An in vitro system to evaluate the effects of ischemia on survival of cells used for cell therapy.
ABSTRACT Maintaining cell viability is a major challenge associated with transplanting cells into ischemic myocardium to restore function. A likely contributor to significant cell death during cardiac cell therapy is hypoxia/anoxia. We developed a system that enabled quantification and association of cell survival with oxygen and nutrient values within in vitro constructs. Myoblasts were suspended in 2% collagen gels in 1 cm diameter x 1 cm deep constructs. At 48 +/- 3 h post-seeding, oxygen levels were measured using microelectrodes and gels were snap-frozen. Bioluminescence metabolite imaging and TUNEL staining were performed on cryosections. Oxygen and glucose consumption and lactate production rates were calculated by fitting data to Fick's second law of diffusion with Michaelis-Menten kinetics. Oxygen levels dropped to 0 mmHg and glucose levels dropped from 4.28 to 3.18 mM within the first 2000 mum of construct depth. Cell viability dropped to approximately 40% over that same distance and continued to drop further into the construct. We believe this system provides a reproducible and controllable test bed to compare survival, proliferation, and phenotype of various cell inputs (e.g., myoblasts, mesenchymal stem cells, and cardiac stem cells) and the impact of different treatment regimens on the likelihood of survival of transplanted cells.
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ABSTRACT: Tissue engineering strategies involving in vitro growth of cells over three-dimensional scaffolds before implantation into the damaged portions represents a significant alternative to current clinical treatment methods. In order to improve this in vitro cell culture system, we need to focus on various engineering aspects, and each aspect has its own advantages and limitations. Undoubtedly, these engineering factors are critical for the successful development of tissues and organ products and the tissue engineering industry as well. These issues include elements of mass transport, biomaterials, biomechanics, and so on. Our focus in this review paper is to discuss the alternative strategies to overcome the mass transfer limitations in the three-dimensional constructs, which have been widely researched for the tissue engineering purposes. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.Asia-Pacific Journal of Chemical Engineering 05/2014; 9(3). DOI:10.1002/apj.1800 · 0.62 Impact Factor
IEEE Engineering in Medicine and Biology Magazine 27(5):109-13. · 26.30 Impact Factor
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ABSTRACT: A major limitation in the development of cellular therapies using human mesenchymal stem cells (hMSCs) is cell survival post-transplantation. In this study, we challenged the current paradigm of hMSC survival, which assigned a pivotal role to oxygen, by testing the hypothesis that exogenous glucose may be key to hMSC survival. We demonstrated that hMSCs could endure sustained near-anoxia conditions only in the presence of glucose. In this in vitro cell model, the protein expressions of Hif-1α and angiogenic factors were upregulated by the presence of glucose. Ectopically implanted tissue constructs supplemented with glucose exhibited four- to fivefold higher viability and were more vascularized compared to those without glucose at day 14. These findings provided the first direct in vitro and in vivo demonstration of the proangiogenic and prosurvival functions of glucose in hMSC upon transplantation and identified glucose as an essential component of the ideal scaffold for transplanting stem cells. STEM CELLS2013;31:526–535Stem Cells 03/2013; 31(3). DOI:10.1002/stem.1299 · 7.70 Impact Factor