Development of Sheep Androgenetic Embryos Is Boosted following Transfer of Male Pronuclei into Androgenetic Hemizygotes

Abstract

Numerous studies have demonstrated the potential use of stem cells for the repair and regeneration of injured tissues. However, tracking transplanted stem cell fate and function in vivo remains problematic. To address these issues, murine embryonic stem (ES) cells were stably transduced with self-inactivating lentiviral vectors carrying either a triple fusion (TF) or double fusion (DF) reporter gene construct. The TF consisted of monomeric red fluorescence protein (mrfp), firefly luciferase (Fluc), and herpes simplex virus truncated thymidine kinase (HSV-ttk) reporter genes. The DF consisted of enhanced green fluorescence protein (egfp) and Fluc reporter genes but lacked HSV-ttk. Stably transduced ES-TF or ES-DF cells were selected by fluorescence activated cell sorting based on either mrfp (TF) or egfp (DF) expression. Afterwards, cells were injected subcutaneously into the right (ES-TF cells) and left (ES-DF cells) shoulders of adult female nude mice. Cell survival was tracked noninvasively by bioluminescence and positron emission tomography imaging of Fluc and HSV-ttk reporter genes, respectively. Imaging signals progressively increased from day 2 to day 14, consistent with ES cell survival and proliferation in vivo. However, teratoma formation occurred in all nude mice after 5 weeks. Administration of ganciclovir (GCV), targeting the HSV-ttk gene, resulted in selective ablation of teratomas arising from the ES-TF cells but not ES-DF cells. These data demonstrate the novel use of multimodality imaging techniques to (1) monitor transplanted ES cell survival and proliferation in vivo and (2) assess the efficacy of suicide gene therapy as a backup safety measure against teratoma formation.

Imaging Neural Stem Cell Graft-Induced Structural Repair in Stroke

“…5B) based on detecting phosphorylation and entrapment in the cells of the radiolabeled reporter probe [ 18 F]fluoro-hydroxymethylbutyl-guanine ([ 18 F]FHBG). The stability and efficiency of this reporter gene has been previously described (3). Imaging signals were stable from week 4 to week 8 after transplantation and correlated with the graft size measured by MRI analysis (Fig.…”

“…Given the triple imaging modality, complexity of the model, and route of cell delivery, further studies are necessary to reconcile discrepancies with previous reports on the pattern of cell migration. We have previously used this vector to efficiently monitor pluripotent mouse embryonic stem cells for tumor formation after subcutaneous injections (3). The study demonstrated that HSV-ttk enables reliable noninvasive imaging and tracking of the marked increase in signal activity-associated subcutaneous tumor formation (3).…”

Endothelial Progenitor Cells (EPCs) as Gene Carrier System for Rat Model of Human Glioma

“…However, most of investigations dealt with local administration of transduced cells followed by in vivo imaging of the gene product by bioluminescence, fluorescence, SPECT or PET scanning [36], [37], [38]. Tracking of intravenously administered transduced cells by nuclear medicine techniques is challenging and requires sensitive imaging modalities, stable transduction and use of radionuclide that will be optimal in respect to energy, half-life and cost.…”

Stem Cell Imaging: From Bench to Bedside

“…Cao et al demonstrated the superiority of this technique compared to more standard 18 F-FDG and 18 F-Fluorothymidine ( 18 F-FLT) PET imaging for detecting teratoma formation following subcutaneous injection in mice (Cao et al, 2009). Alternatively, the PET reporter gene herpes simplex virus truncated thymidine kinase (HSV-ttk) can serve as both a monitor for tumor development and a suicide gene for ablative therapy (Cao et al, 2007a). Specifically, Cao et al transplanted mice with ESCs labeled with either a double-fusion (GFP and FLuc) or a triple-fusion construct (GFP, RLuc, and HSV-ttk).…”