Cell metabolism in response to biomaterial mechanics

[摘要] This project assessed the use of short chain peptide (F2/S) hydrogel biomaterial substrates as an instructional tool for driving stem cell differentiation through fine-tuning of the substrate mechanical properties (altered elasticity or stiffness) to mimic that of naturally occurring tissue types. By doing this, differentiation of mesenchymal stem cells (MSCs) into neuronal cells on a 2 kPa (soft) substrate, chondrocytes on 6 kPa (medium) substrate and osteoblasts on 38 kPa (rigid) substrates was achieved. This non-invasive procedure of influencing stem cell behaviour allows a means of exploring innate cell behaviour as they adopt different cell lineages on differentiation. As such, an LC-MS based metabolomics study was used to profile differences in cell behaviour. Stem cells were observed as having increased metabolic activity when undergoing differentiation compared to their ‘resting’ state when they are observed as metabolically quiescent or relatively inactive. As such, the metabolome, as a reflection of the current state of cell metabolism, was used to illustrate the observed divergence of phenotypes as differentiation occurs on each substrate F2/S type. The project further investigated the potential of endogenous small molecules (metabolites) identified using metabolomics, as effective compounds in driving or supporting cell differentiation in vitro. From this, the compounds cholesterol sulphate and sphinganine were found to induce MSC differentiation along the osteogenic and neurogenic routes respectively. A third compound, GP18:0, was observed to have influence on promoting both osteo- and chondrogenic development. These results highlight the potential role a broad based metabolomics study plays in the identification of endogenous metabolites and ascertaining the role(s) they play in cellular differentiation and subsequent tissue development. Lastly, the use of F2/S substrates as a potential clinical scaffold for the regeneration of cartilage tissue was explored. Long term differentiation of pericytes into chondrocytes cultured in 20 kPa F2/S substrates was assessed and the cellular phenotype of the resultant chondrocytes compared to the more conventionally used induction media method. Pericytes cultured within the biomaterial alone showed a balanced expressed of type II collagen and aggrecan with lessened type X collagen expression compared to the coupled use of induction media which showed a bias towards collagen (both type II and type X) gene expression. This observation suggests that in order to mimic native hyaline cartilage tissue in vitro, the use of biomaterial mechanics is potentially a better approach in guiding stem cell differentiation than the use of chemical cues.

[发布机构] University:University of Glasgow;Department:Institute of Molecular Cell and Systems Biology

[关键词] Stem cells, biomaterials, metabolomics, hydrogels