Human Neural Stem Cells Target Experimental Intracranial Medulloblastoma and Deliver a Therapeutic Gene Leading to Tumor Regression

Abstract

Purpose: Medulloblastoma, a malignant pediatric brain tumor, is incurable in about one third of patients despite multimodal treatments. In addition, current therapies can lead to long-term disabilities. Based on studies of the extensive tropism of neural stem cells (NSC) toward malignant gliomas and the secretion of growth factors common to glioma and medulloblastoma, we hypothesized that NSCs could target medulloblastoma and be used as a cellular therapeutic delivery system. Experimental Design: The migratory ability of HB1.F3 cells (an immortalized, clonal human NSC line) to medulloblastoma was studied both in vitro and in vivo. As proof-of-concept, we used HB1.F3 cells engineered to secrete the prodrug activating enzyme cytosine deaminase. We investigated the potential of human NSCs to deliver a therapeutic gene and reduce tumor growth. Results: The migratory capacity of HB1.F3 cells was confirmed by an in vitro migration assay, and corroborated in vivo by injecting chloromethylbenzamido-Dil^labeled HB1.F3 cells into the hemisphere contralateral to established medulloblastoma in nude mice. In vitro studies showed the therapeutic efficacy of HB1.F3-CD on Daoy cells in coculture experiments. In vitro therapeutic studies were conducted in which animals bearing intracranial medulloblastoma were injected ipsilaterally with HB1.F3-CD cells followed by systemic 5-flourocytosine treatment. Histologic analyses showed that human NSCs migrate to the tumor bed and its boundary, resulting in a 76% reduction of tumor volume in the treatment group (P < 0.01).Conclusion: These studies show for the first time the potential of human NSCs as an effective delivery system to target and disseminate therapeutic agents to medulloblastoma.Medulloblastoma is the most common childhood malignant brain tumor. Although multimodal treatments, including radical surgical resection followed by radiation and chemotherapy, have substantially improved the survival rate for this disease, it remains incurable in about one third of patients.These treatments are also toxic and can lead to long-term disabilities (1, 2). The main cause of death is recurrence associated with tumor dissemination, at which point current therapeutic options have little efficacy (3, 4). Consequently, there is substantial need for novel, effective, low-toxicity therapies for children with medulloblastoma.The discovery of the inherent tumor-tropic properties of neural stem cells (NSC) could serve as a novel adjuvant strategy to current medulloblastoma treatments. Recent studies have shown that NSCs have the capacity to target therapeutic genes to brain tumors, such as malignant glioma (5 -13) and melanoma brain metastasis (14). We have expanded these investigations to determine whether NSCs are capable of targeting medulloblastoma in an orthotopic xenograft animal model. Therapeutic proof-of-concept studies were done using cytosine deaminase (CD) -producing NSCs and systemic 5-fluorocytosine (5-FC) prodrug administration. Our results show for the first time the pote...

Human neural stem cells transduced with IFN-β and cytosine deaminase genes intensify bystander effect in experimental glioma

“…19,20 In this study, we chose the human F3 NSC cell line, as it is a well-characterized and a well-established human NSC line. 3,[5][6][7]11 No signs of local or systemic toxicity were observed in case of animals injected with F3 cells alone. Importantly, these cells can be modified to stably express a therapeutic transgene.…”

“…In NSC-based gene therapy strategies targeting brain tumors, NSCs were mostly used to transport the CD/5-FC prodrug system to the tumor cells. [3][4][5][6][7][8] Recently, Dickson et al 21 showed that in mice, F3 human NSCs transiently expressing human IFN-b displayed tropism for sites of disseminated neuroblastoma, resulting in significant tumor growth. The sustained expression of IFN-b at disseminated sites of microscopic disease represents a novel therapeutic approach.…”

“…In particular, NSCs that are retrovirally transduced with suicide genes such as the cytosine deaminase (CD) gene show a remarkable 'bystander killer effect' on 5-fluorocytosine (5-FC)-treated glioma cells. 3,[5][6][7][8] Interferon-b (IFN-b) is known for its ability to interfere with viral replication and also for its antiproliferative effects on a variety of cancer cells. However, the efficacy of IFN-b is limited because of its extremely short half-life after intravenous administration as well as the systemic toxicity when this protein is administered at doses required to achieve the desired antitumor effect.…”

Self-renewal induced efficiently, safely, and effective therapeutically with one regulatable gene in a human somatic progenitor cell

“…Our ICSP cells proved to be regulatable so as to offset their limited capacity for self-renewal. They matched the predilection of other neural progenitor cell preparations to become neuronal (10) and to be effective in clinical disease models (10)(11)(12)(13)(14)(15)(16). Although, in these experiments, the neural progenitors were obtained from the brain, they could likely be obtained from such more accessible sources as olfactory neuroepithelium or skin.…”

Stem cell technology and engineering for cancer treatment

“…MSCs-based gene therapy has been used to treat several diseases in animal models including glioblastoma (Altaner et al, 2014;Altanerova et al, 2012;Fei et al, 2012;Lee et al, 2009), prostate cancer (Cavarretta et al, 2010), melanoma (Kucerova et al, 2008), gastrointestinal cancer (You et al, 2009), and other malignancies. Along with MSCs, neural stem cells (NSCs) carrying suicide enzyme have shown to reduce tumor volume and to increase survival in mouse model of malignant disease including medulloblastoma (Kim et al, 2006), melanoma brain metastases (Aboody et al, 2006), glioblastoma (Barresi et al, 2003;Ito et al, 2010), breast cancer brain metastases (Joo et al, 2009), prostate cancer , and breast cancer (Yi et al, 2014).…”