title: Analysis of biodistribution and engraftment into the liver of genetically modified mesenchymal stromal cells derived from adipose tissue.
abstract: Presently, orthotopic liver transplant is the major therapeutic option for patients affected by primary liver diseases. This procedure is characterized by major invasive surgery, scarcity of donor organs, high costs, and lifelong immunosuppressive treatment. Transplant of hepatic precursor  cells represents an attractive alternative. These cells could be used either for allogeneic transplantation or for autologous transplant after ex vivo genetic modification. We used stromal cells isolated from adipose tissue (AT-SCs) as platforms for autologous cell-mediated gene therapy. AT-SCs  were transduced with lentiviral vectors expressing firefly luciferase, allowing for transplanted cell tracking by bioluminescent imaging (BLI). As a complementary approach, we followed circulating human α1-antitrypsin (hAAT) levels after infusion of AT-SCs overexpressing hAAT. Cells  were transplanted into syngeneic mice after CCl(4)-induced hepatic injury. Luciferase bioluminescence signals and serum hAAT levels were measured at different time points after transplantation and demonstrate persistence of transplanted cells for up to 2 months after administration.  These data, along with immunohistochemical analysis, suggest engraftment and repopulation of injured livers by transplanted AT-SCs. Moreover, by transcriptional targeting using cellular tissue-specific regulatory sequences, we confirmed that AT-SCs differentiate towards a hepatogenic-like  phenotype in vitro and in vivo. Additionally, in transplanted cells reisolated from recipient animals' livers, we detected activation of the α-fetoprotein (AFP) promoter. This promoter is normally transcriptionally silenced in adult tissues but can be reactivated during liver regeneration,  suggesting commitment towards hepatogenic-like differentiation of engrafted cells in vivo. Our data support AT-SC-mediated gene therapy as an innovative therapeutic option for disorders of liver metabolism.
authors.affiliation: Vascular Biology and Regenerative Medicine, Centro Cardiologico Monzino IRCCS, Milan, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Di Rocco
authors.forename: Antonietta
authors.initials: A
authors.lastname: Gentile
authors.forename: Annalisa
authors.initials: A
authors.lastname: Antonini
authors.forename: Silvia
authors.initials: S
authors.lastname: Truffa
authors.forename: Giulia
authors.initials: G
authors.lastname: Piaggio
authors.forename: Maurizio C
authors.initials: MC
authors.lastname: Capogrossi
authors.forename: Gabriele
authors.initials: G
authors.lastname: Toietta
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D002454:Cell Differentiation; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008107:Liver Diseases / Q000473:pathology / Q000601:surgery*; D008115:Liver Regeneration / Q000502:physiology*; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology*; D051379:Mice; D014018:Tissue Distribution