1. VistaGen Global Leader in Stem Cell Technologies for Pharmaceutical Development Identification of Surrogate Markers for Predicting Drug Responses Advisory Committee for Pharmaceutical Science March 9, 2000

2. VistaGen © 2000 Approach to Identifying Surrogate Markers for Drug Responses  Biology platform based on embryonic stem cell systems – complex, interactive, multi-tissue therapeutic index  High through-put drug prioritization based on an in vitro “therapeutic index” KnowledgeBase  Retrospective KnowledgeBase of successful and failed drugs  Better understanding of species differences for predicting MTD for clinical testing  Model system for evaluating genetic polymorphisms & drug responses

3. VistaGen © 2000 Genesis Screen™: Complex Biology

4. VistaGen © 2000 Genesis Screen™: Complex Biology  Complex tissue development  Suitable for screening –blood –muscle –endothelial (blood vessels) –neuronal –connective tissues –other

5. VistaGen © 2000 ES Cells & Drug Testing Tissues ES Cell Differentiation Differentiation Comparative Bioinformatics MuscleCells Drug Leads Protein & Gene Expression Profiles Protein & Gene Expression Profiles Predictive Efficacy & Toxicity Predictive BoneCells BloodCellsBloodVesselsNeuronalDevelopment

6. VistaGen © 2000 Predictive Toxicity = Pattern Matching Putting History to Work for Us Internal Reference Standards Reference StandardsUnknown Test Compound “Clinical”Effect liver tox cardiac tox kidney tox neuronal tox Cyp 1A1 inhibitor liver tox2

7. VistaGen Ralph Snodgrass, CEO VistaGen, Inc. Mountain View, CA 650-237-0398rsnodgrass@vistagen-inc.com