Assadian Ojan, Taher Fadi, Vass Zoltan, Bayer Sebastian, Assadian Afshin

1. Physical properties of a Methacrylate Dressing in the management
of moisture over a living human fibroblast-derived skin substitute
Assadian O1, Taher F2, Sebastian G. Bayer2, Vass Z1, Leaper DJ3, Assadian A2
1 Medical University of Vienna, Austria, 2 Wilhelminen Hospital Vienna, Austria, 3 Imperial College London, UK
Background
Significant advances have been made in the management of open, chronic wounds,
over the last decades. One such advancement, introduced more than 10 years ago
involves the application of human fibroblasts into the wound bed, which may
secrete dermal collagen, matrix proteins, growth factors, and cytokines to create a
human dermal substitute containing metabolically active living cells and promote
successful healing of chronic wounds. However, the role of secondary dressings
utilized in conjunction with human fibroblasts, as well as the secondary dressing’s
effect on the living cells and on wound healing, has not fully been elucidated.
While manufacturers recommend the use of human fibroblast skin equivalents in
conjunction with standard wound care regimens, some concern remains regarding a
potential inadequacy of traditional dressings, which may not be able to provide an
optimal, moist wound environment with controlled moisture vapor transport for the
live fibroblasts.
Recently, a flexible methacrylate dressing has been developed, which is based on a
dehydrated hydrogel modified into 60–65 µm small particles containing a poly-2-
hydroxyethyl-/poly-2-hydroxypropyl(pHEMA/ pHPMA)-methacrylate backbone
and terminal hydroxyl group which transforms into a wound contour, conforming
matrix once in contact with wound exudate. After aggregation, capillary channels
of approximately 7 nm widths promote removal of exudate from the wound surface
through a high moisture vapor transpiration rate of approximately 12,000
mL/m2/24 h, while at the same time promoting a moist wound environment for
healing. The aggregated dressing contains approximately 68% water, which is
similar to the water content of the skin (72–74%), further increasing its biological
compatibility. Inherent in these properties, there is the potential to compensate the
shortcomings of currently used secondary dressings for use with human fibroblasts.
Transforming Powder can be
applied from sterile pouch to
wound directly, or using
scalpel or spatula.
Close up of the powder
dressing.
Transforming Powder
dressing applied on
wound can be moisture
with saline or antiseptics.
The aggregated polymer
particles create a flexible
dressing with capillary pores
ranging between 4 and 7 nm.
The transformed dressing
allows moisture vapor transport
from the wound and transport of
oxygen to the wound surface.
Transformed Powder
dressing applied to
Simulated Wound
(Sponge with Saline)

2. Methods
The objective of this in-vitro experimental study was to investigate the
application of a transforming methacrylate dressing (TMD) as a
secondary dressing to a human fibroblast dressing (HFD) as a fibroblast-
derived dermal substitute serving as living skin equivalent in a simulated
wound model. HFD consisting of a human fibroblast-derived dermal
substitute product with TMD as a secondary dressing were studied of
fluid transfer and adhesion to a simulated wound model. The main
outcome measures were moisture vapor transmission rate (MVTR),
material water loss, pressure drop, and adhesive force.
Main Results
The amount of moisture removed for the combination of the HFD and
the dressing was substantial enough to provide MVTR through the
substrate at between 8 and 9 liters/m2/24h. The combination of HFD with
TMD resulted in a pressure drop of nearly 300 millitorr (mTorr) and the
TMD provided an anchoring force of 48 g/cm.
Conclusion
Total moisture managed as determined by MVTR for the combined
system is greater than that of the HFD alone and the adhesive force
created is sufficient to anchor the HFD to a simulated wound substrate.
Clinical trials combining HFD with a TMD as a secondary dressing are
warranted to confirm promising findings of the present study in an in-
vivo stetting.
HFD: Human Fibroblast Dressing (Dermagraft®)
TMD: Transforming Methacrylate Dressing (Altrazeal®)
Fig 1. Water loss of dressings and their combination over time

3. Fig 2. Change of moisture vapor transmission rate (MVTR), mg/cm2/ h
HFD: Human Fibroblast Dressing (Dermagraft®)
TMD: Transforming Methacrylate Dressing (Altrazeal®)
Fig 3. Pressure drop under dressings and their combination over time
HFD: Human Fibroblast Dressing (Dermagraft®)
TMD: Transforming Methacrylate Dressing (Altrazeal®)