Cells as vehicles for therapeutic genes to treat liver diseases

In vivo monitoring of magnetically labeled mesenchymal stem cells homing to rabbit hepatic VX2 tumors using magnetic resonance imaging

Although mesenchymal stem cells (MSCs) have been demonstrated to possess a tumor‑homing feature, their tropism to liver tumors has not been delineated in a visible manner. The aim of the present study was to evaluate the tumor‑homing capacity of MSCs and to investigate the spatial and temporal distributions of MSCs in liver tumors using magnetic resonance imaging (MRI). MSCs were colabeled with superparamagnetic iron oxide (SPIO) particles and 4',6‑diamidino‑2‑phenylindole (DAPI), and then transplanted into rabbits with VX2 liver tumors through intravenous injections. The rabbits were subjected to MRI before and at 3, 7 and 14 days after cell transplantation using a clinical 1.5‑T MRI system. Immediately after the MRI examination, histological analyses were performed using fluorescence and Prussian blue staining. At 3 days after injection with labeled MSCs, heterogeneous hypointensity was detected on the MRI images of the tumor. At 7 days after transplantation, the tumor exhibited anisointense MRI signal, whereas a hypointense ring was detected at the border of the tumor. At 14 days after transplantation, the MRI signal recovered the hyperintensity. As demonstrated in the histological analyses, the distribution of the iron particles visualized with Prussian blue staining was consistent with the DAPI‑stained bright fluorescent nuclei, and the particles corresponded to the hypointense region on the MR images. Thus, systemically administered MSCs could localize to liver tumors with high specificity and possessed a migration feature with active tumor growth. These results demonstrated that the targeting and distribution of the magnetically labeled stem cells in the tumor could be tracked for 7 days in vivo using a clinical 1.5‑T MRI scanner.

A MATHEMATICAL MODEL FOR THE TREATMENT OF AIDS-RELATED KAPOSI'S SARCOMA

We formulate a mathematical model to study the dynamics of HIV-1 related Kaposi's Sarcoma (KS) pathogenesis. KS progression is modeled as a dual process involving the primary infection of B cells, which sustains HHV-8 replication and the secondary infection of progenitor cells by HHV-8, which sustains the KS cell replication. We incorporate the pharmacodynamics of highly active antiretroviral therapy (HAART), or combination therapy (HAART plus KS therapy) and consider how each treatment strategy alters the disease progression. Our results indicate that administration of HAART to individuals co-infected with the HIV-1 and HHV-8 viruses can greatly amplify the therapeutic response of low-dose KS therapies. We have found that adherence levels above 85% can significantly reduce the risk of KS and HIV for a treatment periods under 1 year. For longer treatment periods, however, at least 90% adherence level is recommended.

Endothelial progenitor cells: the promise of cell-based therapies for acute lung injury

BACKGROUND

Endothelial progenitor cells (EPCs) are defined as a special type of stem cell that have been found to directly incorporate into injured vessels and that participate in angiogenesis and reconstruction by differentiation into endothelial cells. EPCs are widely used to therapeutically treat cardiovascular disease, limb ischemia and vascular repair. However, the role of EPCs in inflammatory diseases, especially in lung injury, is less studied.

OBJECTIVE

To investigate the application of EPCs to vascular repair, and the role of EPCs in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

METHODS

A computer-based online search was performed in the PubMed database and Web of Science database for articles published, concerning EPCs, angiogenesis, ALI/ARDS and stem cell transplantation

CONCLUSION

EPCs have a therapeutic potential for vascular regeneration and may emerge as novel strategy for the diseases that are associated with ALI/ARDS.

Therapeutic effect of transplanting beta(2)m(-)/Thy1(+) bone marrow-derived hepatocyte stem cells transduced with lentiviral-mediated HGF gene into CCl(4)-injured rats

BACKGROUND

beta(2)m(-)/Thy1(+) bone marrow-derived hepatocyte stem cells (BDHSCs) isolated from the bone marrow of cholestatic rats by magnetic bead cell sorting consistently express characteristics of both stem and liver cells. These stem cells may be good vehicles for gene transfer. Administration of exogenous hepatocyte growth factor (HGF) may be potentially useful for the treatment of liver fibrosis. Because lentiviral vectors integrate stably into the host-cell genome of nondividing and dividing cells, it may efficiently transfect beta(2)m(-)/Thy1(+) BDHSCs in vitro and secrete high-level HGF consistently. Transplantation of beta(2)m(-)/Thy1(+) BDHSCs transduced with lentiviral vectors containing the HGF gene may reduce liver fibrosis in rats.

METHODS

Lentiviral vectors expressing HGF were constructed and used to transduce beta(2)m(-)/Thy1(+) BDHSCs sorted from cholestatic rats in vitro. Transduction efficiency was evaluated and then these cells were transplanted into rats through the portal vein. Liver function as well as histological and immunohistochemical examinations were carried out to assess the therapeutic efficacy on liver fibrosis.

RESULTS

We demonstrated that high-level exogenous HGF was detected in supernatants after beta(2)m(-)/Thy1(+) BDHSCs were transfected with lentiviral vectors expressing HGF. Transplantation of transduced beta(2)m(-)/Thy1(+) BDHSCs significantly enhanced liver function and attenuated liver fibrosis in vivo.

CONCLUSIONS

The present study indicates that transplantation of beta(2)m(-)/Thy1(+) BDHSCs overexpressing the HGF gene may offer a novel approach for promoting liver function and reverse liver fibrosis.

Novel approaches to vaccination against the feline immunodeficiency virus

Inadequate antigen presentation and/or suboptimal immunogenicity are considered major causes in the failure of human immunodeficiency vaccine to adequately protect against wild-type virus. Several approaches have been attempted to circumvent these hurdles. Here we reviewed some recent vaccinal strategies tested against the feline immunodeficiency virus and focused on: (i) improving antigen presentation by taking advantage of the exquisite ability of dendritic cells to process and present immunogens to the immune system; (ii) boosting immune responses with vaccinal antigens presented in a truly native conformation by the natural target cells of infection. Significance of the studies, possible correlates of protection involved, and implications for developing anti-human immunodeficiency virus vaccines are discussed.

Development of a human model to study homing behavior of immune cells into decidua and placental villi under ex vivo conditions

PROBLEM

Homing of lymphocytes and NK cells into the decidua and its regulation has been very controversially discussed. Therefore, we aimed to establish an in vivo simulation method for analysis of homing behavior, which might be also useful for other cells such as stem or tumor cells.

METHOD OF STUDY

A human term placenta has been perfused with medium to elute blood and then with maternal autologous carboxyfluorescein succinimidyl ester (CFSE)-labeled peripheral blood lymphocytes for 3 hr and rinsed for another 2 hr. Tissue was analysed histologically for detection of labeled cells. Labeled lymphocytes and beads in perfusate have been identified and counted by flow cytometry.

RESULTS

At the moment of tissue fixation for histology, the perfusate was free of labeled cells. Labeled perfused lymphocytes have been found adhered and integrated in vessel wall structures, in decidual stroma and as colonies in individual villi.

CONCLUSION

Placenta perfusion with a lymphocyte suspension is feasible without plugging the tube system. Time is sufficient for cells to adhere and to migrate into the stroma. Also some villi have been infiltrated which might be caused by inflammatory stimuli. The perfusion system might be useful to test substances for their capacity to influence homing of lymphocytes or other cells.

Selective or targeted gene/drug delivery for liver tumors: advantages and current status of local delivery

There are various disorders involving the liver. They include metabolic diseases, hepatitis, liver cirrhosis and cancer, the latter of which may be the most serious. Delivery of therapeutic genes or drugs should be targeted to either one of the following cells in the liver: hepatocytes, Kupffer cells and tumor endothelial cells, or to the tumor cells themselves. To maximize the therapeutic effect and minimize systemic toxicity or nontarget injuries, the sufficient amount or dose of genes or drugs should be specifically delivered to a target, with minimal exposure in their active forms to nontarget cells. There are diverse strategies to improve selective delivery or targeting efficiency. In this article, we present potential new therapeutic strategies and clinical developments for liver cancer, with a focus on the progress in the localized delivery of therapeutic agents using image-guided procedures.