Research Marie-Jose Tassignon

Abstract

English Title: Tissue engineering for conjunctival reconstruction: Introducing self-assembled collagen-like-peptide scaffolds for the expansion of human conjunctival-derived cells in a xeno-free and serum-free environment. The human eye is a unique, biological complex but vulnerable entity. It lacks protection of keratinized epithelium against infection and desiccation, as seen in almost every other area of the body. However, the ocular surface is specialised to protect the ocular structures and respond rapidly upon injury, while maintaining a smooth refractive surface to ensure visual acuity. One of the specialised cellular layers contributing to ocular tissue homeostasis is the conjunctiva. This thin mucous membrane belongs to the ocular surface epithelia, covering the sclera and the inside of the eyelids. In some ocular disorders, the conjunctiva is damaged, resulting in extensive scarring and inflammation, which can lead to several pathological conditions such as eyelid distortions, tear film disruptions, severe dry eyes, corneal ulcers and eventually blindness. The management of severe conjunctival surface disorders remains challenging for ophthalmologists worldwide. The conventional treatment comprises the surgical excision of the diseased conjunctiva. Normal wound healing post resection is based on epithelial migration from adjacent healthy conjunctiva to the wounded area. However, this healing process cannot take place in patients lacking sufficient healthy residual conjunctiva. Here, fibrosis and scar formation will occur, often reintroducing several pathological conditions as described above. Hence to avoid sequelae, the ocular surface requires reconstruction post excision using a cellularized conjunctival substitute. In this project, we aim to meet this unmet medical need by creating a cellularized conjunctival substitute for reconstructive surgery. By introducing fully synthetic self-assembling collagen-like-peptide hydrogels as carrier for human conjunctival-derived cells and eliminating all animal-derived components, we aim to provide a safe, consistent and functional conjunctival replacement. The graft's functionality will be tested in vitro by means of specifically designed tests for presence of conjunctival epithelial cells (barrier formation against infectious microbes), mucin-producing goblet cells (tear film stabilization) and stem cells (epithelium renewal).

Researcher(s)

• Promoter: Koppen Carina
• Co-promoter: Tassignon Marie-Jose
• Fellow: Van Acker Sara

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

The overall aim of this project is to develop a scaffold with collagen nanofibre alignment to replace the existing use of human amniotic membranes for ocular surface reconstruction. The expected outcome is a standardized prototype composite graft with improved transparency, mechanical strength, bio-integration and reduced microbial susceptibility, realised through combining biomaterials engineering, protein surface modification and stem cell technologies. During the course of this research we intend to bring this prototype to a proof-of-concept in a rabbit model of limbal stem cell deficiency. This cutting-edge research will lay the groundwork for the development of sustainable biomimetic artificial corneas through an extension of its engineering.

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia
• Fellow: Haagdorens Michel

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

The conjunctiva is a thin membrane, which covers the white part of the eye and the inside of the eyelids. It is essential that this membrane functions correctly as it plays an important role in the maintenance of a healthy ocular surface and the preservation of vision. In some ocular disorders, the conjunctiva is damaged resulting in excessive scarring leading to surface disorders such as severe dry eyes, eyelid distortions and even blindness. Current treatment strategies for conjunctival reconstruction include surgically removing the diseased tissue and placing a human amniotic membrane over the bare sclera to aid in tissue regeneration. However, at times, either due to the nature of the diseased environment or a lack of properly functioning conjunctival epithelial stem cells, there is aberrant wound healing with scar formation, worsening the outlook for ocular reconstruction. In this project, we address this issue by creating a cellularized conjunctival substitute that can be transplanted onto the ocular surface after debridement of diseased tissue. This substitute is expected to reduce/eliminate scar formation and facilitate regeneration by providing a functional conjunctival replacement, containing both mucin-producing goblet cells to stabilize the tear film as well as conjunctival epithelium to establish a barrier to infectious microbes. The human amniotic membrane will be investigated as a biological scaffold for cultivating the cellular grafts for this purpose.

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia
• Fellow: Van Acker Sara

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

Human corneal endothelial cells (HCEnC) regulate fluid and solute transport across the posterior surface of the human cornea and actively maintain the cornea in a dehydrated state, which is crucial for optical transparency.The dual function of the corneal endothelium is described as the "pump-leak hypothesis" which is essential to allow nutrition to the cornea whilst maintaining its avascularity and transparency. There is no evidence that human endothelial cells divide under normal circumstances as they are arrested in G1 phase of the cell cycle, although they can be induced to divide in vitro. When the amount of corneal endothelial cells decreases below a certain threshold, this cell layer can no longer pump sufficient fluid back to the anterior chamber, resulting in an irreversibly swollen, cloudy cornea. Despite its success, corneal transplantation (either full-thickness or partial) is limited worldwide by the shortage of suitable donor corneas incurring long waiting times. Initial progress to overcome this global shortage is the use of one donor cornea for multiple partial keratoplasties ("split-cornea transplantations"), by using one donor cornea for a partial endothelial and a stromal transplantation. This project aims to investigate ex vivo expansion of corneal endothelial cells to develop a cell sheet based therapy. This would overcome donor deficit that limits the treatment of corneal endotheliopathies. The principle is to expand primary human corneal endothelial cells isolated from human cadavers and to seed them on an ideal scaffolding material to introduce these cells in the patient. Specifically in this project we propose the expansion of human corneal endothelial cells (HCEnC) on human lens capsules to obtain a composite graft. The final goal of this project is a proof-of-principle of this functional cell sheet in a rabbit corneal endotheliopathy model.

Researcher(s)

• Promoter: Koppen Carina
• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia
• Fellow: Van den Bogerd Bert

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

This is a fundamental research project financed by the Research Foundation – Flanders (FWO). The project was subsidized after selection by the FWO-expert panel.The human cornea is transparent and depends on this property to allow vision. Damage to the stem cell population that maintains the cornea surface results in Limbal Epithelial Stem Cells Deficiency (LSCD). This results in conjunctival overgrowth of the cornea with stromal scarring, corneal neovascularisation and opacification with decreased visual acuity, pain and photophobia. Current surgical treatment for LSCD includes transplanting large segments of donor excised limbal tissue but has a high risk of complications. Recent research has shown the benefit and feasibility of small limbal grafts cultured on biologically-derived scaffolds, e.g. human amniotic membranes. However, these are optically translucent at best. Being biologically derived they are difficult to standardise and carry potential health risks. Our objective, therefore, is to take a multidisciplinary approach to develop a synthetic alternative with superior cell-interactive properties that circumvents the problems with current limbal stem cell delivery scaffolds. Our research strategy is to exploit the recent introduction of human recombinant collagen that displays nano-fibre alignment under shear deposition to develop transparent, mechanically stable nano-implants that mimic the corneal collagen alignment seen in normal, healthy corneas. In order to further enhance cellular attachment, improved delivery and biointegration, the scaffolds will be enhanced through nano-printing of surface peptides. Collectively we will bring this nano-corneal scaffold to a proof-of-principle in animal models of limbal stem cell deficiency. By providing advancements in corneal regeneration we will be able to gain more insight into regenerative medicine as a whole. The data that we will acquire from this research will help us better understand the role that collagen nano-fibre alignment and surface nano-patterning plays in improving implant integration, and survival eventually paving the way to full thickness synthetic corneal replacements in the future. Our expected results include new scaffolds for delivery of stem cells that will have an impact of healthcare, in particular ophthalmology. However, the technologies developed also form a broader nanotechnology base that can be extended to regeneration of other target organs. An IP protection and dissemination strategy will ensure our economic and scientific impacts.

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

Each year, there are 1.5-2.0 million new cases of monocular corneal blindness due to ocular trauma and corneal ulceration. This includes 500 new cases in Flanders, while only 350 corneal transplants are performed annually. This project aims to develop biomimetic corneal constructs that will be fabricated using 3D printing and which will be seeded with corneal stem cells, which allows cost-effective manufacturing of customized structures with high resolution. This project will focus on innovation via interdisciplinary collaboration between production engineering, biomaterials and cell biology in ophthalmology in order to bring the 3D printed biocornea to a proof-of-concept. The overall goal is to create a biocornea that is optically transparent, with appropriate mechanical and geometric properties that can serve as a replacement for the existing use of cadaveric donor corneas

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia
• Fellow: Matthyssen Steffi

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

The overall aim of this project is to develop a scaffold with collagen nanofibre alignment to replace the existing use of human amniotic membranes for ocular surface reconstruction. The expected outcome is a standardized prototype composite graft with improved transparency, mechanical strength, bio-integration and reduced microbial susceptibility, realised through combining biomaterials engineering, protein surface modification and stem cell technologies. During the course of this research we intend to bring this prototype to a proof-of-concept in a rabbit model of limbal stem cell deficiency. This cutting-edge research will lay the groundwork for the development of sustainable biomimetic artificial corneas through an extension of its engineering.

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia
• Fellow: Haagdorens Michel

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

The overall goal is to create a bio-cornea that is optically transparent, with appropriate mechanical and geometric properties. Bio-compatability and integration will be determined in in vivo rabbit models of corneal transplantation. This project will focus on innovation via interdisciplinary collaboration between production engineering, biomaterials, and cell biology in ophthalmology in order to bring the 3D printed bio-cornea to a proof-ofconcept.

Researcher(s)

• Promoter: Tassignon Marie-Jose
• Co-promoter: Zakaria Nadia

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

The aim of the project is to investigate the role of growth factors secreted by lens fiber cells (LFCs) in the proliferation and differentiation of lens epithelial cells (LECs) left in the capsular bag after extra-capsular cataract extraction (ECCE) and intra-ocular lens (IOL) implantation and the pathophysiology of posterior capsule opacification (PCO) or after cataract. Capsular bags obtained after ECCE on post mortem donor eyes will be cultured according to Wormstone et al. (1997).

Researcher(s)

• Promoter: Tassignon Marie-Jose

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

Ocular hypertension has been recognized as the most important risk factor for the development of primary open angle glaucoma. New categories of drugs effective in reducing iop include topical CAI such as Dorzolamide. Although these new drugs are capable of reducing the IOP as of today a study demonstrating their efficacy in reducing the incidence of glaucoma does not exist. A randomized controlled trial would allow us to assess the efficacy of Dorzolamide in preventing patients affected by ocular hypertension from developing glaucoma.

Researcher(s)

• Promoter: Zeyen Thierry G P
• Co-promoter: Tassignon Marie-Jose

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Van Ooteghem Marcus
• Co-promoter: Ludwig Annick
• Co-promoter: Tassignon Marie-Jose

Research team(s)

Project type(s)

• Research Project

Abstract

In a previous study we showed that propanolol dilates isolated bovine retinal microarteries, possibly because of the Ca2+ antagonistic properties of the drug. In the present study we investigate whether Betaxolol, which is used in the management of glancoma patients, has similar dilatory effects.

Researcher(s)

• Promoter: Tassignon Marie-Jose

Research team(s)

Project type(s)

• Research Project