The National Science Foundation NSF defined Tissue Engineering in as the application of the principles and methods of engineering and life sciences toward fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and the development of biological substitutes to restore, maintain or improve tissue function Shalak and Fox, The two prerequisites for the successful engineering of an organ are suitable cells and a biomaterial or extra celluar matrix component.
A large variety of cells has been proposed for the use in tissue engineering, including pluripotent embryonic stem cells ESC with all their ethical controversies, adult stem cells found inverted papillary urothelial carcinoma pathology outlines most tissues, and committed precursor cells.
While the plasticity of ESC offers the potential to grow an entire organ from a single cell source, the clear differentiation of these cells remains challenging.
Currently, adult cells seem to have certain advantages regarding rapid clinical translation. Most biomaterials used in Tissue Engineering are based on acellular matrices or polyglycolic acid. Both materials must provide tissue support until the cells produce their own extracellular matrix.
Несмотря на разногласия со Стратмором по многим вопросам, Фонтейн всегда очень высоко его ценил.
Солнечные лучи, проходя сквозь этот экран, покрывали стены нежным кружевным узором.
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Ideally, they degrade thereafter without any toxic byproducts. Over the last years we started to understand the influence of the biomechanical environment allowing these cell-biomaterial composites to unfold their full functional potential.
However, many fundamental questions regarding cells and biomaterials remain unanswered. This book will be of interest to anyone interested in the application of Tissue Engineering.
It offers a wide range of topics, including the use of stem cells and adult stem cells, their applications and the development of a tailored biomaterial, highlighting the importance of cell-biomaterial interaction. It offers insights into a Preface wide variety of cells and biomaterials, explaining the groundwork required to open the avenue to the next generation biotechnology, which is Tissue Engineering.
Finally, I would like to express my appreciation to all authors who have contributed to this book. Introduction Since the initial excitement surrounding successful clinical studies of skin inverted papillary urothelial carcinoma pathology outlines engineering more than 20 years ago Gallico et al.
Tissue engineering generally depends upon the use of cultured cells. Since living cells do not fall into any of the existing medical inverted papillary urothelial carcinoma pathology outlines categories, this has created a great challenge for both regulatory agencies inverted papillary urothelial carcinoma pathology outlines commercial inverted papillary urothelial carcinoma pathology outlines.
Although various treatment strategies have been developed, the fundamental technologies and infrastructure to support their widespread adoption are still limited. In this chapter, attention was focused on fundamental technology development. Three major areas, i. The concept of tissue engineering is to regenerate target tissue by mimicking the developmental or regenerative process of that tissue.
Thus, it can be considered an ideal therapeutic option for treating various tissue defects. Tissue engineering of skin, cartilage, and bone has already been shown both feasible and effective in several clinical studies, and its efficacy has attracted significant attention from both patients and doctors.
However, there are several fundamental technologies which need to be improved before widespread practical use of tissue engineering in hospitals or clinics.
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In this chapter, the current status of cell culture media used for clinical tissue engineering and the need for the development of safe and reliable serum-free cell culture media will be discussed with special reference to bone tissue engineering. To regenerate the lost bone tissue, autologous bone grafting is the current gold standard, though this technique is a great burden for patients because transplantable autologous bone must be harvested from a healthy site, which causes donor site morbidity and pain.
Artificial bone substitutes have been developed as alternatives to autologous bone, though bone regeneration with them is inefficient because they lack osteo-inductive properties.
Accordingly, tissue engineering of bone bone tissue engineering has attracted significant interest because it is considered less invasive than autologous bone grafting and more efficient than artificial bone substitutes.
In fact, cell-based bone tissue engineering which utilizes cells, scaffolds, and bioactive molecules has been shown even more effective than artificial bone substitute in both basic and clinical studies.
For cell-based bone tissue engineering, various tissues derived cells are utilized since osteogenic cells can be harvested from bone marrow, periosteum, and adipose tissue, though recent studies indicate that bone marrow stromal cells BMSCs, bone marrow derived multipotent mesenchymal stromal cells, or mesenchymal stem cells are the most reliable cell source because of their superior osteogenic ability Hayashi et al.
However, it is difficult to obtain adequate numbers of transplantable BMSCs from bone marrow aspirates, as they are rare in the bone marrow less than 0. Therefore, ex vivo expansion of BMSCs is required to obtain a sufficient number of transplantable cells. Since BMSCs require several kinds of supportive factors for their growth, it is standard practice to use fetal bovine serum FBSwhile autologous human serum HS and pooled allogeneic HS have also been used. It has been suggested that FBS may not be favorable for clinical applications due to the possible risk of contamination prions, viruses, zoonosis or immunological inverted papillary urothelial carcinoma pathology outlines against xenogeneic serum antigens Agata et al.
Although serious secondary effects of transplanted cells that were cultured in the presence of FBS have not been reported to date, a previous clinical study that utilized BMSCs cultivated in FBS-supplemented media for the treatment of osteogenesis imperfecta showed a fold increase in antibody titer against FBS in the sera of one patient who received BMSCs infusions Horwitz et al.
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Theoretically, use of inverted papillary urothelial carcinoma pathology outlines HS could eliminate the risks of disease transmissions inverted papillary urothelial carcinoma pathology outlines immune reactions. In fact, over mL of peripheral blood is usually required to obtain mL of autologous HS, which is only sufficient to support the growth of BMSCs for a few passages.
Therefore, collection of a sufficient amount of autologous HS is a considerable burden for anaemic patients as well as for healthy female patients with a low body weight. Furthermore, even when a sufficient amount of autologous HS can be obtained from each patient, the constituents of individual HS could vary, which might lead to variations of cell culture outcome. Thus, it is desirable to develop efficient and safe serum-free culture media and eventually serum-independent cell expansion protocols for tissue engineering.
Recently, several companies have launched complete serum-free culture media that can inverted papillary urothelial carcinoma pathology outlines the growth of human mesenchymal stem cells without the addition of sera Table 1. These data indicate that currently available xeno-free, serum-free media may have the potential to replace conventional serum-based media in clinical tissue engineering, though further basic studies are required to ensure its safety and efficacy.
To develop a protocol for bone tissue engineering with serum-free media, we now discuss current findings regarding the character of serum-free expanded cells. Table 1. List of currently available commercial serum-free media and the osteogenic ability of postnatal stem cells cultivated in each product Since the type of expansion medium used in primary culture may affect the viability and type of cell population generated, it is important to compare the cell populations grown in serum-free and serum-containing medium.
Ioanel Sinescu editor emeritus: Prof. Petrior Geavlete, Bucureti Conf. Gabriel Glck, Bucureti Dr.
For this purpose, Lindroos et al. They reported that the expression profiles of examined cell surface antigens were not statistically different Lindroos et al. Our previous study investigated cell surface marker expression by human BMSCs cultured in serum-free medium.
Regenerative Medicine and Tissue Engineering - Cells and Biomaterials
It also showed that the expression profiles enterobius vermicularis taxonomy most of the examined antigens were comparable in both serum-free and serumcontaining groups, though there were some differences in the expression of CD and CD Agata et al.
Since the mean fluorescence intensity of the CD antigen was stronger in serum-free expanded BMSCs, it is possible that a larger population of CDpositive cells was obtained by growth in serum-free medium. In contrast, the CDpositive fraction was more evident in cells cultured in serum-based medium and only a limited number of cells were positive for CD in the serum-free group Agata et al. It is not clear whether serum-free conditions alter the expression of both of these surface markers or bacterii aerobe exemple the conditions selectively support the growth of the CDpositive Regenerative Medicine and Tissue Engineering - Cells and Biomaterials CDdim population.
Nonetheless, cells grown in serum-free media do appear to be different from those grown in serum-containing media, and the information regarding BMSCs grown in serum-containing media may not be used as a reference. Therefore, the feasibility of bone tissue engineering with serum-free expanded BMSCs should be independently investigated from the beginning, though there have already been several clinical trials to show the safety and efficacy of bone tissue engineering with BMSCs grown in serum-containing media.
One of the most important things that should be assured for use in a clinical setting is that transplanted BMSCs do not form tumors inverted papillary urothelial carcinoma pathology outlines the recipient following transplantation.
Since our previous study showed that transplanted BMSCs grown in serum-free medium did not form tumors in nude mice Agata et al. However, further studies are required to confirm their safety because few studies have transplanted serum-free expanded somatic stem cells.
Together with cell transplantation analyses, genomic and chromosomal stabilities must be analyzed, because these data can support the safety of serum-free expanded BMSCs.
In addition to confirming the safety of such transplants, assurance of the osteogenic differentiation ability of transplanted BMSCs is important in clinical bone tissue engineering.
BMSCs grown in serum-containing media are known to differentiate into the osteogenic lineage when they are cultured in osteogenic induction medium serumcontaining media supplemented with dexamethasone, ascorbic acid, and glycerophosphate. However, it was still necessary to determine whether somatic stem cells inverted papillary urothelial carcinoma pathology outlines in serum-free media would behave similarly in the presence of the same osteogenic components.
To date, adipose stem cells, umbilical cord tissue-derived mesenchymal stem cells, and BMSCs those grown in serum-free media have been shown to differentiate into osteogenic cells in the conventional induction medium Lindroos et al. However, it remains unknown whether conventional osteogenic induction medium is optimal for their differentiation, because some of the manufacturers recommend a specially formulated kit for osteogenic induction of serum-free expanded cells.
Therefore, we explored osteogenic induction of BMSCs expanded in serumfree medium, using both a conventional osteogenic induction medium and the commercially supplied osteogenesis kit Agata et al.
Results of alkaline phosphatase ALP assays showed that both treatments were able to induce osteogenic differentiation of serum-free expanded BMSCs, though the increase of ALP activity was more rapid with the osteogenesis kit Fig.
We also performed in vivo transplantation experiments to investigate possible differences in bone forming abilities between cells grown in the two media. As shown in Figure 1B - 1E, cells treated with both osteogenic medium and the osteogenesis kit were able inverted papillary urothelial carcinoma pathology outlines form bone in vivo, and there was no significant difference in the efficacy of bone formation Fig.
These data indicate that bone tissue engineering with serum-free expanded BMSCs can be achieved with either the conventional osteogenic induction medium or the osteogenesis kit.
However, these treatments may not be ideal for induction of osteogenic differentiation of serum-free expanded BMSCs, because both media even the commercially supplied kit contain some serum-derived components. Therefore, to enhance the safety of clinical bone tissue engineering, a completely serum-free osteogenic induction media should be developed.
Osteogenic abilities of serum-free expanded BMSCs after osteogenic induction with either osteogenic medium or osteogenesis kit From Agata et al.