Research Highlights
News & Views
Highlights from the latest articles in regenerative medicine
Ventral root axotomy regeneration after mesenchymal stem cell transplantation Evaluation of: Spejo AB, Carvalho JL, Goes AM, Oliveira AL. Neuroprotective effects of mesenchymal stem cells on spinal motoneurons following ventral root axotomy: synapse stability and axonal regeneration. Neuroscience 250, 715–732 (2013). Spinal nerve compression due to injury or disease can account for major sensory and motor dysfunction. Although the roots may be damaged, the preservation of the connective tissue may remain, therefore promoting successful regeneration. Lesions or crushing of the ventral nerve root in particular trigger disintegration of motoneurons and neurotrophic support due to severing connectivity with target muscle fibers. Further exacerbating the injury, there is loss of synapses, gliosis and gluatmaterigic excitotoxicity occurring acutely. The researchers in the present study utilized a ventral root crush in a rat model with the addition of mesenchymal stem cells (MSCs) to promote the chance of recovery after significant loss of motoneurons. An important and initial step in the study by Spejo et al. involved characterization of the MSCs, isolated from GFP-expressing Lewis rats, which were found to be the conventionally biomarkerexpressing MSCs [1]. In their transplantation model, GFP-expressing MSCs were found at the injection site and anterior horn 4 weeks after injection. Initial observations after lesioning determined that there was significant loss of motoneurons observed in the control groups (crushing and crushing with media). However, the group treated with MSCs had a higher number of surviving neurons. The researchers concluded that MSCs 10.2217/RME.13.72 © 2013 Future Medicine Ltd
may be neuroprotective in this model. Synaptic terminal retention was assessed via immunohistochemistry and indicated a smaller reduction in terminal loss with MSC treatment. Furthermore, the MSC treatment reduced astrogliosis after ventral nerve crush. Synapse preservation was determined to be of the GABAergic type in those animals treated with MSCs. Morphometric analysis 12 weeks after lesion indicated the group with media treatment had a decreased nerve area and smaller myelinated fibers than the cell-treated group. Functional tests revealed that MSC-treated animals demonstrated better motor function when testing intensity of paw stepping and stride length. The study conducted by these researchers demonstrated the feasibility of implanting MSCs into the ventral root crush injury site with optimal effects of preservation of spinal motoneurons and functional recovery. This may be due to connective tissue around the injury being undamaged and able to guide axonal regrowth. Additionally, the neurotrophic effects of the MSC transplantation are also evident in the ventral nerve crush injury model. Could this also translate to the ventral nerve avulsion model? Additional experiments should be conducted to determine this answer. Further work using combinatorial therapies in crush injury should also be conducted to determine the optimal environment for regeneration after acute injury or disease.
Amber E Kerstetter-Fogle Case Western Reserve University, Center for Translational Neuroscience, Department of Neurological Surgery, Cleveland, OH 44106, USA [email protected]
Financial & competing interests disclosure The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
Reference 1
Spejo AB, Carvalho JL, Goes AM, Oliveira AL. Neuroprotective effects of mesenchymal stem cells on spinal motoneurons following ventral root axotomy: synapse stability and axonal regeneration. Neuroscience 250, 715–732 (2013).
Regen. Med. (2013) 8(6), 695–697
part of
ISSN 1746-0751
695
News & Views – Research Highlights
miRNAs targeting in glioma stem cell maintenance Evaluation of: Chen L, Chen X, Chen F et al. MicroRNA-107 inhibits U87 glioma stem cells growth and invasion. Cell. Mol. Neurobiol. 33(5), 651–657 (2013). One of the most malignant cancers of the brain, glioblastoma multiforme (GBM), has an extremely devastating prognosis and not many treatment options. The current standard of care involves resection, chemotherapy and radiation, and essentially only palliative care. The molecular nature of GBM has been studied by many laboratories and classifications have been made based on their gene expression profiles. Assumptions have been made as to genetic expression correlation with prognosis. Therefore, ironing out the details of the common molecular and genetic pathways underlying this devastating disease is paramount to helping thousands of patients worldwide. The researchers in the evaluated manuscript utilized a common GBM cell line, U87, to look at the role of miRNAs in modulating proliferation, invasion and tumorigenesis, in addition to pathways that may be involved [1]. miRNAs have already became implicated in gliomas, including miR-124, miR-137, miR-451, miR-34a and miR-125b. Another miRNA has been implicated but has not been studied in detail in relation to GBM; miR-107 [2]. This particular miRNA has been found to be decreased in the cells expressing the classical stem cell marker CD133. This study set out to elucidate its role in glioma stem cell maintenance and tumorigenecity. Initially, the researchers wanted to make sure miR-107 was downregulated in CD133+ cells and found this to be indeed the case in three separate glioma cell lines. A lentivirus expressing miR-107 was tranduced into CD133+ U87 cells; they found miR-107 was able to be expressed in the glioma stem cells. Upon further evaluation, they determined that the neurospheres expressing miR-107 are reduced and smaller in diameter. Notch has been associated in the proliferation of glioma stem cells and, therefore, Chen et al. evaluated expression 696
Regen. Med. (2013) 8(6)
of Notch2 in cells expressing miR-107 and determined the CD133+ cells of the U87 lines suppressed Notch2 protein [1]. Therefore, miR-107 expression may be inhibitory to Notch2 protein and may explain the lack of large neurospheres. They looked into this additionally by scrutinizing CD133 and Nestin (stem cell markers) expression in the miR-107-transduced cells. They determined that CD133 and Nestin mRNA was reduced significantly in miR-107-expressing glioma stem cells. The behavior of the cells was also assessed after miR-107-induced expression via matrigel invasion assays. Invasion was reduced significantly in cells expressing miR-107 compared with control. Matrix metalloproteinases (MMPs), specifically MMP-2 and MMP-9, were also analyzed owing to their implications in regulating invasion of glioma stem cells. Expression of MMP-2 and MMP-9 were similar in cells expressing miR-107 and those who do not. Investigation of other MMPs, in particular MMP-12, determined this was inhibited by miR-107 expression. On a thought-provoking note, MMP-12 expression is indirectly regulated by Notch2. The true test to the role of miR-107 came from utilizing a flank tumor model. It was determined that cells expressing miR-107 had increased tumor volumes than controls. This study was a simplistic study in the role of miR-107 in glioma neurosphere formation, expression and tumor-inducing abilities; however, the cells utilized were a cell line that most glioma researchers have questioned. Nevertheless, this may be all that was available to these researchers. Moreover, a standard proliferation assay, limited dilution assay or colony formation assay would also have been interesting to tie this into the proliferative capacity of these cells after miR-107 upregulation. Furthermore, immunocytochemistry would have been interesting to determine the protein expression and to ensure the cells were not becoming differentiated due to their overexpression of miR-107. There are a few caveats to this study; nonetheless, it is a start to finding new therapeutic interventions for GBM patients. future science group
Research Highlights –
Reference 1
Chen L, Chen X, Chen F et al. MicroRNA-107 inhibits U87 glioma stem cells growth and invasion. Cell. Mol. Neurobiol. 33(5), 651–657 (2013).
future science group
2
News & Views
Gal H, Pandi G, Kanner AA et al. miR-451 and imatinib mesylate inhibit tumor growth of glioblastoma stem cells. Biochem. Biophys. Res. Commun. 376, 86–90 (2008).
www.futuremedicine.com
697
News & Views
Highlights from the latest articles in regenerative medicine
Ventral root axotomy regeneration after mesenchymal stem cell transplantation Evaluation of: Spejo AB, Carvalho JL, Goes AM, Oliveira AL. Neuroprotective effects of mesenchymal stem cells on spinal motoneurons following ventral root axotomy: synapse stability and axonal regeneration. Neuroscience 250, 715–732 (2013). Spinal nerve compression due to injury or disease can account for major sensory and motor dysfunction. Although the roots may be damaged, the preservation of the connective tissue may remain, therefore promoting successful regeneration. Lesions or crushing of the ventral nerve root in particular trigger disintegration of motoneurons and neurotrophic support due to severing connectivity with target muscle fibers. Further exacerbating the injury, there is loss of synapses, gliosis and gluatmaterigic excitotoxicity occurring acutely. The researchers in the present study utilized a ventral root crush in a rat model with the addition of mesenchymal stem cells (MSCs) to promote the chance of recovery after significant loss of motoneurons. An important and initial step in the study by Spejo et al. involved characterization of the MSCs, isolated from GFP-expressing Lewis rats, which were found to be the conventionally biomarkerexpressing MSCs [1]. In their transplantation model, GFP-expressing MSCs were found at the injection site and anterior horn 4 weeks after injection. Initial observations after lesioning determined that there was significant loss of motoneurons observed in the control groups (crushing and crushing with media). However, the group treated with MSCs had a higher number of surviving neurons. The researchers concluded that MSCs 10.2217/RME.13.72 © 2013 Future Medicine Ltd
may be neuroprotective in this model. Synaptic terminal retention was assessed via immunohistochemistry and indicated a smaller reduction in terminal loss with MSC treatment. Furthermore, the MSC treatment reduced astrogliosis after ventral nerve crush. Synapse preservation was determined to be of the GABAergic type in those animals treated with MSCs. Morphometric analysis 12 weeks after lesion indicated the group with media treatment had a decreased nerve area and smaller myelinated fibers than the cell-treated group. Functional tests revealed that MSC-treated animals demonstrated better motor function when testing intensity of paw stepping and stride length. The study conducted by these researchers demonstrated the feasibility of implanting MSCs into the ventral root crush injury site with optimal effects of preservation of spinal motoneurons and functional recovery. This may be due to connective tissue around the injury being undamaged and able to guide axonal regrowth. Additionally, the neurotrophic effects of the MSC transplantation are also evident in the ventral nerve crush injury model. Could this also translate to the ventral nerve avulsion model? Additional experiments should be conducted to determine this answer. Further work using combinatorial therapies in crush injury should also be conducted to determine the optimal environment for regeneration after acute injury or disease.
Amber E Kerstetter-Fogle Case Western Reserve University, Center for Translational Neuroscience, Department of Neurological Surgery, Cleveland, OH 44106, USA [email protected]
Financial & competing interests disclosure The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
Reference 1
Spejo AB, Carvalho JL, Goes AM, Oliveira AL. Neuroprotective effects of mesenchymal stem cells on spinal motoneurons following ventral root axotomy: synapse stability and axonal regeneration. Neuroscience 250, 715–732 (2013).
Regen. Med. (2013) 8(6), 695–697
part of
ISSN 1746-0751
695
News & Views – Research Highlights
miRNAs targeting in glioma stem cell maintenance Evaluation of: Chen L, Chen X, Chen F et al. MicroRNA-107 inhibits U87 glioma stem cells growth and invasion. Cell. Mol. Neurobiol. 33(5), 651–657 (2013). One of the most malignant cancers of the brain, glioblastoma multiforme (GBM), has an extremely devastating prognosis and not many treatment options. The current standard of care involves resection, chemotherapy and radiation, and essentially only palliative care. The molecular nature of GBM has been studied by many laboratories and classifications have been made based on their gene expression profiles. Assumptions have been made as to genetic expression correlation with prognosis. Therefore, ironing out the details of the common molecular and genetic pathways underlying this devastating disease is paramount to helping thousands of patients worldwide. The researchers in the evaluated manuscript utilized a common GBM cell line, U87, to look at the role of miRNAs in modulating proliferation, invasion and tumorigenesis, in addition to pathways that may be involved [1]. miRNAs have already became implicated in gliomas, including miR-124, miR-137, miR-451, miR-34a and miR-125b. Another miRNA has been implicated but has not been studied in detail in relation to GBM; miR-107 [2]. This particular miRNA has been found to be decreased in the cells expressing the classical stem cell marker CD133. This study set out to elucidate its role in glioma stem cell maintenance and tumorigenecity. Initially, the researchers wanted to make sure miR-107 was downregulated in CD133+ cells and found this to be indeed the case in three separate glioma cell lines. A lentivirus expressing miR-107 was tranduced into CD133+ U87 cells; they found miR-107 was able to be expressed in the glioma stem cells. Upon further evaluation, they determined that the neurospheres expressing miR-107 are reduced and smaller in diameter. Notch has been associated in the proliferation of glioma stem cells and, therefore, Chen et al. evaluated expression 696
Regen. Med. (2013) 8(6)
of Notch2 in cells expressing miR-107 and determined the CD133+ cells of the U87 lines suppressed Notch2 protein [1]. Therefore, miR-107 expression may be inhibitory to Notch2 protein and may explain the lack of large neurospheres. They looked into this additionally by scrutinizing CD133 and Nestin (stem cell markers) expression in the miR-107-transduced cells. They determined that CD133 and Nestin mRNA was reduced significantly in miR-107-expressing glioma stem cells. The behavior of the cells was also assessed after miR-107-induced expression via matrigel invasion assays. Invasion was reduced significantly in cells expressing miR-107 compared with control. Matrix metalloproteinases (MMPs), specifically MMP-2 and MMP-9, were also analyzed owing to their implications in regulating invasion of glioma stem cells. Expression of MMP-2 and MMP-9 were similar in cells expressing miR-107 and those who do not. Investigation of other MMPs, in particular MMP-12, determined this was inhibited by miR-107 expression. On a thought-provoking note, MMP-12 expression is indirectly regulated by Notch2. The true test to the role of miR-107 came from utilizing a flank tumor model. It was determined that cells expressing miR-107 had increased tumor volumes than controls. This study was a simplistic study in the role of miR-107 in glioma neurosphere formation, expression and tumor-inducing abilities; however, the cells utilized were a cell line that most glioma researchers have questioned. Nevertheless, this may be all that was available to these researchers. Moreover, a standard proliferation assay, limited dilution assay or colony formation assay would also have been interesting to tie this into the proliferative capacity of these cells after miR-107 upregulation. Furthermore, immunocytochemistry would have been interesting to determine the protein expression and to ensure the cells were not becoming differentiated due to their overexpression of miR-107. There are a few caveats to this study; nonetheless, it is a start to finding new therapeutic interventions for GBM patients. future science group
Research Highlights –
Reference 1
Chen L, Chen X, Chen F et al. MicroRNA-107 inhibits U87 glioma stem cells growth and invasion. Cell. Mol. Neurobiol. 33(5), 651–657 (2013).
future science group
2
News & Views
Gal H, Pandi G, Kanner AA et al. miR-451 and imatinib mesylate inhibit tumor growth of glioblastoma stem cells. Biochem. Biophys. Res. Commun. 376, 86–90 (2008).
www.futuremedicine.com
697
