Concise Communications
Double-Labeled Transgenic Mouse Model Facilitates Stem Cell Research
Jin Zhang, Shu Li, Jake Chen and Qisheng Tu*
Corresponding Author:
Received: August 24, 2018; Revised: October 28, 2018; Accepted: September 29, 2018
Citation: Zhang J, Li S, Chen J & Tu Q. (2018) Double-Labeled Transgenic Mouse Model Facilitates Stem Cell Research. J Oral Health Dent, 1(2): 39-41.
Copyrights: ©2018 Zhang J, Li S, Chen J & Tu Q. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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INTRODUCTION

A double-labeled transgenic mouse was created in our lab. The male ACTB-EGFP mice (Jackson Lab) mouse was cross-bred with a homozygote mBSP9.0Luc female mouse [1]. We named the mice with both Luc and GFP genes as mBSP9.0Luc/β-ACT-EGFP. The production of the mouse line and the unique features of the cells are illustrated in Figure 1A. Using the Xenogen 200 IVIS Imager we could identify pups that were positive for both genes in the offsprings (Figure 1B, left panel). Bone marrow stem cells (BMSCs) isolated from mBSP9.0Luc/β-ACT-EGFP was cultured and examined [2]. BMSCs possess the pluripotency to differentiate into a variety of cell types, including osteoblasts, chondrocytes, and adipocytes. The cells were cultured in osteogenic medium showing luciferase expression after introduction of luciferin substrate indicating an osteogenic differentiation of the BMSCs. Non-osteogenic treated cells only showed GFP fluorescent light (Figure 1B, right panel).
To test the sensitivity of the IVIS system in detecting signals in a live animal we have performed another round of pilot study using the BMSCs isolated from mBSP9.0Luc/β-ACT-EGFP transgenic mice. After transplantation into the calvarial and mandibular defects in nude mice for 2 and 7 days, respectively, we anesthetized the mice and placed them in the Xenogen imager and luciferase and EGFP expressions were measured using an IVIS Imaging System 200 Series in the live animals  as we did previously [3,4]. Shown in Figure 2 were the representative images displaying strong luciferase and GFP signals in the wound sites. These double-labeled cells are unique and useful for bone tissue engineering and regeneration studies. One genetic marker is a luciferase reporter gene driven by a mouse BSP promoter that regulates the expression of BSP that is specific to mineralized tissues [1,5-7]. The other genetic marker is GFP driven by a β-actin promoter and a cytomegalovirus enhancer. By scanning the mouse using Xenogen IVIS in vivo imaging system which allows real-time, non-invasive exploration of genes and cells in living animals, GFP imaging is used to track the fate and migration of transplanted BMSCs, whereas luciferase imaging serves as a marker for osteogenic differentiation of the transplanted BMSCs because the luciferase-mediated bioluminescence will only be appearing in newly formed bones.  This mouse model will greatly facilitate stem cells research as it permits the determination of where these cells originate and how they undergo osteogenic differentiation.

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