontact low-frequency ultrasound subjects experienced a better quality of healing with less incidence of infection and recidivism.

Consequences of age on ischemic wound healing in rats: altered antioxidant activity and delayed wound closure.

Advertisements targeted at the elderly population suggest that antioxidant therapy will reduce free radicals and promote wound healing, yet few scientific studies substantiate these claims. To better understand the potential utility of supplemental antioxidant therapy for wound healing, we tested the hypothesis that age and tissue ischemia alter the balance of endogenous antioxidant enzymes. Using a bipedicled skin flap model, ischemic and non-ischemic wounds were created on young and aged rats. Wound closure and the balance of the critical antioxidants superoxide dismutase and glutathione in the wound bed were determined. Ischemia delayed wound closure significantly more in aged rats. Lower superoxide dismutase 2 and glutathione in non-ischemic wounds of aged rats indicate a basal deficit due to age alone. Ischemic wounds from aged rats had lower superoxide dismutase 2 protein and activity initially, coupled with decreased ratios of reduced/oxidized glutathione and lower glutathione peroxidase activity. De novo glutathione synthesis, to restore redox balance in aged ischemic wounds, was initiated as evidenced by increased glutamate cysteine ligase. Results demonstrate deficiencies in two antioxidant pathways in aged rats that become exaggerated in ischemic tissue, culminating in profoundly impaired wound healing and prolonged inflammation.