Biomedical Engineering Reference
In-Depth Information
Table 12.1
Clinical limitations and considerations for use of cultured skin
substitutes (CSS)
Limitation
Consideration
Mechanical fragility
Special dressings and nursing care
Susceptibility to microbial contamination
Non-cytotoxic topical agents
Decreased rates of engraftment
Increased regrafting
Increased time to heal
Delay of recovery
Very high cost
Resource allocation
and during wound healing. These genes include cytokines, growth factors and
receptors, antimicrobial proteins and differentiation markers. The analysis sug-
gests that the keratinocytes in CSS are present in an activated state, similar to
wounded human skin. Combined with the expression patterns of MMPs observed
in CSS, these findings are consistent with remodeling of the dermal matrix and
differentiations of the stratified epidermal layer, processes that are observed
during wound healing.
12.4
Clinical considerations
Multiple factors of clinical care can be decisive in whether or not skin repair results
from the treatment of wounds by engineered skin substitutes. Anatomic and
physiologic deficiencies in the epidermal barrier and vascular plexus within skin
substitutes confer practical limitations (Table 12.1) that must be managed to
accomplish efficacy of wound closure. Currently available skin substitutes are
avascular, slower to heal than skin autograft and may be mechanically fragile.
Among the factors that have an impact on the outcome with engineered skin are
wound bed preparation, control of microbial contamination, dressings and nursing
care and survival of transplanted cells during vascularization of grafts. Therefore
multiple factors must be considered prior to using CSS for skin repair.
First, the wound bed must be prepared specifically for CSS. For example, split-
thickness autograft can be grafted onto subcutaneous fat with very high efficacy
(i.e. 80-90%), but cultured epithelial autografts most frequently fail if grafted over
fat. Thus modifications to the wound bed preparation protocol have been made. To
stimulate a vascularized wound bed, fresh cadaver allograft may be applied for 7-
10 days prior to grafting of CSS.
68
Pre-treatment of excised wounds with Integra
®
also stimulates a well-vascularized base to which CSS engraft readily.
38
To ensure
the highest probability of engraftment and healing, each CSS must pass quality
assurance tests and sterility tests prior to grafting. Grafted CSS must then be
protected from microbial infection and mechanical shear until the wound is fully
healed, which requires specialized dressings and nursing care. Attention to these
factors provides an environment which assures the high efficacy of the CSS as a
therapy for wound closure.
