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Thesis (Ph.D.)--Virginia Commonwealth University, 2010. / Prepared for: Dept. of Pathology. Title from title-page of electronic thesis. Bibliography: leaves 139-149.

Skeletal system plays a crucial role in our life. Skeletal diseases and disorders unlike cancer, are not fatal, but affect the quality of our life. Cell-based therapeutic strategies to generate targeted desired cell types for repair or replacement of damaged skeletal tissues are ideal regenerative medicines. Because of the heterogeneous cell types generated from embryonic and mesenchymal stem cells, the ability of progenitor population to differentiate into a target cell type appear to be a better alternative for tissue regeneration. Osteo-chondroprogenitors uniquely co-expressing Sox9 and Runx2 with dual differentiation potential to become chondrocytes and osteoblasts is a progenitor cell which is suitable for cell based therapy of bone disease. Therefore, developing effective strategies to generate sufficient quantities of osteo-chondroprogenitors are essential. Toward this, we took advantage of two lineage conversion approaches. The first strategy was to interrogate the ability of osteoblasts to be reprogrammed into induced pluripotent stem (iPS) cells and another one was to use defined transcription factors to induce chondrocyte lineage from skin fibroblasts. The selection of osteoblasts is based on the fact that it is originally derived from osteo-chondroprogenitor lineage and the stochastic events of iPS induction might revert osteoblasts first to their progenitor state before becoming pluripotent. The second approach is based on a previous report using three transcription factors (Sox9, Klf4 and c-Myc) to reprogramme skin fibroblasts into chondrocyte lineage. Our aim is to examine whether osteo-chondroprogenitors would be formed during the two reprogramming processes using Sox9-EGFP knock-in mice as a reporter. We reasoned that osteoblasts can be reprogrammed into iPS cells by four Yamanaka’s factors with pluripotency as shown by their ability to form teratomas and contribute to chimeric embryos. However base on the limitation of selector marker of osteo-chondroprogenitor we still cannot capture this progenitor during iPS reprogramming. And because of the pluripotency potential, pluripotent reprogramming approach also brings high risk of teratoma formation. Therefore our second objective was performed to examine whether osteo-chondroprogenitors would be formed during lineage reprogramming. Transient appearance of Sox9-EGFP/Runx2+ve cells was observed in the intermediate stage of over 14 days of chondrocyte lineage induction from skin fibroblasts by Sox9, klf4 and c-Myc. Cells expressing Sox9-EGFP/Runx2+ve showed typical molecular markers of osteo-chondroprogenitors. In vitro and in vivo differentiation assays demonstrated that Sox9-EGFP/Runx2+ve cells can differentiate predominantly into osteoblasts and chondrocytes. Taken together our data indicate that cells with osteo-chondrogenic potential could be generated by defined transcription factors-mediated reprogramming processes. / published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Tissue loss and end-stage organ failure caused by disease or injury are two of the most costly problems encountered in modern medicine. To combat these problems, a relatively new field, called tissue engineering, has emerged. This field combines the medical and engineering fields in hopes of establishing an effective method to restore, maintain, or improve damaged tissue. In order to best replace the diseased tissue, many approaches to fabricating new tissue have focused on trying to replicate native tissue. The overall hypothesis of this dissertation is that a direct-write, BioAssembly Tool (BAT) can be utilized to fabricate viable constructs of cells and matrix that have a specified spatial organization and are truly three-dimensional (3D). The results of the studies within this dissertation demonstrate that the BAT can generate viable, spatially organized constructs comprised of cells and matrix by carefully controlling the environmental parameters of the system. A joint hypothesis associated with this dissertation is that 3D microscopy and image processing techniques can be combined to generate accurate representative stacks of images of the tissue within 3D, tissue engineered constructs. The results of the studies examining this hypothesis demonstrate that by taking into account the attenuation with depth in the imaged construct as well as by looking at the intensity and gradient of each voxel, accurate and reproducible thresholding can be achieved. Furthermore, this tool can be utilized to aid in the characterization of 3D tissue engineered constructs. Based on these studies, 3D microscopy and image processing shows promise in accurately representing the cellular volume within a tissue. More importantly, 3D, direct-write technology, specifically the BioAssembly Tool, could be used in the fabrication of viable, spatially organized constructs that can then be implanted into a patient to provide healthy tissue in the place of diseased or damaged tissue.

京都大学 / 0048 / 新制・論文博士 / 博士(医科学) / 乙第13332号 / 論医科博第5号 / 新制||医科||7(附属図書館) / 大阪大学大学院生命機能研究科生命機能専攻 / (主査)教授 河本 宏, 教授 濵﨑 洋子, 教授 髙折 晃史 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

This thesis argues that stem cells cannot be properly regulated when understood in terms of medical treatment only. This is due to the uncertain scope and untested efficacy of stem cell therapy which renders treatment applications tantamount to research involving human subjects. This thesis therefore examines consent as regulatory instrument in context of stem cell related interventions and endeavours to introduce a sufficient consent model for such interventions. To this end, a clinical overview and explanation of stem cells is provided in order to establish an understanding of the field of science in need of regulatory control. This is followed by a background and introduction to consent, a discussion of specific aspects of consent and the National Health Act of 2003 and the Regulations made in terms of the Act to provide insight into consent as understood in South Africa. Consent in international instruments and international law is then examined. The law of the United Kingdom is also analysed by providing an examination of the legal systems in the United Kingdom which is then followed by a discussion of the Human Tissue Act of 2004 and the Human Tissue (Scotland) Act of 2006. Finally, dynamic informed consent is explained and introduced as the recommended consent format for the proper and valid regulation of stem cell therapy-research interventions. At the close of this thesis, the conclusions drawn throughout are compounded and pertinent recommendations are made regarding consent procedures and specifications. / Thesis (LLD)--University of Pretoria, 2016. / Public Law / LLD / Unrestricted

yes / Breast reconstruction is the opportunity that provides the chance of having breast after undergoing surgical removal of the breast tissue due to cancer-related surgery. However, this varies on the stage of the cancer diagnosis and the procedure undertaken. There are many regenerative medicine methods that provide several initiatives and direct solutions to problems such as the development of “bioactive tissue,” which can regenerate adipose tissues with similar normal functions and structures. There have been several studies which have previously explored for the improvement of breast reconstruction including different variations of biomaterials, different fabrication and processing techniques, cells as well as growth factors which enable bioengineers and tissue engineers to reconstruct a suitable breast for patients with breast cancer. Many factors such as shape, proper volume, mechanical properties have been studies but very scattered with not adequate solutions for existing patients worldwide. This review article aims to cover recent advances in biomaterials, which can be used for reconstruction of breasts as well as looking at the various factors that might lead to individuals needing reconstruction and the materials that are available. The focus would be to look at the various biomaterials that are available to use for reconstruction, their properties, and their structural integrity.

Cardiovascular diseases (CVD) are the leading cause of death around the world, being responsible for 31.8% of all deaths in 2017. The leading cause of CVD is Ischemic heart disease (IHD), which caused 8.1 million deaths in 2013. IHD occurs when coronary arteries in the heart are narrowed or blocked, preventing the flow of oxygen and blood into the cardiac muscle, which could provoke acute myocardial infarction (AMI) and ultimately lead to heart failure and death. Cardiac regenerative therapy aims to repair and refunctionalize damaged heart tissue through the application of (1) intramyocardial cell delivery, (2) epicardial cardiac patch, and (3) acellular biomaterials. These approaches have provided benefit of cell localization and tissue structure respectively. However, to improve cell retention and integration, there is a need for the intramyocardial delivery of functional tissues while preserving anisotropic muscle alignment. Here, we developed a biodegradable z-wire scaffold that supports the scalable gel-free production of an array of functional cardiac tissues in a 384-well plate format. The z-wire scaffold design supports cellular alignment, provides tunable mechanical support, and allows for hallmark tissue contraction. When the scaffold is imparted with magnetic properties, individual tissues can be assembled with macroscopic alignment under magnetic guidance. When used in combination with a customized surgical delivery tool, z-wire tissues can be injected directly into the myocardial wall, with controlled tissue orientation according to the injection path. This modular tissue engineering approach, in combination with the use of smart scaffolds, could expand opportunity in functional tissue delivery. / Thesis / Master of Science in Chemical Engineering (MSChE)

Anterior cruciate ligament (ACL) ruptures and tears are significant orthopedic problems that result in discomfort and limited mobility. Fully functional tissue engineered ligament replacements are promising alternatives to current graft choices for repair of ACL disruptions. The cell-based approach to construct engineered ligament grafts presented herein involves the culture of mesenchymal stem cells (MSC) on biodegradable, fibrous polymeric scaffolds to promote tissue formation. Multipotent MSCs are advantageous because of their in vitro proliferative capacity and ease of harvest; however; the promotion of MSC differentiation into mature fibroblasts and subsequent extracellular matrix (ECM) development is unknown. The proposed studies utilized three complementary methods to promote differentiation of MSCs: scaffold architecture, mechanical stretch and over-expression of the transcription factor, scleraxis. First, elastomeric scaffolds were fabricated by electrospinning a segmented poly(esterurethane urea) with variations in fiber diameter and fiber alignment. Primary mesenchymal stem cells and the mesenchymal stem cell line, C3H10T1/2, were seeded on these scaffolds and assumed spindle-shaped morphologies and oriented with the direction of fiber alignment. Fiber diameter affected cellular responses, including the expression of ECM genes (e.g. collagen type 1 and decorin) which were elevated on smaller mean fiber diameter scaffolds initially. However, scleraxis gene expression was greatest on larger mean fiber diameter scaffolds at the end of two weeks. Second, cyclic stretch was applied to C3H10T1/2 cells on semi-aligned scaffolds using a novel bioreactor. Cell attachment was verified during and after the application of mechanical stress by confocal microscopy. Cyclic stretch induced cells to assume a highly elongated morphology; however ECM gene expression changes were moderate. Third, forced constitutive expression of scleraxis was accomplished by nucleofection of C3H10T1/2 cells. Transient mRNA expression, accumulation of the gene product in the cell nucleus, and cell death were observed. Future work will seek to refine the experimental methods, including the development and testing of an inducible scleraxis transgene and the application of longer periods of mechanical stimulation. Finally, these complementary approaches may be combined to further extend this work in pursuit of directed differentiation of stem cells and the ensuing generation of a robust tissue graft. / Ph. D.

Tendon and ligament injuries are common orthopedic problems that have an enormous impact on the quality of life of affected patients. Despite the frequency at which these injuries occur, current treatments are unable to restore native function to the damaged tissue. Because of this, reinjury is common. It is well known that mechanical stimulation is beneficial for promoting tendon and ligament development and tissue homeostasis; however, the specific mechanisms remain unclear. The transcription factor scleraxis (Scx) is an interesting candidate for mediating the tendon and ligament mechanoresponse, as it has been shown that Scx expression is induced by cyclic mechanical strain in tenocytes and is required for mechanically-induced stem cell tenogenesis. Moreover, Scx expression is increased in adult tendons following exercise. The studies described in this dissertation therefore focus on the combined role of Scx and mechanical stimulation in two contexts: 1) influencing ligament cell differentiation and 2) regulating adult tenocyte behavior. In the first study, transient Scx overexpression combined with mechanical strain in a 3D collagen hydrogel model was investigated as a means of deriving mature ligament cells from stem cells for use in ligament tissue engineering. Scx overexpression in C3H10T1/2 cells cultured in collagen hydrogels under static strain resulted in increased construct contraction and cell elongation, but no concurrent increase in the expression of ligament-related genes or production of glycosaminoglycans (GAG). When combined with low levels of cyclic strain, Scx overexpression resulted in increased mechanical properties of the tissue constructs, increased GAG production, and increased expression of ligament-related genes compared to cyclic strain alone. Together, these results demonstrate that Scx overexpression combined with cyclic strain can induce ligament cell differentiation and suggest that Scx does so by improving the mechanosensitivity of cells to cyclic strain. In the second study, the role of Scx in adult tenocyte mechanotransduction was explored using RNA-sequencing (RNA-seq) and small interfering RNA (siRNA) technologies. Equine tenocytes were exposed to siRNA targeting Scx or a control siRNA and maintained under cyclic mechanical strain prior to being submitted for RNA-seq. Comparison of the resulting transcriptomes revealed that Scx knockdown decreased the expression of several genes encoding important focal adhesion adaptor proteins. Correspondingly, Scx-depleted tenocytes showed abnormally long focal adhesions, decreased cytoskeletal stiffness, and an impaired ability to migrate on soft surfaces. This suggests that Scx regulates the tenocyte mechanoresponse by promoting the expression of focal adhesion-related genes. Combined, the results of these studies support a role for Scx in tendon and ligament cell mechanotransduction and identify the regulation of genes related to maintaining the cell-extracellular matrix connection and cytoskeletal dynamics as a potential mechanism. These findings enhance our understanding of how mechanical stimulation influences cell behavior and provide new research directions and methodologies for future studies of tendon and ligament mechanobiology. / Ph. D. / Tendon and ligament injuries are very common, but current treatments are unable to completely repair the damaged tissue. We know that exercise plays an important role during the development of tendons and ligaments and in keeping them healthy during adulthood. Despite this, we do not understand exactly how either of these processes occur. A tendon and ligament related protein called scleraxis (Scx) appears to be important in translating mechanical strain into a cellular response. As such, Scx could be useful for making ligament cells from stem cells, which could then be used in custom-engineered, patient-specific tissue grafts for surgical repair of torn ligaments. Studying what Scx does in adult tendon cells could also help us to understand how tendon cells sense and respond to exercise or physical changes in their environment. To explore whether or not Scx can promote stem cell differentiation, we generated stem cells with increased levels of Scx and put them into 3D collagen constructs. When the constructs were held under static tension, cells with increased Scx became longer and were better able to organize the collagen compared to normal cells. When we exercised the constructs, cells with increased Scx also had higher levels of ligament-related genes and resulted in stiffer constructs compared to normal cells. Increasing Scx expression in combination with mechanical strain could therefore be a useful way to make ligament cells that can be used in engineered replacement tissues. To explore the function of Scx in adult tendon cells, we created tendon cells with decreased levels of Scx and exposed them to mechanical strain. We then generated a database of all the genes affected by the decrease in Scx. Analysis of this database revealed that decreasing the levels of Scx also decreased the expression of genes associated with several pathways involved in linking the internal skeleton of the cell to the extracellular environment. This suggested that Scx helps facilitate the ability of a tendon cell to sense and respond to its surroundings. To evaluate this, we examined the ability of tendon cells with decreased Scx to migrate on different surfaces, the stiffness of the internal skeleton, and the structure of the protein complexes responsible for anchoring cells to a surface. As predicted by our gene database, we found that decreasing Scx levels also decreases the stiffness of the cell’s internal skeleton, changes the shape of the anchoring complexes, and impairs the ability of tendon cells to migrate on soft surfaces. These results show that Scx governs tendon cell function by affecting the cell’s ability to interact with its local environment.