Why multiply cells in a pot?
A container in which the appropriate environmental conditions are maintained (temperature, pH, concentration of dissolved oxygen, etc.) so that inside it it is possible to grow cells, tissues or to carry out a chemical process that involves organisms or substances biochemically active. That Holy Grail, which gives life and might seem like something from science fiction, is known as a bioreactor or fermenter. The origins of this technology, as used today, date back to the First World War due to the need for citric acid production at that time. Another example of a milestone in fermentation technology in the field of biotechnology comes from World War II and the need to produce antibiotics on a large scale. This is the case of penicillin, a milestone that brought improvements and greater knowledge in biotechnological processes. Not in vain, not only in wars do bioreactors evolve. Precisely now they represent an emerging technological niche, due to the need to reduce the consumption of plastic and replace it with paper and wood, which requires the production of millions of trees per year. The bioreactor or fermenter is the heart of any bioprocess. It is an element present in areas such as Biology, Chemistry, Biochemistry or Medicine, among others. You have heard a lot about them recently as they have been a key element in the manufacture of some of the coronavirus vaccines. Specifically, the manufacturers of AstraZeneca have described their production as a biotech production process. Since viruses are particles and are not capable of replicating on their own, but rather require host cells to do so, the first stage of obtaining the aforementioned vaccine involves growing the adenovirus within human kidney cell lines in large industrial bioreactors , which can have a capacity of up to 2,000 liters in the case of mammalian cell production. Although the need to obtain a vaccine against Covid-19 has aroused the interest of society about its manufacturing process, the truth is that per se it is not something new. Obtaining viral vaccines using cell lines is common. Thus, vaccines against rubella, rabies, chicken pox, polio, rotavirus or hepatitis A, among others, have been produced by this method for decades. What is true and remarkable is that the need for new vaccines due to the pandemic caused by Covid-19 has accelerated another biotechnological milestone for the approval of RNA-based vaccines, in whose production a bioreactor is also involved. Bioreactors represent an emerging technological niche, due to the need to reduce the consumption of plastic and replace it with paper and wood    In the Region of Murcia, located in the Fuente-lamo Technology Park, there is BIONET, a company dedicated  according to its website  to the manufacture of laboratory, pilot and industrial equipment for the biotechnology sector, focused on bioreactors / fermenters and cross-flow filtration systems, as well as a provider of engineering and process development services related to bioprocesses for companies that want to produce biomass or biomolecules, through microbial fermentation or through cell culture processes , that is, among its many services is the development and manufacture of bioreactors for the production of microorganisms such as bacteria, yeasts, fungi and animal or insect cells. Fuensanta Verd, an industrial doctoral student at the Polytechnic University of Cartagena, works there, whose doctoral thesis is developed in the company under a contract from the UPCT-BIONET Chair. The objective is to develop a line of research for bioreactors or fermenters dedicated to plant cells. My thesis seeks to characterize and optimize the growth of plant cells in bioreactors because they are a middle ground between cells of bacteria and those of animals , he says. And he explains: The cultivation of bacterial cells in bioreactors is easier. These types of cells grow fast, are more resistant and usually do not have many special requirements. However, due to their simpler cellular machinery, in certain cases they are not valid to produce certain biologically active biomolecules as more complex proteins, which give rise to vaccines or certain metabolites of interest. On the contrary, animal cells would be valid for the manufacture of such products, but their culture is more expensive: their growth is slower, they are more susceptible to contamination, and their requirements are usually greater than those of bacterial cells. Plant cells would be in the middle: they are capable of producing a great variety of proteins and metabolites of interest that bacterial cells cannot and, in turn, are not as delicate as animal cells . Vaccines    The researcher assures that there are numerous companies that demand bioreactors to carry out, among other purposes, somatic embryogenesis (a process that allows going from dedifferentiated plant cells to embryos that will give rise to complete plants, similar to seeds, for their production in mass). According to Fuensanta Verd, all plant cells can completely de-differentiate themselves and act like animal stem cells, that is, as totipotent cells. This means that they have the ability to become any type of cell, which allows them to generate a complete plant, a seed, an embryo, etc. In short, it is very interesting from the point of view of plant multiplication . The interest of the work developed by Fuensanta Verd lies in the fact that it investigates a model plant. The Nicotianabenthamiana, already used as a model organism in studies of plant-pathogen relationships and which is now on the rise because there are those who use it as a base to develop processes to produce vaccines against Covid-19, among other vaccines. In order to use a plant or other cell type in the production of a vaccine, transgenic lines must be made in which it is expressed in the gene or genes that encode the antigens used. Subsequently, the leaves are taken and processed to isolate the chosen proteins or RNA. Among other things, it is necessary to let the plant grow and that already marks certain times that cannot be accelerated. Also, there is a risk that it may become contaminated. The level of asepsis required to produce tomatoes in a greenhouse is not the same as to produce a protein that you want to inject into a patient. These problems disappear if it is possible to work with plant cells in a bioreactor since they take up little space and millions of cells can be generated in each one; it is a watertight and aseptic space. This makes it possible to directly obtain plant cells and get them to expel the protein or RNA into the liquid and only by filtering could vaccines be produced. And it could also work in continuous mode, to increase the productivity of the process, without waiting for the plants to grow and hardly any residue is generated. There are quite a few studies on the whole plant as a model for the production of proteins and metabolites of interest. In fact, it has been used to develop a successful vaccine against the Ebola virus. In addition, it is being used to produce some of the ingredients in vaccines against Covid-19. However, there is little scientific data about its cultivation in a bioreactor to produce compounds of interest. But the really interesting thing would be to carry out production in a bioreactor, since it would greatly accelerate the process , indicates Verd who intends to characterize Nicotianabenthamiana in order to work with it in bioreactors. Likewise, together with the Genetics and Plant Biology group of the Polytechnic University of Cartagena, he will carry out studies on how culture conditions and stress affect cell growth and the production of proteins and other compounds of interest. Specifically, the project in which the UPCT doctoral student is working will consist of: with cultures of the Nicotianabenthamiana species previously established under in vitro conditions, first carry out cell culture tests in liquid medium in flasks. In this way, the aim is to optimize the culture medium on a small scale to increase the yield. After this, the cells will be cultured in the bioreactor, where the culture conditions will be controlled, such as aeration, temperature, pH, dissolved oxygen. At this point we will also seek to find the optimal conditions for cultivation, to maximize yield. Likewise, the cultures will be subjected to certain conditions so that somatic embryogenesis takes place; observing and determining which are the best conditions for this process to be as successful as possible. With the results obtained from these experiments, the foundations can be laid to be able to carry out this kind of crops with other plant species. So that advice can be given to potential clients who are interested in this type of cell culture. In short, with the results obtained, it is expected to achieve a competitive position at the national and international level of scientific development at the UPTC and of the Bionet company in the development of technologies for the production of plant cells in bioreactors.