Current Issue : January - March Volume : 2012 Issue Number : 1 Articles : 7 Articles
Stem cell research plays an important role in orthopedic regenerative medicine today. Current literature provides us with promising\r\nresults from animal research in the fields of bone, tendon, and cartilage repair. While early clinical results are already published\r\nfor bone and cartilage repair, the data about tendon repair is limited to animal studies. The success of these techniques remains\r\ninconsistent in all three mentioned areas. This may be due to different application techniques varying from simple mesenchymal\r\nstem cell injection up to complex tissue engineering. However, the ideal carrier for the stem cells still remains controversial. This\r\npaper aims to provide a better understanding of current basic research and clinical data concerning stem cell research in bone,\r\ntendon, and cartilage repair. Furthermore, a focus is set on different stem cell application techniques in tendon reconstruction,\r\ncartilage repair, and filling of bone defects....
We identify the presence of progenitor cells during retinal development in the dog, as this species represents a natural model for\nstudying several breed-specific degenerative retinal disorders. Antibodies to detected progenitor cells (Pax6, C-kit, and nestin) and\nganglion cells (BDNF, Brn3a, and Thy1) were used in combination with H3 for the purpose of identifying proliferating cells. Pax6,\nnestin, C-kit, and H3 were localized mainly in the neuroblastic layer of the retina during the embryonic stage. During the fetal stage,\nproteins were expressed in the inner neuroblastic layer (INL) as well as in the outer neuroblastic layer; BDNF, Thy1, and Brn3a\nwere also expressed in the INL. During the neonatal stage only C-kit was not expressed. Proliferating cells were present in both\nundifferentiated and differentiated retina. These results suggest that, during canine retinogenesis, progenitor cells are distributed\nalong the retina and some of these cells remain as progenitor cells of the ganglion cells during the first postnatal days....
The development of a technique to induce the transformation of somatic cells to a pluripotent state via the ectopic\r\nexpression of defined transcription factors was a transformational event in the field of regenerative medicine. The\r\ndevelopment of this technique also impacted ophthalmology, as patient-specific induced pluripotent stemcells (iPSCs) may\r\nbe useful resources for some ophthalmological diseases. The lens is a key refractive element in the eye that focuses images\r\nof the visual world onto the retina. To establish a new model for drug screening to treat lens diseases and investigating lens\r\naging and development, we examined whether human lens epithelial cells (HLECs) could be induced into iPSCs and if lensspecific\r\ndifferentiation of these cells could be achieved under defined chemical conditions. We first efficiently\r\nreprogrammed HLECs from age-related cataract patients to iPSCs with OCT-4, SOX-2, and KLF-4. The resulting HLECderived\r\niPS (HLE-iPS) colonies were indistinguishable from human ES cells with respect to morphology, gene expression,\r\npluripotent marker expression and their ability to generate all embryonic germ-cell layers. Next, we performed a 3-step\r\ninduction procedure: HLE-iPS cells were differentiated into large numbers of lens progenitor-like cells with defined factors\r\n(Noggin, BMP and FGF2), and we determined that these cells expressed lens-specific markers (PAX6, SOX2, SIX3, CRYAB,\r\nCRYAA, BFSP1, and MIP). In addition, HLE-iPS-derived lens cells exhibited reduced expression of epithelial mesenchymal\r\ntransition (EMT) markers compared with human embryonic stem cells (hESCs) and fibroblast-derived iPSCs. Our study\r\ndescribes a highly efficient procedure for generating lens progenitor cells from cataract patient HLEC-derived iPSCs. These\r\npatient-derived pluripotent cells provide a valuable model for studying the developmental and molecular biological\r\nmechanisms that underlie cell determination in lens development and cataract pathophysiology....
In recent years, the incredible boost in stem cell research has kindled the expectations of both patients and physicians.\r\nMesenchymal progenitors, owing to their availability, ease of manipulation, and therapeutic potential, have become one of the\r\nmost attractive options for the treatment of a wide range of diseases, from cartilage defects to cardiac disorders. Moreover, their\r\nimmunomodulatory capacity has opened up their allogenic use, consequently broadening the possibilities for their application. In\r\nthis review, we will focus on their use in the therapy of myocardial infarction, looking at their characteristics, in vitro and in vivo\r\nmechanisms of action, as well as clinical trials....
The stem cell microenvironment is involved in regulating the fate of the stem cell with respect to self-renewal, quiescence,\nand differentiation. Mathematical models are helpful in understanding how key pathways regulate the dynamics of stem cell\nmaintenance and homeostasis. This tight regulation and maintenance of stem cell number is thought to break down during\ncarcinogenesis. As a result, the stem cell niche has become a novel target of cancer therapeutics. Developing a quantitative\nunderstanding of the regulatory pathways that guide stem cell behavior will be vital to understanding how these systems change\nunder conditions of stress, inflammation, and cancer initiation. Predictions from mathematical modeling can be used as a clinical\ntool to guide therapy design. We present a survey of mathematical models used to study stem cell population dynamics and\nstem cell niche regulation, both in the hematopoietic system and other tissues. Highlighting the quantitative aspects of stem cell\nbiology, we describe compelling questions that can be addressed with modeling. Finally, we discuss experimental systems, most\nnotably Drosophila, that can best be used to validate mathematical predictions....
Cartilage defects represent a common problem in orthopaedic practice. Predisposing factors include traumas, inflammatory\r\nconditions, and biomechanics alterations. Conservative management of cartilage defects often fails, and patients with this lesions\r\nmay need surgical intervention. Several treatment strategies have been proposed, although only surgery has been proved to\r\nbe predictably effective. Usually, in focal cartilage defects without a stable fibrocartilaginous repair tissue formed, surgeons\r\ntry to promote a natural fibrocartilaginous response by using marrow stimulating techniques, such as microfracture, abrasion\r\narthroplasty, and Pridie drilling, with the aim of reducing swelling and pain and improving joint function of the patients.\r\nThese procedures have demonstrated to be clinically useful and are usually considered as first-line treatment for focal cartilage\r\ndefects. However, fibrocartilage presents inferior mechanical and biochemical properties compared to normal hyaline articular\r\ncartilage, characterized by poor organization, significant amounts of collagen type I, and an increased susceptibility to injury,\r\nwhich ultimately leads to premature osteoarthritis (OA). Therefore, the aim of future therapeutic strategies for articular cartilage\r\nregeneration is to obtain a hyaline-like cartilage repair tissue by transplantation of tissues or cells. Further studies are required to\r\nclarify the role of gene therapy and mesenchimal stem cells for management of cartilage lesions....
Tissue engineering is a pioneering field with huge advances in recent times. These advances are not only in the understanding of\nhow cells can be manipulated but also in potential clinical applications. Thus, tissue engineering, when applied to skeletal muscle\ncells, is an area of huge prospective benefit to patients with muscle disease/damage. This could include damage to muscle from\ntrauma and include genetic abnormalities, for example, muscular dystrophies. Much of this research thus far has been focused\non satellite cells, however, mesenchymal stem cells have more recently come to the fore. In particular, results of trials and further\nresearch into their use in heart failure, stress incontinence, andmuscular dystrophies are eagerly awaited. Although no doubt, stem\ncells will have much to offer in the future, the results of further research still limit their use....
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