Clinical Trials with Mesenchymal Stem Cells: An Update:

In the last year, the promising features of mesenchymal stem cells (MSCs), including their regenerative properties and ability to differentiate into diverse cell lineages, have generated great interest among researchers whose work has offered intriguing perspectives on cell-based therapies for various diseases. Currently the most commonly used adult stem cells in regenerative medicine, MSCs, can be isolated from several tissues, exhibit a strong capacity for replication in vitro, and can differentiate into osteoblasts, chondrocytes, and adipocytes. However, heterogeneous procedures for isolating and cultivating MSCs among laboratories have prompted the International Society for Cellular Therapy (ISCT) to issue criteria for identifying unique populations of these cells. Consequently, the isolation of MSCs according to ISCT criteria has produced heterogeneous, nonclonal cultures of stromal cells containing stem cells with different multipotent properties, committed progenitors, and differentiated cells. Though the nature and functions of MSCs remain unclear, nonclonal stromal cultures obtained from bone marrow and other tissues currently serve as sources of putative MSCs for therapeutic purposes, and several findings underscore their effectiveness in treating different diseases. To date, 493 MSC-based clinical trials, either complete or ongoing, appear in the database of the US National Institutes of Health. In the present article, we provide a comprehensive review of MSC-based clinical trials conducted worldwide that scrutinizes biological properties of MSCs, elucidates recent clinical findings and clinical trial phases of investigation, highlights therapeutic effects of MSCs, and identifies principal criticisms of the use of these cells. In particular, we analyze clinical trials using MSCs for representative diseases, including hematological disease, graft-versus-host disease, organ transplantation, diabetes, inflammatory diseases, and diseases in the liver, kidney, and lung, as well as cardiovascular, bone and cartilage, neurological, and autoimmune diseases

Aging of the inceptive cellular population: the relationship between stem cells and aging

The average life expectancy worldwide has about doubled and the global population has increased six fold over the past century. With improving health care in the developed world there is a proportional augmentation in the treatment necessary for elderly patients occasioning the call for increased research in the area of aging and age-related diseases. The manifestation of this research has been focalized on the causative cellular processes and molecular mechanisms involved. Here we will discuss the efforts of this research in the area of stem cells, delving into the regulatory mechanisms and how their de-regulation could be attributed to aging and age-related diseases

Is it Possible to Improve the Success Rate of Cellular Therapy Based on Mesenchymal Stem Cells?

Non-clonal stromal cultures, containing a variable amount of Mesenchymal Stem Cells (MSCs), can be easily isolated from a small aspirate of bone marrow and expanded in vitro. As such, these cultures are currently used as a source of putative MSCs for therapeutic purposes. Nowadays, dozens of clinical trials aim to treat a number of diseases, primarily immune system-related diseases, with MSCs. Moreover, several private companies are setting up clinical trials to exploit the immunomodulation and tissue repair properties of MSCs. Nevertheless, besides some successes, specifically in the treatment of immunological diseases, MSC therapies have experienced many failures. There are some issues to be analyses that may improve the success rate of MSC therapy. This editorial will briefly address some concerns associated with MSC transplants

Role of glycosphingolipid SSEA-3 and FGF2 in the stemness and lineage commitment of multilineage differentiating stress enduring (MUSE) cells

Multilineage differentiating Stress Enduring (MUSE) cells are endogenous, stress-resistant stem cells, expressing pluripotency master genes and able to differentiate in cells of the three embryonic sheets. Stage-Specific Embryonic Antigen 3 (SSEA-3), a glycosphingolipid (GSL), is the marker for identifying MUSE cells and is used to isolate this population from mesenchymal stromal cells. GSLs modulate signal transduction by interacting with plasma membrane components. The growth factor FGF2, important for MUSE cells biology, may interact with GSLs. Specific cell surface markers represent an invaluable tool for stem cell isolation. Nonetheless their role, if any, in stem cell biology is poorly investigated. Functions of stem cells, however, depend on niche external cues, which reach cells through surface markers. We addressed the role of SSEA-3 in MUSE cell behaviour, trying to define whether SSEA-3 is just a marker or if it plays a functional role in this cell population by determining if it has any relationship with FGF2 activity

Brg1 chromatin remodeling factor is involved in cell growth arrest, apoptosis and senescence of rat mesenchymal stem cells.

Self-renewal, proliferation and differentiation properties of stem cells are controlled by key transcription factors. However, their activity is modulated by chromatin remodeling factors that operate at the highest hierarchical level. Studies on these factors can be especially important to dissect molecular pathways governing the biology of stem cells. SWI/SNF complexes are adenosine triphosphate (ATP)-dependent chromatin remodeling enzymes that have been shown to be required for cell cycle control, apoptosis and cell differentiation in several biological systems. The aim of our research was to investigate the role of these complexes in the biology of mesenchymal stem cells (MSCs). To this end, in MSCs we caused a forced expression of the ATPase subunit of SWI/SNF (Brg1 – also known as Smarca4) by adenoviral transduction. Forced Brg1 expression induced a significant cell cycle arrest of MSCs in culture. This was associated with a huge increase in apoptosis that reached a peak 3 days after transduction. In addition, we observed signs of senescence in cells having ectopic Brg1 expression. At the molecular level these phenomena were associated with activation of Rb- and p53-related pathways. Inhibition of either p53 or Rb with E1A mutated proteins allowed us to hypothesize that both Rb and p53 are indispensable for Brg1-induced senescence, whereas only p53 seems to play a role in triggering programmed cell death. We also looked at the effects of forced Brg1 expression on canonical MSC differentiation in adipocytes, chondrocytes and osteocytes. Brg1 did not induce cell differentiation per se; however, this protein could contribute, at least in part, to the adipocyte differentiation process. In conclusion, our results suggest that whereas some ATP-dependent chromatin remodeling factors, such as ISWI complexes, promote stem cell self-renewal and conservation of an uncommitted state, others cause an escape from ‘stemness’ and induction of differentiation along with senescence and cell death phenomena

Long-Lasting Effects of Human Mesenchymal Stem Cell Systemic Administration on Pain-Like Behaviors, Cellular, and Biomolecular Modifications in Neuropathic Mice

Background: Neuropathic pain (NP) is an incurable disease caused by a primary lesion in the nervous system. NP is a progressive nervous system disease that results from poorly defined neurophysiological and neurochemical changes. Its treatment is very difficult. Current available therapeutic drugs have a generalized nature, sometime acting only on the temporal pain properties rather than targeting the several mechanisms underlying the generation and propagation of pain. Methods: Using biomolecular and immunohistochemical methods, we investigated the effect of the systemic injection of human mesenchymal stem cells (hMSCs) on NP relief. We used the spared nerve injury (SNI) model of NP in the mouse. hMSCs were injected into the tail vein of the mouse. Stem cell injection was performed 4 days after sciatic nerve surgery. Neuropathic mice were monitored every 10 days starting from day 11 until 90 days after surgery. Results: hMSCs were able to reduce pain-like behaviors, such as mechanical allodynia and thermal hyperalgesia, once injected into the tail vein. An anti-nociceptive effect was detectable from day 11 post surgery (7 days post cell injection). hMSCs were mainly able to home in the spinal cord and pre-frontal cortex of neuropathic mice. Injected hMSCs reduced the protein levels of the mouse pro-inflammatory interleukin IL-1β and IL-17 and increased protein levels of the mouse anti-inflammatory interleukin IL-10, and the marker of alternatively activated macrophages CD106 in the spinal cord of SNI mice. Conclusion: As a potential mechanism of action of hMSCs in reducing pain, we suggest that they could exert their beneficial action through a restorative mechanism involving: (i) a cell-to-cell contact activation mechanism, through which spinal cord homed hMSCs are responsible for switching pro-inflammatory macrophages to anti-inflammatory macrophages; (ii) secretion of a broad spectrum of molecules to communicate with other cell types. This study could provide novel findings in MSC pre-clinical biology and their therapeutic potential in regenerative medicine

Cerebral connectivity and psychotic personality traits: A diffusion tensor imaging study

This study aims to investigate the relationship between regional connectivity in the brain white matter and the presence of psychotic personality traits, in healthy subjects with psychotic traits. Thirteen healthy controls were administered the MMPI-2, to assess psychotic traits and, according to MMPI results, a dichotomization into a group of "high-psychotic” and "low-psychotic” was performed. Diffusion tensor imaging (DTI) was used as a non-invasive measure, in order to obtain information about the fractional anisotropy (FA), an intravoxel index of local connectivity and, by means of a voxelwise approach, the between-group differences of the FA values were calculated. The "high-psychotic” group showed higher FA in the left arcuate fasciculus. Subjects with low scores for psychotic traits had significantly higher FA in the corpus callosum, right arcuate fasciculus, and fronto-parietal fibers. In line with previous brain imaging studies of schizophrenia spectrum disorders, our results suggest that psychotic personality traits are related to altered connectivity and brain asymmetr

Impact of lysosomal storage disorders on biology of mesenchymal stem cells: Evidences from in vitro silencing of glucocerebrosidase (GBA) and alpha-galactosidase A (GLA) enzymes.

Lysosomal storage disorders (LDS) comprise a group of rare multisystemic diseases resulting from inherited gene mutations that impair lysosomal homeostasis. The most common LSDs, Gaucher disease (GD), and Fabry disease (FD) are caused by deficiencies in the lysosomal glucocerebrosidase (GBA) and alpha-galactosidase A (GLA) enzymes, respectively. Given the systemic nature of enzyme deficiency, we hypothesized that the stem cell compartment of GD and FD patients might be also affected. Among stem cells, mesenchymal stem cells (MSCs) are a commonly investigated population given their role in hematopoiesis and the homeostatic maintenance of many organs and tissues. Since the impairment of MSC functions could pose profound consequences on body physiology, we evaluated whether GBA and GLA silencing could affect the biology of MSCs isolated from bone marrow and amniotic fluid. Those cell populations were chosen given the former's key role in organ physiology and the latter's intriguing potential as an alternative stem cell model for human genetic disease. Our results revealed that GBA and GLA deficiencies prompted cell cycle arrest along with the impairment of autophagic flux and an increase of apoptotic and senescent cell percentages. Moreover, an increase in ataxia-telangiectasia-mutated staining 1 hr after oxidative stress induction and a return to basal level at 48 hr, along with persistent gamma-H2AX staining, indicated that MSCs properly activated DNA repair signaling, though some damages remained unrepaired. Our data therefore suggest that MSCs with reduced GBA or GLA activity are prone to apoptosis and senescence due to impaired autophagy and DNA repair capacity

Environmental microplastics (EMPs) exposure alter the differentiation potential of mesenchymal stromal cells

Humans are exposed to environmental microplastic (MPs) that can be frequent in surrounding environment. The mesenchymal stromal cells are a heterogeneous population, which contain fibroblasts and stromal cells, progenitor cells and stem cells. They are part of the stromal component of most tissue and organs in our organisms. Any injury to their functions may impair tissue renewal and homeostasis. We evaluated the effects of different size MPs that could be present in water bottles on human bone marrow mesenchymal stromal cells (BMMSCs) and adipose mesenchymal stromal cells (AMSCs). MPs of polyethylene terephthalate (MPs-PET) (<1 μm and <2.6 μm) were tested in this study. PET treatments induced a reduction in proliferating cells (around 30%) associated either with the onset of senescence or increase in apoptosis. The AMSCs and BMMSCs exposed to PET showed an alteration of differentiation potential. AMSCs remained in an early stage of adipocyte differentiation as shown by high levels of mRNA for Peroxisome Proliferator Activated Receptor Gamma (PPARG) (7.51 vs 1.00) and reduction in Lipoprotein Lipase (LPL) mRNA levels (0.5 vs 1.0). A loss of differentiation capacity was also observed for the osteocyte phenotype in BMMSCs. In particular, we observed a reduction in Bone Gamma-Carboxy glutamate Protein (BGLAP) (0.4 for PET1 and 0.6 for PET2.6 vs 0.1 CTRL) and reduction in Osteopontin (SPP1) (0.3 for PET 1 and 0.64 for PET 2.6 vs 0.1 CTRL). This pioneering mesenchymal cell response study demonstrated that environmental microplastic could be bioavailable for cell uptake and may further lead to irreversible diseases