Augmented dried versus cryopreserved amniotic membrane as an ocular surface dressing

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Abstract

Purpose

Dried amniotic membrane (AM) can be a useful therapeutic adjunct in ophthalmic surgery and possesses logistical advantages over cryopreserved AM. Differences in preservation can significantly influence the bio- chemical and physical properties of AM, affecting clinical efficacy. This study investigates a novel drying technique and the biochemical and structural effects on AM and following pre-treatment of AM with novel lyoprotectants.

Methods

AM was cryopreserved (CPAM) or dried (DAM) with and without pre-treatment with lyoprotectants. Structural and visual comparisons were assessed using electron microscopy. Localisation, expression and release of AM biological factors were determined using immunofluorescence and immunoassays. The biocompatibility of AM preparations co-cultured with primary corneal epithelial cell (CEC) or keratocyte monolayers were assessed using standard cellular health assays.

Results

Drying devitalised AM epithelium, but less so than cryopreservation, and cellular damage was reduced in DAM pre-treated with lyoprotectant. DAM alone, and pre-treated with lyoprotectant showed greater factor retention efficiencies and bioavailability compared to CPAM. In addition cellular health assays showed that DAM alone and pre-treated with lyoprotectant are compatible and superior substrates compared to CPAM for CEC expansion, with increased proliferation and reduced cytotoxicity profiles. This was supported by improved wound healing in CEC co-cultured with DAM and pre-treated DAM, compared to CPAM.

Conclusion

Our modified preservation process and our resultant optimised DAM has enhanced structural properties and biochemical stability and is a superior substrate to conventional CPAM.

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