Current Stem Cell Research & Therapy - Volume 11, Issue 4, 2016

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease affecting primarily the population of motor neurons, even though a non-cell autonomous component, involving neighbouring non-neuronal cells, is more and more described. Despite 140 years of disease experience, still no efficient treatment exists against ALS. The inability to readily obtain the faulty cell types relevant to ALS has impeded progress in drug discovery for decades. However, the pioneer work of Shinya Yamanaka in 2007 in the stem cell field was a real breakthrough. Recent advances in cell reprogramming now grant access to significant quantities of CNS disease-affected cells. Induced pluripotent stem cells (iPSc) have been recently derived from patients carrying mutations linked to familial forms of ALS as well as from sporadic patients. Precise and mature protocols allow now their differentiation into ALS-relevant cell subtypes; sustainable and renewable sources of human motor neurons or glia are being available for ALS disease modelling, drug screening or for the development of cell therapies. In few years, the proof-of-concept was made that ALS disease-related phenotypes can be reproduced with iPSc and despite some remaining challenges, we are now not so far to provide platforms for the investigation of ALS therapeutics. This paper also reviews the pioneering studies regarding the applicability of iPSc technology in ALS animal models. From modest slowing down of ALS progression to no severe adverse effects, iPSc-based cell therapy resulted in promising premises in ALS preclinical paradigms, although long-term surveys are highly recommended.

Stem cell replacement is providing hope for many degenerative diseases that lack effective therapeutic methods including multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. Transplantation of neural stem cells or mesenchymal stem cells is a potential therapy for MS thanks to their capacity for cell repopulation as well as for their immunomodulatory and neurotrophic properties. Induced pluripotent stem cell (iPSC), an emerging cell source in regenerative medicine, is also being tested for the treatment of MS. Remarkable improvement in mobility and robust remyelination have been observed after transplantation of iPSC-derived neural cells into demyelinated models. Direct reprogramming of somatic cells into induced neural cells, such as induced neural stem cells (iNSCs) and induced oligodendrocyte progenitor cells (iOPCs), without passing through the pluripotency stage, is an alternative for transplantation that has been proved effective in the congenital hypomyelination model. iPSC technology is rapidly progressing as efforts are being made to increase the efficiency of iPSC therapy and reduce its potential side effects. In this review, we discuss the recent advances in application of stem cells, with particular focus on induced stem/progenitor cells (iPSCs, iNSC, iOPCs), which are promising in the treatment of MS.

A large body of work has been published on transplantation of a wide range of neural stem and progenitor cell types derived from the developing and adult CNS, as well as from pluripotent embryonic stem cells, in models of traumatic spinal cord injury (SCI). However, many of these cell-based approaches present practical issues for clinical translation such as ethical cell derivation, generation of potentially large numbers of homogenously prepared cells, and immune rejection. With the advent of induced Pluripotent Stem (iPS) cell technology, many of these issues may potentially be overcome. To date, a number of studies have demonstrated integration, differentiation into mature CNS lineages, migration and long-term safety of iPS cell transplants in a variety of SCI models, as well as therapeutic benefits in some cases. Given the clinical potential of this advance in stem cell biology, we present a concise review of studies published to date involving iPS cell transplantation in animal models of SCI.

Rheumatoid arthritis (RA) is a chronic, systemic and progressive autoimmune disease of connective tissues common in middle age. Dysregulation of the tissue homeostasis involving inflammation is the hallmark of disease pathogenesis, inducing autoimmune insults that frequently lead to permanent disability. Although the advent of immunosuppressive and anti-inflammatory drugs and, more recently, pathogenic TNF-TNF-R axis-targeting biologics significantly delayed progressive joint destruction with significant reduction of disability and physical improvement, a large proportion of RA patients failed to respond to the treatment. In this regard, mesenchymal stem/stromal cells (MSC) are particularly attractive to the refractory patients to the pharmacologic intervention for their immunosuppressive/anti-inflammatory capacity as well as tissue reparative and/or regenerative potential. Local or systemic delivery of MSCs led to promising results in preclinical as well as in clinical studies of RA and thus proposing that these cells can be further exploited for their therapeutic application in RA and other degenerative connective tissue diseases. Mechanistically, paracrine factors appear to be the main contributors of MSC-mediated tissue regeneration in a number of preclinical and clinical studies rather than direct tissue cell replacement. More recently, extracellular vesicles (EVs) released from MSCs emerged as key paracrine messengers that can also participate in the healing process through influencing the local microenvironment with anti-inflammatory effects. It is highly likely that the use of these EVs becomes beneficial in the treatment of RA. Yet, identification of key components involved in the regenerative process needs to be assessed for developing efficient MSC-based strategy of RA treatment.

Human mesenchymal stem cells (hMSCs) are multipotent non-hematopoietic precursor cells with the ability to differentiate into several tissue types. The use of hMSCs has gained significant importance in cancer therapies as well as a large number of degenerative disease therapies due to their homing abilities. However, these cells may undergo spontaneous transformation leading to them bypassing naturally built-in cell controls that could lead to senescence and carcinogenesis. Therefore, although MSCs have great potential for cancer therapy, they also risk the development of cancer, which provides them with double-faced characteristics for both cancer development and therapy. The potential use of hMSCs in therapeutics from the aspect of in vitro expansion of hMSCs and telomere dynamic is discussed.

Epigenetics harbours all regulatory information that, beyond nucleotide sequences, allows cells to “make decisions” throughout their lifetime in response to the external environment. The information can be transitory or relatively stable, and is even transmittable either to daughter cells or to the next generations through the germ line. Recent discoveries shed light on numerous connections between metabolites and epigenetic chromatin-modifying enzymes, providing a link between the metabolic state of the cell and epigenetics, and ultimately between metabolism, gene expression and cell fate. In this review, we discuss the possible connections between metabolism and epigenetic regulation of stem cell differentiation and self-renewal. Moreover, we describe pertinent literature that could explain how altered metabolic state and nutrition can contribute to disease development through epigenetic modifications. A special section is dedicated to the emerging link between the circadian clock, metabolic transcriptional regulation by epigenetic mechanisms and their implication in stem cell homeostasis.

Cell culture is a core and basic technique in biotechnology and is widely applied in biology, medicine, drug research and development. Traditional two-dimensional cell culture methods have undergone great developments. However, with in-depth basic research, higher requirements are needed to better mimic the in vivo environment to accurately observe cell behavior and explore its mechanisms. To comply with this situation, the three-dimensional cell culture technique emerged and has made profound advances in sustaining inherent cell properties. Here, we briefly review the development of this technique, including the main approaches to form three-dimensional microtissues, and its application and potential for future clinical therapies.