Cultured skin substitutes: a review

Skin substitutes composed of cultured cells and biopolymers provide alternative materials for study of skin biology and pathology, treatment of skin wounds, safety testing of consumer products, and therapeutic delivery of gene products. Most frequently, substitutes for epidermis consist of cultured keratinocytes and dermal substitutes consist of resorbable biopolymers populated with cultured fibroblasts. Preclinical models characterize cellular morphogenesis, antigen expression, and barrier properties in vitro, and recovery of tissue function after grafting. Clinical considerations include time required to prepare cultured autografts, time required for graft vascularization, management of microbial contamination in wounds, mechanical fragility of cultured grafts, and high cost. Safety in graft preparation generally requires the use of materials and procedures that comply with standards for quality assurance. Efficacy of engineered skin substitutes has been evaluated predominantly by subjective criteria, but evaluation may become more objective and quantitative by application of noninvasive biophysical instrumentation. Future directions with engineered skin substitutes are expected to include gene therapy by addition or deletion of selected gene products and establishment of international standards for fabrication and assessment of engineered skin.