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ABSTRACT: Statins are potent inhibitors of cholesterol synthesis. Several statins are available with different molecular and pharmacokinetic properties. Simvastatin is more lipophilic than pravastatin and has a higher affinity to phospholipid membranes than atorvastatin, allowing its passive diffusion through the cell membrane. In vitro studies on bone marrow stromal cells, osteoblast-like cells, and embryonic stem cells have shown statins to have cholesterol-independent anabolic effects on bone metabolism; alas, statins were supplemented in osteogenic medium, which does not facilitate elucidation of their potential osteoinductive properties. Embryonic stem cells (ESCs), derived from the inner cell mass of the blastocyst, are unique in that they enjoy perpetual self-proliferation, are pluripotent, and are able to differentiate toward all the cellular lineages composing the body, including the osteogenic lineage. Consequently, ESCs represent a potentially potent cell source for future clinical cellular therapies of various bone diseases, even though there are several hurdles that still need to be overcome. Herein we demonstrate, for the first time to our knowledge, that simvastatin induces murine ESC (mESC) differentiation toward the osteogenic lineage in the absence of osteoinductive supplements. Specifically, we found that a simvastatin concentration in the micromolar range and higher was toxic to the cells and that an effective concentration for osteoinduction is 0.1 nM, as shown by increased alizarin red staining as well as increased osteocalcin and osetrix gene expression. These results suggest that in the future, lipophilic simvastatin may provide a novel pharmacologic agent for bone tissue engineering applications.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 11/2010; 25(11):2470-8. · 6.04 Impact Factor
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ABSTRACT: Transplantation of encapsulated living cells is a promising approach for the treatment of a wide variety of diseases. Bioactive glass (bioglass) can be used for drug delivery and other regenerative medicine applications. First of all, we established a scenario of bioglass-incorporated alginate encapsulation. Then we studied the expansion of encapsulated murine embryonic stem cells (mESCs) in bioreactors with exposure to 70s bioglass. Finally, an integrated osteogenic differentiation of encapsulated mESCs with the presence of 70s bioglass was investigated. The proliferation and viability of mESCs which had been encapsulated with 70s bioglass was enhanced compared to the regular control and bioglass-conditioned medium culture group. Embryoid body (EB) formation assessment demonstrated the undifferentiated pluripotency of dissociated mESCs. However, no significant difference was observed between the bioglass-incorporated encapsulation group, the bioglass-conditioned medium culture group and the control in terms of expression-specific osteogenic markers. Therefore, the 70s bioglass particles could be incorporated into the integrated bioprocessing of mESCs in 3D bioreactors, which is applicable to bone tissue engineering, such as in diseased or damaged bone restoration. These findings have potential implications and applications for tissue engineering where bioglass substrates could be used for the production of bioengineered bone both in vitro and in vivo. In addition, it would be possible to inject the mineralized tissue-filled and bioglass-incorporated alginate hydrogels directly into the defect area.
Journal of Tissue Engineering and Regenerative Medicine 01/2009; 3(1):63-71. · 3.28 Impact Factor
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Mark R Placzek,
I-Ming Chung,
Hugo M Macedo,
Siti Ismail,
Teresa Mortera Blanco,
Mayasari Lim, Jae Min Cha,
Iliana Fauzi,
Yunyi Kang,
David C L Yeo,
Chi Yip Joan Ma,
Julia M Polak,
Nicki Panoskaltsis,
Athanasios Mantalaris
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ABSTRACT: In recent years, the potential of stem cell research for tissue engineering-based therapies and regenerative medicine clinical applications has become well established. In 2006, Chung pioneered the first entire organ transplant using adult stem cells and a scaffold for clinical evaluation. With this a new milestone was achieved, with seven patients with myelomeningocele receiving stem cell-derived bladder transplants resulting in substantial improvements in their quality of life. While a bladder is a relatively simple organ, the breakthrough highlights the incredible benefits that can be gained from the cross-disciplinary nature of tissue engineering and regenerative medicine (TERM) that encompasses stem cell research and stem cell bioprocessing. Unquestionably, the development of bioprocess technologies for the transfer of the current laboratory-based practice of stem cell tissue culture to the clinic as therapeutics necessitates the application of engineering principles and practices to achieve control, reproducibility, automation, validation and safety of the process and the product. The successful translation will require contributions from fundamental research (from developmental biology to the 'omics' technologies and advances in immunology) and from existing industrial practice (biologics), especially on automation, quality assurance and regulation. The timely development, integration and execution of various components will be critical-failures of the past (such as in the commercialization of skin equivalents) on marketing, pricing, production and advertising should not be repeated. This review aims to address the principles required for successful stem cell bioprocessing so that they can be applied deftly to clinical applications.
Journal of The Royal Society Interface 12/2008; 6(32):209-32. · 4.40 Impact Factor
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ABSTRACT: Embryonic stem cell (ESC) culture is fragmented and laborious and involves operator decisions. Most protocols consist of 3 individual steps: maintenance, embryoid body (EB) formation, and differentiation. Integration will assist automation, ultimately aiding scale-up to clinically relevant numbers. These problems were addressed by encapsulating undifferentiated murine ESCs (mESCs) in 1.1% (w/v) low-viscosity alginic acid, 0.1% (v/v) porcine gelatin hydrogel beads (d = 2.3 mm). Six hundred beads containing 10,000 mESCs per bead were cultured in a 50-mL high-aspect-ratio vessel bioreactor. Bioreactor cultures were rotated at 17.5 revolutions per min, cultured in maintenance medium containing leukemia inhibitory factor for 3 days, replaced with EB formation medium for 5 days followed by osteogenic medium containing L-ascorbate-2-phosphate (50 microg/mL), beta-glycerophosphate (10 mM), and dexamethasone (1 microM) for an additional 21 days. After 29 days, 84 times as many cells per bead were observed and mineralized matrix was formed within the alginate beads. Osteogenesis was confirmed using von Kossa, Alizarin Red S staining, alkaline phosphatase activity, immunocytochemistry for osteocalcin, OB-cadherin, collagen type I, reverse transcriptase polymerase chain reaction, microcomputed tomography (micro-computed tomography) and Fourier transform infrared spectroscopic imaging. This simplified, integrated, and potentially scaleable methodology could enable the production of 3-demensional mineralized tissue from ESCs for potential clinical applications.
Tissue Engineering 01/2008; 13(12):2957-70. · 4.02 Impact Factor
