the 2007 Abstract Presentations - Wound Healing Society

Abstracts
3
FREEZING ALTERS THE VISCOELASTIC RESPONSE OF
UNINJURED SKIN AND HEALING WOUNDS
D.T. Corr 1,2 , C.L. Gallant-Behm 2 , N.G. Shrive 2 , D.A. Hart 2
1 Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY,
2 The McCaig Centre, University of Calgary, Calgary, AB, Canada
Aim: To determine if the practice of freezing skin, for storage and later testing,
alters its viscoelastic behavior, and the influences of wounding and directionality
on that behavior. We hypothesized that freezing would change the
absolute material property values significantly, but would not change the
relative effect of specimen orientation or scarring.
Methods: Tissue was harvested 70 days following full thickness wounding in
juvenile female domestic pigs (N = 12). Skin sections were halved, one half
tested fresh, and the others frozen and stored at 80 1C for subsequent testing.
Samples were obtained in the cranial-caudal and dorsal-ventral directions, for
both scar tissue and uninjured skin, and were evaluated using in vitro stress
relaxation in an INSTRON universal test machine. Frozen tissue was thawed
slowly, and equilibrated to room temperature prior to testing. Specimens were
kept moist throughout testing.
Results: Frozen skin produced similar values to those of fresh skin in many
instances. However, significant differences were observed in peak load, relaxation
rate, and total relaxation (p o 0.05). Freezing appears to increase the
viscous response (faster, larger relaxation) of uninjured skin, without similarly
affecting scars, indicating that tissue morphology may affect the retention of
moisture with freezing/thawing. Moreover, the significant trends in these
properties observed in fresh specimens - with respect to specimen direction
and scarring, were altered with freezing, yielding notably different directional
and scarring trends. Thus, freezing produced changes in both the absolute
values and relative response to specimen direction and scarring.
Conclusions: Freezing skin samples does alter tissue viscoelastic properties,
indicating that conclusions drawn from frozen skin and scar samples are not
indicative of what may be observed with fresh skin.
Acknowledgements: AIF, Ernst & Young, NSERC and CIHR.
4
A COMPARISON OF FUNCTIONAL CHARACTERISTICS OF
CULTURED KERATINOCYTES FOLLOWING SEVERE BURN
COMPARED TO NON-BURNED CONTROLS
G.G. Gauglitz, M.G. Jeschke, G.Hv. Donnersmarck, E. Faist, D.N. Hernond,
S. Zedler
Introduction: Keratinocytes are not only important for structural support of
the epidermis but also secrete biologically relevant growth factors that are an
integral part of inflammatory response and immune function. The aim of the
present study was to determine whether cultured keratinocytes obtained from
the proximity of a full thickness burn wound exert a different cytokine and
growth factor expression profile compared to keratinocytes obtained from
normal skin.
Method: Seventeen non-burned patients and 17 severely burned patients
(TBSA 4 25%) were included in the study. Immunohistochemistry was used
to detect cytokeratin, vimentin and other proteins in order to allow comparison
of cellular composition in allografts prepared from discarded tissue following
breast reduction versus autologous cultured keratinocytes. Skin cells were
cultured under standard conditions and in-vitro expression of mediators in the
culture media was quantified at 3, 10 and 15 days, using the Bioplex
immunoassay (10 cytokines and 5 growth factors). Statistical analysis was
performed by t-test with significance accepted at p o 0.05.
Results: Leukocytes, macrophages, dendritic, endothelial cells and fibroblasts
could not be detected in either autologous or in allogeneic transplants.
Histological analysis revealed an increased proportion of terminal differentiated
suprabasal cells in the allograft group compared to a higher proportion
of proliferative basal cells in the autologous group. Both culture groups
expressed large amounts of IL-1RA and IL-8 with no significant difference
between the groups. IL-6 and GM-CSF were significantly increased in the burn
group during the first 15 days of culture compared to controls (p o 0.05).
Conclusion: Epidermal basal cells from burns show increased proliferative
activity with increased mediator release. By skin grafting is a life-saving
procedure.
5
WOUND COVERAGE WITH MICROBIAL NANOCELLULOSE
IN TREATMENT OF DONOR SITE WOUNDS AND SKIN
AUTOGRAFTS AFTER SEVERE BURNS
Ludwik K. Branski 1 , Wojciech Czaja 2 , Marc G. Jeschke 1 ,
William B. Norbury 1 , Oscar E. Masters 1 , Yoshimitsu Nakano 1 ,
Daniel L. Taber 1 , R. Malcolm Brown 2 and David N. Herndon 1
1 Shriners Hospital for Children and University of Texas Medical Branch,
Galveston, Texas,
2 University of Texas at Austin
Introduction: In severely burned patients, early wound closure is essential and
the choice of the correct dressing paramount. Microbial Nanocellulose (NC),
an inert material produced by Acetobacter xylinum, has emerged as a new
coverage material that is very conformable, can hold a large amount of liquid,
and retains a high mechanical strength, therefore making it an ideal wound
dressing. Our aim was to compare NC and standard dressing material in a
porcine burn wound model.
Materials and Methods: Third degree burn wounds (Treatment: n = 10, control:
n = 8) were created using hot aluminum, excised 24 h post injury and
grafted with autologous skin transplant (4:1 meshgraft, wound size: 50 cm 2 ).
Donor sites (Treatment: n = 10, Control: n = 8) were created using an electric
dermatome. Oil emulsion dressing (Adaptic s , Ethicon, Inc.) was used as
control. Dressing changes were performed and standardized digital photographs
taken at 2, 5, 9 and 14 days post injury. Re-epitheliazation, graft
adherence, rate of infections, hematoma, fibrin deposition and rate of hypergranulation
were assessed at each time point using a macroscopic grading scale.
Results: In grafted wounds covered with NC, infections and hematoma occurred
significantly less than in the controls at day 5 and 9 (p o 0.05). Graft adherence
was significantly improved at day 9 (p o 0.003). Donor site wounds treated with
NC showed significantly less fibrin deposition, hematoma, hypergranulation, and
increased re-epitheliazation at day 9 (p o 0.04). 60% of the wounds in the NCgroup
vs. 20% in the control group were completely healed at this timepoint.
Conclusion: In a large animal trial, Microbial Nanocellulose accelerates wound
healing and proves to be a safe and efficacious wound coverage material for
donor sites and grafted wounds.
6
BISMUTH SUBGALLATE/BORNEAL (SUILE) VS.
NANOCRYSTALLINE SILVER IN THE HUMAN FOREARM
BIOPSY MODEL FOR ACUTE WOUND HEALING
Thomas E. Serena, MD, FACS 1,2 , Laura K.S. Parnell 3 , Michelle Kauffman 1
1 Gannon University,
2 Penn North Centers for Advanced Wound Care, NewBridge Medical Research,
3 Precision Consulting
Background: The human forearm biopsy model has been employed to evaluate
established and novel agents in acute wounds. Bismuth Subgallate/Borneol
(Suile) is a new product with FDA permission for the treatment of partial
thickness wounds. It was shown to be more effective than Bacitracin in an
earlier forearm biopsy study. It has been suggested that its efficacy is due to its
anti-inflammatory properties; although, it also has significant antimicrobial
activity. This study focuses on its comparison to a commonly used antimicrobial
dressing, Acticoat 3 TM (Smith and Nephew). Actcoat is a silver-coated
high-density polyethylene mesh.
Methods: In a randomized, investigator-blinded study, 40 normal healthy
volunteers underwent two 6 mm full-thickness skin punch biopsies on the flexor
surface of each forearm (two wounds/subject). Biopsies were randomly assigned
to receive Suile or Acticoat 3. Wounds were examined, measured and
photographed daily until healed. Adverse events were monitored. Time-tocomplete
closure was determined.
Results: Direct quantitative and qualitative comparisons of wound healing
were observed. There was a trend toward more rapid healing in the Suile group
particularly when the time to closure was examined on an individual basis:
comparing the healing times between a subject’s two biopsies. The subjects
reported more that the Suile dressing was more comfortable and demonstrated
less skin discoloration.
Conclusion: Suile has been shown to be an effective wound healing agent in the
forearm biopsy model. Based on the results of this and earlier studies its effect in
this model appears to be due largely to its anti-inflammatory properties as
opposed to its antimicrobial activity. Finally, the human forearm biopsy model
has several advantages: direct comparison within subjects, rapid study completion,
good patient compliance, and experience with products prior to embarking
on larger clinical trials in wounds.
Acknowledgement: Unrestricted Grant from Hedonist Biochemical Technologies.
Co.
Wound Rep Reg (2007) 15 A14–A54 c 2007 by the Wound Healing Society
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