We published some new articles.


Neighborhood watch – Professional journal club:

High-molecular-weight kininogen: breaking bad in lethal endotoxemia.
Hofman ZLM, De Maat S, Maas C.
J Thromb Haemost. 2017 Dec 11. doi: 10.1111/jth.13924. [Epub ahead of print]


With one of my personal contact system “heroes”:

The Search for Biomarkers in Hereditary Angioedema.
Kaplan AP, Maas C.
Front Med (Lausanne). 2017 Nov 22;4:206. doi: 10.3389/fmed.2017.00206.

With our esteemed former colleague Claudia:

Amplified endogenous plasmin activity resolves acute thrombotic thrombocytopenic purpura in mice.
Tersteeg C, Joly BS, Gils A, Lijnen R, Deckmyn H, Declerck PJ, Plaimauer B, Coppo P, Veyradier A, Maas C, De Meyer SF, Vanhoorelbeke K.
J Thromb Haemost. 2017 Dec;15(12):2432-2442. doi: 10.1111/jth.13859. Epub 2017 Oct 27.

With our friends from Giessen:

Coagulation factor XII regulates inflammatory responses in human lungs.
Hess R, Wujak L, Hesse C, Sewald K, Jonigk D, Warnecke G, Fieguth HG, de Maat S, Maas C, Bonella F, Preissner KT, Weiss B, Schaefer L, Kuebler WM, Markart P, Wygrecka M.
Thromb Haemost. 2017 Oct 5;117(10):1896-1907. doi: 10.1160/TH16-12-0904. Epub 2017 Aug 17.

With our friends from Berlin:

Hereditary Angioedema with Normal C1 Inhibitor: Update on Evaluation and Treatment.
Magerl M, Germenis AE, Maas C, Maurer M.
Immunol Allergy Clin North Am. 2017 Aug;37(3):571-584. doi: 10.1016/j.iac.2017.04.004. Review.

With our friends from Giessen (again):

Antihistone Properties of C1 Esterase Inhibitor Protect against Lung Injury.
Wygrecka M, Kosanovic D, Wujak L, Reppe K, Henneke I, Frey H, Didiasova M, Kwapiszewska G, Marsh LM, Baal N, Hackstein H, Zakrzewicz D, Müller-Redetzky HC, de Maat S, Maas C, Nolte MW, Panousis C, Schermuly RT, Seeger W, Witzenrath M, Schaefer L, Markart P.
Am J Respir Crit Care Med. 2017 Jul 15;196(2):186-199. doi: 10.1164/rccm.201604-0712OC.

Jan-Jaap’s work:

Iron nanomedicines induce Toll-like receptor activation, cytokine production and complement activation.
Verhoef JJF, de Groot AM, van Moorsel M, Ritsema J, Beztsinna N, Maas C, Schellekens H.
Biomaterials. 2017 Mar;119:68-77. doi: 10.1016/j.biomaterials.2016.11.025. Epub 2016 Nov 21.

…I should update this more often…

NEW PAPER! Hofman et al. – Cleaved kininogen as a biomarker for bradykinin release in hereditary angioedema

Zonne Hofman has done it! She published her solution to a diagnostic problem in the Journal of Allergy and Clinical Immunology.
Bradykinin is a powerful inflammatory molecule, but nearly impossible to measure in the blood of patients, because it is rapidly degraded. We looked whether we could detect changes in the ‘parent molecule’ kininogen that take place during bradykinin production with home-made nanobodies. In the end, we developed a bio-assay (let’s call it the Kalli-cHK assay) that is able to quantify cHK levels in blood plasma of patients with hereditary angioedema (HAE).
This is going to be a catalyst for clinical research on HAE, as well as many other inflammatory conditions in which bradykinin is a prime suspect!

You can find the paper here.

Assay principle

Research Grant from Trombosestichting Nederland

I recently received some amazing news in the middle of the great funding massacre that nearly killed me only a few days earlier.
My project “Nature’s Nanoparticles” was granted funding by Trombosestichting Nederland! I am very thankful! This means that we can investigate the properties of platelet polyphosphate nanoparticles in health and cardiovascular disease.

I believe that polyphosphate nanoparticles are the ‘cement’ that keeps the bricks (cells) of a blood clot together (drawn below). If a blood clot is torn apart, this material is exposed to the blood stream, calling in reinforcements for repair and strengthening of the blood clot via a specialized enzyme system. Excessive strengthening via this pathway will lead to vascular occlusion, which is a problem in thrombosis. However, I expect that a lack of this mechanism will cause thrombi to become unstable, resulting in shedding microthrombi into the vasculature. This could be equally dangerous. The aim is to evaluate the safety profile of interfering with the ‘thrombus-stabilization machinery’.

I can’t wait to get started! We already found the perfect person for the job!

New paper! Barendrecht et al. – Live-cell Imaging of Platelet Degranulation and Secretion Under Flow.

We recently made a video with JoVE (Journal of Visualized Experiments). It was really fun! You can find the movie and paper here.
It took me quite some time to prepare the ‘movie-script’ (really different than writing a normal publication), but it does count as a real publication on pubmed!

Arjan and Silvia organized the ‘show’ on the filming day (impressively organized) and all of us had to say a few words. I was reminded how terrible I am in front of a camera! It was much more comfortable to hold the Director Clapper (La Claqueta in spanish) ;).
I think the JoVE concept is valuable – to share methodology and eliminate as many hurdles as possible as a joint scientific community.

Crystals on the surface of cells

We just published our latest discovery. There’s crystals on the surface of cells!
You can find them in this week’s issue of Blood (Link). An image from our paper made it to the cover, there was a very nice commentary written about it (Link) and it was selected as one of the issue highlights.
Yeah, these crystalline particles are beautiful by themselves (at least, I think so), but like the double-rainbow guy asks: “What does it all mean?” We think they form some kind of scaffold for molecular interaction. In the blood stream, this should help to keep blood clots together under the harsh conditions of flowing blood.
We described the basic mechanism for it a few months ago in The Journal of Thrombosis and Haemostasis (Link). Although I wanted to keep the concept ‘under the radar’ until we had published the experimental evidence, it ended up on the cover of JTH as well. Oops! Well, at least I have some decoration for the walls of my room here at the UMC Utrecht.

If you want to read these papers, but don’t have access, please let me know via email. I can send a digital copy for personal use.

Bose QC35 Headphones

I treated myself to a pair of these wireless headphones. They’re not cheap. But they turn out to be great – for me. Wired headphones have always been a problem. Wire breaks, jack plugs slipping out during a walk or bike ride. Pfff.

These are bluetooth. Easy to connect to devices. I must admit that the electronic voice is a bit disturbing. She tells you the battery level quite well, but the rest sounds like a bad spelling contest. About the battery, it lasts for a long time. I charge this thing once or twice a week. Doesn’t take long to charge, either.

Personally, I think the sound is great. I am sure there is higher quality for the true audiophiles. Guess I am just not one of them. Great sound, independent of music style or volume. There is little room to tweak it, though. There is an app – but it doesn’t add much.

The active noise cancelling is one of the reasons I bought this. I never experienced it before, but it is really impressive! Total isolation when at work in the room I share with two colleages (and their visitors). I noticed some pressure on my ears while having a cold (similar to diving). It also really cancels out the monotonous noise of ventilators, engines etc. As predicted, great for traveling.

The QC35’s come together with some optional wires and plugs, as well as a handy sturdy protective case for transport (and todler protection), which the headphones can fold into. I am personally happpy that these look ‘normal’. The ‘luxury look’ (to my opinion) is more for a younger audience. The set is robust and I can wear them for hours at a time without discomfort. Even when I wear glasses.

To conclude: these things have been a real treat!




Global Forum for Hereditary Angioedema, Madrid

About a week ago (13-15 November), I went to Madrid for a presentation at the Global Forum for Hereditary Angioedema. I had my talk on the opening Friday night. This is an excellent moment for a talk, because the audience is still fresh and remembers the information you’re trying to share. Furthermore, I had a joint presentation with Prof. Marco Cicardi, a highly respected researcher and clinician in this field. The presentation was interactive; I could ask ‘pop-quiz’-styled question that could be answered by the audience via tablets that were provided. Takes some getting used to, but great fun! From the answers to these questions, I was reminded of what the (mainly clinical) audience really needs. Back to the lab – we’ll figure this out.

In conclusion: It has been an inspiring event!


A great saturday with an award for dessert

I recently had a very interesting saturday, when I had to give two talks. I started out at Sanquin, Amsterdam in the morning. Dr. Rob Fijnheer and Prof. Jan Voorberg hosted the annual TTP patient day at this institute. A place where patients with this rare and life-threatening disorder can exchange experiences and receive an update on the scientific progress in TTP research. I was invited to speak there on our work. It took some ‘conversion’ to get the message across, but I think we got it done! Actually, I will keep these metaphors for more general purposes: von Willebrand Factor acts as velcro, and plasmin can be a ‘backup goalie’ for ADAMTS13 in TTP.



IMG_6839 IMG_6847









The second talk was in a conference on Laboratory Hematology in the Hague; a completely different audience with loads of technical experience. I shared our findings on the workings of the plasma contact activation system, both in the diagnostic setting and in pathology. Afterwards, I had a lot of nice discussion, which felt rewarding after nervously being stuck in traffic jams (beach visitors were blocking my way to the Hague). Finally, I had a very nice talk with Prof. Catherine Hayward, an reknown expert on (platelet) Factor V; an intriguing molecule.

What a crazy day, I had to change gears on all topics that I try to investigate. A few days later, I received the awesome news that I was nominated for an Eberhard F. Mammen Young Investigator Award for my second talk. A great honour! I am now writing an invited review on the subject that will be published in Seminars in Thrombosis and Hemostasis later this year.

In conclusion: great day, great outcome!


Support from the patients: HAEi Grant

Thumbs-upYesterday, I received the great news that HAEi; the international organisation for patients with hereditary angioedema will financially support our research over the next two years with a grant of 100,000 dollars.

Only a few years ago, it was brought to my attention that the disease angioedema is strongly linked to excessive activity of the enzyme system that we once hope to fully understand. By studying this disease, we really do seem to obtain a better understanding of these enzymes, but more importantly, our insights into these trouble-making enzymes appears helpful to understand the disease better as well. And where there’s better understanding of a disease, there of course is a chance of better therapy.

I think this grant will provide a strong impulse to our work. I expect that we should be able to identify the trigger for attacks of angioedema in the human body.

Here is a public lecture (in Dutch) on a the clinical diagnostics of a HAE patient, presented by Prof.dr. Marcel Levi, a clinical expert on this disease.

Leo Vroman; undercover blood researcher


bron: Leo Vroman, Bloed. Em. Querido’s Uitgeverij / Wetenschappelijke Uitgeverij, Amsterdam 1968

Last saturday, it was in the news that Leo Vroman had passed away at the respectable age of 98. In the Netherlands, he is/was quite famous for his poetry, for which he received prestigious awards, including the P.C. Hooft award.

In early 2008, our department’s previous Professor, Prof.dr. Jan Sixma informed me that my most recent experiments seemed to offer an explanation for the puzzling observations that Leo Vroman had made decades earlier. I did not even know that he ever did experiments!? – Leo Vroman was a poet: my grandfather was a fan of his work. In retrospect, it was obvious. He wrote the books with the titles: “Blood” and “Warm, red, wet and lovely”; sounds like a blood researcher to me! Furthermore, the Vroman effect (blood proteins sticking to non-natural surfaces in a sequential order) was named after him. I just never really made the connection.


SonnenborghAround the same time, I visited a cultural festival,  at observatory the Sonnenborgh in Utrecht, one of Vroman’s favorite places. I read in the program that Leo Vroman would be interviewed  via direct satellite connection – interesting. They wanted to hear about his poetry, but he made it quite clear: “First and foremost, I am a blood researcher. Poetry comes second.”. He also said: “I google myself regularly to see if anyone has picked up on my research work.” By that time, Prof.Sixma had provided me with his address and told me that I should let Leo know what was going on. I didn’t.

Later on, while I was working as a postdoc in Sweden (2010), I decided to write him a letter – something you do not very often. I explained what I had found. A few weeks later, I received one back! Very cool; it even had a kind of 8-bit drawing of a rose in the upper right corner (later, I came to understand that digital drawing through programming was his new hobby). I really should dig that letter up again for better safekeeping.

FB1Later on, Leo became an active Facebook member. On a few instances, we had discussions on the extrapolation of his previous work to more recent times. Very funny! He was not mild in his comments.


In 2012, a committee of the Dutch Society on Thrombosis and Haemostasis Research went to the USA (where he lived) to award Leo with the van Creveld Medal. A real honor! It is like the P.C. Hooft award for blood researchers. I hope he loved every minute of it!

FB2They even asked me to come along (I helped to arrange the meeting between my new Facebook friend and the committee a bit), but I was not able to join (I don’t even remember why: some grant proposal deadline or something like that). Too bad, would have been great to meet in person.

Well, anyway, I think we’re getting pretty close (matter of months) to solving what the physiological function of FXII and associates is. It does not appear to have much to do with protein adsorption, though. Sorry Leo! But it would have been great to convince you of this … although I expect that it would not have been easy to do so.

Warme groet,