Abstract
Purpose :
To identify the lipid signature of retinal cells in porcine retinal sections and microarrays of Müller glia and Retinal Ganglion cells (RGCs) in primary cell culture, by Matrix Assisted Laser Desorption Ionization Imaging Mass Spectrometry (MALDI-IMS).
Methods :
Primary cultures of Müller glia and RGCs were established from adult pig retinas and retinal slices were obtained from adult pigs (n=6) for the in vivo studies. For the in vitro studies, isolated membranes and whole cells from primary cell cultures were printed onto glass slides using a non-contact microarrayer (Nano Plotter). The LTQ-Orbitrap XL analyzer was used to scan the samples in negative ion mode and the RGCs and Müller cells were then identified immunohistochemically. The spectra acquired were aligned and normalized, and a statistical analysis was carried out to select the lipids specific to each cell type in retinal sections and in the microarrays. The peaks of interest were identified by MS/MS analysis.
Results :
A cluster analysis of the MS spectra from the retinal sections identified the regions that correspond to the areas of RGCs and Müller glia, as confirmed by immunohistochemistry in previously scanned sections. The relative density of certain lipids differed significantly (p-value ≤ 0.05) between areas of Müller glia and RGCs. Likewise, the in vitro analyses showed different densities of lipids between RGCs and Müller glia cultures. Finally, a comparative analysis of the lipid profiles obtained from retinal sections and microarrays suggests a collection of six lipids that are characteristic of retinal cells. These lipids were identified by MS/MS.
Conclusions :
The lipid composition of the retina in vivo is preserved in primary cell cultures, as lipids in the RGC layer of the retina were also identified in RGC cultures and membranes. Some differences in lipids were found between RGCs and Muller glia. Further studies into these specific lipids and of their behavior in pathological conditions may well help to identify novel therapeutic targets.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.