Role of the MEK/ERK pathway in chondrogenic differentiation: Establishment of a protocol for the generation of MEK1-knockout hTERT ASCs and assessment of their differentiation potential

With a population growing older every year, development of new treatment approaches for osteoarthritis and other degenerative joint diseases is called for. Next to conventional treatments, tissue engineering in combination with the use of adipose-derived mesenchymal stem cells (ASCs) is a promising candidate for future treatment approaches. However, the signalling events involved in the differentiation processes are not yet fully understood. One prominent signalling pathway is the MEK-ERK signalling cascade,
regulating cell proliferation, differentiation and survival. This pathway was reported to play a significant role in the differentiation of mesenchymal stem cells into the adipogenic, osteogenic and adipogenic lineage, respectively. However, results are contradictory. A new tool that will help to elucidate the role of MEK in chondrogenesis has emerged recently: The clustered regularly interspaced palindromic repeat (CRISPR) technology. This technology uses an RNA-guided nuclease to target a specific site of the genome. It can be used to introduce double strand breaks, which can lead to a frameshift mutation and gene knockout. Thus, it proves to be a versatile tool in the field of genomic engineering. Our aim was to establish a reliable and easy to adjust protocol for the generation of knockout human telomerase reversed transcriptase (hTERT) immortalized ASC lines. Furthermore, with these knockout cell lines,
we want to investigate the role of different proteins involved in the MEK/ERK signalling cascade in chondrogenic differentiation. So far, this method allowed us to generate 2 MEK1 ablated cell lines. In the future, we plan to investigate the differences between MEK isotypes and study the impact of MEK1 deletion on mechanotransduction.