Enhanced antitumor effects of bone marrow transplantation in combination with fibroblast-mediated IL-2 and IL-3 gene therapy

Combined immunotherapy and antiangiogenic therapy of cancer with microencapsulated cells

An alternative form of gene therapy involves immunoisolation of a nonautologous cell line engineered to secrete a therapeutic product. Encapsulation of these cells in a biocompatible polymer serves to protect these allogeneic cells from host-versus-graft rejection while recombinant products and nutrients are able to pass by diffusion. This strategy was applied to the treatment of cancer with some success by delivering either interleukin 2 or angiostatin. However, as cancer is a complex, multifactorial disease, a multipronged approach is now being developed to attack tumorigenesis via multiple pathways in order to improve treatment efficacy. A combination of immunotherapy with angiostatic therapy was investigated by treating B16-F0/neu melanoma-bearing mice with intraperitoneally implanted, microencapsulated mouse myoblasts (C2C12) genetically modified to deliver angiostatin and an interleukin 2 fusion protein (sFvIL-2). The combination treatment resulted in improved survival, delayed tumor growth, and increased histological indices of antitumor activity (apoptosis and necrosis). In addition to improved efficacy, the combination treatment also ameliorated some of the undesirable side effects from the individual treatments that have led to the previous failure of the single treatments, for example, inflammatory response to IL-2 or vascular mimicry due to angiostatin. In conclusion, the combination of immuno- and antiangiogenic therapies delivered by immunoisolated cells was superior to individual treatments for antitumorigenesis activity, not only because of their known mechanisms of action but also because of unexpected protection against the adverse side effects of the single treatments. Thus, the concept of a "cocktail" strategy, with microencapsulation delivering multiple antitumor recombinant molecules to improve efficacy, is validated.

Adenoviral interleukin-3 gene-radiation therapy for prostate cancer in mouse model

PURPOSE

The radiosensitizing effect of IL-3 gene therapy was evaluated on the syngeneic mouse prostate cancer model.

METHODS AND MATERIALS

An adenoviral vector was used to deliver the mIL-3 alpha gene into syngeneic murine prostate (TRAMP-C1) cancer cells growing in a subcutaneous site and the tumor response to irradiation was assessed.

RESULTS

Ad-mIL-3 gene therapy showed no tumor growth delay without radiation. However, intratumoral Ad-mIL-3 injection with radiation therapy showed marked tumor growth delay that was significantly greater than that of radiation alone.

CONCLUSIONS

The combined intratumoral Ad-mIL-3 gene therapy and radiation therapy is a valuable option for further clinical evaluation.

Chemoattraction, adhesion and activation of natural killer cells are involved in the antitumor immune response induced by fractalkine/CX3CL1

Fractalkine (FK, also called neurotactin or CX3CL1) is a CX3C chemokine that can chemoattract T lymphocytes, monocytes, dendritic cells (DC) and natural killer (NK) cells. One of our previous studies demonstrated that FK in soluble form can chemoattract T cells and DC and membrane-bound FK can adhere T cells and DC. Vaccination with 3LL lung carcinoma cells gene-modified with FK (3LL-FK) induces potent antitumor CTL response. The aim of the present study is to investigate whether NK cells participate in FK-induced antitumor immunity. We found that NK activity was increased in mice inoculated with 3LL-FK and in vivo depletion of NK cells resulted in the decreased tumor growth inhibition of 3LL-FK, indicating that NK cells play an important role in the antitumor immunity induced by FK. Further studies showed 3LL-FK could chemoattract, adhere NK cells and attract more NK cells to infiltrate into tumor tissue. Incubation of NK cells with 3LL-FK could increase the cytotoxicity of NK cells against YAC-1 cells and even against NK-resistant parental 3LL cells. IL-12 production increased more significantly in the 3LL-FK tumor nodules. Taken together with CTL response induced by 3LL-FK, our data demonstrate that FK, expressed by gene-modified tumor cells, can induce potent antitumor effect through different mechanisms, one of which involves chemoattraction of NK cells into tumor sites and activation of NK cells.

Dendritic cells support hematopoiesis of bone marrow cells

BACKGROUND

We previously observed that vaccination of normal mice with bone marrow (BM) -derived dendritic cells (DCs) could increase the number of peripheral white blood cells (WBCs) and platelets. In the present study, we investigated the potential of DCs to support the hematopoiesis of BM cells in vitro and in vivo.

METHODS

In the absence of exogenous cytokines, the expansion of CD34+ stem cells was observed when cultured with DC-derived supernatant or contact cocultured with DC. After culture in supernatant of DCs or contact coculture with DCs for 3 days, CD34+ progenitor cells were cultured in the semisolid media to test their ability to generate the clonogeneic cells. Then, BM cells combined with DCs or not were transferred into lethally irradiated syngeneic recipients to determine the effects of DCs on hematopoietic recovery.

RESULTS

After culture in the supernatant of DCs, especially in the supernatant of OVA-DCs (OVA-stimulated DC), the proliferation of CD34+ stem cells and generation of clonogeneic cells were augmented in correspondence with the concentration of DCs. After contact coculture with DCs, the proliferation of CD34+ stem cells and generation of clonogeneic cells were more significant than that in noncontact cultures. Moreover, when cultured with DCs or supernatant of DCs, CD34+ progenitor cells were preferentially differentiated to megakaryocytes. After coculture with OVA-DCs, markedly greater generation of colony forming units-granulocyte/macrophages (CFU-GM): colony forming units-megakaryocytes (CFU-MK) was found than that in coculture with unstimulated DCs. Pretreatment of DC with antibodies to thrombopoietin (TPO), interleukin (IL) -6, IL-12, or anti-mouse intercellular adhesion molecule-1 (ICAM-1) could inhibit the ability of DCs to support the generation of CFU-GM, CFU-MK. After transplant with BM cells and DCs, the number of peripheral platelets of the recipients increased significantly and, to a lesser extent, peripheral WBC counts increased. The survival periods were significantly prolonged when the lethally irradiated mice were transplanted with BM cells combined with DCs or OVA-DCs. High levels of TPO, IL-6, and IL-12 could be detectable in the supernatant of DCs, and TPO expression by DCs was further confirmed by reverse transcription-polymerase chain reaction analysis and intracellular staining with anti-TPO antibody.

CONCLUSIONS

We first demonstrated that DCs, especially antigen-stimulated DCs, can promote the expansion of hematopoietic progenitors and support hematopoiesis, preferentially support megakaryopoiesis of BM cells, by expressing soluble factors, including TPO, IL-6, IL-12, and by direct cell-to-cell interaction with stem cells in vitro and in vivo.