Going green

Dr Gilbert Gorr talks to NGP about the clinical uses, environmental advantages and the huge future potential of moss for greenovation.

It was while working on his PhD in Biotechnology at Hamburg University, that Dr Gilbert Gorr, now Chief Scientific Officer at greenovation, began working with mosses and established the use of the technology. The outcome of his PhD has become the basic patent that greenovation are in fact dealing with. In 2000, Gorr joined the company to establish the moss as a safe and cost-effective production platform for complex biopharmaceuticals.

Compared to conventional expression organisms like bacteria, mosses are far more complex organisms and display more sophisticated post-translational modification capabilities and through this the researcher. Gorr and colleagues had been able to establish several expression tools with mosses. One is the stable transformation for sustainable production of biopharmaceuticals in photobioreactors on a large scale. The other technology that greenovation have established is a transient expression system, which allows them to provide small quantities to customers for a first characterisation of a protein of interest. Gorr and colleagues had been able to engineer the moss due to the glycan structure and they now have several strains on their hands.

“The best glycan pattern is at least the most similar to the human glycan pattern,” explains Gorr, “and therefore we have removed the plant-specific sugar residues on the core structure of the N-glycans. We are also able to add some specific mammalian-like residues on the terminal end so we have a portfolio of strains showing different glycan structures available.”

Advantages

Using the genetically engineered moss is extremely valuable to greenovation because of the numerous advantages, such as it being safe to humans and the environment, as well as being easy to handle. There are no moss or plant viruses known that would be pathogenic to humans and due to the contained system there is no environmental issue that may be connected with the release of transgenic plants into the environment. Gorr is also, for example, able to subcultivate the mosses once a week or once every two weeks, which is much easier than every second day as is standard with CHO cells meaning that there is less time spent for subcultivation and less wastage of materials as animal cells, which need much more care.

Due to moss being photoautotrophic it’s a very robust organism and only requires a very simple growth medium compared to the complex media needed for animal cell systems, therefore Gorr et al, can avoid any addition of animal-derived products or other recombinant products from other organisms, leaving a medium containing just a few minerals and no organic compounds in it. In addition they are dealing with a fully differentiated organism – or tissue, in their case – that is exceptionally stable under completely different conditions, leaving them the flexibility to design the surrounding media according to the demands of the produced protein.

Dr. Gorr goes on to add: “Another issue is that the moss is haploid on a molecular level, we are not just dealing with two alleles on two chromosome sets we have just one. This means that all genetic engineering results directly in the genotype we’re interested in, which is a real advantage compared to other systems.”

Additionally, there are cost savings from the medium composition of water and minerals, as well as lower investments for glass fermenters compared to steel fermenters, which are used for animal cell cultures. The average cost savings are around 50 percent depending on the product. Time-to-market is comparable to traditional systems. A transient expression system allows feasibility studies and the making of complex molecules in short-time. The development of stable production strain does not require crossing steps or regeneration of whole plants.

Asked if there were any disadvantages Gorr starts laughing before adding, “that’s difficult to say!” But he does go on to add that there are some concerns against alternative methods and technologies, such as plant-based expression systems, in the pharma industry as many scientists prefer to work with more familiar E. coli or CHO cells. As the technology is just a few years old it is not able to compete in producing large amounts, however, Gorr remains optimistic and believes that in the near future similar amounts will be available.

Photobioreactor

Gorr is co-inventor of the cultivation of mosses in photobioreactors with respect to the secretion of the target protein into the medium, along with his colleague Professor Ralf Reski. This technology is based on the cultivation of the moss Physcomitrella patens, in a glass fermenter. The moss protonema is grown under photoautotrophic conditions in a medium, which consists essentially of water and minerals. Light and carbon dioxide serve as the only energy and carbon sources, which means it is very environmentally sound. One advantage of this technology over other plant expression systems is, that the produced proteins are secreted into the surrounding medium and that there is no degradation by proteases.

Currently the photobioreactor could be not only used by greenovation but as the technology develops the photobioreactor could be put directly into every facility that wishes to use it.

Challenges

The main challenges for greenovation, in terms of integrating their technology into other companies is to demonstrate that they can make improved products. Actually the main focus of greenovation is in the market segment of antibodies fighting cancer. These antibodies get their improved therapeutic efficacy by glyco-engineering using greenovation®´s bryotechnology. The modification of the sugar structures attached to the antibodies lead to the reinforcement of the effector function and thus to the more effective destruction of cancer cells. Gorr explains that they are involved in many deals with other biotech companies to test if their antibodies show the same improvements by using greenovation®´s bryotechnology, and he also mentions that they are interested in implementing expression technology into big pharma companies who can use greenovation’s improving technologies as alternative expression system in the early beginning of drug development. But the therapeutic potential of the bryotechnology is not only restricted to improved antibodies. “We think that cytokines and such kinds of products can be produced in our technology much better than in CHO cells due to the feedback loops for all these cytokines,” adds Gorr.

He goes on to say that the main challenge is convincing people in big pharma that their process could be an alternative, that they do not to have to replace everything they have used in the past but to think about it as an complimentary technology with many advantages.

On the up

Gorr’s hopes to work with big pharma came true when greenovation secured a collaboration deal with a global player, Bayer, in 2006. Although this is just one of many collaborations this particular deal is important as it demonstrates to greenovation that their technology is of interest to big pharma. Gorr: “Bayer’s acquisition of Schering makes them into one of the leading specialty pharma companies in the world, and that is very important to us. We also have a very good relationship with the people at Bayer because of the good communication and feedback they provide.”

greenovation have also recently received their first US patent in the area of plant-based glyco-engineering, Gorr explains how significant this is: “Although we have a very strong situation in Europe regarding patents, which we are very happy with, this is our first US-issued patent, and the US is the biggest market of all so it is brilliant to be able to work on this as many of our customers are in the US.”

Future

Gorr believes that it is only a matter of time before other companies begin using mosses as an alternative to animal cell cultures. He goes on to say that presently greenovation are at the stage of designing and proving feasibility studies in order to see how products can be improved or enhanced in preclinical and clinical phases, by the use of their technology. “It will really come to the situation where we will put products from the mosses into humans during clinical studies,” says Gorr. “I am positive that we will reach this stage in the next one or two years.”