Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system involving dysregulated encephalitogenic T cells. Myeloid-derived suppressor cells (MDSCs) have been recognized for their important function in regulating T-cell responses. Recent studies have indicated a role for MDSCs in autoimmune diseases, but their significance in MS is not clear. Here, we assessed the frequencies of CD14 HLA-DR monocytic MDSCs (Mo-MDSCs) and CD33 CD15 CD11b HLA-DR granulocytic MDSCs (Gr-MDSCs) and investigated phenotypic and functional differences of Mo-MDSCs at different clinical stages of MS and in healthy subjects (HC). Increased frequencies of Mo-MDSCs (P < 0.05) and Gr-MDSCs (P < 0.05) were observed in relapsing-remitting MS patients during relapse (RRMS-relapse) compared to stable RRMS (RRMS-rem). Secondary progressive MS (SPMS) patients displayed a decreased frequency of Mo-MDSCs and Gr-MDSCs compared to HC (P < 0.05). Mo-MDSCs within RRMS patients expressed significantly higher cell surface protein levels of CD86 and CD163 compared to SPMS patients. Mo-MDSCs within SPMS exhibited decreased mRNA expression of interleukin-10 and heme oxygenase 1 compared to RRMS and HC. Analysis of T-cell regulatory function of Mo-MDSCs demonstrated T-cell suppressive capacity in RRMS and HCs, while Mo-MDSCs of SPMS promoted autologous T-cell proliferation, which aligned with a differential cytokine profile compared to RRMS and HCs. This study is the first to show phenotypic and functional shifts of MDSCs between clinical stages of MS, suggesting a role for MDSCs as a therapeutic target to prevent MS disease progression.

Vascular changes, including blood brain barrier destabilization, are common pathological features in multiple sclerosis (MS) lesions. Blood vessels within adult organs are reported to harbor mesenchymal stromal cells (MSCs) with phenotypical and functional characteristics similar to pericytes. We performed an immunohistochemical study of MSCs/pericytes in brain tissue from MS and healthy persons. Post-mortem brain tissue from patients with early progressive MS (EPMS), late stage progressive MS (LPMS), and healthy persons were analyzed for the MSC and pericyte markers CD146, platelet-derived growth factor receptor beta (PDGFRb), CD73, CD271, alphasmooth muscle actin, and Ki67. The MS samples included active, chronic active, chronic inactive lesions, and normal-appearing white matter. MSC and pericyte marker localization were detected in association with blood vessels, including subendothelial CD146 1 PDGFRb 1 Ki67 1 cells and CD73 1 CD271 1 PDGFRb 1 Ki67 -cells within the adventitia and perivascular areas. Both immunostained cell subpopulations were termed mesenchymal perivascular cells (MPCs). Quantitative analyses of immunostainings showed active lesions containing increased regions of CD146 1 PDGFRb 1 Ki67 1 and CD73 1 CD271 1 PDGFRb 1 Ki67 -MPC subpopulations compared to inactive lesions. Chronic lesions presented with decreased levels of CD146 1 PDGFRb 1 Ki67 1 MPC cells compared to control tissue. Furthermore, LPMS lesions displayed increased numbers of blood vessels harboring greatly enlarged CD73 1 CD271 1 adventitial and perivascular areas compared to control and EPMS tissue. In conclusion, we demonstrate the presence of MPC subgroups in control human brain vasculature, and their phenotypic changes in MS brain, which correlated with inflammation, demyelination and MS disease duration. Our findings demonstrate that brain-derived MPCs respond to pathologic mechanisms involved in MS disease progression and suggest that vessel-targeted therapeutics may benefit patients with progressive MS. STEM CELLS TRANSLATIONAL MEDICINE 2017;6:1840-1851 SIGNIFICANCE STATEMENTThis immunohistochemical study characterized vascular cells phenotypically similar to pericytes and mesenchymal stromal cells (MSCs) in brain tissue of multiple sclerosis (MS) and healthy persons. We found variations in phenotype, distribution, and proliferation of cells co-expressing markers for MSCs and pericytes that associated with inflammation and MS disease duration. Tissue from long standing MS presented with increased numbers of blood vessels that harbored expanded perivascular areas of cells staining positive for MSCs/pericyte markers. This is the first study to show involvement of MSC/pericyte phenotypic changes in MS pathology and highlights that vessel-targeted treatments may benefit late stage MS.

Objectives/Hypothesis: This study aimed to determine whether local injection of human mesenchymal stromal cells (MSC) could modulate the early inflammatory response within injured vocal folds (VFs) to promote wound-healing processes.Study Design: Experimental xenograft model. Methods: VF injury was surgically induced by bilateral resection of the lamina propria of rabbits, and MSC were immediately injected into the injured area of both VFs. Animals were sacrificed on days 2, 4, and 24. Histological analyses were performed by hematoxylin and eosin, Masson's Trichrome, and elastin staining. Cell death was visualized by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and the M2 macrophage marker, CD163, detected by immunohistochemistry. Persistence of injected MSC was evaluated by fluorescent in situ hybridization (FISH). Quantitative polymerase chain reaction was performed on the contralateral VF.Results: Histological examination at days 2 and 4 indicated that MSC were able to reduce tissue inflammation, with gene expression analysis confirming a significant reduction of proinflammatory markers, interleukin (IL)-1β, and IL-8. FISH demonstrated low-level persistence of injected MSC at both time points, and TUNEL confirmed localized cell death at the injury site. Increased levels of CD163+ anti-inflammatory macrophages indicated a change in the immune milieu, supporting wound resolution. Evidence of a more organized collagen matrix suggests that MSC may enhance the production of a functional repair tissue after injury, despite their low-level persistence within the tissue.Conclusions: This study demonstrates that MSC are able to positively modulate the early wound-healing response through resolution of the inflammatory phase and promotion of tissue repair.

Bone marrow derived mesenchymal stromal cells (BM-MSCs) have emerged as a possible new therapy for Multiple Sclerosis (MS), however studies regarding efficacy and in vivo immune response have been limited and inconclusive. We conducted a phase I clinical study assessing safety and clinical and peripheral immune responses after MSC therapy in MS. Seven patients with progressive MS were intravenously infused with a single dose of autologous MSC (1–2 × 106 MSCs/kg body weight). The infusions were safe and well tolerated when given during clinical remission. Five out of seven patients completed the follow up of 48 weeks post-infusion. Brain magnetic resonance imaging (MRI) showed the absence of new T2 lesions at 12 weeks in 5/6 patients, while 3/5 had accumulated new T2 lesions at 48 weeks. Patient expanded disability status scales (EDSS) were stable in 6/6 at 12 weeks but declined in 3/5 patients at 48 weeks. Early changes of circulating microRNA levels (2 h) and increased proportion of FOXP3+ Tregs were detected at 7 days post-infusion compared to baseline levels. In conclusion, MSC therapy was safe and well tolerated and is associated with possible transient beneficial clinical and peripheral immunotolerogenic effects.

Visual grading of chromogenically stained immunohistochemical (IHC) samples is subjective, time consuming, and predisposed to considerable inter- and intra-observer variations. The open-source digital analysis software, CellProfiler has been extensively used for fluorescently stained cells/tissues; however, chromogenic IHC staining is routinely used in both pathological and research diagnostics. The current investigation aimed to compare CellProfiler quantitative chromogenic IHC analyses against the gold standard manual counting. Oral mucosal biopsies from patients with chronic graft-versus-host disease were stained for CD4. Digitized images were manually counted and subjected to image analysis in CellProfiler. Inter-observer and inter-platform agreements were assessed by scatterplots with linear regression and Bland-Altman plots. Validation comparisons between the manual counters demonstrated strong intra-observer concordance (r = 0.979), particularly when cell numbers were less than 100. Scatterplots and Bland-Altman plots demonstrated strong agreement between the manual counters and CellProfiler, with the number of positively stained cells robustly correlating (r = 0.938). Furthermore, CellProfiler allowed the determination of multiple variables simultaneously, such as area stained and masking to remove any nonstained tissue and white gaps, which also demonstrated reliable agreement (r = >0.9). CellProfiler demonstrated versatility with the ability to assess large numbers of images and allowed additional parameters to be quantified. CellProfiler allowed rapid high processing capacity of chromogenically stained chronic inflammatory tissue that was reliable, accurate, and reproducible and highlights potential applications in research diagnostics.