Advances in Wound Care

This study compares two different negative pressure wound therapy (NPWT) modalities in the treatment of venous leg ulcers (VLUs), the ultraportable mechanically powered (MP) Smart Negative Pressure (SNaP^®) Wound Care System to the electrically powered (EP) Vacuum-Assisted Closure (V.A.C.^®) System.

Patients with VLUs from 13 centers participated in this prospective randomized controlled trial. Each subject was randomly assigned to treatment with either MP NPWT or EP NPWT and evaluated for 16 weeks or complete wound closure.

Forty patients (n=19 MP NPWT and n=21 EP NPWT) completed the study. Primary endpoint analysis of wound size reduction found wounds in the MP NPWT group had significantly greater wound size reduction than those in the EP NPWT group at 4, 8, 12, and 16 weeks (p-value=0.0039, 0.0086, 0.0002, and 0.0005, respectively). Kaplan–Meier analyses showed greater acceleration in complete wound closure in the MP NPWT group. At 30 days, 50% wound closure was achieved in 52.6% (10/19) of patients treated with MP NPWT and 23.8% (5/21) of patients treated with EP NPWT. At 90 days, complete wound closure was achieved in 57.9% (11/19) of patients treated with MP NPWT and 38.15% (8/21) of patients treated with EP NPWT.

These data support the use of MP-NPWT for the treatment of VLUs.

In this group of venous ulcers, wounds treated with MP NPWT demonstrated greater improvement and a higher likelihood of complete wound closure than those treated with EP NPWT.

The contemporary treatment of a full-thickness burn consists of early eschar excision followed by immediate closure of the open wound using autologous skin. However, most animal models study burn wound healing with the persistence of the burn eschar. Our goal is to characterize a murine model of burn eschar excision to study wound closure kinetics.

C57BL/6 male mice were divided into three groups: contact burn, scald burn, or unburned control. Mice were burned at 80°C for 5, 10, or 20 s. After 2 days, the eschar was excised and wound closure was documented until postexcision day 13. Biopsies were examined for structural morphology and α-smooth muscle actin. In a subsequent interval-excision experiment (80°C scald for 10 s), the burn eschar was excised after 5 or 10 days postburn to determine the effect of a prolonged inflammatory focus.

Histology of both contact and scald burns revealed characteristics of a full-thickness injury marked by collagen coagulation and tissue necrosis. Excision at 2 days after a 20-s burn from either scald or contact showed significant delay in wound closure. Interval excision of the eschar, 5 or 10 days postburn, also showed significant delay in wound closure. Both interval-excision groups showed prolonged inflammation and increased myofibroblasts.

We have described the kinetics of wound closure in a murine model of a full-thickness burn excision. Both contact and scald full-thickness burn resulted in significantly delayed wound closure. In addition, prolonged interval-excision of the eschar appeared to increase and prolong inflammation.

Herein, we tested the effects of high levels of supplemental estrogen treatment on cutaneous wound healing.

Female mice were implanted with a 17β-estradiol (E₂) secreting pellet or placebo before receiving a full-thickness dermal excisional wound. Mice receiving the E₂ pellet attained hormone levels that are comparable to those achieved during pregnancy. At 1, 3, and 5 days after injury, the dermal excision wound was examined for their histologic appearance, rate of closure, and chemokine levels.

Wound closure, assessed by percent reepithelialization, was slower in E₂-treated mice relative to placebo (42.6%±6.6% vs. 70.0%±5.3%, respectively, 3 days after injury). In addition, there was a marked reduction in the subepithelial inflammatory infiltrate and granulation tissue in E₂-treated mice relative to placebo. Wound levels of monocyte chemoattractant protein-1 (MCP-1) were increased by 3 days after injury and continued to rise at 5 days after injury in placebo-treated mice (p<0.01). By contrast, MCP-1 levels were significantly reduced at 3 and 5 days after injury in E₂-treated mice relative to placebo-treated controls (p<0.01). This attenuation could be reversed by treatment with an estrogen receptor antagonist.

High levels of estrogen are able to suppress normal wound closure.

Dermal wound healing can be altered by manipulating the gonadal steroid hormone levels. In particular, high levels of estrogen can be utilized to slow down the rate of wound healing through a reduction in the inflammatory response.

Platelet-rich plasma (PRP) is a popular choice for the treatment of chronic wounds. Current dogma attributes these healing properties to the peptide growth factors of PRP. However, PRP is also rich in bioactive lipids whose contribution to healing has not been characterized and warrants investigation due to the protease-rich environment of chronic wounds.

The lipid fraction of PRP was tested with respect to proliferation and migration of primary adult human dermal fibroblasts (HDFa)±exposure to chronic wound fluid (CWF). This fraction was also characterized via LC-MS/MS for bioactive lipids. A synthetic formulation of the bioactive lipid composition was developed and tested for the ability to overcome proliferative growth arrest induced by CWF.

The data demonstrate the ability of the lipid fraction of PRP to significantly enhance the migration and proliferation of HDFa, and to overcome the proliferative growth arrest induced by CWF. Furthermore, the synthetic lipid formulation generated following characterization of the PRP lipidome demonstrated a similar ability to overcome proliferative arrest of HDFa in the presence of CWF.

For the first time, we demonstrate the relevance of the lipid fraction of PRP toward the biology of wound healing. These studies open the possibility of altering the lipid profile of PRP via diet or exogenous pathway manipulation to obtain a better healing outcome.

The lipid fraction of PRP is under investigated and yet relevant component in wound healing. The current study demonstrates the relevance of this fraction in wound healing by PRP.

Nanofibers for tissue scaffolding and wound dressings hold great potential in realizing enhanced healing of wounds in comparison with conventional counterparts. Previously, we demonstrated good fibroblast adherence and growth on a newly developed scaffold, Tegaderm™-Nanofiber (TG-NF), made from poly ɛ-caprolactone (PCL)/gelatin nanofibers electrospun onto Tegaderm (TG). The purpose of this study is to evaluate the performance and safety of TG-NF dressings in partial-thickness wound in a pig healing model.

To evaluate the rate of reepithelialization, control TG, human dermal fibroblast-seeded TG-NF(+) and -unseeded TG-NF(−) were randomly dressed onto 80 partial-thickness burns created on four female and four male pigs. Wound inspections and dressings were done after burns on day 7, 14, 21, and 28. On day 28, full-thickness biopsies were taken for histopathological evaluation by Masson-Trichrome staining for collagen and hematoxylin–eosin staining for cell counting.

No infection and severe inflammation were recorded. Wounds treated with TG-NF(+) reepithelialized significantly faster than TG-NF(−) and control. Wound site inflammatory responses to study groups were similar as total cell counts on granulation tissues show no significant differences. Most of the wounds completely reepithelialized by day 28, except for two wounds in control and TG-NF(−). A higher collagen coverage was also recorded in the granulation tissues treated with TG-NF(+).

With better reepithelialization achieved by TG-NF(+) and similar rates of wound closure by TG-NF(−) and control, and the absence of elevated inflammatory responses to TG-NF constructs, TG-NF constructs are safe and demonstrated good healing potentials that are comparable to Tegaderm.