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1

Non-invasive assessmant of immunosuppression and prevention of allograft rejection using bioluminescence imaging

100%
Janowski M., Engels C., Gorelik M., Lukomska B., Bulte J., Walczak P.
Acta Neurobiologiae Experimentalis
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2011
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tom 71
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nr S
Neurotransplantation of allogeneic cells is currently being practiced in double-blinded clinical trials. Overall, the general outcome of these studies has been disappointing and may depend in part upon suboptimal control of host immune response. Immune rejection of allografts has been studied in animal models, but most investigations have been limited to histopathological studies, which can not report on the time course of rejection. One technique that can be used to study the biodynamics of graft rejection over time is bioluminescent imaging (BLI) based on the constitutive expression of the reporter gene luciferase. Using BLI, we report here on the fate of intracerebral grafts of firefly luciferase-positive glial restricted precursors, that were followed for 3 weeks in immunocompetent Balb/C mice under administration of different immunosuppresive regimens. Controls included immunodeficient rag2 -/- mice and non-immune suppressed immunocompetent Balb/C mice. Immunodeficient mice revealed continuous growth of BLI signal. Non-immune suppressed mice showed graft rejection in approximately 75% of 23 animals; the other 25% was characterized by absence of apparent rejection and also continued growth of BLI signal. The administration of cyclosporine (10 mg/kg bw, i.p.) was less effective for prevention of graft rejection (55% of 7 animals), than rapamycin/FK506 (both 1 mg/kg bw, i.p.) two drug combination (20% of 10 animals). Graft rejection was observed exclusively during the second week postgrafting, apparently as a sudden disappearance of BLI signal. Histological evaluation of transplanted cells corroborated well with the BLI data. Inflammatory processes were not observed in immunodeficient mice but, surprisingly, a significant infiltration of inflammatory cells still occurred in grafts with excellent survival. Immunosuppressive treatment did not seem to affect that and it was similar in both graft rejecting and graft accepting mice.
2

Guiding cell-based therapy for neurological diseases with noninvasive cellular imaging

84%
Walczak P., Gorelik M., Levy M., Rumpal N., Rifkin R., Muja N., Kim H., Kerr D., Bulte J.
Acta Neurobiologiae Experimentalis
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2009
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tom 69
|
nr 3
Taking advantage of recent developments in molecular biology and imaging, we have developed a system for monitoring status of transplanted cells non-invasively. We use high-resolution MRI to acquire information about the position of grafted cells and reporter gene-based bioluminescent imaging (BLI) to monitor their survival and differentiation. Here, we report on two different approaches for the in vivo imaging of glial precursors cells (GRPs). Approach I: Monitoring of the targeted, intravascular cerebral delivery of GRPs. Cells were engineered to express VLA-4 integrin (to enhance vascular adhesion) and were labeled with the MR contrast agent Feridex. Recipient rats were injected i.p. with lipopolysaccharide, a known inducer of endothelial VCAM-1 expression, and the cells were infused into the carotid artery. MRI demonstrated extensive hypointense regions, indicating successful targeting. Approach II: Monitoring of the survival and differentiation of intracerebrally injected GRPs. Cells were engineered to express luciferase under the control of a constitutive or the cell-type-specifi c promoters and were injected into the brain of immunodefi cient or immunocompetent mice. BLI demonstrated that transplanted GRPs survived for extended periods of time in immunodefi cient animals, while, in immunocompetent animals, rejection was initiated two weeks after grafting. With cell type-specifi c promoters, we were able to visualize the process of glial differentiation in vivo.
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