Development of an amniotic membrane tissue allograft for use as a wound dressing

Numerous techniques have been reported for preparing and sterilizing amniotic membrane (AM) for use in clinical applications; however, these preparations either do not render completely sterile tissue or are detrimental to molecules unique to the tissue matrix, thus compromising beneficial wound-healing properties of the AM graft. The objective of this work was to produce a sterile human AM tissue graft utilizing a novel preparation technique involving supercritical carbon dioxide (SCCO₂). AM tissue was subjected to various sterilization treatments that optimized the duration of exposure to SCCO₂ and amount of peracetic acid (PAA) to achieve a sterility assurance level of 10-6 log reduction in bacterial load. The effect of sterilization on the histological, biophysical, and biochemical properties of the AM graft was evaluated and compared to that of the native tissue. AMs treated with SCCO₂ were found to be excellent substrates for adipose-derived stem cell (ASC) attachment and proliferation in vitro. Human ASCs attached to all AM grafts after 24 hours of culture, irrespective of sterilization treatment, and continued to proliferate over the next few days. Furthermore, we evaluated the sterilized AM grafts with regards to integration into a full-thickness excision wound and their ability to promote wound healing in vivo. The current study's results indicate SCCO₂ can be used to sterilize AM tissue grafts while simultaneously preserving the biological attributes which make it appealing for use in numerous clinical and tissue engineering applications.