Abstract

RationaleCongenital diaphragmatic hernia (CDH) results in lung hypoplasia. In severe cases, tracheal occlusion (TO) can be offered to promote lung growth. However the benefit is limited, and novel treatments are required to supplement TO. Vascular endothelial growth factor (VEGF) is downregulated in animal models of CDH and could be a therapeutic target, but its role in human CDH is not known. ObjectivesTo investigate whether VEGF supplementation could be a suitable treatment for CDH-associated lung pathology. MethodsFetal lungs from CDH patients were used to determine pulmonary morphology and VEGF expression. A novel human ex vivo model of fetal lung compression recapitulating CDH features was developed and used to determine the effect of exogenous VEGF supplementation (Figure 1A). A nanoparticle-based approach for intra-pulmonary delivery of VEGF was developed by conjugating it on functionalized nanodiamonds (ND-VEGF) and was tested in experimental CDH in vivo. O_FIG O_LINKSMALLFIG WIDTH=138 HEIGHT=200 SRC="FIGDIR/small/581170v1_fig1.gif" ALT="Figure 1"> View larger version (77K): org.highwire.dtl.DTLVardef@2ba882org.highwire.dtl.DTLVardef@4413d2org.highwire.dtl.DTLVardef@17155aborg.highwire.dtl.DTLVardef@1af7c73_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1C_FLOATNO (A) Schematic of the study design based on the analysis of the early-stage CDH fetal lung sections to assess early hypoplasia and VEGF impairment. In parallel, a human compression-based CDH model will be developed to validate the CDH phenotype and test a therapeutical approach to rescue lung hypoplasia. (B) H&E analysis of 18 and 22 pcw post-mortem CDH human lung tissue reveals impaired epithelial development compared to control healthy tissue at matching developmental stages. Scale bar 100m. (C) Morphometric analysis of CDH and healthy lung tissue at 18-22 pcw reveals decreased values of volume densities of air space (Vair%) and corresponding higher values of volume densities of alveolar septa (Vsep%) in CDH tissues compared to healthy tissue at the same developmental stages. A similar trend can be observed for the mean linear intercept of air space (Lma%) and its corresponding mean linear intercept of septal thickness (Lmw%). (D) Histologic analysis of VEGFA, KDR, Ki67 and NKX2-1 markers in normal and CDH fetal lung tissue at 18 and 22 pcw. Scale bar 100m. (E) Quantification of epithelial VEGFA and KDR expression reported in D shows a significant decrease for both markers in CDH compared to healthy samples. Correspondingly, the percentage of Ki67-positive epithelial cells is significantly lower in CDH compared to healthy samples, with no significant differences in the number of NKX2-1-positive cells. ***<p=0.001. (F) Immunofluorescence analysis of ECAD in normal and CDH fetal lung tissue at 18 and 22 pcw. Scale bar 100m. (G) Quantification of epithelial nuclear density based on results in Figure F shows no significant differences between CDH and healthy tissue. C_FIG Measurements and Main ResultsVEGF expression was downregulated in distal pulmonary epithelium of human CDH fetuses in conjunction with attenuated cell proliferation. The compression model resulted in impaired branching morphogenesis similar to CDH and downregulation of VEGF expression in conjunction with reduced proliferation of terminal bud epithelial progenitors; these could be reversed by exogenous supplementation of VEGF. Prenatal delivery of VEGF with the ND-VEGF platform in CDH fetal rats resulted in lung growth and pulmonary arterial remodelling that was complementary to that achieved by TO alone with appearances comparable to healthy controls. ConclusionsThis innovative approach could have a significant impact on the treatment of CDH.