Genetic Engineering & Biotechnology News

JAN15 2018

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20 | JANUARY 15, 2018 | | Genetic Engineering & Biotechnology News Jennifer L. Weber, Jeffery J. Scibek, and Jessica L. Martin Microcarriers are 100- to 300-micron-sized beads that support the attachment and growth of adherent cells in stirred culture. They enable more cost-effective cell produc- tion by reducing the fixed costs (e.g., footprint and labor) and variable costs (e.g., media con- sumption) in large-scale manufacturing. A critical parameter that needs to be con- sidered when selecting the optimal microcar- rier is the intended use of the product. For cell therapy applications, a viable, functional cell is the desired product. Unfortunately, most commercially available microcarri- ers have significant disadvantages that hin- der their use for cell therapy applications. Most microcarriers are composed of a solid matrix, which requires that the microcarrier be separated from the dissociated cells dur- ing downstream processing. This separation step is not trivial; it adds complexity and ex- pense to the overall production process. Another limitation observed with microcar- riers is the inability to efficiently dissociate cells following cell expansion due to the strength of cell attachment. For these microcarriers, over- all cell yield is significantly reduced and, more importantly, the functionality of the harvested cells may be impacted by the harsh cell disso- ciation methods that are required. An Innovative Solution Corning dissolvable microcarriers pro- vide an ideal solution for large-scale cell ex- pansion. The dissolvable microcarriers are composed of cross-linked polysaccharide polymers that can be efficiently dissolved during the cell harvest step (Figure 1). The ability to completely dissolve the microcarri- er results in simpler downstream purification processes and eliminates the need to physi- cally separate the cells and microcarriers. The microcarriers are quickly dissolved through the addition of a harvest solution containing EDTA, pectinase, and a standard cell culture protease. When calcium ions are chelated by EDTA, the microcarrier polymer destabilizes, and subsequent polymer degra- dation is achieved by pectinase. An addition- al cell culture protease (e.g., trypsin, Thermo Fisher Scientific's Gibco TrypLE, or Innova- tive Cell Technologies' Accutase) breaks down cell-cell interactions and extracellular matrices, resulting in a single-cell suspension in a solution of small sugar oligomers. Corning dissolvable microcarriers are opti- cally transparent, consisting of ~250-μm-size beads with a density of 1.01–1.03 g/cm 3 and a surface area of 5,000 cm 2 /g. Their narrow distribution in size and surface area, compared with other commercially available microcarri- ers, supports a more uniform cell seeding and growth to confluence, resulting in a homoge- neous cell suspension. Further, the narrow mi- crocarrier size range and density support bet- ter alignment of agitation speed with complete microcarrier suspension within a bioreactor. Backed by Data Several studies have demonstrated equiv- alent or better cell expansion and recovery using dissolvable microcarriers instead of traditional microcarriers. Scientists have demonstrated: • Successful multipassage human mes- enchymal stem cell (hMSC) expansion on dissolvable microcarriers in serum-free me- dia (CLS-BP-PST-020 and CLS-AN-480). • Better or equivalent hMSC growth in less time with higher cell recoveries on dissolv- able microcarriers compared with polystyrene microcarriers; experiments were confirmed for both adipose- and bone marrow– derived hMSCs from different cell donors (www. ences/resources/webinars.html). • Dissolvable microcarriers support the expansion and recovery hMSCs in 5-L bio- reactors. Cells were recovered from dissolv- able microcarriers in 20 minutes and retained standard elongated morphology, normal karyotype, and multipotency (CLS-AN-470). • Increased human induced pluripotent stem cell (hiPSC) productivity per day on dis- solvable microcarriers compared with Matri- gel-coated polystyrene microcarriers. Dissolv- able microcarriers supported an easier and less aggressive cell recovery process compared with that required for hiPSC recovery from poly- styrene microcarriers (Internal Corning data shared on conference poster and presentation). • Efficient MRC5 and Vero cell growth and recovery on dissolvable microcarriers in spinner flasks and bioreactors. (CLS-PST- BP05 and CLS-BP-PST-020). Dissolvable microcarriers support effi- cient cell production and recovery for several cell types including: hMSC, hiPSC, Vero, and MRC5. This new generation of dissolv- able microcarrier supports the effective and efficient recovery of high cell yields without the need for microcarrier separation, result- ing in a more cost-effective and less labori- ous harvest process that supports cell health maintenance and functionality. System Enables Improved Scale Up Next-Gen Microcarrier Advances Cell Therapy Bioprocessing Jennifer L. Weber and Jeffery J. Scibek are development associates, cell biology, at Corning Life Sciences. Jessica L. Martin ( is product line manager, bioprocess at Corning Life Sciences. Website: References available online. Tutorial Figure 1. Ionically cross-linked pectic acid microcarriers are dissolved during cell harvest with a solution of EDTA and pectinase. The Only Peer-Reviewed Journal Focusing on the Human Aspect of Gene Therapy Providing comprehensive, end-to-end coverage of the research, methods, and clinical developments that are driving today's most critical gene therapy advances Editor-in-Chief Terence R. Flotte, MD Deputy Editors, Europe Nathalie Cartier, MD Thierry VandenDriessche, PhD Deputy Editors, US Barry J. Byrne, MD, PhD Mark A. Kay, MD, PhD Human Gene Therapy Editor Guangping Gao, PhD Methods Editor Hildegard Büning, PhD Clinical Development Editor James M. Wilson, MD, PhD Sign up for free email alerts

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