Project description:PAX6-related Aniridia is a sight-threatening disease due to progression of secondary glaucoma and aniridia associated keratopathy (AAK). Changes or loss of limbal epithelial progenitors causes the epithelial surfaces defects. We analyzed how PAX6 contribute to this with a two-step approach. 1) mRNA Sequencing of limbal epithelial cells isolated from controls and aniridia patients. 2) confirming the bioinformatical and literature-based result list on a siRNA based primary aniridia cell model (PAX6- knockdown). With this approach genes which are directly influenced by PAX6 should be distinguishable from genes secondary affected by AAK disease state. Therefore epithelial cells were isolated from the limbus region of two patients with aniridia and cultured in KSFM medium. Normal cells were obtained from limbus region of cadaveric control patients. For the siRNA based anridia cell model cells were transfected with lipofectamine and 5 nM siRNA against PAX6 or scrambled control. All cells were lysed to obtain DNA, RNA and protein. Reduction of PAX6 protein was controlled by Western Blot. Aniridia and Control Poly-A enriched RNA-librarys were subjected to Next Generation Sequencing. The differential analysis was a combination of quantification with RSEM and differential tests with edgeR. Gene lists were filtered by comparing to NCBI GEO Datasets, annotation with DAVID and manually annotation using literature search. For the resulting filtered gene list qPCR primer were ordered and postulated changes were verified with qPCR on siRNA based aniridia- cell model (Namely: TP63, ABCG2, ADH7, ALDH1A1, PITX1, DKK1, DSG1, K12, K3, K13, SPINK6, SPINK7, CTSV, SPERPINB1). We could identify genes which might be regulated by PAX6. We could show that SPINK7 mRNA coding for a protease inhibitor is downregulated in patients as well as in our primary aniridia cell model. ALDH1A1 and AHD7 mRNAs were reduced in limbal epithelial cells of aniridia patients (AN-LEC). Both transcripts were downregulated upon PAX6 knockdown in our cell model.Our siRNA-based aniridia cell model is a tool to proof identified PAX6 affected genes which might drive AAK pathogenesis. We could demonstrate, that this is the fact for transcripts coding for retinol converting enzymes. This provides evidence that PAX6 might drive corneal epithelial differentiation process by direct or indirect controlling retinoic acid signaling processes.
Project description:Heterozygous PAX6 gene mutations leading to haploinsufficiency are the main cause of congenital aniridia, a rare and progressive panocular disease characterized by reduced visual acuity. Up to 90% of patients suffer from aniridia-related keratopathy (ARK), caused by a combination of factors including limbal epithelial stem-cell (LSC) deficiency, impaired healing response and abnormal differentiation. It usually begins in the first decade of life, resulting in recurrent corneal erosions, sub-epithelial fibrosis and corneal opacification. Unfortunately, there are currently no efficient treatments available for these patients and no in vitro model for this pathology. We used CRISPR/Cas9 technology to introduce into the PAX6 gene of LSCs a heterozygous nonsense mutation found in ARK patients. Nine clones carrying a p.E109X mutation on one allele were obtained with no off-target mutations. Compared to the parental WT-LSCs, heterozygous mutant LSCs displayed reduced expression of PAX6 and marked slow-down of cell proliferation, migration and detachment. Remarkably, addition to the culture medium of recombinant PAX6 protein fused to a cell penetrating peptide was able to activate the endogenous PAX6 gene and to rescue phenotypic defects of mutant LSCs, suggesting that administration of such recombinant PAX6 protein could be a promising therapeutic approach of congenital aniridia. More generally, our results demonstrate that introduction of disease mutations into LSCs by CRISPR/Cas9 genome editing allows creating relevant cellular models of ocular disease that should greatly facilitate screening of novel therapeutic approaches.
Project description:Corneal epithelial stem cells reside in the limbus that is the transitional zone between the cornea and conjunctiva, and are essential to maintain the homeostasis of corneal epithelium. However, their characterization is poorly understood. Therefore, we constructed gene expression profiles of limbal epithelial SP and non-SP cell using RNA-sequencing. As a result, limbal epithelial SP cells have immature cell phenotypes with endothelial/mesenchymal cell markers, while limbal epithelial non-SP cells have epithelial progenitor cell markers.
Project description:ABCB5 is marker for Limbal epithilal stem cells. A comparison between ABCB5+ versus ABCB5- cultured human limbal epithelial cells was carried out to evaluate the properties of the limbal stem cell ABCB5+ with a special focus on their role in inflammation and angiogenesis.
Project description:Limbal epithelial stem cell (LESC) deficiency represents a significant clinical problem especially in bilateral cases. Induced pluripotent stem cells (iPSC) may be a promising source of LESC, allowing standardized and continual propagation and banking. The objective of this study was to generate iPSC from human limbal epithelial cultures and differentiate them back into limbal epithelial cells using substrata mimicking the natural LESC niche. Using Yamanaka’s episomal vectors limbal-derived iPSC were reprogrammed from LESC cultured from donor corneoscleral rims and from human skin fibroblasts. A clone from limbal-derived iPSC expressed stemness markers, had a diploid karyotype, and produced teratomas in nude mice representing three germ layers. Compared to parental LESC, this clone had fewer specific gene methylation changes revealed using the Illumina Infinium Methylation 450k Beadchips than compared to skin fibroblasts. The expression of putative LESC markers was examined by quantitative RT-PCR and immunostaining in limbal-derived and fibroblast-derived iPSC cultured on denuded human amniotic membrane or denuded cornea. Limbal-derived iPSC had markedly stronger expression of PAX6, ABCG2, Np63, keratins 14, 15, 17, and N-cadherin than fibroblast-derived iPSC. On denuded corneas, limbal-derived iPSC showed the expression of differentiated corneal keratins 3 and 12. The data suggest that iPSC differentiation to a desired lineage may be facilitated by their generation from the same tissue. This may be related to preservation of parental tissue epigenetic methylation signatures in iPSC and use of biological substrata similar to the natural niche of parental cells. The data pave the way for generating transplantable LESC from limbal-derived iPSC. Bisulphite converted DNA from the 12 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:We first reported that WNT16 has the advanced effect on the proliferation and stemness maintenance of human limbal epithelial stem cells. To investigte the potential mechanism of WNT16 regulation, RNA-seq was used to analyze the differential expressed genes and relative cellular pathways between WNT16-treated and wild type human limbal epithelial stem cells.
Project description:Purpose: To evaluate conjunctival cell microRNA and mRNA expression in relation to observed phenotype and genotype of aniridia-associated keratopathy (AAK) in a cohort of subjects with congenital aniridia. Methods: Using impression cytology, bulbar conjunctival cells were sampled from 20 subjects with congenital aniridia and 20 age and sex-matched healthy control subjects. RNA was extracted and microRNA and mRNA analysis was performed using microarrays. Results were related to the presence and severity of AAK determined by a standardized clinical grading scale and to the genotype (PAX6 mutation?) determined by clinical genetics. Results: Of the 2549 microRNAs analyzed, 21 were differentially expressed relative to controls. Among these miR-204-5p, an inhibitor of corneal neovascularization, was downregulated 26.8-fold, while miR-5787 and miR-224-5p were upregulated 2.8 and 2.4-fold relative to controls, respectively. At the mRNA level, 539 transcripts were differentially expressed, among these FOSB and FOS were upregulated 17.5 and 9.7-fold respectively, and JUN by 2.9-fold, all components of the AP-1 transcription factor complex. Pathway analysis revealed dysregulation of several enriched pathways including PI3K-Akt, MAPK, and Ras signaling pathways in aniridia. For several microRNAs and transcripts, expression levels aligned with AAK severity, while in very mild cases with missense or non-PAX6 coding mutations, gene expression was only minimally altered. Conclusion: In aniridia, specific factors and pathways are strongly dysregulated in conjunctival cells, suggesting that the conjunctiva in aniridia is abnormally maintained in a pro-angiogenic and proliferative state, promoting the aggressivity of AAK in a mutation-dependent manner. Transcriptional profiling of conjunctival cells at the microRNA and mRNA levels presents a powerful, minimally-invasive means to assess the regulation of cell dysfunction at the ocular surface.
Project description:Limbal stem cells including epithelial and stromal/Mesenchymal stem cells that contribute to sustained corneal homeostasis, maintain their ability to act as self-renewal progenitor cells by virtue of their limbal niche and intercellular communication. Extracellular vehicles (EVs), including exosomes (Exos), are important paracrine mediators through their cargo transfer for intercellular communication in various stem cell niches. Previously we have shown the differential cargos and regulatory roles of limbal stromal cell (LSC)-derived Exos, in limbal epithelial cells (LEC) in normal (N) and diabetic (DM) limbal niche. In the present study, to have a comprehensive knowledge of reciprocal LEC-LSC crosstalk, we investigated the proteomics and miRNA profile of exosomes derived from LEC and their regulatory roles in LSC in N and DM limbus. Our study showed wound healing and proliferation rates in primary N-LSC were significantly enhanced upon treatment by normal LEC-derived Exos (N-Exos), but not by diabetic Exos (DM-Exos). Further, N-Exos treated LSC showed downregulation of keratocyte markers, ALDH3A1 and lumican, but not keratocan, and upregulation of MSC markers, CD105, CD90, and CD73 compared to the DM-Exos treated LSC. Using next generation sequencing (NGS) and proteomics analysis, we revealed some miRNAs and proteins in the Exos that affect the cellular crosstalk and the function of the cornea. We also documented differences in DM vs. normal LEC-derived Exo’s cargos. Overall, DM-Exos have less effect on LSC proliferation, wound healing, and stem cell maintenance than N-Exos, likely by transferring their cargo proteins and/or regulatory miRNAs targeting cell cycle, ERK/MAPK, TGF-β, EMT, PI3K-Akt-mTOR signaling molecules. This suggests that the small RNA and protein cargo differences in DM vs. N LEC-derived Exos could contribute to the disease state. Our study revealed a complex contribution of Exos to health and diabetic state of corneal homeostasis and suggests the potential of EV therapeutics for diabetic cornea regenerative medicine