Abstract
Purpose :
Amniotic membrane (AM) has been shown to enhance corneal wound healing due to the abundance of growth factors, cytokines, and extracellular matrix proteins inherent to this tissue. As such, AM has significant clinical utility as a biological dressing for a number of ophthalmic and soft tissue applications. Our lab has developed a sterile, shelf-stable AM tissue graft utilizing a novel supercritical carbon dioxide (SCCO2) sterilization process in conjunction with lyophilization. The purpose of the current study was to investigate the incorporation and release profile of ophthalmic-relevant antibiotics in our AM graft product.
Methods :
Fresh placentas were procured through the Cooperative Human Tissue Network (Southern Division). The AM was isolated by blunt dissection, rinsed with a balanced saline solution and placed epithelial side up on nitrocellulose paper. The tissue was then subjected to SCCO2 sterilization and lyophilization (L-AM). L-AM and native AM (2 cm2) were loaded with commonly used ophthalmic bactericidals, moxifloxacin or ciprofloxacin at 500 µg/mL, 1 mg/mL, 2 mg/mL concentrations. The antibiotic-loaded membranes were allowed to air dry overnight after which AM was placed in 1mL PBS and aliquots taken at designated time points with PBS replaced after each sampling. Uptake-release kinetics for each loaded AM was measured by UV-Vis absorbance specific for antibiotics tested.
Results :
Amniotic membrane lyophilized prior to antibiotic loading (L-AM) demonstrated more than a 2-fold uptake of antibiotics compared to native AM. Approximately 50% of loaded antibiotic was released from AM within the first 5 min, and all concentrations of antibiotics tested displayed similar release profiles. Antibiotics continued to be released in decreasing concentrations over time out to 4 hrs.
Conclusions :
Our method of sterilization combined with lyophilization creates a tissue graft that can be used as a bandage or scaffold for ocular therapeutic applications without the need for costly and limiting storage requirements. Here we demonstrate the ability to preload lyophilized AM with commonly used ophthalmic antibiotics. The incorporation of antibiotics into our shelf-stable AM ocular bandage adds additional therapeutic value to the inherent biomolecules already present in this tissue (i.e. PTX3). Future studies include evaluating the efficacy of this tissue in treating infections in an ocular animal model.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.