Validation and assessment of an antibiotic-based, aseptic decontamination manufacturing protocol for therapeutic, vacuum-dried human amniotic membrane

Abstract

Amniotic membrane (AM) is used to treat a range of ophthalmic indications but must be presented in a non-contaminated state. AM from elective caesarean sections contains natural microbial contamination, requiring removal during processing protocols. The aim of this study was to assess the ability of antibiotic decontamination of AM, during processing by innovative low-temperature vacuum-drying. Bioburden of caesarean section AM was assessed, and found to be present in low levels. Subsequently, the process for producing vacuum-dried AM (VDAM) was assessed for decontamination ability, by artificially loading with Staphylococcus epidermidis at different stages of processing. The protocol was highly efficient at removing bioburden introduced at any stage of processing, with antibiotic treatment and drying the most efficacious steps. The antibacterial activity of non-antibiotic treated AM compared to VDAM was evaluated using minimum inhibitory/biocidal concentrations (MIC/MBC), and disc diffusion assays against Meticillin-resistant Staphylococcus aureus , Meticillin-resistant S . epidermidis , Escherichia coli , Pseudomonas aeruginosa and Enterococcus faecalis . Antibacterial activity without antibiotic was low, confirmed by high MIC/MBC, and a no inhibition on agar lawns. However, VDAM with antibiotic demonstrated effective antibacterial capacity against all bacteria. Therefore, antibiotic decontamination is a reliable method for sterilisation of AM and the resultant antibiotic reservoir is effective against gram-positive and –negative bacteria.

Synergistic efficacy of colistin and silver nanoparticles impregnated human amniotic membrane in a burn wound infected rat model

“…The literature proves that using nanoparticles with a smaller diameter (< 30 nm) increases the antibacterial activity of AgNPs against K. pneumoniae and S. aureus 27 . Marsit et al, (2019) reported excellent antibacterial activity of dried amniotic membranes loaded with polymyxin B against P. aeruginosa 20 . There could be several possible explanations for our results.…”

“…The stock solutions of colistin and AgNPs were prepared by adding 150 mg of colistin sulfate powder and AgNP powder separately into 100 mL of de-ionized water (20 min of sonication of AgNPs suspension with vortexing repeatedly for 5 days) in screw-capped glass bottles. A volume of 15.6 mL from the respective stock solutions was picked up and then added individually into 50 mL of distilled water in other screw-capped bottles to make 0.468 mg/mL dilutions of colistin and AgNPs for final use 17 , 19 , 20 . The formula used to calculate dilutions of colistin and AgNPs can be found in Supplementary Fig.…”

Prospects and Challenges of Translational Corneal Bioprinting

“…However, hAM has several limitations. The theoretic possibility of disease transmission, variation of growth factor content depending on the storage method, [22] and donor characteristics, [23] the processing following caesarean section is demanding, particularly to avoid bacterial contamination, [24] and, ultimately, the exact mechanism of action remains unclear [21]. For these reasons, and given the variable quality of this material and its reduced transparency, [18] new studies focused on the investigation of biological and synthetic alternatives.…”

Corneal Epithelial Stem Cells–Physiology, Pathophysiology and Therapeutic Options

“…Therefore, many techniques have been developed to preserve most of the biological properties of amniotic membranes by storage techniques and to prevent disease transmission to recipients [ 204 , 205 , 206 ]. In 2021, a cohort study from Queen Victoria Hospital and Maidstone Hospital showed that a dry and stable human amniotic membrane-derived matrix, Omnigen ® using OmniLenz ® (NuVision Therapies, Nottingham, UK), can easily be applied in the clinical setting with biochemical stability and efficiency as a novel tool to treat LSCD [ 207 , 208 ].…”