Efficacy of intrathecal mesenchymal stem cell-neural progenitor therapy in progressive MS: results from a phase II, randomized, placebo-controlled clinical trial.

BACKGROUND: Mesenchymal stem cell-neural progenitors (MSC-NPs) are a bone marrow mesenchymal stem cell (MSC)-derived ex vivo manipulated cell product with therapeutic potential in multiple sclerosis (MS). The objective of this study was to determine efficacy of intrathecal (IT) MSC-NP treatment in patients with progressive MS. METHODS: The study is a phase II randomized, double-blind, placebo-controlled clinical trial with a compassionate crossover design conducted at a single site. Subjects were stratified according to baseline Expanded Disability Status Scale (EDSS) (3.0-6.5) and disease subtype (secondary or primary progressive MS) and randomized into either treatment or placebo group to receive six IT injections of autologous MSC-NPs or saline every two months. The primary outcome was EDSS Plus, defined by improvement in EDSS, timed 25-foot walk (T25FW) or nine-hole peg test. Secondary outcomes included the individual components of EDSS Plus, the six-minute walk test (6MWT), urodynamics testing, and brain atrophy measurement. RESULTS: Subjects were randomized into MSC-NP (n = 27) or saline (n = 27) groups. There was no difference in EDSS Plus improvement between the MSC-NP (33%) and saline (37%) groups. Exploratory subgroup analysis demonstrated that in subjects who require assistance for ambulation (EDSS 6.0-6.5) there was a significantly higher percentage of improvement in T25FW and 6MWT in the MSC-NP group (3.7% ± 23.1% and - 9.2% ± 18.2%) compared to the saline group (-54.4% ± 70.5% and - 32.1% ± 30.0%), (p = 0.030 and p = 0.036, respectively). IT-MSC-NP treatment was also associated with improved bladder function and reduced rate of grey matter atrophy on brain MRI. Biomarker analysis demonstrated increased MMP9 and decreased CCL2 levels in the cerebrospinal fluid following treatment. CONCLUSION: Results from exploratory outcomes suggest that IT-MSC-NP treatment may be associated with a therapeutic response in a subgroup of MS patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT03355365, registered November 14, 2017, https://clinicaltrials.gov/study/NCT03355365?term=NCT03355365&rank=1 .

Mesenchymal stem cell-neural progenitors are enriched in cell signaling molecules implicated in their therapeutic effect in multiple sclerosis.

Mesenchymal stem cell-neural progenitors (MSC-NP) are a neural derivative of MSCs that are being investigated in clinical trials as an autologous intrathecal cell therapy to treat patients with secondary progressive (SP) or primary progressive (PP) multiple sclerosis (MS). MSC-NPs promote tissue repair through paracrine mechanisms, however which secreted factors mediate the therapeutic potential of MSC-NPs and how this cell population differs from MSCs remain poorly understood. The objective of this study was to define the transcriptional profile of MSCs and MSC-NPs from MS and non-MS donors to better characterize each cell population. MSCs derived from SPMS, PPMS, or non-MS bone marrow donors demonstrated minimal differential gene expression, despite differences in disease status. MSC-NPs from both MS and non-MS-donors exhibited significant differential gene expression compared to MSCs, with 2,156 and 1,467 genes upregulated and downregulated, respectively. Gene ontology analysis demonstrated pronounced downregulation of cell cycle genes in MSC-NPs compared to MSC consistent with reduced proliferation of MSC-NPs in vitro. In addition, MSC-NPs demonstrated significant enrichment of genes involved in cell signaling, cell communication, neuronal differentiation, chemotaxis, migration, and complement activation. These findings suggest that increased cell signaling and chemotactic capability of MSC-NPs may support their therapeutic potential in MS.

Nanosensor-based monitoring of autophagy-associated lysosomal acidification in vivo.

Autophagy is a cellular process with important functions that drive neurodegenerative diseases and cancers. Lysosomal hyperacidification is a hallmark of autophagy. Lysosomal pH is currently measured by fluorescent probes in cell culture, but existing methods do not allow for quantitative, transient or in vivo measurements. In the present study, we developed near-infrared optical nanosensors using organic color centers (covalent sp3 defects on carbon nanotubes) to measure autophagy-mediated endolysosomal hyperacidification in live cells and in vivo. The nanosensors localize to the lysosomes, where the emission band shifts in response to local pH, enabling spatial, dynamic and quantitative mapping of subtle changes in lysosomal pH. Using the sensor, we observed cellular and intratumoral hyperacidification on administration of mTORC1 and V-ATPase modulators, revealing that lysosomal acidification mirrors the dynamics of S6K dephosphorylation and LC3B lipidation while diverging from p62 degradation. This sensor enables the transient and in vivo monitoring of the autophagy-lysosomal pathway.

Mesenchymal stem cell-derived neural progenitors attenuate proinflammatory microglial activation via paracrine mechanisms.

Background: Mesenchymal stem cell-derived neural progenitor cell (MSC-NP) therapy is an experimental approach to treat multiple sclerosis. The influence of MSC-NPs on microglial activation was investigated. Methods: Microglia were stimulated in the presence of MSC-NP-conditioned media, and proinflammatory or proregenerative marker expression was assessed by quantitative PCR and ELISA. Results: Microglia stimulated in the presence of MSC-NP-conditioned media displayed reduced expression of proinflammatory markers including CCL2, increased expression of proregenerative markers and reduced phagocytic activity. The paracrine effects of MSC-NPs from multiple donors correlated with TGF-ß3 gene expression and was reversed by TGF-ß signaling inhibition. Conclusion: MSC-NPs promote beneficial microglial polarization through secreted factors. This study suggests that microglia are a potential therapeutic target of MSC-NP cell therapy.

Multiple sclerosis (MS) is a chronic inflammatory disease of the brain and spinal cord that leads to neuronal damage and neurological disability. A novel cell therapy has been developed aiming to slow or reverse neurological disability in patients with MS. The treatment approach utilizes bone marrow cells called mesenchymal stem cell-derived neural progenitors (MSC-NPs) that are injected into the spinal fluid of the patient. Microglia are an innate immune cell in the brain known to contribute to MS disease progression. This study explores whether microglia might be a therapeutic target of MSC-NP therapy. We found that MSC-NPs inhibited the inflammatory activation of microglia and increased proregenerative markers in microglia. These effects were mediated by the factors secreted by MSC-NPs, possibly including a secreted protein called TGF-ß. Overall, this study highlights a potential therapeutic mechanism of MSC-NP therapy in MS.

Genetic code expansion to enable site-specific bioorthogonal labeling of functional G protein-coupled receptors in live cells.

For use in site-specific bioorthogonal labeling of expressed G protein-coupled receptors (GPCRs) in live cells, we developed a luciferase-based reporter assay. The assay was used to compare amber codon suppression efficiency, receptor functionality, and efficiency of different bioorthogonal labeling chemistries. We used the assay system to compare side-by-side the efficiency of incorporation of three different noncanonical amino acids [4-azido-l-phenylalanine (azF), cyclopropene-l-lysine (CpK), and trans-cyclooct-2-en-l-lysine (TCOK)] at three different sites on a GPCR using three different genetic code expansion plasmid systems. As a model GPCR, we engineered an epitope-tagged C-C chemokine receptor 5 (CCR5)-RLuc3 fusion for expression in HEK293T cells. Satisfactory incorporation of azF, CpK, and TCOK into heterologously expressed CCR5 was achieved. We also carried out cell-based calcium mobilization assays to measure the function of the engineered CCR5, and in the same cells, we performed bioorthogonal labeling of the engineered mutants using heterobivalent compounds containing bioorthogonal tethering groups linked to either a small-molecule fluorophore or a peptide. Favorable reaction kinetics of tetrazine-containing compounds with CCR5 harboring TCOK was observed. However, bioorthogonal labeling in live cells of CCR5 harboring CpK with tetrazine-containing compounds using the inverse electron demand Diels-Alder ligation was overall slightly more efficient than other reactions tested.