Skin Stem Cells: A Neuroprotective Therapy for Multiple Sclerosis?
University of Edinburgh
Siddharthan Chandran MD, PhD
2 year grant, $45,000 per year, totaling $90,000
The unmet clinical problem
This study is concerned with developing treatments for Secondary Progressive Multiple Sclerosis (SPMS) patients. The majority of patients with MS develop a relapsing-remitting form of the disease followed by secondary progression, characterized by accumulation of irreversible disability. Neurodegeneration represents the primary pathological substrate of progression. Treatments for MS have two aims: to prevent (disease modifying) and to repair damage. Although considerable advances have been made in the former, there are presently no treatments to repair fixed disability. Patients with SPMS are bereft of any restorative therapies. The lack of such therapies represents a substantial gap in the treatment of MS. There is a great need to develop treatments that limit and prevent neurodegeneration.
Studies in animal models have demonstrated the beneficial effects of exogenous cell populations making experimental human cellular therapy a realistic proposition. Studies have shown beneficial effect of cell transplantation when cells are administered at early stages of the disease. However, this is not relevant to the target group of SPMS patients who need interventions that will work after the onset of disability. Specifically, SPMS patients require therapies that have demonstrated efficacy upon administration beyond the acute or early relapse-remitting phase. In addition, it remains unclear whether mode of delivery influences outcome.
This collaborative study seeks to answer two clinically relevant questions using a potentially autologous and readily accessible stem cell population:
- Do autologous skin stem cell populations have a neuroprotective effect when delivered at the point equivalent to SPMS?
- Does mode of delivery influence therapeutic efficacy?
Cellular therapies promote neuroprotection
Stem cell based therapies have been shown to be neuroprotective in models of multifocal inflammatory disease, independent of directed differentiation for example through proneurotrophic, repair and immune modulatory mechanisms. The demonstration that intravenous administration of stem cells leads to delivery throughout the inflammatory neuraxis resulting in axonal protection and functional improvement in animal models of MS is encouraging and opens the prospect of systemic delivery. Neural precursors (NPCs) have been shown to have efficacy. Noting practical and ethical limitations of acquiring sufficient human NPCs, these studies support the further study of novel stem cell populations as neuroprotective therapies in MS. Skin derived stem cells (SKPs) represent one such population.
Skin stem cells
We and others have identified he adult human dermal papilla as a highly enriched niche for stem cells with neuronal and glial potential. As yet, there have been no studies examining the neuroprotective effect of SKPS in animal models of SPMS. Together, these findings raise the prospect of systemic delivery of putative cellular therapy that can, through a variety of mechanisms, promote neuroprotection.
Cellular therapies must be tested in the appropriate animal model
Modelling MS represents a particular challenge given its clinical and pathological heterogeneity. The vast majority of EAE models mainly reflect the impact of acute inflammatory processes. We have developed and characterised an animal model of SPMS [chronic EAE in Biozzi AB/H mice (CEAE)]. This model mirrors many of the pathological and clinical features of SPMS and thus represents the ideal model to test the therapeutic effect of SKPs delivered intravenously and intrathecally at two time points (arrow) that represent RR and SPMS.
Work that has led up to this project, experimental plan & outcome measures
This research is a logical follow on study to our long-standing collaborative (Chandran/Baker) studies and thus all experimental infrastructure, capability are in place for expeditious delivery of the outcomes over 24 months. SKP isolation and characterization, generation of GFP+ cell populations, transplantation, ABH-CEAE, histological and clinical / behavioural testing are routine procedures in the lab – see CV. We propose to examine the delivery of SKPs at the relapsing-remitting and secondary progressive phases. SKPs will be administered into the tail vein or by the intraventricular route between D38-40 (RR) and D60-70 (chronic progressive). Behavioural and histological analysis will be undertaken at 1, 2, 4 and 6 weeks post-transplantation with appropriate CNS (brain, spinal cord) and lympahatic organs (spleen, lymph nodes) being removed. Detailed quantitative histological analysis (using software developed and modified in-house) will be undertaken to identify graft derived cells using antigens against GFP as well as to perform quantitative axonal counts. Examination of phenotypic differentiation of SKPs will be made based on immunoreactivity to a wide number of established markers including that of oligodendroglial markers. Quantitative assessment of remyelinated and demyelinated axons will be undertaken on 1 um toludine blue stained sections with ultrastructural sampling. Behavioural analysis and functional recovery using the open field locomotor score and clinical scoring will be examined prior to the transplantation of MSCs and SKPs and then at weekly intervals following transplantation for evidence of reduction in disease progression and amelioration of the functional deficits. Together we will provide a detailed analysis of disease progression, clinical scoring and histological analysis including quantitative measurements of axonal damage/protection and remyelination.
Outcome
These experiments will begin to answer the clinically important question of whether cell transplantation (systemic) of novel adult derived populations influences the clinical evolution of disease, specifically disability, contingent on time of delivery.
This grant will underwrite the salary costs for two-years of a highly accomplished post-doctoral fellow whose current funding will expire in July 2009. This individual (Dr D Webber), is well placed to undertake the proposed experiments, having experience in stem cell culture, animal surgery, and histological and behavioural analysis. Twenty four months is a realistic timeframe to complete, analyze and publish the research given that the model and skin stem cell expertise are established models / procedures in the host lab.