25 Years of PlasmidFactory: A Success story Built on Independence and Ingenuity
(December 9, 2025) Being accomplished for a quarter of a century – not manny companies can do that, especially not in the life sciences industry.founder and former managing director Martin Schleef and his successor dirk Winnemöller reveal the secret behind the success of PlasmidFactory.
Laboratory journal: mr.Schleef, Mr.Winnemöller, the PlasmidFactory is celebrating its 25th anniversary this year, we warmly congratulate you. Though, it is indeed not a given that biotech companies will last this long. How did the idea of starting a company come about?
Martin Schleif: Before founding the company, I worked at Qiagen in Hilden for six years and was involved in the production of DNA there. There, several colleagues and I had the idea of implementing what we do here, embedded in the large company, entirely on our own, the way we wont. We wanted to be a pure service provider that produces DNA for customers. This wasn’t directed against Qiagen – but it wasn’t financially supported by the company either. It was simply the independence of a good idea.
Your company location has been Bielefeld since the beginning. How did you choose this city?
Dirk Winnemöller (Tow): I did my doctorate in Bielefeld and still had contacts at the university there. We needed a laboratory and actually had no start-up capital.There were no empty laboratory rooms and we couldn’t buy new equipment either. Luckily, Bielefeld University found our idea interesting.That was at a time when there was no talk of students starting spin-offs. This was only intensified later. In short, we didn’t spin off directly from the university, but with their support.
In the frist few years they were completely without risk capital and quickly had to become self-sufficient. How did you do that?
Tow: Renting equipment and rooms has helped us a lot. We rented the equipment at full cost, but were able to complete a few jobs with it that earned us a little capital. We were then able to buy our own equipment and soon only had to pay the laboratory rent.
The necessary equipment is often a massive cost item. Were you able to afford new equipment after your first orders?
Tow: No, not at all. We bought our first fermenters on eBay. We put together a whole one out of two broken ones. The two fermenters arrived by ship from the USA. There was also a Pfizer sticker stuck on it as a scrap dealer had pulled it out of the trash and then resold it. The import was a bit difficult, though. The fermenters were declared as stainless steel scrap – they were no longer functional – but were called bioreactors, which really worried the importer. We first had to explain what a fermenter was and used beer brewing as an exmaple.
Instead of raising millions in one round of financing – as is common practice today – did you expand the company piece by piece?
Tow: Exactly. It was a bit like Monopoly. We made a little money and then invested it in something that could make us more money. So we were actually able to build the PlasmidFactory without any outside help. We did receive loans from the local savings bank,but in homeopathic doses. We have never borrowed more money than we could have repaid in an emergency.
are purely a service provider.
Would you say you had a harder time back then than today’s startups?
Tow: I don’t know that. But I believe that it is no longer so easy to get money today. Still,young people still come to us who want to start their own business and ask how we did it. I think that’s great. The advice I always give is that it is indeed frequently enough better to work with a larger partner first to get on your own feet.
you, Mr. Schleef, once said in an interview with Laborjournal from 2018 said that the PlasmidFactory is a kind of copy shop for plasmids. Would you both still sign it like that?
Winnemöller: No, I think calling us a “copy shop” is only part of the truth. We can copy plasmids well and not every copy shop achieves the same quality.For us,however,our further growth is more crucial: the minicircles,a plasmid 2.0 so to speak. We can create such a minicircle from a normal plasmid. Then it is not simply copied, but improved. Applications are then possible that do not work with standard plasmids. This also sets us apart from other companies.
How does a normal plasmid become a minicircle and what advantages do these constructs have?
Tow: From the outside, plasmids and minicircles look very similar: they are ring-shaped, double-stranded and supercoiled.However,the Minicircle is missing something: the Origin of Replication (ORI,origin of replication). For normal applications of plasmids you need this ORI, and usually also antibiotic resistance as a selection marker. This all takes up space and includes components that are not needed for cell therapy, for example. This also increases the capacity for the gene of interest to be expressed. Smaller molecules are also easier to transport into the nuclei and lack CpG motifs that can trigger immune reactions.
And do you remove these components of conventional plasmids?
Tow: Exactly. In the end we have a small, ring-shaped, supercoiled and therefore highly condensed expression unit that actually only contains the transcription unit that is to be expressed. due to the small size, we achieve a transfection efficiency that is comparable to that of lentiviruses.In addition, lentiviruses prefer to integrate their DNA into the chromatin at locations where genes are located. This can lead to problems. We thus suggested early on that minicircles could be used to produce CAR-T cells.
Winnemöller: For this purpose, we are cooperating, such as, with Michael Hudecek from the University of Würzburg (Hudecek is director and research group leader of the Translational CAR-T Research Program).We also see a lot of potential when it comes to the question of scalability towards affordable cell and gene therapies, because this requires suitable technical means.
There seems to be something wrong with cell therapy. Novo Nordisk and Takeda are getting out (we reported on LJ online “Cell therapies cut off?” – Link),in Germany they are lagging behind.Are you concerned that there could be a wholesale shift away from cell therapy?
Winnemöller: Well, companies that don’t have a functioning business case for
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