Analysis of the Biocompatibility of Different Intraocular Lens (IOL) Material Using Mass Spectrometry Tisssue Imaging

The cataract corresponds to the total or partial opacification of the lens of the eye preventing the passage of the light. At present, the surgery is the only effective treatment to overcome the cataract. The surgical intervention consists in removing the cloudy lens and to replace it by an artificial intraocular lens (IOL). The in vivo implantation of these synthetic lenses involves the evaluation of several factors as their physico-chemical properties, their capacities to interact with lens epithelial cells and proteins, as well as their biocompatibility. During a previous study, we demonstrated major differences concerning the tackiness (atomic force microscopy), the cellular adhesion and the protein adsorption of various polymer disks intended for the manufacturing of intraocular lenses. The aim of this work was to correlate a histological analysis to a mass spectrometry imaging analysis performed on the same sample. To estimate the biocompatibility of the biomaterials, an animal testing was realized in rabbits. The various polymers were implanted subcutaneously. After one month, the 2 cm x 3 cm pieces of rabbit skin and underlying muscle with a 2 cm thickness were removed, fixed with formaldehyde 10% during six days, treated for the paraffin inclusion and stored at room temperature until use. Slices of 5 µm thickness were performed using a microtome. Paraffin was removed and tissue sections were washed in graded ethanol baths. The slices were then stained with the hematoxylin and eosin dyes. The analysis of stained sections showed different histo-morphological features according to the implanted polymer. For MALDI MSI purposes, on tissue protein digestion was performed using trypsin (1) and the MALDI matrix (α-cyanohydroxycinnamic acid, 5 mg/mL in ACN/0.2% TFA 70:30) was deposited using an ImagePrep automated sprayer (Bruker Daltonics, Bremen, Germany). Experiments were carried out using an UltraFlex II TOF/TOF mass spectrometer (Bruker Daltonics, Bremen, Germany). MALDI imaging can show the detection of different proteomic profiles according to the tested biomaterials, which may be considered as biocompatibility markers. The MALDI images of these markers are then correlated with the histo-morphological profiles. Consequently, mass spectrometry imaging can become a powerful tool in the evaluation of the biocompatibility of artificial implants in biomedical application.LIONEL, Procédé innovant de mise en œuvre de lentilles intraoculaires souples à partir d’un matériau de type nanocomposit