The June Wilson Award
Applicant Dr Neelam Gurav (Research Fellow)
Biomaterials, Biomimetics and Biophotonics Group.
KingsCollegeLondon
REGENERATION OF THE INTERVERTEBRAL DISC
Introduction
Cartilage is a relatively simple three-dimensional connective tissue that has no intrinsic powers of regeneration, there are a number of conditions where such regeneration could be of enormous benefit clinically, and one such area is in the treatment of degenerated intervertabral discs (IVD). The IVD is a cartilaginous tissue that provides for weight-bearing, load distribution, flexibility and energy dissipation in the spine. To date, there has been little success in finding synthetic replacements using polymers or metal alloys that can match the mechanical properties of the highly specialized tissues of the IVD.
The approach to treating disease or tissue damage is currently undergoing a paradigm change from replacing of severely damaged organs, to the endeavour to stimulate the body to activate inherent healing mechanisms.Tissue engineering TE) is a radically new concept for thetreatment of disease and injury. Our group has interests in TE strategies for functional disc repair based on tissue and cellular augmentation using bioabsorbable, bioactive or synthetic matrices. The project that I am working on is focusing on the regeneration of the IVDwith specific reference to engineered matrices to facilitate cell ingrowth and biological signalling cues leading to in-situ bone and cartilage regeneration.The main objective is to understand the basic biology of tissue regeneration and the ability of cells to be “switched on by specific biological signalling cues such as growth factors or cytokines. This information will assist in the development of effective strategies and tools to initiate and control the regenerative process.Stem cells are uncommitted entities capable of both self-renewal and differentiation into multiple cell lineages. Mesenchymal stem cells (MSCs), have been identified as a population of organized hierarchical postnatal stem cells with the potential to differentiate into osteoblasts and chondrocytes (also adipocytes, cardiomyocytes, myoblasts and neural cells).Stem cell signalling concern the conditions in which the cells are grown, such that they receive the right nutrients and signals to adopt and/or retain the required characteristics for the desired endpoint. This is a very important aspect of the scientific basis for tissue engineering since these cells have to be stimulated to produce the required tissue phenotype because they are not intrinsically able to do so. The biological signalling factors and their concentration profile over time provide the essential key to cell behaviour.
Aim
The overall aim of this project is develop new therapeutic approaches utilising bone marrow MSCs for repair and regeneration of the various components of the IVD. More specifically, this involves studies of the basic biology of the cells and their response to signalling molecules, together with the development of novel scaffolds that together can be applied to regenerate the IVD.
Materials & Methods
MSCs will be examinedfor their potential to be induced to chondrocytic cells in vitro. Using qRT-PCR and protein expression studies, differentiation potential of these cells in conditioned medium will be assessed for cartilage specific genes; this will be compared to chondrocytes derived from adult human articular cartilage. The extra cellular matrix produced by the stem cells will be compared to normal chondrocytes to determine the effect of specific growth factors singly or in combination. Stem cells will be loaded into different novel injectable gel systems; specific cell-material interactions will be examined in order to determine whether material properties are able to regulate multiple cell functions, such as cell viability, growth, differentiation, maintenance of cell phenotype, apoptosis, and proliferation.
Results to date
Initial data has shown that there are distinct differences in the extracellular matrix produced and proliferation rates of stem cells cultured in conditioned medium with different growth factors.
Future work
Using in vitro, long-term, high-density, micromass cultures that recapitulate the process of chondrogenesis, chondrocyte maturation, we would like to investigate the importance of a balance between proliferation and differentiation in cartilage maturation, focusing specifically on the effects of different isoforms of transforming growth factor-. A more in depth analysis of the genes involved during theseprocesses (specific genes involved in chondrogenesis such as Sox-9; matrix genes for Collagen II and X) will provide important information for the regeneration of the soft tissue aspects of IVD.