Establishment and performance assessment of an in-house 3D Reconstructed Human Cornea-Like Epithelium (RhCE) as a screening tool for the identification of liquid chemicals with potential eye hazard

Establishment of human corneal epithelial organoids for ex vivo modelling dry eye disease

Dry eye disease (DED) is a growing public health concern affecting millions of people worldwide and causing ocular discomfort and visual disturbance. Developing its therapeutic drugs based on animal models suffer from interspecies differences and poor prediction of human trials. Here, we established long-term 3D human corneal epithelial organoids, which recapitulated the cell lineages and gene expression signature of the human corneal epithelium. Organoids can be regulated to differentiate ex vivo, but the addition of FGF10 inhibits this process. In the hyperosmolar-induced DED organoid model, the release of inflammatory factors increased, resulting in damage to the stemness of stem cells and a decrease in functional mucin 1 protein. Furthermore, we found that the organoids could mimic clinical drug treatment responses, suggesting that corneal epithelial organoids are promising candidates for establishing a drug testing platform ex vivo. In summary, we established a functional, long-term 3D human epithelial organoid that may serve as an ex vivo model for studying the functional regulation and disease modelling.

Corneal epithelium models for safety assessment in drug development: Present and future directions

The human corneal epithelial barrier plays a crucial role in drug testing studies, including drug absorption, distribution, metabolism, and excretion (ADME), as well as toxicity testing during the preclinical stages of drug development. However, despite the valuable insights gained from animal and current in vitro models, there remains a significant discrepancy between preclinical drug predictions and actual clinical outcomes. Additionally, there is a growing emphasis on adhering to the 3R principles (refine, reduce, replace) to minimize the use of animals in testing. To tackle these challenges, there is a rising demand for alternative in vitro models that closely mimic the human corneal epithelium. Recently, remarkable advancements have been made in two key areas: microphysiological systems (MPS) or organs-on-chips (OoCs), and stem cell-derived organoids. These cutting-edge platforms integrate four major disciplines: stem cells, microfluidics, bioprinting, and biosensing technologies. This integration holds great promise in developing powerful and biomimetic models of the human cornea.

The Communication between Ocular Surface and Nasal Epithelia in 3D Cell Culture Technology for Translational Research: A Narrative Review

There is a lack of knowledge regarding the connection between the ocular and nasal epithelia. This narrative review focuses on conjunctival, corneal, ultrastructural corneal stroma, and nasal epithelia as well as an introduction into their interconnections. We describe in detail the morphology and physiology of the ocular surface, the nasolacrimal ducts, and the nasal cavity. This knowledge provides a basis for functional studies and the development of relevant cell culture models that can be used to investigate the pathogenesis of diseases related to these complex structures. Moreover, we also provide a state-of-the-art overview regarding the development of 3D culture models, which allow for addressing research questions in models resembling the in vivo situation. In particular, we give an overview of the current developments of corneal 3D and organoid models, as well as 3D cell culture models of epithelia with goblet cells (conjunctiva and nasal cavity). The benefits and shortcomings of these cell culture models are discussed. As examples for pathogens related to ocular and nasal epithelia, we discuss infections caused by adenovirus and measles virus. In addition to pathogens, also external triggers such as allergens can cause rhinoconjunctivitis. These diseases exemplify the interconnections between the ocular surface and nasal epithelia in a molecular and clinical context. With a final translational section on optical coherence tomography (OCT), we provide an overview about the applicability of this technique in basic research and clinical ophthalmology. The techniques presented herein will be instrumental in further elucidating the functional interrelations and crosstalk between ocular and nasal epithelia.

Addressing Human Skin Ethnicity: Contribution of Tissue Engineering to the Development of Cosmetic Ingredients

Recent publications describe various skin disorders in relation to phototypes and aging. The highest phototypes (III to VI) are more sensitive to acne, with the appearance of dark spots due to the inflammation induced by Cutibacterium acnes (previously Propionibacterium acnes). Dryness with aging is due to a lower activity of specific enzymes involved in the maturation of lipids in the stratum corneum. To observe and understand these cutaneous issues, tissue engineering is a perfect tool. Since several years, pigmented epidermis with melanocytes derived from specific phototypes allow to develop in vitro models for biological investigations. In the present study, several models were developed to study various skin disorders associated with phototypes and aging. These models were also used to evaluate selected ingredients’ ability to decrease the negative effects of acne, inflammation, and cutaneous dryness. Hyperpigmentation was observed on our reconstructed pigmented epidermis after the application of C. acnes, and pollutant (PM10) application induced increased inflammatory cytokine release. Tissue engineering and molecular biology offer the capability to modify genetically cells to decrease the expression of targeted proteins. In our case, GCase was silenced to decrease the maturation of lipids and in turn modify the epidermal barrier function. These in vitro models assisted in the development of ethnic skin-focused cosmetic ingredients.

Pharmacological evaluation of innovative eye drop formulations containing TS-polysaccaride, hyaluronic acid and glycyrrhizin for irritative ocular diseases using in vitro reconstituted human corneal epithelium model

In vitro reconstructed human corneal tissue models are closer to in vivo human corneal tissue in term of morphology, biochemical and physiological properties, and represent a valid alternative to animal use for evaluating the pharmacological effects ophthalmic topically applied medical devices. In this experimental work the in vitro reconstructed human corneal tissues have been used for assessing the potential beneficial effects of an innovative ophthalmic formulation containing hyaluronic acid, glycyrrhizin and TS-polysaccharide for the treatment of symptomatic states on the eye surface including dry eye, itching, foreign body sensation and redness due allergic reaction. Corneal tissues have been treated with benzalkonium chloride for 24 h to induce cell damage and then treated with the tested items for 16 h. After the incubation period, tissue viability, TNF-α, IL-6 and MMP-9 have been assessed. Diclofenac has been used as reference anti-inflammatory drug. The novel formulation protected the tissues against benzalkonium chloride damage, while exerted a mild but not significant reduction of the anti-inflammatory mediator TNF-α.

3D in vitro corneal models: A review of current technologies

Three-dimensional (3D) in vitro models are excellent tools for studying complex biological systems because of their physiological similarity to in vivo studies, cost-effectiveness and decreased reliance on animals. The influence of tissue microenvironment on the cells, cell-cell interaction and the cell-matrix interactions can be elucidated in 3D models, which are difficult to mimic in 2D cultures. In order to develop a 3D model, the required cell types are derived from the tissues or stem cells. A 3D tissue/organ model typically includes all the relevant cell types and the microenvironment corresponding to that tissue/organ. For instance, a full corneal 3D model is expected to have epithelial, stromal, endothelial and nerve cells, along with the extracellular matrix and membrane components associated with the cells. Although it is challenging to develop a corneal 3D model, several attempts have been made and various technologies established which closely mimic the in vivo environment. In this review, three major technologies are highlighted: organotypic cultures, organoids and 3D bioprinting. Also, several combinations of organotypic cultures, such as the epithelium and stroma or endothelium and neural cultures are discussed, along with the disease relevance and potential applications of these models. In the future, new biomaterials will likely promote better cell-cell and cell-matrix interactions in organotypic corneal cultures.