New strategies for improving the biotechnological production of pharmaceuticals and biopharmaceuticals in plant cell and organ cultures

Resumen

Outline of the PhD thesis The thesis is presented as a compendium of publications and includes six different sections: General Introduction, Objectives, Results, General Discussion, Conclusions and References. The General Introduction summarizes the state of the art of Plant Cell and Organ Cultures (Plant Biofactories) and their applications for the pipeline production of Cosme-, Pharma- and Biopharmaceuticals. Objectives describes the overall aim of the PhD thesis, as well as the specific goals of each chapter of the Results section. The five chapters of the Results section are based on published scientific articles in ISI journals, where the PhD candidate is always the first author and in each article and when possible according with the editorial rules, it is mentioned that it forms part of his PhD thesis. Each chapter clearly refers to a particular goal of Plant Biofactories employed for the production of biologically active high added-value compounds. Briefly: a) Chapter 1 aims to demonstrate the effectiveness of plant in vitro cultures of Centella asiatica for the production of centellosides in optimized conditions by adding elicitors and potential precursors. Centellosides are widely utilized for their therapeutical properties and C. asiatica cell lines are also currently applied as cosmetic ingredients. b) Chapter 2 focuses on the biotechnological production of t-resveratrol, a bioactive compound found in wine and other foods, in engineered hairy roots of tobacco. The study aims to demonstrate the power of metabolic engineering tools for designing new organisms with modified metabolic capacities and their utility for the production of scarcely distributed plant compounds. c) Chapter 3 provides a paradigmatic example of how a metabolic pathway can be extended in a host organism by means of metabolic engineering tools. Silybum marianum cell cultures, which have the natural ability to produce polyphenol silymarins, are shown to have a previously unexplored capacity for the heterologous production of t-resveratrol, a new polyphenol in this plant species. d) Chapter 4 aims to demonstrate the broad capacity of plant cells for bioconverting exogenous substrates to target products, showing that tobacco hairy roots and their derived cell cultures can biotransform t-resveratrol into the more active metabolites t-piceatannol and t-pterostilbene, both high added-value compounds scarcely distributed in nature. e) Chapter 5 describes the production of the truncated human tissue plasminogen activator (K2S) in tobacco cell cultures derived from transplastomic plants, aiming to avoid the disadvantages of biopharmaceutical production in field transgenic crops. The Discussion section includes a general discussion of the main results obtained and described in the five chapters of the PhD thesis in the context of recent studies and the objectives of the thesis. In the Conclusions section, the main conclusions derived from the results reported in the five chapters are briefly summarized. The References include the complete references of all the articles cited in the general sections of the PhD thesis.