Soluble Factors Released by Endogenous Viable Cells Enhance the Antioxidant and Chemoattractive Activities of Cryopreserved Amniotic Membrane

Objective: Regulation of oxidative stress and recruitment of key cell types are activities of human amniotic membrane (hAM) that contribute to its benefits for wound treatment. Progress in tissue preservation has led to commercialization of hAM. The majority of hAM products are devitalized with various degrees of matrix alteration. Data show the importance of hAM matrix preservation, but little is known about the advantages of retaining viable endogenous cells. In this study, we compared the antioxidant and chemoattractive properties of viable intact cryopreserved hAM (int-hAM) and devitalized cryopreserved hAM (dev-hAM) to determine the benefits of cell preservation. Approach: We evaluated the ability of int-hAM and dev-hAM to protect fibroblasts from oxidant-induced cell damage, to suppress oxidants, and to recruit fibroblasts and keratinocytes in vitro. Results: Both the int-hAM-derived conditioned medium (CM) and the int-hAM tissue rescued significantly more fibroblasts from oxidant-induced damage than dev-hAM (844% and 93% more, respectively). The int-hAM CM showed a 202% greater antioxidant capacity than dev-hAM. The int-hAM CM enhanced the recruitment of fibroblasts and normal and diseased keratinocytes to a greater extent than dev-hAM (1,555%, 315%, and 151% greater, respectively). Innovation and Conclusion: Int-hAM, in which all native components are preserved, including endogenous viable cells, demonstrated a significantly greater antioxidant and fibroblast and keratinocyte chemoattractive potential compared to dev-hAM, in which viable cells are destroyed. The release of soluble factors that protect fibroblasts from oxidative injury by hAM containing viable cells is a mechanism of hAM antioxidant activity, which is a novel finding of this study.