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Wang, F., Hao, H., Zhao, S., Zhang, Y., Liu, Q., Liu, H., Liu, S., Yuan, Q., Bing, L., Ling, E., & Hao, A 2011, “Roles of activated astrocyte in neural stem cell proliferation and differentiation,” Stem Cell Research, vol. 2011, no. 7, pp. 41-53.
In the introduction, the authors provide an unambiguous background on the use of neural stem cells (NSCs) in treating neural disorders. It is known that astrocytes produce certain substances, which play significant roles in deciding the outcomes of neural stem cells. Neural stem cells can be used in nervous disorders. However, the key challenge lies in maintaining the ability of the propagation of stem cells as well as deciding the type of cells that are formed. The neighbouring microenvironment of the stem cells is thought to play a significant role in influencing the fate of stem cells. Wang et al. (2011) provide numerous examples of previous studies showing the role of astrocytes in the central nervous system. It is shown that astrocytes affect the development of mesenchymal stem cells obtained from bone marrow. Then again, the precise substances and their mode of action in deciding the fate of neural stem cells remain unknown. Therefore, the authors seek to determine whether the effects observed in mesenchymal stem cells are replicated in NSCs. The general experimental procedure is well illustrated. Astrocytes triggered by lipopolysaccharides are used to imitate the effects of activities of astrocytes following inflammatory injury. In addition, the authors provide the implications of their findings on the treatment of neurological disorders. However, the authors do not explicitly state the hypotheses of their investigation. Therefore, it is unclear whether a null or alternative hypothesis is being tested by the outcomes of the investigation.
The materials and methods section comes after the results and discussion sections, which is unusual as most papers usually have the materials and methods section appearing before the results and discussion. Bits of information on the experimental procedures are also given alongside the results. There is an order in the experimental steps followed by the researchers since each step is illustrated under its subheading. The experimental design followed by the authors makes it easy to answer the research questions. In addition, the procedure lists the materials and equipment employed in the research. This information is adequate to enable one replicate the experimental procedure. The methods are explained systematically except in cases where given protocols are used. In such instances, the names of the authors who first developed the protocols are mentioned, for example, the preparation of astrocytes follows the procedure described by McCarthy and de Vellis in 1980 (Wang et al. 2011). However, it is difficult to determine whether the sampling is appropriate or inappropriate since the researchers do not mention the number of samples analyzed. The statistical analysis section describes the statistical tests performed on the results as well as the statistical parameters used in the study, which are means and standard deviations of various experimental procedures.
The results section, which is well organized with subheadings, clearly explains the outcomes of each test. The means and standard deviations of the outcomes are clearly illustrated for each test. In addition, the statistical differences between treatment groups are provided at 0.05 level of significance. The differences are considered statistically significant if the values of P are less than 0.05 (Wang et al. 2011). Western blot images of the various outcomes are also illustrated alongside graphical representations of the means and standard deviations of the various tests. The quantitative methods used in this paper are appropriate for the kind of information that the authors intend to bring out. For example, in the determination of the effect of various astrocyte-conditioned media on NSCs, cell viability and the assimilation of BrdU by the stem cells is established at different time intervals. These parameters (cell viability and BrdU absorption) are quantified and reported as means and standard deviations. Statistical comparisons of the mean cell viability and BrdU absorption in various media reveal that astrocyte-conditioned medium substantially enhances the propagation of NSCs.
The discussion section is adequately supported by the results of the study. For example, the authors assert that astrocytes triggered by lipopolysaccharides exude certain substances that are responsible for enhancing the rate of propagation of NSCs. This assertion is corroborated by the mean cell viability of NSCs grown in the presence of various ACMs. In addition, these observations agree with previous studies on the molecules produced by activated astrocytes (Wang et al. 2010, p. 48). Wang et al. show how the outcomes of their investigation relate to previous studies regarding the role of astrocytes in the multiplication and development of NSCs (2011). The authors fill the literature gap on the effects of triggered astrocytes on NSCs under inflammatory conditions. It is obvious that astrocytes triggered by inflammation largely influence the fate of NSCs compared to unstimulated astrocytes. These claims are substantiated by clearly outlined results. In addition, the assertions are in line with the findings of earlier studies performed on mesenchymal stem cells. Overall, the discussion section of the paper fulfils the aims of the investigation. However, the authors do not arrive at a clear-cut conclusion following their investigation.
Tran, L. A., Krishnamurthy, R., Muthupillai, R., Cabreira-Hansen, M. G., Willerson, J. T., Perin, E. C., & Wilson, L. J 2010, “Gadonanotubes as magnetic nanolabels for stem cell detection,” Biomaterials, vol. 2010, no. 31, pp. 9482-9491.
The introduction provides a clear background to the problem under investigation. There is a need for highly developed methods of tracking cells inside a living body to monitor the development as well as the relationship of the new cells with the host cells. Therefore, non-invasive techniques of keeping an eye on the stem cells are essential for the success of stem cell therapy. Currently, the only method involves the removal of part of the host tissues for immunohistochemistry analysis. The authors give magnetic resonance imaging (MRI) as the ideal method of monitoring stem cells inside a living host. However, contrast agents are required to change the signals of magnetic resonance in successful imaging. Gadolinium’s properties make it a suitable contrast agent in MRI. Tran et al., therefore, focus on the use of gadolinium-based contrast agents in enhancing magnetic resonance imaging (2010). The authors openly describe what they intend to achieve, which is to determine the suitability of gadonanotubes to trace mesenchymal stem cells in living hosts. Tran et al. (2010) give a summary of relevant research on contrast agents, and explore the possibility of utilizing gadolinium as a tracer in living cells. Their work is an extension of the findings of other authors. A brief explanation of the general experimental design and the expected outcomes is provided. Additionally, Tran et al. intend to determine the biological effects of gadonanotubes on mesenchymal stem cells. However, the authors do not provide a precise hypothesis that their investigation seeks to support or refute.
The paper explains how the data are collected, the steps followed in obtaining the sample, preparation of the sample, as well as the tests carried out. All this information is presented in a systematic manner with subheadings for each subsection thereby making it easy for the reader to replicate the experiment. In instances where detailed explanations are missing, the authors cite the source of their procedure. In addition, the materials and equipment used are adequately described. However, it is difficult to decide the appropriateness of the sampling method as there is no mention of the number of samples used. Under the subheading ‘cell culture studies,’ the authors indicate “MSCs were harvested and isolated from the bone marrow of male pigs as described elsewhere” (Tran et al. 2010, p. 9483). It is not clear how many pigs are used to obtain the mesenchymal stem cells. The article clarifies the kind of data collected. For example, in the population doubling time assay, the experimenters record the average time taken for the number of mesenchymal stem cells to increase twofold. Overall, the authors are meticulous in their description of measurements such as time (minutes, hours and days), temperature (degrees centigrade) and concentrations (micromoles, millimoles, micrograms per millilitre and so on).
The results of the investigation are laid out in a coherent sequence. The authors intend to establish the potential of gadonanotubes as in vitro tracers for magnetic resonance imaging as well as the effects of GNTs on living cells. The quantitative techniques as depicted by the results of the study are appropriate for this quest. For instance, it is expected that GNTs should be eliminated from living cells after fulfilling their role of enhancing MR imaging. A pulse-chase investigation is carried out by quantifying the concentration of Gd3+ ions in labelled cells under varying conditions to determine the ability of GNTs to leave the cells (Tran et al. 2010). Similarly, the rate of proliferation of labelled cells is compared to the rate of propagation of unlabelled cells. A comparison of the propagation rate of labelled and unlabelled cells reveals that unlabelled cells multiply much faster than the labelled cells implying that Gd3+ leads to the death of cells within the first 48 hours. These findings are significant in a clinical setting because they illustrate the expected outcomes if gadonanotubes are used to label stem cells. Conversely, in the evaluation of the self-renewal attributes and propagation dynamics of mesenchymal stem cells labelled with GNTs, the “colony-forming unit fibroblast (CFU-F) and population doubling time (PDT) assays” of the labelled cells are carried out (Tran et al. 2010, p. 9489). These tests make use of averages (colony-forming units and time in hours) as well as standard deviations. A comparison of these parameters in labelled and unlabelled cells reveals the efficacy of GNT labelling of MSCs. Therefore, it can be deduced that the quantitative methods used are appropriate for the kind of information needed because the methods not only provide numerical data, but also correspond to the physiological processes that take place in the cells.
The discussion and conclusion of the paper are backed up by the results. For example, the researchers claim that the best labelling concentration that does not alter the viability of cells is attained at 27 micromoles of Gd3+, which corresponds to 98 percent of viable cells. Images of transmission emission microscopy, which are part of the results, confirm the uptake of the nanoparticles. The authors indicate that these findings agree with previous studies on the uptake of other nanoparticles. However, explicit comparisons cannot be made due to the variations in the preparation and dispensation of the nanoparticles. The authors also assert that gadonanotubes do not alter the properties of mesenchymal stem cells. This assertion is supported by the findings of the study, which show that the labelled stem cells can develop into various types of cells such as adipocytes, chondrocytes and osteocytes (Tran et al. 2010).
The implication of this finding is that the mesenchymal stem cells labelled with gadonanotubes are capable of preserving their restorative ability. However, the authors do not quantify the differentiation potential of MSCs labelled with gadonanotubes. Consequently, the authors suggest that additional quantitative examinations are necessary to confirm the abilities of mesenchymal stem cells labelled with GNTs. It is also evident that GNTs alter the cell adhesion properties of mesenchymal stem cells to fibronectin and collagen I, the principal constituents of the extracellular matrix (Tran et al. 2010). MSCs labelled with GNTs exhibit lower adhesion to the extracellular matrix than unlabelled cells. However, the precise mechanisms through which GNTs alter cell adhesion attributes are unknown. The authors recommend that additional investigations be carried out to establish the precise mode of inhibition of cell adhesion. Overall, the authors deduce that gadonanotubes epitomize a novel, high-performance biotechnology for the tagging of stem cells and perhaps in vivo cell tracing using magnetic resonance imaging. These deductions are fully supported by the results of the study. Therefore, it can be concluded that the authors are aware of the gaps in their work that require further investigations.
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