Alternative Sources of Neurons and Glia from Somatic Stem Cells

Epiregulin promotes osteogenic differentiation and inhibits neurogenic trans-differentiation of adipose-derived mesenchymal stem cells via MAPKs pathway

Mesenchymal stem cells (MSCs) exists low efficiency to trans-differentiate into other germinal layer cell types. One key issue is to discover the effect of important factor on MSCs differentiation abiltiy. In this study, we investigated the role and mechanism of epiregulin (EREG) on the osteogenic differentiation and neurogenic trans-differentiation in adipose-derived stem cells (ADSCs). We discovered that the depletion of EREG inhibited the osteogenic differentiation in vitro. And 25 ng/mL recombinant human epiregulin protein (rhEREG) effectively improved the osteogenic differentiation of EREG-depleted-ADSCs. Depletion of EREG promoted the formation of neural spheres, and increased the expressions of nestin, βIII-tubulin, NeuroD, NCAM, TH, and NEF in ADSCs. Then, 25 ng/mL rhEREG significantly inhibited these neurogenic differentiation indicators. Inhibition of p38 MAPK, JNK, or Erk1/2 signaling pathway separately, blocked the rhEREG-enhanced osteogenic differentiation ability and the rhEREG-inhibited neurogenic trans-differentiation ability of ADSCs. In conclusions, EREG promoted the osteogenic differentiation and inhibited the neurogenic trans-differentiation potentials of ADSCs via MAPK signaling pathways.

Mesenchymal stem cells spontaneously express neural proteins in culture and are neurogenic after transplantation

Reports of neural transdifferentiation of mesenchymal stem cells (MSCs) suggest the possibility that these cells may serve as a source for stem cell-based regenerative medicine to treat neurological disorders. However, some recent studies controvert previous reports of MSC neurogenecity. In the current study, we evaluate the neural differentiation potential of mouse bone marrow-derived MSCs. Surprisingly, we found that MSCs spontaneously express certain neuronal phenotype markers in culture, in the absence of specialized induction reagents. A previously published neural induction protocol that elevates cytoplasmic cyclic AMP does not upregulate neuron-specific protein expression significantly in MSCs but does significantly increase expression of the astrocyte-specific glial fibrillary acidic protein. Finally, when grafted into the lateral ventricles of neonatal mouse brain, MSCs migrate extensively and differentiate into olfactory bulb granule cells and periventricular astrocytes, without evidence of cell fusion. These results indicate that MSCs may be "primed" toward a neural fate by the constitutive expression of neuronal antigens and that they seem to respond with an appropriate neural pattern of differentiation when exposed to the environment of the developing brain.

Characterization and neural differentiation of fetal lung mesenchymal stem cells

Mesenchymal stem cells (MSCs) have been successfully isolated from a broad range of adult, fetal, and other nonembryonic tissues. Fetal lung has been identified as a rich source of MSCs. However, the biological characteristics and differentiation potential of fetal lung MSCs remain to be explored. In this study, we established a series of methods for isolation and expansion of fetal lung MSCs. These MSCs could withstand more than 40 passages without obvious decline in proliferation ability, significant changes in morphology, and expression of cell markers. Flow cytometric analysis showed that fetal lung MSCs expressed CD13, CD29, CD44, CD90, CD105, CD166, and HLA-ABC, but not CD14, CD31, CD34, CD38, CD41a, CD42b, CD45, CD49d, CD61, CD106, CD133, and HLA-DR. Cell cycle analysis revealed that when the MSCs reached their log phase of growth, more than 90% of the cells were in G0/G1 phase while the proportion of cells in S phase and G2/M phase were about 5.56% and 2.08% cells, respectively. These MSCs could differentiate into neural cells in addition to their mesenchymal differentiation potential. Our data suggest that the fetal lung MSC population is an alternative source of stem cells for cell-based therapy of neurological defects or mesenchymal-originating diseases.

Hematopoietic cells maintain hematopoietic fates upon entering the brain

Several studies have reported that bone marrow (BM) cells may give rise to neurons and astrocytes in vitro and in vivo. To further test this hypothesis, we analyzed for incorporation of neural cell types expressing donor markers in normal or injured brains of irradiated mice reconstituted with whole BM or single, purified c-kit⁺Thy1.1^loLin⁻Sca-1⁺ (KTLS) hematopoietic stem cells (HSCs), and of unirradiated parabionts with surgically anastomosed vasculature. Each model showed low-level parenchymal engraftment of donor-marker⁺ cells with 96–100% immunoreactivity for panhematopoietic (CD45) or microglial (Iba1 or Mac1) lineage markers in all cases studied. Other than one arborizing structure in the olfactory bulb of one BM-transplanted animal, possibly representing a neuronal or glial cell process, we found no donor-marker–expressing astrocytes or non-Purkinje neurons among >10,000 donor-marker⁺ cells from 21 animals. These data strongly suggest that HSCs and their progeny maintain lineage fidelity in the brain and do not adopt neural cell fates with any measurable frequency.

Isolation and culture of human muscle-derived stem cells able to differentiate into myogenic and neurogenic cell lineages

BACKGROUND

Skeletal-muscle-derived stem cells seem to be a distinct population of immature progenitors of satellite cells, but their functional properties remain unclear, especially in human adult tissue. We investigated their differentiation in samples of skeletal muscle obtained from adults undergoing cardiovascular surgery.

METHODS

Samples were obtained from the brachioradialis muscle of 12 patients in whom the radial artery was the conduit for myocardial revascularisation. The stem cells were isolated by a procedure similar to that used for rat gastrocnemius and cultured in medium optimised for growth of neural stem cells. Cytometry was used for phenotypic characterisation and immunocytochemistry and RT-PCR to assess differentiation. Immunohistochemistry was used to examine engraftment of skeletal-muscle-derived stem cells into injured rat spinal cord.

FINDINGS

The skeletal-muscle stem cells consisted of two distinct types: one with the typical spindle morphology of satellite cells, the other of rounded cells. Some cultures could be maintained for longer than 6 months. The cells were mainly positive for desmin and to a lesser extent CD105, vimentin, and AC133/CD133, but negative for FLK-1/KDR, CD34, CD31, CD45, von Willebrand factor, Ve-cadherins, and BCL2. After in-vitro differentiation, the cells were able to organise skeletal-muscle fibres and stained positively for striated-muscle actin, smooth-muscle actin, and desmin. Moreover, they differentiated into astrocytes and neurons, as confirmed by positive staining for characteristic proteins.

INTERPRETATION

Adult human skeletal muscle includes a population of progenitor stem cells that can generate cells of the same lineage and cells with neurogenic properties. Muscle may therefore be a tissue source for the isolation of pluripotent stem cells for development of cell-based therapies for human myogenic and neurogenic diseases.

Mid-trimester fetal blood-derived adherent cells share characteristics similar to mesenchymal stem cells but full-term umbilical cord blood does not

Stem cell transplantation is a promising treatment for many conditions. Although stem cells can be isolated from many tissues, blood is the ideal source of these cells due to the ease of collection. Mesenchymal stem cells (MSCs) have been paid increased attention because of their powerful proliferation and pluripotent differentiating ability. But whether MSCs reside in blood (newborn umbilical cord blood and fetal or adult peripheral blood) is also debatable. The present study showed that MSC-like cells could be isolated and expanded from 16-26 weeks fetal blood but were not acquired efficiently from full-term infants' umbilical cord blood (UCB). Adherent cells separated from postnatal UCB were heterogeneous in cell morphology. Their proliferation capacity was limited and they were mainly CD45+, which indicated their haematopoietic derivation. On the contrary, MSC-like cells shared a similar phenotype to bone marrow MSCs. They were CD34- CD45- CD44+ CD71+ CD90+ CD105+. They could be induced to differentiate into osteogenic, adipogenic and neural lineage cells. Single cell clones also showed similar phenotype and differentiation ability. Our results suggest that early fetal blood is rich in MSCs but term UCB is not.

Stem cells in the treatment of amyotrophic lateral sclerosis (ALS)

Until fairly recently, interest in stem cells was restricted to neurobiology studies on the principles of embryonic development. This situation has changed rapidly in the last few years when neuronal stems and precursors were isolated in vitro, thus allowing expansion and controlled differentiation of selective populations of neuronal cells. This theoretically unlimited reserve would then supply specific cells for transplantation in diseases characterized by widespread degeneration of selective cell populations as motor neurons in Amyotrophic Lateral Sclerosis (ALS). The recent evidence of cell transdifferentiation has further amplified the potential therapeutic use of stem cells. Stem cell technology is at an early stage but the desperate need for a therapy in ALS patients may legitimize clinical trials in absence of conclusive scientific evidence. This paper discusses the premises for stem cell therapy in ALS.