Stefano Pluchino

Professor of Regenerative Neuroimmunology, University of Cambridge
My team studies whether the accumulation of neurological disability observed in patients with progressive forms of multiple sclerosis (PMS) can be slowed down using stem cell therapies. In particular, our aim is to understand the basic mechanisms that allow exogenously delivered neural stem cells (NSCs) to create an environment that preserves damaged axons or prevents neurons from dying. Using stem cells as a model to identify the critical factors that prevent neurodegeneration is an exciting new frontier of regenerative medicine, which is just being tested in humans.

I have been first or senior author in seminal papers that have established the potential of somatic NSC-based experimental therapies for PMS. My early studies identified a critical role around the route of cell injection4 and the mechanisms of NSC accumulation in the chronically inflamed CNS, as well as revealing an unexpected ability of NSC therapies to provide neurotrophic support and inhibit detrimental host immune responses in vivo.

My team has also focused on defining the nature and function of intercellular signalling mediated by extracellular membrane vesicles (EVs) from NSCs. Using a series of computational analyses and high-resolution imaging techniques, we have demonstrated that EVs deliver functional IFN-g/Ifngr1 complexes to target cells.

We have also discovered that EVs harbour L-asparaginase activity catalysed by the enzyme Asparaginase-like protein 1. While the translation of EV therapies into clinical regenerative therapies is still some way from being fully achievable, both these studies on NSC EVs serve as complementary models of how stem cell grafts might signal to the host to mediate repair through a range of complementary actions.

Our most recent work describes a delayed accumulation of the pro-inflammatory tricarboxylic acid (TCA) cycle intermediate succinate in the cerebrospinal fluid (CSF) of mice with experimental autoimmune encephalomyelitis (EAE), a model of chronic MS. We have identified a new complementary mechanism by which directly induced NSCs (iNSCs) respond to endogenous inflammatory metabolic signals to inhibit the activation of type-1 mononuclear phagocytes (MPs) in vivo after transplantation. Transplanted iNSCs respond to the succinate released by type-1 inflammatory macrophages and microglia in the CSF, which then signals to iNSCs via succinate receptor 1 (SUCNR1) and initiates the secretion of prostaglandin E2 and the scavenging of extracellular succinate.

Our research has therefore recalibrated the classical view that neural grafts only function through structural cell replacement and opened up a new therapeutic avenue by which to use exogenously delivered NSCs.

By understanding the mechanisms of intercellular (stem cell) signalling, diseases of the central nervous system (CNS) may be treated more effectively, and significant neuroprotection may be achieved with new tailored NSC therapeutics.