Development of a three-dimensional lacrimal gland tissue construct in vitro
Dry eye syndrome (DES) is a complex, multifactorial disease that can eventually cause loss of vision. It has a number of aetiologies but one is dysfunction of the lacrimal gland (LG). In this instance, lacrimal fluid is either not produced, or production is incorrect in its composition or volume. Currently, treatments for DES remain palliative and so no curative treatment exists. Given that this disease is moderately prevalent, regenerative medicine approaches to clinical therapy for treatment of DES are becoming increasingly appealing.
This project will build on previous work performed by Dr. med. Kristina Spaniol who successfully demonstrated that cultured porcine LG cells could be re-seeded into very small portions (3mm in diameter) of decellularised porcine lacrimal glands. The cells were able to proliferate and maintain their function for up to 30 days in vitro. This work is important since it demonstrates proof-of-concept for this application.
Beyond this, the current project aims to scale up these earlier findings to a tissue dimension that would be clinically useful (i.e. one that could accommodate a sufficient number of functional cells to replace the normal function of an healthy LG). However, this introduces an increased level of complexity since vascularisation of the decellularised tissue will be required due to the short ischaemia time LG cells and limited diffusivity of oxygen and nutrients through tissue matrices.
To address this, we will collaborate with Dr. Marco Metzger and his team at the Universitätsklinik Würzburg who have expertise in decellularisation of small intestine submucosa (SIS). SIS has already been shown to be an excellent scaffold for many other cell types due to its extracellular matrix composition and, since it is an intact tissue (albeit decellularised), has pre-existing vascular architecture. This project will exploit SIS in two formats: firstly as a 2D substrate for lacrimal gland cell culture; and later as a 3D scaffold for lacrimal gland cell culture complete with vascularisation.
In 2D, parenchymal lacrimal gland cells will be cultured alone, or with endothelial cells or mesenchymal stem cells (MSC), or both. Culture success will be determined using numerous techniques to characterise cultures with particular emphasis on clinically relevant functional capabilities. Later, using the 3D system (BioVaSc), cultures will be further characterised. Endothelial cells isolated from foreskin will be seeded into the blood vessels of the SIS, before lacrimal gland cells are seeded into the central lumen of the SIS. This approach is far more biomimetic and clinically applicable than previous approaches to tissue engineering and will hopefully, eventually, be of benefit to DES patients.