Vegf-A mRNA transfection as a novel approach to improve mouse and human islet graft revascularisation
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The initial avascular period following islet transplantation seriously compromises graft function and survival. Enhancing graft revascularisation to improve engraftment has been attempted through virus-based delivery of angiogenic triggers, but risks associated with viral vectors have hampered clinical translation. In vitro transcribed mRNA transfection circumvents these risks and may be used for improving islet engraftment.
Mouse and human pancreatic islet cells were transfected with mRNA encoding the angiogenic growth factor vascular endothelial growth factor A (VEGF-A) before transplantation under the kidney capsule in mice.
At day 7 post transplantation, revascularisation of grafts transfected with Vegf-A (also known as Vegfa) mRNA was significantly higher compared with non-transfected or Gfp mRNA-transfected controls in mouse islet grafts (2.11- and 1.87-fold, respectively) (vessel area/graft area, mean ± SEM: 0.118 ± 0.01 [n = 3] in Vegf-A mRNA transfected group (VEGF) vs 0.056 ± 0.01 [n = 3] in no RNA [p < 0.05] vs 0.063 ± 0.02 [n = 4] in Gfp mRNA transfected group (GFP) [p < 0.05]); EndoC-bH3 grafts (2.85- and 2.48-fold. respectively) (0.085 ± 0.02 [n = 4] in VEGF vs 0.030 ± 0.004 [n = 4] in no RNA [p < 0.05] vs 0.034 ± 0.01 [n = 5] in GFP [p < 0.05]); and human islet grafts (3.17- and 3.80-fold, respectively) (0.048 ± 0.013 [n = 3] in VEGF vs 0.015 ± 0.0051 [n = 4] in no RNA [p < 0.01] vs 0.013 ± 0.0046 [n = 4] in GFP [p < 0.01]). At day 30 post transplantation, human islet grafts maintained a vascularisation benefit (1.70- and 1.82-fold, respectively) (0.049 ± 0.0042 [n = 8] in VEGF vs 0.029 ± 0.0052 [n = 5] in no RNA [p < 0.05] vs 0.027 ± 0.0056 [n = 4] in GFP [p < 0.05]) and a higher beta cell volume (1.64- and 2.26-fold, respectively) (0.0292 ± 0.0032 μl [n = 7] in VEGF vs 0.0178 ± 0.0021 μl [n = 5] in no RNA [p < 0.01] vs 0.0129 ± 0.0012 μl [n = 4] in GFP [p < 0.001]).
Vegf-A mRNA transfection before transplantation provides a promising and safe strategy to improve engraftment of islets and other cell-based implants.
KeywordsCell therapy Diabetes Gene delivery Graft revascularisation Islet transplantation Messenger RNA Pancreatic beta cell RNA delivery VEGFA
Gfp mRNA transfected group
In vitro transcription
modified Vegf-A mRNA transfected group
Severe combined immunodeficiency
Vegf-A mRNA transfected group
Vascular endothelial growth factor A
The authors thank V. Laurysens, A. Demarré and E. Quartier (BENE, Vrije Universiteit Brussel, Brussels, Belgium) for technical help. We also thank J. van den Ameele (Andrea Brand Lab, Gurdon Institute, University of Cambridge, Cambridge, UK) for revising the manuscript.
WS, EdK, CG, CH, KT, LB, HH and NDL designed and conceived the experiments. WS, YV, YH, GL and SDG acquired and analysed the data. EdK provided human islets. CH and KT provided Gfp mRNA, Vegf-A mRNA and modified Vegf-A mRNA. WS, YV, YH, CH, KT, CG, LB, HH and NDL interpreted the data. WS and NDL drafted the article. All authors revised the article and approved of the final version. NDL is the guarantor of this work.
The authors acknowledge support by grants from the Research Foundation Flanders (FWO), the VUB Research Council, Stichting Diabetes Onderzoek Nederland, the European Union Sixth and Seventh Framework Program, the Wetenschappelijk Fonds Willy Gepts (WFWG) of the UZ Brussel and the Belgian Federal Science Policy (IAPVII-07). WS is a PhD fellow of Research Foundation Flanders.
Duality of interest
The authors declare that there is no duality of interest associated with this manuscript.
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