Effect of combined cytostatic cyclosporin A and cytolytic suicide gene therapy on the prevention of experimental graft-versus-host disease

Suicide gene-modified killer cells as an allogeneic alternative to autologous cytokine-induced killer cell immunotherapy of hepatocellular carcinoma

Adoptive immunotherapy using autologous cytokine-induced killer (CIK) cells reduces the recurrence rate of hepatocellular carcinoma (HCC) in association with transarterial chemoembolization or radiofrequency. However, a large‑scale development of this immunotherapy remains difficult to consider in an autologous setting, considering the logistical hurdles associated with the production of this cell therapy product. A previous study has provided the in vitro and in vivo proof‑of‑concept that allogeneic suicide gene‑modified killer cells (aSGMKCs) from healthy blood donors (a cell therapy product previously demonstrated to provide anti‑leukemic effects to patients receiving allogeneic hematopoietic transplantation) may exert a potent anti‑tumor effect towards HCC. Therefore, the development of a bank of 'ready‑for‑use' aSGMKCs was proposed as an approach allowing for the development of immunotherapies that are more convenient and on a broader scale than that of autologous therapies. In the present study, aSGMKCs were compared with CIK cells generated according to three different protocols. Similar to CIK cells, the cytotoxic activity of aSGMKCs toward the Huh‑7 HCC cell line was mediated by tumor necrosis factor‑related apoptosis‑inducing ligand, tumor necrosis factor‑α and interferon‑γ. Furthermore, the frequency of natural killer (NK), NK‑like T and T cells, and their in vitro and in vivo cytotoxicity activities were similar between aSGMKCs and CIK cells. Thus, the present study demonstrated that aSGMKCs are similar to CIK cells, further suggesting the possibility for future use of aSGMKCs in the treatment of solid tumors, including HCC.

Control of mouse graft-versus-host disease following allogeneic bone marrow transplantation by blocking the CD28/B7 signaling pathway with lentiviral vector-mediated RNA interference

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective way to cure hematological malignancies. However, graft-versus-host disease (GVHD) following transplantation limits the clinical application to some extent. The donor T lymphocytes play a central role in the occurrence and development of GVHD. Control of GVHD by inhibition of T cell proliferation by blocking the CD28/B7 signaling pathway with RNA interference has not been examined. In this study, we constructed a lentiviral vector carrying CD28 shRNA and generated genetically engineered splenocytes through transduction in a murine allogeneic bone marrow transplantation model. The survival and the occurrence of GVHD in transplanted mice were monitored every day. Liver, intestine, skin, and other tissues from the mice in each group were used for histological examination. We also determined plasma concentrations of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-13, and interferon gamma (IFN-γ). Recipient bone marrow from mice that had survived for an extended period was examined to detect chimerism. We succeeded in suppressing the expression of CD28 gene and controlling mouse GVHD following allogeneic bone marrow transplantation in the engineered spleen cell group. These suggest that blocking the CD28/B7 signal transduction pathway with lentiviral vector-mediated RNA interference effectively controlled the occurrence of mouse GVHD following allogeneic bone marrow transplantation. Its mechanism could be due to the inhibition of T cell proliferation and, simultaneously, the promotion of the differentiation of TH0 to TH2 cells, thereby reducing GVHD in the mouse transplantation model.

Different serum enzyme levels are required to rescue the various systemic features of the mucopolysaccharidoses

Mucopolysaccharidoses (MPSs) are lysosomal storage disorders characterized by progressive accumulation of glycosaminoglycans (GAGs) in various tissues. Enzyme replacement therapy (ERT) for several MPSs is available to date. However, the efficacy of ERT is limited, in particular in compartments such as bone, cartilage, the brain, and the eyes. We selected a rodent model of an MPS, with no central nervous system storage, to study the impact, on systemic features of the disease, of various stable levels of exogenous enzymes produced by adeno-associated viral vector (AAV)-mediated liver gene transfer. Low levels (6% of normal) of circulating enzyme were enough to reduce storage and inflammation in the visceral organs and to ameliorate skull abnormalities; intermediate levels (11% of normal) were required to reduce urinary GAG excretion; and high levels (>or=50% of normal) rescued abnormalities of the long bones and motor activity. These data will be instrumental to design appropriate clinical protocols based on either enzyme or gene replacement therapy for MPS and to predict their impact on the pathological features of MPS.

Ganciclovir-mediated elimination of HSV-Tk+ T cells and cure of graft-vs-host disease in an allogeneic bone marrow transplantation model in the rat

OBJECTIVE

Suicide gene therapy for leukemia aims to benefit from T cells in the BM graft, by reducing the probability of leukemia relapse (GVL), while severe complications of graft-vs-host disease (GVHD) may be avoided. In an allogeneic rat BMT model we defined the conditions to induce a lethal GVHD with HSV-Tk gene-transduced T cells. We studied the feasibility to rescue the animals by conditional elimination of the T cells with ganciclovir (GCV) treatment.

METHODS

Allogeneic T cells transduced with a retroviral vector encoding the HSV-Tk suicide gene were added in varying numbers to a BM graft. Expression of HSV-Tk strongly increases the cytolytic effect of GCV, thereby allowing elimination of overreactive T cells at will. Various experimental conditions were tested in the rat model.

RESULTS

A relation between the number of HSV-Tk(+) T cells added to the BM graft and GVHD development was found. GCV treatment resulted in selective HSV-Tk(+) T-cell elimination in blood and tissues but not in abrogation of GVHD due to persistence of HSV-Tk(-) T cells. T cells in unmanipulated rat BM normally have a low risk to induce GVH but when they are administered in combination with high numbers of HSV-Tk(+) T cells there is an apparent increase in their GVH-inducing potential. When HSV-Tk(+) T cells are added to T cell-depleted BM a consequently developing GVH can be controlled by GCV treatment with 60-70% of the animals surviving.

CONCLUSIONS

We show that T cell-mediated suicide gene therapy within the context of allo-BMT can be applied with success. The apparent limitation in the number of transduced as well as nontransduced T cells that can be safely added to the BM graft should be taken into consideration when designing human suicide gene therapy protocols.

Graft-versus-leukemia effect after suicide-gene-mediated control of graft-versus-host disease

Clinical data indicate that after allogeneic hematopoietic stem cell transplantation (HSCT) for hematological malignancies, the graft-versus-leukemia (GVL) effect is in large part mediated by the graft-versus-host reaction (GVHR), which also often leads to graft-versus-host disease (GVHD). Controlling alloreactivity to prevent GVHD while retaining GVL poses a true dilemma for the successful treatment of such malignancies. We reasoned that suicide gene therapy, which kills dividing cells expressing the thymidine kinase (TK) "suicide" gene using time-controlled administration of ganciclovir (GCV), might solve this dilemma. We have previously shown that after infusion of allogeneic TK T cells along with HSCT to an irradiated recipient, an early and short GCV treatment efficiently prevents GVHD by selectively eliminating alloreactive T cells while sparing nonalloreactive T cells, which can then contribute to immune reconstitution. Nevertheless, it remained to be established that this therapeutic strategy retained the desired GVL effect. Hypothesizing that a contained GVHR would be essential, we evaluated the GVL effect using different protocols of GCV administration. We were able to show that when the GCV treatment is initiated at, or close to, the time of grafting, GVHD is controlled but GVL is lost. In contrast, when the onset of GCV administration is delayed until day 6, a potent GVL effect is retained while GVHD is still controlled. These data emphasize that, by a time-optimized scheduling of the administration of GCV, this TK/GCV strategy can be tuned to efficiently treat malignant hemopathies.