The influence of fibroblast on the arachnoid leptomeningeal cells in vitro

Characterization of primary human leptomeningeal cells in 2D culture

Maintaining the integrity of brain barriers is critical for a healthy central nervous system. While extensive research has focused on the blood-brain barrier (BBB) of the brain vasculature and blood-cerebrospinal fluid barrier (BCSFB) of the choroid plexus, the barriers formed by the meninges have not received as much attention. These membranes create a barrier between the brain and cerebrospinal fluid (CSF), as well as between CSF and blood. Recent studies have revealed that this barrier has been implicated in the development of neurological and immunological disorders. In order to gain a deeper comprehension of the functioning and significance of the meningeal barriers, sophisticated models of these barriers, need to be created. The aim of this paper is to investigate the characteristics of commercially available primary leptomeningeal cells (LMCs) that form the meningeal barriers, in a cultured environment, including their morphology, proteomics, and barrier properties, and to determine whether passaging of these cells affects their behaviour in comparison to their in vivo state. The results indicate that higher passage numbers significantly alter the morphology and protein localisation and expression of the LMCs. Furthermore, the primary cell culture co-stained for S100A6 and E-cadherin suggesting it is a co-culture of both pial and arachnoid cells. Additionally, cultured LMCs showed an increase in vimentin and cytokeratin expression and a lack of junctional proteins localisation on the cell membrane, which could suggest loss of epithelial properties due to culture, preventing barrier formation. This study shows that the LMCs may be a co-culture of pial and arachnoid cells, that the optimal LMC passage range is between passages two and five for experimentation and that the primary human LMCs form a weak barrier when in culture.

Lymphatic cells do not functionally integrate into 3D organotypic brain slice cultures, but aggregate around penetrating blood vessels

Brain slice culture (BSC) is a well-known three-dimensional model of the brain. In this study, we use organotypic slices for studying neuro-lymphatic physiology, to directly test the longstanding assumption that the brain is not a hospitable milieu for typical lymphatic vessels. An additional objective is to model fluid egress through brain perivascular space systems and to visualize potential cellular interactions among cells in the leptomeninges including alterations of cellular geometry and number of processes. Immortalized lymphatic rat cell lines were used to seed organotypic brain slices. The brain slice model was characterized by monitoring morphologies, growth rates, degree of apoptosis, and transport properties of brain slices with or without a lymphatic component. The model was then challenged with fibroblast co-cultures, as a control cell that is not normally found in the brain. Immortalized lymphatic cells penetrated the brain slices within 2-4 days. Typical cell morphology is spindly with bipolar and tripolar forms well represented. Significantly more indigo carmine marker passed through lymphatic seeded BSCs compared to arachnoid BSCs. Significantly more indigo carmine passed through brain slices co-cultured with fibroblast compared to lymphatic and arachnoid BSCs alone. We have developed an organotypic model in which lymphatic cells are able to interact with parenchymal cells in the cerebrum. Their presence appears to alter the small molecule transport ability of whole-brain slices. Lymphatic cells decreased dye transport in BSCs, possibly by altering the perivascular space. Given their direct contact with the CSF, they may affect convectional and diffusional processes. Our model shows that a decrease in lymphatic cell growth may reduce the brain slice's transport capabilities.