Bone Tissue Engineering - Book Report/Review Example

Article Review; Bone Tissue Engineering Nishi, Matsumoto, Dong and Uemura (pg. 422) provide a clear conceptual framework by beginning with a brief introduction pertaining to the bone tissue engineering technology. According to Nishi et.al (pg. 422) bone tissue engineering is regarded as the perfect alternative for bone grafting. This is mainly because contrary to grafting, bone tissue engineering provides the advantage of being able to produce a specific shaped, as well as size capable of matching any bone defect. Additionally, the technique is also regarded as less tedious compared to grafting, which may often require recurrent surgeries to fit the graft, and may sometimes fail to serve the intended function. Nevertheless, not all implanted tissues tend to work as expected because of non-vascularization that may render a tissue necrotic as a result of failure to form blood vessels. Vascularization is therefore of the essence, but is usually a great challenge in the regeneration of bones. Nishi et.al (pg. 422) conducted a study dubbed Engineered bone tissue associated with vascularization utilizing a rotating wall vessel bioreactor. The study was mainly geared towards investigating a method of performing vascularization, which is crucial towards developing a bone tissue of appropriate sizes and shape for implantation in patients with bone defects. The lack of vascularization has commonly resulted in necrosis of in vivo seeded cells. Thus, Nishi’s et.al (2009) study was therefore one of the first bone tissue engineering associated with vascularization. Using a rotating wall vessel, they co-cultured the bone marrow mesenchymal stem cells and endothelial cells derived from mesenchymal stem cells within a scaffold. They consequently analyzed the derived tissue and established that it was possible to obtain a vascularized bone tissue. Nishi et.al (pg. 422) presents an appropriate step-by-step method that they carried out to facilitate the study providing relevant reasons and justification for their preferred choice or course of action. To begin with, they assert that all their activities were carried as per the Japan Government regulations that govern the use of laboratory animals. Subsequently they outline the process of extraction and culturing of the bone marrow mesenchyme stem cells from femurs of ten-day-old white Japanese rabbits. This is followed by another step by step procedure of the differentiation of the extracted and cultured mesenchymal cells into endothelial cells, which entailed harvesting the MSCs at 90% culture confluency using 0.25% trypsin-ethylenediamine tetraacetic acid (EDTA). In addition, they present yet another step-by-step process of co-culturing the mesemchymal stem cells and the endothelium cells derived from the mesenchymal cells in the scaffold. They explained that the process was carried out in a 3D scaffold of D, D-L-L polylactic acid because three dimensional cultures tend to provide a more favorable physiological environment for cells compared to its counterpart two dimensional cultures. Moreover, they justify the use of 3D dimensional cultures by pointing out that 3D cultures allows the use of rotating wall vessels that tend normally improve nutrient supply, while also increase the rate of removal of metabolic wastes. They also provide adequate analytical methods that were incorporated at the various stages of the experiment. They present the first analysis in the experiment at the second stage involving the differentiation of MSCs into endothelial cells. After washing the ECs derived from the MSCs, they employed flow cytometry system, as well as the Flow Jo 7.6 software for data analysis. This enhanced the overall reliability of the experiment. Subsequently, the co-cultured cells were also statistically analyzed using a t-test to determine cells sizes among other aspects. The obtained values were then plotted on graph. The main histochemical analyses included the use of Image J 1.45s software that was used to calculate the relative cell area relative to the scaffold. Overall, Nishi’s et.al (pg. 422) methods, study design and the overall conceptual framework support the reports’ main topic. As per the topic, the work presents a rotating wall vessel bioreactor technique and procedure aimed at engineering a bone tissue with vascularizing as an alternative for bone grafting. The main idea of the report is to develop a vascularized bone tissue, which is usually to obtain because of the procedure and techniques involved. The article abstract also plays a crucial role of providing an extensive overview of the report. Not only does it explains the importance of the bone tissue engineering, but it also provide a glimpse of the various steps and stages involved in the experiment. Similarly, the abstract goes further as to provide an overview of the various analytical methods involved in the experiment, as well as the results that were obtained at the end of the experiment. In general, the report title, as well as the report abstract, are integral towards developing a general understanding or the intended purpose of the study. Nish et.al (pg. 423) adds more weight to their experiment by providing a real image graphic presentation of the three step-by-step procedure of culturing the BMC. The procedure begins from the scaffolding of the endothelial cell derived from the bone marrow cells (BMC), followed by culturing of the MSCs into ECs in an endothelial cell growth medium using the RMV bioreactor, and ending with the addition of the MSCs into an osteogenic differentiation medium for differentiation of the MSCs into MSC-derived ECs. All the fundamental elements are labeled appropriately in the illustrations. The last procedure was the histochemical analysis that entailed estimating the percentage of cell area relative to the scaffold. This involved fixing the recovered tissue into a series of agents beginning with 4% paraformaldehyde in PBS for one week at a temperature of 4 degrees Celsius. Similarly, Nishi et.al (pg. 422) employs various graphical presentations to explain some of the various results obtained at various stages of the experiment. In figure 2, they present a graph illustrating the growth and differentiation of the MSCs into ECs at certain time interval. This is also accompanied by pictorial confirmation of the seeding cell density at zero to seven days. By the seventh day, the ECs density was estimated at 2 X 105 cells/cm2. This led to the conclusion that the MSCs were actually differentiating into the supposed ECs. Subsequently, they also provide another graphical presentation depicting the analysis of engineered tissues by culturing in the endothelial cell growth medium. The image analysis depicted in figure 3 from (a) to (e) illustrates that the seeding densities of cells per scaffolding were increasing with time. On the other hand, figure 4 illustrates the quality of the tissue as a bone that they conducted using the hematoxylin and eosin, and the osteopontin and osteocalcin staining methods. They postulated that positive staining was a sign of vascularization. Each of the illustrations demonstrates how each of cells were growing and spreading in the scaffold. Positive staining results indicated vascularization. Subsequently, Nishi et.al (2009) further illustrates the effect of co-culturing MSCs and ECs in figure 5. They hypothesized that co-culturing is crucial to accelerate vascularization. Similarly they also postulated that the RWC bioreactor also played an important role in the growth of the cultures in the scaffold. Image a to d illustrates that cells in the stationary culture aggregated on some parts of the scaffold and failed to vascularize. On the contrary, those in the RWV bioreactor spread throughout the scaffold and grew well to vascularize. To determine the effects of co-culturing, they included a control experiment involving culturing of human umbilical endothelial cells (HUVECs). The HUVECs however failed to grow well like the ECs derived from the MSCs. They attributed this to the lack of osteoblasts that have proliferative activities that enhances vascularization. Nishi’s et.al (pg. 422) concludes their report by drawing from the major data findings from the experiment as a whole. For instance, they conclude by pointing out that the results obtained from the histochemical analysis confirmed the generation of vascularized bone tissue. This particularly pertains to the positive staining results obtained when hematoxylin and eosin staining was applied. Furthermore, they posits that following successful generation of bone tissue with vascular-like structures, some of the various procedures and techniques that were employed in the experiment played various specific important roles. For instance, the inability of cells to grow well in a stationary culture led to the conclusion that the RWV bioreactor facilitated cell growth in the scaffold. Similarly, following the inability of the HUVECs to go well, they concluded that ECs derived from MSCs were crucial towards enhancing distribution, as well as proliferation of cells in the scaffold. Read More