Genome Editing Using Engineered Nucleases / 대한정형외과연구학회지

Genome editing is a useful research tool essentially applicable to gene therapy in the field of biotechnology, pharmaceutics and medicine. Scientists have developed three types of programmable nucleases for genome editing, and these include: Zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas (CRISPR-associated) system particularly derived from bacterial adaptive immune system. Programmable nucleaseses occur double strand breaks (DSBs) on target strand, and a repair mechanism of DSBs introduces either non-homologous end joining (NHEJ) or homology directed repair (HDR), where the pathway is determined by presence of donor DNA template. In this sense, we can generate gene insertion, gene correction, point mutagenesis and chromosomal translocations via endogenous repair mechanism. However, these nucleases exhibit several discrepancies in the aspects of their compositions, targetable sites, efficiency and other characteristics. Here, we discuss on various characteristics of three programmable nucleases and potential outcomes of DSBs. Acknowledging the distinctions among these programmable nucleases will help scientists to select appropriate tools in genome engineering.

Analysis of gene expression during odontogenic differentiation of cultured human dental pulp cells

OBJECTIVES: We analyzed gene-expression profiles after 14 day odontogenic induction of human dental pulp cells (DPCs) using a DNA microarray and sought candidate genes possibly associated with mineralization. MATERIALS AND METHODS: Induced human dental pulp cells were obtained by culturing DPCs in odontogenic induction medium (OM) for 14 day. Cells exposed to normal culture medium were used as controls. Total RNA was extracted from cells and analyzed by microarray analysis and the key results were confirmed selectively by reverse-transcriptase polymerase chain reaction (RT-PCR). We also performed a gene set enrichment analysis (GSEA) of the microarray data. RESULTS: Six hundred and five genes among the 47,320 probes on the BeadChip differed by a factor of more than two-fold in the induced cells. Of these, 217 genes were upregulated, and 388 were down-regulated. GSEA revealed that in the induced cells, genes implicated in Apoptosis and Signaling by wingless MMTV integration (Wnt) were significantly upregulated. CONCLUSIONS: Genes implicated in Apoptosis and Signaling by Wnt are highly connected to the differentiation of dental pulp cells into odontoblast.

Interaction of Mesenchymal Stem Cells and Osteoblasts for in vitro Osteogenesis

It has recently been reported that bone marrow-derived mesenchymal stem cells (MSCs), which are systemically administrated to different species, undergo site-specific differentiation. This suggests that the tissue specific cells may cause or promote the differentiation of the MSCs toward their cell type via a cell-to-cell interaction that is mediated not only by hormones and cytokines, but also by direct cell-to-cell contact. In this study, in order to assess the possible synergistic interactions for osteogenesis between the two types of cells, the MSCs derived from rabbit bone marrow were co-cultured with rat calvarial osteoblasts in direct cell-to-cell contact in a control medium (CM) and in an osteogenic medium (OM). The cell number, alkaline phosphatase activity, and amount of calcium deposition were assayed in the cultures of MSCs, osteoblasts, and co-cultures of them in either OM or CM for up to 40 days. The cell numbers and the alkaline phosphatase activities in the co-culture were somewhere in between those of the osteoblast cultures and the MSC cultures. The amounts of deposited calcium were lower in the co-culture compared to those of the other cultures. This suggests that there are little synergistic interactions during osteogenesis in vitro between the rat osteoblasts and rabbit MSCs.