Enhancing skin epidermal stability - Biomaterials for Treating Skin Loss - page 133

thickness skin graft was added to improve epidermal integrity/stability (Hollander
et al ., 2001).
The clinical take rate and stability of cultured epidermal cells are greatest when
there is a functional dermal element remaining. With a dermal element in place, the
take rate of Laserskin ® was found to be significantly lower in a porcine model
when keratinocyte seeding densities were reduced by half (Myers et al ., 1997). In
a more recent study, keratinocytes were delivered on Laserskin ® to full thickness
porcine wounds pretreated with Hyalomatrix ® . Delays in keratinocyte application
reduced take rates, however, this was reduced by repeated pre-treatment with
Hyalomatrix ® and a maximal take rate of 57.2% was measured (Myers et al .,
2007). The use of co-cultures of fibroblasts and keratinocytes has not fully been
examined although autologous fibroblast feeder layers, instead of murine 3T3 cells
have been used in a small number of clinical applications (Lam et al ., 2001).
Although hyaluronic acid is known to play an important role in wound healing,
clinical experience with this polymer is limited. Positive results have, however,
been recorded in a number of indications.
Burns
A combination of the dermal Hyalograft-3D ® and keratinocyte seeded Laserskin ®
has been used successfully (Scalise et al ., 2001) to treat patients with burn injuries,
diabetic, vascular and post-traumatic ulcers. No observations were made regarding
the stability of the grafts and the timing of long term follow up varied considerably
between patients. In another study involving six patients (Travia et al ., 2003), it
was determined that a dermal element is required to heal full thickness burns and
that the use of the TissueTech system (dermal and epidermal hyaluronic elements)
provides some positive results in terms of overall healing. In the treatment of a full
thickness burn (Harris et al ., 1999), interdigitations resembling rete ridges were
visible 24 days after grafting at the DEJ indicating good stability of Laserskin ®
grafted over Hyaff NW (Hyalograft-3D ® ) and after a 7-week period there was no
unusual scarring.
Take rates of 60-100% were observed in grafted Laserskin ® with a layer of
allogeneic fibroblasts on the upper surface onto which a layer of keratinocytes
were grown. Low numbers and lack of information about the burn depth meant that
little information could be gathered regarding the stability of the sheets. However,
they remained clinically intact at 12 weeks post graft (Harris et al. , 1999).
Scar revision/nevus
The manufacturer's instructions recommend the use of irradiated 3T3 cells as a
feeder layer for keratinocyte culture on Laserskin ® . However, Chan et al . (2001)
raised doubts over the use of 3T3 cells, as washing failed to remove them entirely.
They suggest an alternative method of cultivation using autologous or allogeneic