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Dr Niels Haan

Dr Niels Haan

Research Associate, Neuroscience & Mental Health Research Institute

School of Medicine

Email
haann@cardiff.ac.uk
Campuses
3.28 - Desk 39, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ

During my undergraduate degree I couldn’t make my mind up between neuroscience and immunology, so I ended up doing both: neuroimmunology. My other big interest is in the field of adult neurogenesis. I have now worked on these topics as a research associate for several years, recently focusing on these topics in the context of psychiatric disease. Currenlt I work on the effects psychitaric risk genes have on neuroimmunological processes.

Current research:

Effects of psychiatric risk genes on adult neurogenesis

Within the DEFINE Wellcome Trust Strategic award, I use animal models carrying heterozygous deletions of known psychiatric risk genes to study their role in regulating adult hippocampal neurogenesis (AHN). Altered AHN has been described in schizophrenia patients, and has been implicated in the therapeutic mechanism of anti-depressive drugs.

Using both in vivo experiments and post-natal primary stem cell cultures from rodent models, I study the effects of schizophrenia risk genes on the proliferation, differentiation and survival of adult born neurons. In collaboration with colleagues, we have found differing effects of a number of risk genes on AHN.

I am now planning on expanding this work though in vivo lineage tracing of adult born neurons in these psychiatric risk models, and to study their structure and functional integration.

Regulation of adult neurogenesis by the immune system

The immune system is an emerging regulator for basal neurogenesis. T-cells have been implicated in control of proliferation, but microglia have not been studied extensively. I am studying the role of microglia in both the control of proliferation of stem cells and of the survival of newly born neurons. Preliminary evidence suggests microglia have an important role in regulating the number of new neurons.

Using a combination of primary cultures and transgenic animals I am studying the mechanisms of this regulation. Extending this into pathological conditions with neuroimmunological involvement is one of my goals.

Other interests

Adult neurogenesis in non-canonical locations

A longstanding interest of mine, and what I did my PhD on, is the presence of adult neurogensis in areas other than those currently recognised (hippocampus and lateral ventricle). Formation of new neurons in the hypothalamus has been shown by me and others. The functionality of this is still largely unknown, but current evidence suggests a role in energy balance.

This also raises interesting questions in the context of psychiatric disease, where a common side effect of treatment with anti-psychotic drugs (which affect neurogenesis) is significant weight gain.

Astrocytes in disease and injury

As the most common cell type in the central nervous system, astrocytes were until recently also the most overlooked cells. Reactive astrocytes, activated by disease or injury, play a very prominent role in neuronal survival and functioning. I have previously shown that there is a two way interaction between astrocytes and the immune system in the injured central nervous system. Immune activation drives the activation and proliferation of astrocytes, but they are then in turn capable of limiting the immune response.

I am interested in the functioning of astrocytes, and their interaction with microglia, in the healthy brain, and in models of psychiatric risk.

External profiles