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Shoumyo Majumdar, Xiaokun Wang, Jemin Jeremy Chae, Jeeyeon Sohn, James Qin, Jennifer Elisseeff; A versatile approach to modulate collagen fibrillogenesis to alter optical and biological properties of corneal implants.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3375.
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© ARVO (1962-2015); The Authors (2016-present)
Collagen fibrillogenesis can be controlled by pH, temperature, and ionic strength. Using these factors, we have previously developed a type I collagen based ‘vitrigel’ biomaterial with cornea mimetic fibril alignment and lamella formation via a controlled self-assembly process. In our current study, we aim to further gain control over modulation of fibrillogenesis in ‘vitrigel’ biomaterials through alternative gelation techniques, and assess the role of fibrillar networks in optical and biological properties and performance in vivo.
Ammonia-Mediated Collagen (AMC) gelation was achieved through exposure of 5mg/ml bovine collagen to ammonia vapors for different durations, gelation at 37°C, followed by slow vitrification at 5°C for 1 day and 40°C for 1 week and rehydration in buffer. Materials were tested for transparency in the visible spectrum, and fibrillogenesis was visualized using SHG microscopy. In vitro biocompatibility was tested using primary rabbit epithelial cells, followed by in vivo implantation in rabbit model.
AMC vitrigels were prepared at thicknesses up to 400 µm after vitrification, with different transparencies measured using microplate reader; in turn, transparency corresponded to variation in degree of fibrillogenesis as evidenced through Second Harmonic Generation microscopy (Figure 1). Biocompatibility of materials was verified through proliferation studies and immunostaining for epithelial cell markers; in vivo implantation using interrupted sutures in pilot animal demonstrated stability and viability as corneal implant material (Figure 2).
AMC vitrigels demonstrate that material properties including transparency can be easily influenced by the underlying ultrastructure, which was modulated using varying degrees of ammonia exposure. AMC materials also demonstrate the cytocompatibility through in vitro studies, in addition to suturability, biocompatibility and integration with host cornea in vivo.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Transparency of AMC membranes over visible light spectrum corresponds to degree of collagen fibrillogenesis with low, medium and high ammonia exposure times.
AMC vitrigels demonstrate in vitro biocompatibility and stain for K14 epithelial marker. AMC implanted in rabbit using interrupted sutures show full reepithelialization and integration with host cornea by day 31.
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