Dataset Information

Olfactory Ensheathing Cells: A Trojan Horse for Glioma Gene Therapy.

ABSTRACT:

Background

The olfactory ensheathing cells (OECs) migrate from the peripheral nervous system to the central nervous system (CNS), a critical process for the development of the olfactory system and axonal extension after injury in neural regeneration. Because of their ability to migrate to the injury site and anti-inflammatory properties, OECs were tested against different neurological pathologies, but were never studied in the context of cancer. Here, we evaluated OEC tropism to gliomas and their potential as a "Trojan horse" to deliver therapeutic transgenes through the nasal pathway, their natural route to CNS.

Methods

OECs were purified from the mouse olfactory bulb and engineered to express a fusion protein between cytosine deaminase and uracil phosphoribosyltransferase (CU), which convert the prodrug 5-fluorocytosine (5-FC) into cytotoxic metabolite 5-fluorouracil, leading to a bystander killing of tumor cells. These cells were injected into the nasal cavity of mice bearing glioblastoma tumors and OEC-mediated gene therapy was monitored by bioluminescence imaging and confirmed with survival and ex vivo histological analysis. All statistical tests were two-sided.

Results

OECs migrated from the nasal pathway to the primary glioma site, tracked infiltrative glioma stemlike cells, and delivered therapeutic transgene, leading to a slower tumor growth and increased mice survival. At day 28, bioluminescence imaging revealed that mice treated with a single injection of OEC-expressing CU and 5-FC had tumor-associated photons (mean [SD]) of 1.08E + 08 [9.7E + 07] vs 4.1E + 08 [2.3E + 08] for control group (P < .001), with a median survival of 41 days vs 34 days, respectively (ratio = 0.8293, 95% confidence interval = 0.4323 to 1.226, P < .001) (n = 9 mice per group).

Conclusions

We show for the first time that autologous transplantation of OECs can target and deliver therapeutic transgenes to brain tumors upon intranasal delivery, the natural route of OECs to the CNS, which could be extended to other types of cancer.

SUBMITTER: Carvalho LA

PROVIDER: S-EPMC6410949 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Olfactory ensheathing cells are one of the few central nervous system regenerative cells discovered so far. It is characterized by its lifelong nerve regeneration function, and it can also release a variety of neurotrophic factors and neural adhesion molecules. It is considered to be the glial cell with the strongest myelination ability. Olfactory ensheathing cells and Schwann cells have phenotypes in common, they can promote axon regeneration(R. Doucette, 1995). Olfactory ensheathing cells have the characteristics of Schwann cells and astrocytes, but the overall performance tends to be the former, which has two unique characteristics. First, it exists not only in the peripheral nerves (Schwann cells), but also in the central nervous system (astroglia); second, the olfactory mucosa has the ability to regenerate life-long, including human olfactory ensheathing cells(J. C. Bartolomei and C. A. Greer, 2000). Regeneration is a process in which olfactory ensheathing cells participate in efficient regulation, although the specific mechanism is not yet clear. Olfactory ensheathing cells are different from astrocytes and Schwann cells, but at the same time have the characteristics of these two cells(S. C. Barnett, 2004), like Schwann cells help axon growth, but more than Schwann cells It can make axons grow long distances, that is, it has stronger migration(A. Ramon-Cueto et al., 1998); there are also astrocytes that have a nutritional effect on the survival of neurons and the growth of axons, but olfactory ensheathing cells can also wrap neurons forms myelin sheath to support the growth of nerve processes(R. Devon and R. Doucette, 1992; J. Gu et al., 2019). There are two characteristics that make olfactory ensheathing cells the best choice for the treatment of neurological diseases(S. C. Chiu et al., 2009; J. Kim et al., 2018; M. Abdel-Rahman et al., 2018). Olfactory ensheathing cells are gradually used to treat spinal cord injuries and have shown amazing effects(J. C. Bartolomei and C. A. Greer, 2000; K. J. Liu et al., 2010; R. Yao et al., 2018). Olfactory ensheathing cells that have been used in research are usually derived from the olfactory bulb(E. H. Franssen et al., 2007), but it is easier to obtain olfactory ensheathing cells from the olfactory mucosa in clinical practice(M. Ryszard et al., 2006), so the difference between the olfactory ensheathing cells from the olfactory bulb and the olfactory mucosa There are more and more studies(B. M. U. et al., 2007), and previous studies have shown that they not only have many similar functions, but also have many differences(M. W. Richter et al., 2005; L. Wang et al., 2014; K. E. Smith et al., 2020). Because olfactory ensheathing cells derived from the olfactory bulb are not easy to obtain, olfactory ensheathing cells derived from the olfactory mucosa have become the focus of attention. Although we know that olfactory ensheathing cells from two sources have nerve repair functions, it is not clear why the two different sources of olfactory ensheathing cells have different therapeutic effects. Nicolas G. once studied that the genetic difference between the two cells and found that there are many genes related to wound repair and nerve regeneration(G. Nicolas et al., 2010). We have reason to guess that olfactory ensheathing cells from these two sources will also have a large difference in protein level. Our research group wants to use the current mature transcriptome and proteomic sequencing technologies to explore the difference between olfactory ensheathing cells from the olfactory bulb and olfactory mucosa, and explain why the two sources of olfactory ensheathing cells shows different therapeutic effects, hope to provide a new theoretical basis for future clinical treatment.

Project description:Solid tumours account for 90% of all cancers. Gene therapy represents a potential new modality for their treatment. Up to now, several approaches have been developed, but the most efficient ones are the viral vector based gene therapy systems. However, viral vectors suffer from several deficiencies: firstly most vectors currently in use require intratumoural injection to elicit an effect. This is far from ideal as many tumours are inaccessible and many may have already spread to other parts of the body, making them difficult to locate and inject gene therapy vectors into. Second, because of cell heterogeneity within a given cancer, the vectors do not efficiently enter and kill every cancer cell. Third, hypoxia, a prevalent characteristic feature of most solid tumours, reduces the ability of the viral vectors to function and decreases viral gene expression and production. Consequently, a proportion of the tumour is left unaffected, from which tumour regrowth occurs. Thus, cancer gene therapy has yet to realise its full potential. The facultative or obligate anaerobic bacteria have been shown to selectively colonise and regerminate in solid tumours when delivered systemically. Among them, the clostridial spores were easy to produce, stable to store and safe to use as well as having extensive oncolytic ability. However, research in animals and humans has shown that oncolysis was almost always interrupted sharply at the outer rim of the viable tumour tissue where the blood supply was sufficient. These clostridial spores, though, could serve as "Trojan horse" for cancer gene therapy. Indeed, various spores harbouring genes for cancerstatic factors, prodrug enzymes, or proteins or cytokines had endowed with additional tumour-killing capability. Furthermore, combination of these "Trojan horses" with conventional chemotherapy or radiation therapies often significantly perform better, resulting in the "cure" of solid tumours in a high percentage of animals. It is, thus, not too difficult to predict the potential outcomes for the use of clostridial spores as "Trojan horse" vectors for oncolytic therapy when compared with viral vector-mediated cancer therapy for it be replication-deficient or competent. However, to move the "Trojan horse" to a clinic, though, additional requirements need to be satisfied (i) target tumours only and not anywhere else, and (ii) be able to completely kill primary tumours as well as metastases. Current technologies are in place to achieve these goals.