Biomedical Engineering Reference
In-Depth Information
distinctly different from what it was
in vivo
(Rennekampff
et al.
, 1997). Taken
together, these results indicate that care must therefore be used when interpreting
in vitro
studies.
In addition to supporting acute full-thickness wound healing, the RTM is
supportive of tissue formation in delayed wound healing models (Pietramaggiori
et al.
, 2008). When placed in genetically diabetic mice, the intact RTM not only
supported generation of a dense and vascularized wound tissue, but also demon-
strated an elevated fibroblastic cell proliferation noticeable within 9 days of
treatment. Cell proliferation declined to levels similar to non-treated controls by 21
days following treatment and the resulting tissue more closely resembled normal
dermis complete with epidermal migration from the wound periphery. Although
these responses were slightly enhanced by incorporating platelet-rich plasma into
the RTM, these results suggest the RTM stimulated enhanced tissue formation in
the wound which may ultimately provide accelerated healing when treating
chronic wounds.
10.4.2
Clinical studies of skin healing
The wound healing responses demonstrated in model systems have been translated
into clinical wound healing practice. In the treatment of full-thickness burns, RTM
demonstrated an equivalent graft take rate to STSG alone (Wainwright, 1995).
Histological analysis of biopsies taken at 16 days after grafting showed normal
collagen structure, fibroblast recellularization, neovascularization and re-epitheli-
alization in the absence of inflammatory cells. However, elasticity and cosmesis of
the healed wound with RTM were considered to be superior to STSG alone as
judged by both the patient and surgeon. These functional findings were confirmed
in a multi-center trial although the qualitative cosmetic assessments of the two
treatments were found to be equivalent (Wainwright
et al.
, 1996).
Smaller studies of burn patients have also replicated the ability of the RTM to
support immediate thin STSG grafting, although no statistical qualitative differ-
ences between test and control groups were found (Gore, 2005; Munster
et al.
,
2001; Sheridan
et al.
, 1998; Sheridan and Choucair, 1997). However, donor sites
for thin STSG harvesting exhibited faster healing times, thereby allowing more
rapid reharvesting, if necessary (Gore, 2005). Studies of grafting at joint areas,
such as hands, feet or shoulders (
Fig. 10.11
), with RTM and STSG have produced
good cosmetic results in these visible areas with limited scarring or contracture
(Lattari
et al.
, 1997; Tsai
et al
., 1999). Similar results with respect to graft take and
reduced contracture have been shown in a larger study evaluating performance
across a wide study demographic exhibiting variations in patient age, burn site, and
involved surface area (Callcut
et al
., 2006; Lattari
et al.
, 1997).
Cymetra, a particulate, injectable form, is similar to sheet AlloDerm RTM in that
it has been shown to support cell ingrowth and tissue regeneration without
producing inflammatory responses and host rejection (Maloney
et al.
, 2004;
