STAMCELLER-Stamcelleforskning

The goal was to develop strategies which stem cells could develop to bone cells, and with an artificial vekstativ form integrable and strong bone substitute. Stem cells isolated from either adipose tissue and bone marrow were tested to see if the tissue origin were significant for the cells ability to grow into mature bone cells, and the capability to form collagen-based extracellular matrix was used as a marker for this. The cells from adipose tissue, called HAT-MSC, performed best in our setup. An ultra-porous TiO2 scaffold, developed at the Department of Biomaterials, University of Oslo, was chosen as 3-dimensional support for stem cells during development. The effects of four bone-stimulating factors (simvastain, leptin, forskolin and dexamethasone) were tested in this experimental set-up. In a layout with 16 combinations of these four factors, dexamethasone was identified as one of the key regulators of osteogenic maturation of stem cells based on the gene expression profiles. Cells were cultured for up to 2 months, and analysis of the proteins they secreted confirmed that hat MSC grown on TiO2 scaffolding mature into bone-forming cells. Not only choice, but also dose and delivery method of bone-stimulating factors may affect the maturation of cells. The factors were encapsulated in hydrogel or polyphenol and attached to the scaffold to provide a slow release of these to the cells. Simvastain and enamel matrix derivative (EMD), two products are shown to have bone-stimulating effect were tested. This strategy gave maturation of fat-derive MSCs into bone-forming cells in the scaffolds. In a similar setup were stem cells, scaffolds and various stimulating factors incapsulted in both alginate and polyphenol, tested in microgravity. Microgravity simulates the forces cells will be exposed to in vivo. In tissue engineering situation the interface between scaffold, added cells and stimulating factors and the host tissue can be enclosed in a fibrous network. In an attempt to simulate this situation, both cells and EMD were enclosed by hydrogel, and the effect on their cell growth and maturation evaluated. Our conclusion is that the combinations of stem cells from adipose tissue and TiO2 scaffolds have potential for clinical use.

The project involve at developing the use of stem cells for bone engineering. The main stem cell type to be used in this project is mesenchymal stem cells (MSC). These cells are stem cells based on the fact that they can self renew and differentiate to ce lls typical of several lineages, and cells derived from a single cloned cell can, upon transplantation, give rise to functional offspring and functional differentiated tissue. The project will also involve the use of a recently isolated population of endo thelial progenitor cells (EPC) for improved vascularization of graft materials and stem cell seeded scaffolding materials. The project will emply a wide range of methods to characterize the differentiation of MSC to osteoblasts, and to describe the intera ction between the differentiating MSC and vessel-forming EPC. We will analyse factors which regulate gene expression such as epigenetics, micro-RNAs and transcription factors, regulators of translation and post-translational modifications and perform assa ys to determine extracellular matrix (ECM) protein synthesis and expression, cell/ECM interactions, cell/biomaterial and ECM/biomaterial interactions. This will improve fundamental processes associated with growth and differentiation of stem cells, and es tablish cell lines that may be used therapeutically. Presently the group the only one in Norway using stem cells in tissue engineering applications. The end point of the present project is to establish protocols for repair of damaged bone tissue, with the aim of initiating a phase 1 clinical trial with a stem cell seeded bone graft substitute developed in this project for use in a selected patient population. Many groups of patients will benefit from the development of a bone graft substitute based on ste m cells and biomaterials, including patients with skeletal cancers, patients with other forms of bone loss, and patients with osteoporosis and other chronic degenerative bone diseases.