Hyun-Myoung Cha

Scaffold-free three-dimensional culture systems for mass production of periosteum-derived progenitor cells.

Mesenchymal stem cells (MSCs) are capable of self-renewal and can differentiate into various types of cells for therapeutic purposes. MSCs are frequently cultured in a two-dimensional (2D) system. However, MSCs can lose their differentiation capacity over time in this culture system. In addition, the available surface area for the propagation of cells is limited. Therefore, various three-dimensional (3D) culture systems have been developed. In this study, we developed the scaffold-free 3D culture systems for the expansion of periosteum-derived progenitor cells (PDPCs) as spheres. The spheroid formation of PDPCs was induced using a rotation platform. The spheres maintained their viability and proliferation ability. Moreover, expression levels of the stemness marker genes and proteins were higher in cells grown on 3D culture system than in 2D culture system. In conclusion, a simple and economical 3D culture system has been developed that can increase the potential of PDPCs for clinical use.

Co-overexpression of Mgat1 and Mgat4 in CHO cells for production of highly sialylated albumin-erythropoietin

Terminal sialic acids on N-glycan of recombinant human erythropoietin are very important for in vivo half-life, as this glycoprotein has three N-glycosylation sites. N-acetylglucosaminyltransferases I, II, IV, and V (i.e. Mgat1, Mgat2, Mgat4, and Mgat5) catalyze the formation of a glycan antennary structure. These enzymes display different reaction kinetics for a common substrate and generally show low expression in Chinese hamster ovary (CHO) cells. Therefore, genetic control of Mgat expression is an effective method to increase sialic acid contents by enhancing glycan antennarity. To produce highly sialylated albumin-erythropoietin (Alb-EPO), we co-overexpressed the Mgat1 and Mgat4 genes in CHO cells and determined the optimal ratio of Mgat1:Mgat4 gene expression. All transfected cell lines showed increased gene expression of Mgat4, including Mgat1 overexpressing cell line. Sialic acid content of Alb-EPO was highest in co-transfected cells with excess Mgat4 gene, and these cells showed a higher tri- and tetra-antennary structure than control cells. Based on these results, we suggest that co-transfection of the Mgat1 and Mgat4 genes at a ratio of 2:8 is optimal for extension of antennary structures. Also, regulation of Mgat gene expression in the glycan biosynthesis pathway can be a novel approach to increase the terminal sialic acids of N-glycans.

중간엽줄기세포 증식을 위한 누에 실샘 유래 무혈청 배지 첨가제@@@Serum-free media supplement from silkworm Gland for the expansion of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are must be cultured in chemically defined, xeno-free culture system for cell-based therapies. One major overcome for their clinical use is the unsafety of fetal bovine serum (FBS), which is a crucial part of all media currently used for the culture of MSCs. Previously, we developed novel methods the production of silkworm gland hydrolysate (SGH). Also, we showed the effect of the SGH on the cell growth promotion. We demonstrated whether the characteristics of MSCs were maintained in the serum-free media containing SGH during long-term cultivation. The results of microscopic observation showed that the morphology of stem cells were not different between the media containing 10% FBS and 1 mg/mL SGH. After the long-term culture of MSCs in serum-free media containing SGH, the rate of MSCs growth was well maintained. The analysis of anti-apoptotic effect of SGH showed that early apoptosis of MSCs was reduced by 3.7-fold. Furthermore, MSCs specific surface markers and stemness gene expression (Nanog, Sox2) were preserved as that of MSCs in the media containing 10% FBS. In conclusion, we demonstrate that the SGH can be used as useful supplement for MSCs cultivation in serumfree media.

중간엽줄기세포 증식을 위한 누에 실샘 유래 무혈청 배지 첨가제

Mesenchymal stem cells (MSCs) are must be cultured in chemically defined, xeno-free culture system for cell-based therapies. One major overcome for their clinical use is the unsafety of fetal bovine serum (FBS), which is a crucial part of all media currently used for the culture of MSCs. Previously, we developed novel methods the production of silkworm gland hydrolysate (SGH). Also, we showed the effect of the SGH on the cell growth promotion. We demonstrated whether the characteristics of MSCs were maintained in the serum-free media containing SGH during long-term cultivation. The results of microscopic observation showed that the morphology of stem cells were not different between the media containing 10% FBS and 1 mg/mL SGH. After the long-term culture of MSCs in serum-free media containing SGH, the rate of MSCs growth was well maintained. The analysis of anti-apoptotic effect of SGH showed that early apoptosis of MSCs was reduced by 3.7-fold. Furthermore, MSCs specific surface markers and stemness gene expression (Nanog, Sox2) were preserved as that of MSCs in the media containing 10% FBS. In conclusion, we demonstrate that the SGH can be used as useful supplement for MSCs cultivation in serumfree media.