Functional transfer of integrin co-receptor CD98hc by small extracellular vesicles improves wound healing in vivo.

Extracellular vesicles (EVs) mediate intercellular communication. EVs are composed of a lipid bilayer and contain cytosolic proteins and RNAs. Studies highlight EVs striking functions in cell-cell crosstalk.

Duloxetine enhances PAX6 expression and suppresses innate immune responses in murine LPS-induced corneal inflammation.

Background-aim: PAX6 is a key regulator of eye development and epithelial homeostasis in the cornea. When deficient, chronic corneal inflammation, neovascularization and limbal stem cell deficiency can occur. Here we investigated the potential of duloxetine, a generic serotonin reuptake inhibitor that can upregulate PAX6 in vitro, for its in vivo activity in the context of corneal inflammation.

miR-184 represses β-catenin and behaves as a skin tumor suppressor.

miR-184-knockout mice display perturbed epidermal stem cell differentiation. However, the potential role of miR-184 in skin pathology is unclear. Here, we report that miR-184 controls epidermal stem cell dynamics and that miR-184 ablation enhances skin carcinogenesis in mice.

Eyes open on stem cells.

Recently, the murine cornea has reemerged as a robust stem cell (SC) model, allowing individual SC tracing in living animals. The cornea has pioneered seminal discoveries in SC biology and regenerative medicine, from the first corneal transplantation in 1905 to the identification of limbal SCs and their transplantation to successfully restore vision in the early 1990s. Recent experiments have exposed unexpected properties attributed to SCs and progenitors and revealed flexibility in the differentiation program and a key role for the SC niche.

Identification of the regulatory circuit governing corneal epithelial fate determination and disease.

The transparent corneal epithelium in the eye is maintained through the homeostasis regulated by limbal stem cells (LSCs), while the nontransparent epidermis relies on epidermal keratinocytes for renewal. Despite their cellular similarities, the precise cell fates of these two types of epithelial stem cells, which give rise to functionally distinct epithelia, remain unknown. We performed a multi-omics analysis of human LSCs from the cornea and keratinocytes from the epidermis and characterized their molecular signatures, highlighting their similarities and differences.

Production and Limbal Lineage Commitment of Aniridia Patient-Derived Induced Pluripotent Stem Cells.

Congenital aniridia is caused by heterozygous mutations on the PAX6 gene leading to reduced amount of PAX6 protein (haploinsufficiency), abnormal eye development, and aniridia-associated keratopathy (AAK). This progressive corneal opacification resembles late-onset limbal stem cell (LSC) deficiency, leading to disrupted corneal epithelial renewal. The factors leading to AAK are not known and defects in native LSC differentiation and/or features leading to ocular surface dysfunction like inflammation and loss of innervation could contribute to development of AAK.

Future directions in managing aniridia-associated keratopathy.

Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management.

MAPK Pathways in Ocular Pathophysiology: Potential Therapeutic Drugs and Challenges.

Mitogen-activated protein kinase (MAPK) pathways represent ubiquitous cellular signal transduction pathways that regulate all aspects of life and are frequently altered in disease. Once activated through phosphorylation, these MAPKs in turn phosphorylate and activate transcription factors present either in the cytoplasm or in the nucleus, leading to the expression of target genes and, as a consequence, they elicit various biological responses. The aim of this work is to provide a comprehensive review focusing on the roles of MAPK signaling pathways in ocular pathophysiology and the potential to influence these for the treatment of eye diseases.

Fibroblast growth factor-2 bound to specific dermal fibroblast-derived extracellular vesicles is protected from degradation.

Fibroblast growth factor-2 (FGF2) has multiple roles in cutaneous wound healing but its natural low stability prevents the development of its use in skin repair therapies. Here we show that FGF2 binds the outer surface of dermal fibroblast (DF)-derived extracellular vesicles (EVs) and this association protects FGF2 from fast degradation. EVs isolated from DF cultured in the presence of FGF2 harbor FGF2 on their surface and FGF2 can bind purified EVs in absence of cells.

Congenital aniridia beyond black eyes: From phenotype and novel genetic mechanisms to innovative therapeutic approaches.

Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities and systemic features making congenital aniridia a complex syndromic disorder rather than a simple isolated disease of the iris. Moreover, foveal hypoplasia is now recognized as a more frequent feature than complete iris hypoplasia and a major visual prognosis determinant, reversing the classical clinical picture of this disease. Conversely, iris malformation is also a feature of various anterior segment dysgenesis disorders caused by PAX6-related developmental genes, adding a level of genetic complexity for accurate molecular diagnosis of aniridia.

The antipsychotropic drug Duloxetine rescues PAX6 haploinsufficiency of mutant limbal stem cells through inhibition of the MEK/ERK signaling pathway.

Aniridia is a panocular disease causing progressive severe visual impairment and blindness due to PAX-6 haploinsufficiency. One of the most disabling ocular symptoms is aniridia-related keratopathy (ARK), a progressive corneal opacification due to epithelial impairment, vascular and conjunctival pathologies. There is currently no available treatment to prevent progressive visual loss.

TAp63 regulates bone remodeling by modulating the expression of TNFRSF11B/Osteoprotegerin.

MSC, mesenchymal stem cells; OPG, osteoprotegerin; RUNX2, Run-trelated transcription factor 2.

Ritanserin, a potent serotonin 2A receptor antagonist, represses MEK/ERK signalling pathway to restore PAX6 production and function in aniridia-like cellular model.

Aniridia is a panocular inherited rare eye disease linked to heterozygous mutations on the PAX6 gene, which fail to properly produce sufficient protein essential for normal eye development and function. Most of the patients suffer from aniridia-related keratopathy, a progressive opacification of the cornea. There is no effective treatment for this blinding disease.

Purification of Extracellular Microvesicles Secreted by Dermal Fibroblasts.

Extracellular vesicles (EVs) secreted by all cells are key players in information transfer within a tissue or organism. With their highly cell-specific protein and RNA content, EVs can propagate cellular signals and modulate distant cells' behavior. Dermal fibroblasts are supportive cells for all skin cells and the roles of their EVs start to come to light only recently.

Single-cell RNA-seq identifies a reversible mesodermal activation in abnormally specified epithelia of p63 EEC syndrome.

Mutations in transcription factor p63 are associated with developmental disorders that manifest defects in stratified epithelia including the epidermis. The underlying cellular and molecular mechanism is however not yet understood. We established an epidermal commitment model using human induced pluripotent stem cells (iPSCs) and characterized differentiation defects of iPSCs derived from ectrodactyly, ectodermal dysplasia, and cleft lip/palate (EEC) syndrome patients carrying p63 mutations.

Extracellular Vesicles from Activated Dermal Fibroblasts Stimulate Hair Follicle Growth Through Dermal Papilla-Secreted Norrin.

Dermal papilla cells (DPCs) play a pivotal role in the regulation of hair follicle (HF) growth, formation, and cycling, mainly through paracrine mechanisms. In the last decade, extracellular vesicles (EVs) have been recognized as a new paracrine mechanism that can modify the physiological state of recipient cells by transferring biological material. Herein, we investigated the effect of EVs isolated from stimulated human dermal fibroblasts (DFs) on DPC activation and HF growth.

SOX2 Regulates P63 and Stem/Progenitor Cell State in the Corneal Epithelium.

Mutations in key transcription factors SOX2 and P63 were linked with developmental defects and postnatal abnormalities such as corneal opacification, neovascularization, and blindness. The latter phenotypes suggest that SOX2 and P63 may be involved in corneal epithelial regeneration. Although P63 has been shown to be a key regulator of limbal stem cells, the expression pattern and function of SOX2 in the adult cornea remained unclear.

Modeling of Aniridia-Related Keratopathy by CRISPR/Cas9 Genome Editing of Human Limbal Epithelial Cells and Rescue by Recombinant PAX6 Protein.

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 of the corneal epithelium. It usually begins in the first decade of life, resulting in recurrent corneal erosions, sub-epithelial fibrosis, and corneal opacification.

microRNA-184 Induces a Commitment Switch to Epidermal Differentiation.

miR-184 is a highly evolutionary conserved microRNA (miRNA) from fly to human. The importance of miR-184 was underscored by the discovery that point mutations in miR-184 gene led to corneal/lens blinding disease. However, miR-184-related function in vivo remained unclear.

Induced pluripotent stem cell-derived limbal epithelial cells (LiPSC) as a cellular alternative for in vitro ocular toxicity testing.

Induced pluripotent stem cells hold great potential to produce unlimited amount of differentiated cells as cellular source for regenerative medicine but also for in vitro drug screening and cytotoxicity tests. Ocular toxicity testing is mandatory to evaluate the risks of drugs and cosmetic products before their application to human patients by preventing eye irritation or insult. Since the global ban to use animals, many human-derived alternatives have been proposed, from ex-vivo enucleated postmortem cornea, primary corneal cell culture and immortalized corneal epithelial cell lines.

Pluripotent Stem Cells and Other Innovative Strategies for the Treatment of Ocular Surface Diseases.

The cornea provides two thirds of the refractive power of the eye and protection against insults such as infection and injury. The outermost tissue of the cornea is renewed by stem cells located in the limbus. Depletion or destruction of these stem cells may lead to blinding limbal stem cell deficiency (LSCD) that concerns millions of patients around the world.

Pluripotent stem cells as a cellular model for skin: relevance for physiopathology, cell/gene therapy and drug screening.

The skin represents the largest tissue in the human body. Its external part, the epidermis, accomplishes vital functions such as barrier protection, thermoregulation and immune function. The mammalian skin epidermis has been for decades the paradigm for studying the molecular events that occur in tissue homeostasis and repair.