A British and Australian research team reveal superior scaffolds and substates on which to grow stem cells in U.S. Patent Application 20090305417.
Although mammalian cell culture is a multi-billion dollar business, as measured both by the value of its products such as therapeutic proteins (e.g. interferons, humanized monoclonal antibodies, protein hormones) as well as the equipment and consumables required to carry out the process, the successes represent only a small and distinct sub-set of all cell types. Typically, large-scale mammalian culture uses cells that have been selected to grow well in the conditions used and the end use (e.g. high-level production of a valuable protein) does not require a highly differentiated cell line. Many widely used cell culture lines are derived from neoplastic tissues and are said to be transformed, that is their genetic material has been mutated (by insertion, deletion or rearrangement) to remove normal controls on cell growth and as such they are atypical of normal differentiated cells.
The process by which a whole organism made up of large numbers of different cell types is produced from a single fertilized egg is complex, involving structural and environmental differences between cells as they grow and divide. The resulting differentiated cell types maintain their phenotype as a result of the interplay between cell-cell interactions, the circulating environmental signals (pH, small molecules, dissolved gases, proteins etc) and the programmed expression of the cellular genome, itself influenced by epigenetic changes brought about by the process of differentiation. There is a need for improved cell culture surfaces to facilitate the culture of certain cell types.
The ex vivo growth of eukaryotic cells derived from multicellular organisms inevitably represents an approximation to the naturally occurring in vivo conditions and unsurprisingly there are many areas where the current techniques are found wanting.
Professor Robert Short (Director, Mawson Institute, South Australia, AU), Dr. Patricia Murray (University of Liverpool, GB) and Dr. Kristina Parry (Plasso Technology Ltd, Rotherham, GB) developed a cell culture surface made of a substrate and a polymer comprised of a carboxylic acid monomer, in which the carboxylic acid concentration of the polymer is from 3% to 33%. The surface advantageously is able to better emulate the natural in vivo cellular environment. It has a wide range of applications in fundamental biological research as well as the development of novel therapies such as tissue engineering and organ replacement
The cell culture substrate may be made of a non-porous polymer for example the substrate may be a solid phase substrate such as a plastics or a glass substrate. The substrate may be a porous or fibrous material such as a woven or non-woven material. Examples of substrate include particles such as nano-particles, beads (e.g polymeric, glass), tapes, ribbons, fibres, polymer films, gels and textiles. The substrate consists of the carboxylic acid containing polymer, for example the substrate may be a scaffold (for example for tissue engineering) formulated from the carboxylic acid containing polymer. The substrate may be a non-woven mesh of the carboxylic acid containing polymer.
Short, Murray and Parry's cell culture product has a cell culture medium which does not contain serum. The cell culture medium may be supplemented with an agent that promotes cell proliferation without differentiation such as a mitogen, a human leukaemia inhibitory factor (LIF), or a growth factor such as a human growth factor, a human epidermal growth factor or human basic fibroblast growth factor. However it is preferable that the cell culture medium does not contain a mitogen and does not contain a growth factor.
The requirement in cell culture for a complex culture medium which typically contains either biological fluids (e.g. foetal calf serum) or specific biomolecules (growth factors) intended as serum replacements is both expensive and requires extensive and expensive quality control testing before it can be used. Moreover, the use of such biological supplements introduces the possibility of contamination with infectious agents (viruses, prions), raising significant safety issues for any resultant therapy. Thus the absence of serum in the cell culture medium is desirable. For stem cells, the presence of feeder cells in the cultures raises similar issues about the purity, homogeneity and safety of derived cells. The cell culture receptacle developed by Short, Murray and Parry does not contain feeder cells.
The requirement in cell culture for a complex culture medium which typically contains either biological fluids (e.g. foetal calf serum) or specific biomolecules (growth factors) intended as serum replacements is both expensive and requires extensive and expensive quality control testing before it can be used. Moreover, the use of such biological supplements introduces the possibility of contamination with infectious agents (viruses, prions), raising significant safety issues for any resultant therapy. Thus the absence of serum in the cell culture medium is desirable. For stem cells, the presence of feeder cells in the cultures raises similar issues about the purity, homogeneity and safety of derived cells. The cell culture receptacle developed by Short, Murray and Parry does not contain feeder cells.
Recently there has been a tremendous interest in undifferentiated cells known as stem cells because these are potentially able to differentiate into either all other cell types (totipotent cells) or certain cell lineages (pluripotent cells). For these cells the challenge is to provide culture conditions that allow the propagation of the undifferentiated cells whilst retaining their ability to differentiate.
