The Roles of Hypoxia in the<i>In Vitro</i>Engineering of Tissues

Malda, Jos; Klein, Travis J.; Upton, Zee

doi:10.1089/ten.2006.0417

Cited by 247 publications

(227 citation statements)

References 98 publications

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“…In vivo, low oxygen pressure (hypoxia) plays a vital role in the development and regeneration of skeletal tissue. Hypoxia activates a series of cellular processes through the hypoxia pathway 1 , including stem cell recruitment 2 , angiogenesis 3 and stem cell differentiation [4][5] . Under normoxic conditions, the hypoxia inducible factor 1α (HIF-1α, the transcription factor responsible for the activation of the hypoxia pathway) is constitutively synthesized in the cytoplasm but immediately degraded via proteosomes.…”

Section: Introductionmentioning

confidence: 99%

“…Under hypoxia osteoblasts increase expression of vascular endothelial growth factor (VEGF), an angiogenic growth factor central to the establishment and repair of blood vessel networks 11 . More recently, hypoxia has also been shown to stimulate the production of angiogenic factors by both mesenchymal stem cells (MSC) 2 -progenitor cells already used commercially in cartilage tissue engineering 12 -and by osteoblasts cultured in 3D constructs 10 . Currently one of the major problems in bone tissue engineering is the absence of a mature microvasculature 5,13 .…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of hypoxia-mimicking bioactive glasses for skeletal regeneration

et al. 2010

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The cellular response to hypoxia is vital for skeletal tissue development and regeneration. Numerous processes, including progenitor cell recruitment, proliferation and differentiation, are activated through the hypoxia pathway in a low oxygen pressure environment. Novel materials-based strategies designed to activate the hypoxia pathway are therefore of great interest for orthopaedic tissue engineering.Here resorbable bioactive glasses (BG) were designed to activate the hypoxia pathway by substitution of Co 2+ for Ca 2+ in the BG and substitution of Co 2+ and Ca 2+ /+2Na + for Si 4+ . This allowed for the controlled release of cobalt, whilst controlling BG bioactivity (apatite-forming ability). Two series of soda-lime-phosphosilicate glasses were manufactured with increasing concentrations of cobalt. Compositions were calculated to maintain constant network connectivity (2.13) by considering cobalt as an intermediate oxide in the first series, and as a network modifier in the second series. Mg 2+ and Zn 2+ were added to one of the Co 2+ -containing glasses to inhibit HCA formation since delay or inhibition of HCA formation is essential for the use of BG in soft tissues, as is the case of cartilage.Cobalt was present in both the silicate and phosphate phases of the BG. In addition, evidence was found for it playing a dual role in the silicate phase, acting as both an intermediate oxide and taking part in the network as well as being a network modifying oxide. Consistent with an intermediate oxide role, the presence of cobalt in the BG was shown to decrease ion release. HCA formation was delayed with cobalt additions. Mg 2+ and Zn 2+ further delayed HCA formation.Cobalt release was found to be proportional to cobalt content of the BGs enabling the controlled delivery of cobalt in therapeutic active doses.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of hypoxia-mimicking bioactive glasses for skeletal regeneration

et al. 2010

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“…Additionally, the reduction of the proliferation rates can be explained by the development of cell-aggregates and proliferation resistance caused by limited space in the beads (Xu et al 2013). Furthermore, the reduced cell growth is also combined with the accumulation of metabolic end products and hypoxia within three dimensional cell culture systems (Malda et al 2007;Jonitz et al 2011a). Moreover, any influence of penicillin and streptomycin on proliferation and influence of lactate in HeLa cells in 2D cultures could not be verified (Duewelhenke et al 2006).…”

Section: Discussionmentioning

confidence: 99%

3 dimensional cell cultures: a comparison between manually and automatically produced alginate beads

et al. 2015

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Cancer diseases are a common problem of the population caused by age and increased harmful environmental influences. Herein, new therapeutic strategies and compound screenings are necessary. The regular 2D cultivation has to be replaced by three dimensional cell culturing (3D) for better simulation of in vivo conditions. The 3D cultivation with alginate matrix is an appropriate method for encapsulate cells to form cancer constructs. The automated manufacturing of alginate beads might be an ultimate method for large-scaled manufacturing constructs similar to cancer tissue. The aim of this study was the integration of full automated systems for the production, cultivation and screening of 3D cell cultures. We compared the automated methods with the regular manual processes. Furthermore, we investigated the influence of antibiotics on these 3D cell culture systems. The alginate beads were formed by automated and manual procedures. The automated steps were processes by the Biomek Ò Cell Workstation (celisca, Rostock, Germany). The proliferation and toxicity were manually and automatically evaluated at day 14 and 35 of cultivation. The results visualized an accumulation and expansion of cell aggregates over the period of incubation. However, the proliferation and toxicity were faintly and partly significantly decreased on day 35 compared to day 14. The comparison of the manual and automated methods displayed similar results. We conclude that the manual production process could be replaced by the automation. Using automation, 3D cell cultures can be produced in industrial scale and improve the drug development and screening to treat serious illnesses like cancer.

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“…It has been linked to maintenance, proliferation, survival, and differentiation of various types of stem cells and influences the lineage commitment of multipotent cells. [5][6][7][8] Cell response to reduced oxygen tension is primarily regulated by hypoxia-inducible factors (HIFs). 9,10 HIFs are transcription factors that belong to the bHLH-PAS (basic Helix-Loop-Helix-PER-ARNT-SIM) family.…”

Section: Introductionmentioning

confidence: 99%

Tracking Hypoxic Signaling in Encapsulated Stem Cells

Sahai

McFarland²,

Skiles³

et al. 2012

Tissue Engineering Part C: Methods

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Oxygen is not only a nutrient but also an important signaling molecule whose concentration can influence the fate of stem cells. This study details the development of a marker of hypoxic signaling for use with encapsulated cells. Testing of the marker was performed with adipose-derived stem cells (ADSCs) in two-dimensional (2D) and 3D culture conditions in varied oxygen environments. The cells were genetically modified with our hypoxia marker, which produces a red fluorescent protein (DsRed-DR), under the control of a hypoxia-responsive element (HRE) trimer. For 3D culture, ADSCs were encapsulated in poly(ethylene glycol)-based hydrogels. The hypoxia marker (termed HRE DsRed-DR) is built on a recombinant adenovirus and ADSCs infected with the marker will display red fluorescence when hypoxic signaling is active. This marker was not designed to measure local oxygen concentration but rather to show how a cell perceives its local oxygen concentration. ADSCs cultured in both 2D and 3D were exposed to 20% or 1% oxygen environments for 96 h. In 2D at 20% O 2 , the marker signal was not observed during the study period. In 1% O 2 , the fluorescent signal was first observed at 24 h, with maximum prevalence observed at 96 h as 59% -3% cells expressed the marker. In 3D, the signal was observed in both 1% and 20% O 2 . The onset of signal in 1% O 2 was observed at 4 h, reaching maximum prevalence at 96 h with 76% -4% cells expressing the marker. Interestingly, hypoxic signal was also observed in 20% O 2 , with 13% -3% cells showing positive marker signal after 96 h. The transcription factor subunit hypoxia inducible factor-1a was tracked in these cells over the same time period by immunostaining and western blot analysis. Immunostaining results in 2D correlated well with our marker at 72 h and 96 h, but 3D results did not correlate well. The western blotting results in 2D and 3D correlated well with the fluorescent marker. The HRE DsRed-DR virus can be used to track the onset of this response for encapsulated, mesenchymal stem cells. Due to the importance of hypoxic signaling in determination of stem cell differentiation, this marker could be a useful tool for the tissue engineering community.

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The Roles of Hypoxia in theIn VitroEngineering of Tissues

Cited by 247 publications

References 98 publications

Synthesis and characterization of hypoxia-mimicking bioactive glasses for skeletal regeneration

Synthesis and characterization of hypoxia-mimicking bioactive glasses for skeletal regeneration

3 dimensional cell cultures: a comparison between manually and automatically produced alginate beads

Tracking Hypoxic Signaling in Encapsulated Stem Cells

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