Fabricating tissues: Analysis of farming versus engineering strategies

Cheema, Umber; Nazhat, Showan N.; Alp, Burçak; Foroughi, F; Anandagoda, Nelomi; Mudera, Vivek; Brown, Robert A.

doi:10.1007/bf02931797

Cited by 25 publications

(37 citation statements)

References 11 publications

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“…Hence for a typical initial gel volume of 5 ml, the percentage of collagen was 0.2 %, which increased to 11 % following compression (measured by dry/wet weight ratio), which corresponds to a 58-fold increase. The cell density would be expected to change by the same degree from a total of 100 000 cells/ml (or 0.5 million cells/ construct) to a final density of 5.8 million cells/ml; 200 000 cells/ ml (or 1 million cells/construct) to 11.6 million cells/ml; 400 000 cells/ml (or 2 million cells/ construct) to 23.2 million cells/ml [15].…”

Section: Methodsmentioning

confidence: 99%

Spatially defined oxygen gradients and vascular endothelial growth factor expression in an engineered 3D cell model

Cheema

Brown

Alp

et al. 2007

Cell. Mol. Life Sci.

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Tissue hypoxia results in rapid angiogenesis in vivo, triggered by angiogenic proteins, including vascular endothelial growth factor (VEGF). Current views of tissue viability are founded on whether 'deeper-lying' cells receive sufficient nutrients and oxygen for normal activity and ultimately survival. For intact tissues, levels of such essential nutrients are governed by micro-vascular perfusion. However, there have been few effective quantitatively defined 3D models, which enable testing of the interplay or interdependence of matrix and cell density, and path diffusion on oxygen consumption in vitro. As a result, concepts on cell vulnerability to low oxygen levels, together with the nature of cellular responses are ill defined. The present study has adapted a novel, optical fibre-based system for in situ, real-time oxygen monitoring within three-dimensionally-spiralled cellular collagen constructs, which were then unfurled to enable quantitative, spatial measurements of VEGF production in different parts of the same construct exposed to different oxygen levels. A VEGF response was elicited by cells exposed to low oxygen levels (20 mmHg), primarily within the construct core.

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Section: Methodsmentioning

confidence: 99%

Spatially defined oxygen gradients and vascular endothelial growth factor expression in an engineered 3D cell model

Cheema

Brown

Alp

et al. 2007

Cell. Mol. Life Sci.

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“…Tendons and fibroblasts are rich in fibroblasts which secrete ECM containing collagen type I/III, elastin and proteoglycans (Carvalho et al 2000;Chan and Leong 2008;Cheema et al 2007;Cleary et al 1967). Collagen and fibrin gel encapsulation of fibroblasts have been shown to have promise for tissue engineering of tendons and ligaments.…”

Section: Ligament and Tendonmentioning

confidence: 99%

Cell encapsulation using biopolymer gels for regenerative medicine

2010

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To cite this version:Nicola C. Hunt, Liam M. Grover. Cell encapsulation using biopolymer gels for regenerative medicine. Biotechnology Letters, Springer Verlag, 2010, 32 (6), pp.733-742. <10.1007/s10529-010-0221-0>. Abstract There has been a consistent increase in the mean life expectancy of the population of the developed world over the past century. Healthy life expectancy, however, has not increased concurrently. As a result we are living a larger proportion of our lives in poor health and there is a growing demand for the replacement of diseased and damaged tissues. While traditionally tissue grafts have functioned well for this purpose, the demand for tissue grafts now exceeds the supply. For this reason, research in regenerative medicine is rapidly expanding to cope with this new demand. There is now a trend towards supplying cells with a material in order to expedite the tissue healing process. Hydrogel encapsulation provides cells with a three dimensional environment similar to that experienced in vivo and therefore may allow the maintenance of normal cellular function in order to produce tissues similar to those found in the body. In this review we discuss biopolymeric gels that have been used for the encapsulation of mammalian cells for tissue engineering applications as well as a brief overview of cell encapsulation for therapeutic protein production. This review focuses on agarose, alginate, collagen, fibrin, hyaluronic acid and gelatin since they are widely used for cell encapsulation. The literature on the regeneration of cartilage, bone, ligament, tendon, skin, blood vessels and neural tissues using these materials has been summarised.

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“…In fact, the collagen-layer thickness after re-swelling (24 h) was 65 per cent of that when it was initially prepared (36.5 mm). The initial plastic compression, prior to HA contact, increased the collagen density from 0.2 per cent to 11.6 + 0.4% [4]. Assuming such a nominal initial collagen density of 12 per cent [4], this suggests that the elastic -plastic transition [15] collagen density (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…The initial plastic compression, prior to HA contact, increased the collagen density from 0.2 per cent to 11.6 + 0.4% [4]. Assuming such a nominal initial collagen density of 12 per cent [4], this suggests that the elastic -plastic transition [15] collagen density (i.e. that density to which the collagen returned 24 h after HA treatment) is 18-19% collagen (w/v).…”

Section: Discussionmentioning

confidence: 99%

Hyaluronan hydration generates three-dimensional meso-scale structure in engineered collagen tissues

Anandagoda

Ezra

Cheema

et al. 2012

J. R. Soc. Interface.

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Here, we show that the local incorporation of osmotically active hyaluronan into previously compressed collagen constructs results in further rapid dehydration/compression of collagen layers, channel formation and generation of new interfaces; these novel structures, at the nano-micro (i.e. meso-scale) were formed within native collagen gels, in a highly predictable spatial manner and offer important new methods of fabricating scaffolds (e.g. tubes and openspirals) with potential for use in tissue regeneration such as in peripheral nerves and small vessels. This paper tests the possibility that the local fluid content of a dense collagen network can be controlled by incorporation of an osmotically active (native) macromolecule-hyluronan. This is an exemplar physiological, osmotic swelling agent. Hyaluronan is commonly secreted by cells deep in connective tissues, so is a good candidate for this role in a cell-driven system balancing mechanical compaction of bulk tissue collagen. These constructs may have potential as functional in vitro models representing developmental and pathological processes.

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Fabricating tissues: Analysis of farming versus engineering strategies

Cited by 25 publications

References 11 publications

Spatially defined oxygen gradients and vascular endothelial growth factor expression in an engineered 3D cell model

Spatially defined oxygen gradients and vascular endothelial growth factor expression in an engineered 3D cell model

Cell encapsulation using biopolymer gels for regenerative medicine

Hyaluronan hydration generates three-dimensional meso-scale structure in engineered collagen tissues

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