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Developmental and Stem Cell Biology

Embryonic development is a fascinating process requiring a very precise spatiotemporal regulation of cellular proliferation and subsequent differentiation. Nonetheless, it is apparent that not a single cascade but rather regulatory networks encompassing very divergent signaling pathways are required for the successful completion of the developmental program. There are a few model systems addressing experimentally these issues and the developing vertebrate limb is one of the more popular ones. It not only permits studying the embryonic events, but also allows investigating pathological and repair processes in postnatal life.
Our research focuses on two aspects of joint and skeletal biology. We investigate the molecular and cellular events governing the formation of the vertebrate limb using developmental models. We also, using stem cell technology, are exploring the possibility of creating cell populations that have the ability to rebuild bone, cartilage and eventually the full joint and growing limb in vitro.

Developmental biology (Project leader: Prof. Przemko Tylzanowski)

This theme encompasses the investigation of the function of novel genes associated with joint formation and/or disease using zebrafish and chick developmental models. We use several strategies to accomplish that goal. In one of them a large scale collaborative, TREAT-OA (FP7) used Genome Wide Association Studies (GWAS) to identify in patient cohorts several candidate genes associated with osteoarthritis including the COG5 gene cluster consisting of six genes (BCAP29, COG5, DS4L, GR22, HBP1 and PRKAR2B). At present there is not sufficient information available permitting to associate any of the genes with known signaling networks. Consequently, we have embarked on the in vivo functional characterization of these genes. For the pathway discovery we use the developing zebrafish model organism.
Another strategy uses human genetics to identify genes and/or mutations resulting in hereditary skeletal malformations (in collaboration with the Center for Human Genetics KU Leuven). Using this approach we have recently identified, using chick model system, the mechanism underlying a synpolydactyly in patients carrying HOXD13 mutations.

To understand the molecular aspects of limb development we also explore the function of Wnt and Bone Morphogenetic Protein regulated events. Specifically, using various mouse genetic models, we investigate the delicate balances between these ligands and their antagonists, FRZB and noggin respectively, and their regulatory function in limb patterning and osteochondrogenic differentiation.

Stem Cell Biology (Project Leader: Prof. Dr. Frank Luyten)

This track aims to integrate developmental and stem cell biology as a basis for cell based therapies for musculoskeletal disease. Specifically, we intend to decipher the in vitro requirements for stem cell differentiation into functional mesodermal cells. This is essential as there is a lack of cell populations that display favourable expansion and differentiation capacity for stem cell mediated musculoskeletal regeneration. Furthermore, these populations often fail to recapture coordinated in vivo tissue development, a process which is known to be reactivated during postnatal tissue repair. We propose that though molecular manipulation of adult and pluripotent cells, populations can be created with the ability to form fully differentiated limb tissues. We have recently served proof of principle for this approach through the specification of chondroprogenitor culture conditions required to produce cartilage intermediates that undergo endochondral remodelling in vivo. The innovative aspect of this approach relates to the establishment of a platform which has the ability to create and analyse the capacity of in vitro-derived populations to the formation of a higher tissue structure. This research track is operated in collaboration with the Stem Cell Institute Leuven.

Chondroprogenitor cells

In vivo endochondral bone remodelling of in vitro differentiated chondroprogenitor cells


  • Mouse genetics and embryology using sophisticated genetic techniques, unique mouse genetic models as well as limb explants and/or stem cell cultures derived from these mice. The team has a strong expertise in phenotyping of midgestation through newborn mouse embryos, histomorphological and molecular analysis and light microscopy imaging techniques (DIC-Nomarski, polarized light, fluorescence), reporter assays.
  • The team has established, , the developing chick model system to study the molecular events regulating limb and joint development, and is unique in Flanders. Many tools have been accumulated to make this model system robust, including the techniques of in ovo micromanipulations, virus delivery, silencing using miRNA, protein delivery using beads and extensive molecular tools to document limb development.
  • Established pathway identification pipeline to place novel genes associated with skeletogenesis with known signaling cascades and networks using zebrafish. An expertise in fish transgenesis, micromanipulation, advanced imaging and molecular analysis has been also established by the team.
  • Creation of in vitro 3D models of tissue development using adult and pluripotent stem cells. The team has established differentiation conditions allowing the formation of a range of cartilage and bone forming progenitors.
  • Established methodology for the evaluation of molecular mechanisms underlying differentiation of progenitor populations to mature and functional terminally differentiated cartilage and bone cells. This involves techniques such as transcriptome profiling in conjunction with bioinformatic analysis leading to the identification of gene networks driving cellular differentiation.


Frank Luyten, Acting Chief

Scott Roberts, guest professor

Przemko Tylzanowski, senior scientist

Inge Van Hoven, technician

Selected publications

  • Bellon E, Luyten FP, Tylzanowski P.  Delta-EF1 is a negative regulator of Ihh in the developing growth plate.  J Cell Biol 2009; 187(5):685-99.
  • Brison N, Debeer P, Fantini S, Oley C, Zappavigna V, Luyten FP, Tylzanowski P.  An N-terminal G11A mutation in HOXD13 causes synpolydactyly and interferes with Gli3R function during limb pre-patterning.  Hum Mol Genet 2012;21(11):2464-75.
  • Weiss HE, Roberts SJ, Schrooten J, Luyten FP.  A semi-autonomous model of endochondral ossification for developmental tissue engineering.  Tissue Eng Part A 2012; 18(13-14): 1334-43.
  • Roberts SJ, Chen Y, Moesen M, Schrooten J, Luyten FP.  Enhancement of osteogenic gene expression for the differentiation of human periosteal derived cells.  Stem Cell Res 2011; 7(2):137-44.
  • Roberts SJ, Geris L, Kerckhofs G, Desmet E, Schrooten J, Luyten FP.  The combined bone forming capacity of human periosteal derived cells and calcium phosphates.  Biomaterials 2011;32(19):4393-405.



Post-doctoral position- KU Leuven, Belgium

Fascination with pattern formation in living organisms is millennia old. One of the biological models to investigate this process is the developing limb. Our understanding of limb development has progressed greatly over the last half century. However, the intricate interactions between biochemical (e.g. genes, proteins) and biophysical (e.g. cell-cell interactions) factors become too complex to be understood without the help of computational modeling. In order to successfully continue the quest for a deeper insight into the complex control of genesis of biological structures and functions, further advances in the computational as well as the experimental models are necessary.
Recently, we began MatheMorphosis, an interdisciplinary research project that aims to follow an integrative approach to study the biophysical and biochemical regulation of limb development. We will establish a multiscale, multiphysics model (in silico) of the early stages of limb development, exploring various ways to optimize, validate and question the model and its predictions. Concomitantly, we will develop a robust in vivo (in ovo) platform based on the recombinant limb technique in the chick that allows to incorporate in vitro engineered cell populations and assess their capacity to form complex tissues. This experimental model will provide a dedicated test bed to evaluate specific model predictions and thereby advancing the state-of-the-art in both computational modeling and limb development.
We are searching for a post-doc for the biological part of the project. S(h)e will be responsible in the first instance for the establishment of conditions required for the investigation of the ‘recombinant limb technique’. Secondly, s(h)e will investigate the conditions required for stem cell differentiation into limb bud mesenchymal cells using chick and mouse models.
The candidate should have a background in developmental/cell biology and an interest in tissue morphogenesis. Additionally, it is expected from the candidate to be trained in molecular embryology, stem cell biology and/or limb development. knowledge of osteo-chondrogenic differentiation processes would be advantageous. The candidate should be able to work independently in a team-oriented project. It is expected from the candidate to be fluent in spoken and written English.
We offer a work in a very interdisciplinary dynamic team led by Lies Geris ( , Bart Smeets (from and Przemko Tylzanowski ( The labs are located in the center of KU Leuven Health Sciences Campus (picture below) with over 4000 researchers working under one roof, many core facilities, very wll communicated with the main airport as well as key train stations.
The position is available IMMEDIATELY.
For further information, please contact Prof. Przemko Tylzanowski ( To apply, please send a motivation letter with names and contact coordinates (email and/or phone) of two referees to the above email address.
University of Leuven is located 20 km from Brussels (Belgium) in a college town of Leuven. Belgium has been ranked top for academic research and innovation consistently over the many years.

Prof. Przemko Tylzanowski Skeletal Biol. Engin. Res. Center Developmental and Stem Cell Biology Lab Department of Development and Regeneration University of Leuven ON1 box 813 Herestraat 49 3000 Leuven, Belgium

Office Phone: +32 16 37 98 64     Lab Phone: +32 16 34 61 35

Fax: +32 16 34 62 00                      Skype: przemko.lab