Abstract
Purpose :
Corneal injuries collectively represent a major global human health challenge, affecting hundreds of millions of people each year. Thus, there is a critical need for treatments that drive proper corneal wound healing. Polyphosphate (PolyP) is a biocompatible inorganic linear polymer composed of phosphate units. In the past few years, studies have shown that PolyP functions as a storage reservoir for ATP, regulates cell responses to stress, and increases cell proliferation. In this study we hypothesized that collagen crosslinked via electrostatic interactions using PolyP will form complexes that can support corneal wound healing by providing additional energy to facilitate cellular growth and normal cell function.
Methods :
PolyP-collagen complex was formed by adding PolyP45 to bovine collagen type 1. The presence of PolyP in the complexes was confirmed by adding DAPI and reading the fluorescence intensity using excitation/emission settings of 350/550 nm. Corneal epithelial cells (CECs) were seeded on PolyP-collagen complexes. Cell phenotype and morphology were evaluated via staining with CK3, ZO-1 and phalloidin. The intracellular content of PolyP and mitochondrial morphology was evaluated using DAPI and TOM 22 respectively, after 16 hours of cell starvation. Corneal wound healing was evaluated using an ex vivo model of organ culture. A lamellar keratectomy was performed in rabbit corneas followed application of PolyP-collagen. Corneal wound size was monitored daily using fluorescein.
Results :
CECs seeded on PolyP-collagen expressed CK3, ZO-1 and were able to proliferate forming a monolayer. Serum and glucose-starved CECs that were not treated with PolyP-collagen exhibited reduced intracellular PolyP and fragmented mitochondria morphology. Starved CECs treated with PolyP-collagen showed increased intracellular PolyP and normal tubulated mitochondrial morphology. PolyP-collagen treated rabbit corneas had 75% of the wounds healed by day 5 compared to 0% from the untreated group.
Conclusions :
CECs showed normal phenotype and biocompatibility in the presence of PolyP-collagen complexes. In addition, CECs were able to uptake PolyP-collagen that may have helped supply ATP to maintain normal mitochondrial function under starvation conditions. We suggest that intracellular PolyP levels may contribute to enhanced corneal wound healing and tissue regeneration
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.