Standards in Scienti c Communities II Cell Viability Module 3 Lecture 4 20 109 Spring 2010 Lecture 3 review Systems What can you learn from a con dence interval A t test Can I have three inverters Devices What three general engineering principles might help make biology more engineerable I need a few DNA binding proteins Parts Get me this DNA DNA Image by MIT OpenCourseWare See D Endy Nature 438 449 2 Topics for Lecture 4 Standards in tissue engineering introduction writing exercise discussion Cell viability your data relation to diffusion 3 How valued are TE standards 2007 strategic plan for TE clinical success by 2021 24 int l leaders in TE listed high priority areas 1 3 named standards Analysis concept dominance progress so far standards 7th of 14 4 Cell sourcing characterization 7 tie Standardized models P C Johnson et al Tissue Eng 13 2827 2007 2007 US govt strategic plan Courtesy of Mary Ann Liebert Inc Used with permission Source Johnson P C et al Strategic Directions in Tissue Engineering Tissue Eng 13 no 12 2007 2827 2837 doi 10 1089 ten 2007 0335 standards listed as part of implementation strategy 4 How useful are TE standards See 2005 editorial by A Russell proposes need for standards in data collection and sharing Choose and respond to a student excerpt 10 Pros cons etc Can we standardize this TE construct 5 Module progress week 2 Day 3 viability cytotoxicity testing Groups generally found mostly live mostly round some clustering How do we explain the results How can we improve the assay What conditions killed cells Image from W F Yellow Group 6 Factors affecting cell viability Cell related density interactions Cytokine related proliferative apoptotic Materials related bulk permeability macro porosity toxicity 7 Diffusion in 3D constructs Nutrients O2 Affected by Dalginate R Concentration pro le can be solved DE O2 toward center steepness f D O2 bulk O2 construct size R cell density diffusivity D conc in medium O2 bulk Dliq center position r edge 8 Signi cance of diffusion in TE Characteristic limit 100 m Diffusion and viability pro les correlated How can we make thick tissues in vitro dynamic perfusion culture in vivo promote rapid angiogenesis Photo removed due to copyright restrictions perfusion system zeiss com sg 9 Modeling cell viability in TE constructs Porous PLGA scaffolds Seeded cells as in A or B Observed after 10 days Model includes Diffusion O2 use Cell growth A Cells in odd layers B Cells in all layers Model assumes O2 bulk is constant Quasi steady state Dunn et al Tissue Eng 12 705 2006 Courtesy of Mary Ann Liebert Inc Used with permission Source Dunn J C Y et al Analysis of Cell Growth in Three Dimensional Scaffolds Tissue Eng 12 no 4 2006 705 716 10 Dunn et al results for cell viability center Cell density A more uniform than B Cell growth matches O2 tension Claim of predictive capability 1M cells cm3 1M cells cm3 Distance from edge 11 Courtesy of Mary Ann Liebert Inc Used with permission Source Dunn J C Y et al Analysis of Cell Growth in Three Dimensional Scaffolds Tissue Eng 12 no 4 2006 705 716 Lecture 4 conclusions Strategies besides standardization may take precedence in some BE elds Cell viability in TE constructs is affected by cell material and soluble factors Modeling can elucidate nutrient diffusion and cell viability pro les Next time transcript and protein assays advice for module 2 report revision 12 MIT OpenCourseWare http ocw mit edu 20 109 Laboratory Fundamentals in Biological Engineering Spring 2010 For information about citing these materials or our Terms of Use visit http ocw mit edu terms