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Oliver Borsch, Sílvia Llonch, Sylvia Gasparini, Marius Ader; Donor-host material transfer is photoreceptor-specific and comprises mRNA but not mitochondria. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2881.
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© ARVO (1962-2015); The Authors (2016-present)
Recent studies demonstrated that subretinally transplanted photoreceptors remain at the injection site and, instead of structurally integrating into the host tissue, mainly exchange cytoplasmic material with endogenous host photoreceptors by an as yet unknown mechanism. In order to better understand this process, we aimed to assess whether material transfer is (I) photoreceptor-specific and (II) which cytoplasmic components are transferred.
In order to evaluate (I) the material transfer potential of non-photoreceptor cells after transplantation, we isolated different neuronal (retinal and cortical neurons), and non-neuronal (bone marrow) donor cell types from a Cre-driven fluorescent (tdTomato) reporter mouse line (Ai9) and subretinally transplanted cell suspensions into photoreceptor-specific Cre-expressing mice (B2-Cre, n=4/group). (IIa) To analyse whether mRNA is exchanged, male donor photoreceptors isolated from postnatal day (P) 4 Nrl-GFP reporter mice were transplanted into adult wild-type female hosts (n=4). Single cell RT-qPCR of FACS-sorted GFP+ cells was conducted to assess the presence of GFP-mRNA within female host cells (n=54). (IIb) Exchange of larger cytoplasmic components such as organelles, i.e. mitochondria, was investigated by transplanting P4 donor photoreceptors isolated from a double reporter mouse line labelling mitochondria and cell membranes independently (mito-Dendra2/membrane tdTomato) into adult wild-type mice (n=4).
While (I) transplanted photoreceptors in the in vivo Cre/loxP assay led to reporter expression in both donor and host photoreceptors (3307±2381), only marginal fluorescence was visible upon transplantation of other retinal cells (452±217; p≤0.05), cortical neurons (10±9; p≤0.01) or bone marrow cells (0; p≤0.01), indicating that material transfer is largely photoreceptor-specific. (IIa) Single cell RT-qPCR of the GFP+ host (female) photoreceptors revealed that mRNA is exchanged between donor and host cells (25%). (IIb) After transplanting donor photoreceptors with fluorescent cell membranes and mitochondria, host photoreceptors only displayed the donor membrane-reporter (245±60) but no donor mitochondria signal, indicating that mitochondria are not transferred.
Our results indicate that material transfer is photoreceptor-specific and comprises the transfer of mRNA but not mitochondria.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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