Next-generation imaging voor het lab en de industrie


Sprekers en Sessies

Subcellular imaging in living mice reveals new insights in cancer

prof.dr. Jacco van Rheenen

 Jacco_van_Rheenen_ZwartWit_Interview_ScienceLab_May17_150"Although histological techniques have provided important information on epithelial stem cells and cancer, they draw static images of dynamic processes. To study dynamic processes, we have developed various imaging windows to image intestinal, liver and breast tissue, and visualize the behavior of individual cells at subcellular resolution for several weeks with two-photon intravital microscropy (IVM). In this talk I will discuss how we have used these techniques to study the identity and (migratory) behavior of (cancer) stem cells during pubertal mammary morphogenesis and tumor growth, and to study the plasticity of tumor heterogeneity. 

Our IVM experiments illustrate that cellular properties and fate of (cancer) stem cells are highly dynamic and change over time.
For example, we show in healthy and tumorigenic tissues, that cells can acquire and lose stem cell properties, illustrating that stemness is a state as opposed to an intrinsic property of a cell.
Moreover, our data implies that the behavior and even the identity of stem cells cannot be linked directly to a single molecular profile or specific markers, but must be defined functionally.

In the last part of the talk, I will discuss a project where we have studied the plasticity of migratory and metastatic behavior. An aspect that complicates tumor heterogeneity is that cells may exchange active biomolecules through the release and uptake of extracellular vesicles (EVs). Our data shows, in living mice, that malignant tumor cells, through transfer of EVs, enhance the migratory behavior and metastatic capacity of more benign cells.
Taken together, these data exemplify that tumor heterogeneity and tumor microenvironment are far more complex than currently anticipated, which has profound consequences for our ideas on the mechanisms of tumor progression and for designing optimal treatment strategies".

Jacco van Rheenen is senior group leader at the Oncode Institute-Netherlands Cancer Institute, and full professor at the University Medical Center Utrecht. For his work on intravital microscopy of cancer, he received multiple awards including the Vidi Award, ERC consolidator grant, Stem Cell Young Investigator award, and the Dr. Josef Steiner Cancer Research Foundation Award.

Electrochemical Roughening of Pt(111) : surface site reactivity
dr. Leon Jacobse

  Leon Jacobse_150"Platinum plays a central role in a wide variety of electrochemical devices. Electrode degradation, especially under oxidizing conditions, forms an important barrier for the widespread application of such devices. Although it is known that repeated oxidation and reduction of platinum electrodes results in irreversible surface structure changes, over thirty years of research did not yet yield to a conclusive description of this process on the atomic level; not even for well-defined single crystal surfaces.

Using a special EC-STM, which is capable of measuring the electrochemical signals simultaneously during imaging in operando, we directly correlate, for the first time, the evolution of the electrochemical (hydrogen desorption) signal of Pt(111) to the observed roughening of the surface.
In the later stages, we find a strong correlation between the evolution of the roughness and the absorption peaks clearly indicating that each created step contributes equally strong to the adsorption signal as well as to the roughness. However, and fully surprising, in the early stages step edges are created that do not contribute to the electrochemical signal.

A more detailed analysis of the EC-STM images provides information on the atomic-scale structure of the formed Pt nano-islands and their evolution. Correlating the resulting density of specific surface sites to the different hydrogen adsorption features in the voltammetry, allows us to determine the electrochemical reactivity of formed step and kink sites on the roughened surface. This finally delivers an insight on how to describe the electrochemical reactivity not only of the observed nano-islands but also of Pt nanoparticles in general."

Leon Jacobse studied Chemistry at Leiden University. In 2013, he graduated cum laude on his research regarding the interaction between gas-phase oxygen and well defined platinum surfaces. For his PhD, with Prof. Marc Koper, he switched to the field of electrochemistry. In a collaboration with the University of Warwick, he developed a new mode for imaging local electrochemical reactivity (voltammetric scanning electrochemical cell microscopy). Back in Leiden he focused on the atomic scale surface dynamics of Pt(111) using electrochemical scanning tunneling microscopy [1]. The combination of the clean environment and the high imaging quality gives important insights in the decades old puzzle of describing the reactivity of platinum surfaces at a fundamental level.

[1] Jacobse, L., Huang, Y.-F., Koper, M. T. M., & Rost, M. J. (2018). Correlation of surface site formation to nanoisland growth in the electrochemical roughening of Pt(111). Nature Materials, 1.


Understanding transcriptional bursting at the single-molecule level
dr. Tineke Lenstra

 Lenstra_150Transcriptional in single cells is a stochastic process and arises from the random collision of molecules.  This stochastic behaviour results in variability in gene activity between cells, and as well as within a cell over time.  Understanding the kinetics of transcription in a single cell is important to understand the underlying regulatory mechanisms. We use single-molecule RNA labeling techniques to visualize the dynamics of transcription in single living cells. Using this imaging method, our lab and other labs have shown that transcription often occurs in bursts of transcription, where period of high transcriptional activity are followed by periods of inactivity. Although transcriptional bursting is highly conserved, the molecular mechanisms are largely unknown.

In this talk, I will show how we used our single-molecule imaging assay to understand how the dynamic binding of transcriptional activators determine transcriptional bursting. To measure the binding kinetics of transcriptional activators in living cells, we combined our RNA imaging method with a technique called single-molecule tracking, which measures the diffusion and binding of individual transcription factor molecules in living cells. Overall, uur data support a model where the kinetic binding of transcription factors determines the number of polymerases that initiate during a burst.

Tineke Lenstra is a junior group leader at the Netherlands Cancer Institute in Amsterdam, where her lab focuses on the regulatory mechanisms of stochastic transcription in eukaryotic cells. For her work, Tineke has received a number of awards, including the “NCI Director's Innovation Award" and the ERC starting grant.



Raman Spectroscopie op de Nanoschaal
dr. Thomas Hartman MSc en Katinka Wondergem MSc

"Wanneer nanostrucutren van goud of zilver beschenen worden met licht, vindt er een zeer intense, lokale versterking van het elektromagnetisch veld plaats. Dit heeft geleid tot de ontwikkeling van “surface-enhanced Raman spectroscopy”, oftewel SERS. Deze microspectroscopische analysemethode is zo gevoelig, dat het zelfs in staat is één individueel molecuul te detecteren op de nanostructuur. We kunnen alleen niet met grote zekerheid bepalen waar dit molecuul precies zit, omdat de resolutie van een conventionele optische microscoop beperkt is tot enkele micrometers. In combinatie met het gebruik van een “near field” microscoop kan deze beperking overkomen worden. De nanostructuur versterkt dan alleen het electromagnetische veld op de locatie van de “near field” antenne. Deze techniek heet “tip-enhanced Raman spectroscopy”, oftewel TERS. Hierdoor hebben SERS en TERS beide vele applicaties gevonden in verschillende onderzoeksvelden, van fundamenteel natuurkundig onderzoek, naar het ontrafelen van reactiemechanismes in de scheikunde, tot toepassing als nanoantenne in cellen voor biologie."

Katinka Wondergem en Thomas Hartman zijn beide PhD-kandidaten in de groep Anorganische Chemie en Katalyse aan de Universiteit Utrecht, onder Bert Weckhuysen. In oktober 2014 begonnen ze aan hun onderzoek op het gebied van “surface-enhanced Raman spectroscopy” (SERS) en de implementatie daarvan in heterogene katalyse, onder andere voor hydrogenatie reacties. Thomas houdt zich voornamelijk bezig met industriële reacties over verschillende katalysatoren en dragermaterialen. Hij heeft recentelijk een artikel uitgebracht over de toepassing van SERS voor het bestuderen van hydrogenatie reacties bij hoge temperaturen. Katinka’s onderzoek richt zich deels op hydrogenatie reacties over platina en verder houdt ze zich bezig met fotokatalytische reacties, die ze bestudeert met “tip-enhanced Raman spectroscopy” (TERS). Samen hebben ze een artikel geschreven over de toekomst van SERS in katalyse, dat in 2016 bij de best gelezen artikelen van het Journal of Physical Chemistry hoorde. Ook maakten zij een filmpje bij dit artikel.


Mass Spectrometry imaging in clinical research
dr. Benjamin Balluf, Maastricht University


Presentation titel to be announced
Marco Snikkers, Ocean Optics

Marco Snikkers_150