Prolonged survival and vascularization of xenografted human glioblastoma cells in the central nervous system of cyclosporine A treated rats

Visualization of Inflammation at Early Stage of Lung Cancer in Xenografted Temporally Immunosuppression Rats by Ferrioxamine Magnetic Resonance Imaging

Physiological responses such as chronic inflammation and angiogenesis could be used as biomarkers for early detection of cancer with noninvasive imaging modalities. The present study reports the application of magnetic resonance imaging instrument to image the binding of ferrioxamine with hemin that allows visualizing the chronic inflammation foci of lung tissue of immunocompromised rats xenografted using small cell lung carcinoma. A low concentration of ferrioxamine (0.05 ± 0.02 μM·kg⁻¹ of rat weight) deposited on tissue outside the vasculature was found to diffuse across the capillary walls to the interstitial space and inflammation foci, which provided a clear enhancement of T1-weighted gradient-echo sequence images. Ferrioxamine imaging allowed the determination of inflammatory sites and their localization in 3D fat-suppressed maximum intensity projections. The smallest dimension of foci that can be clearly determined is about 0.1 mm³. In concomitant to the in vivo imaging, analysis of histological tissue section showed the development of inflammatory sites. This study provides evidence that medical imaging instrument such as MRI scanner allows researchers to correlate images taken with MRI with those using high-resolution microscopy. Moreover, ferrioxamine is a useful molecular probe for determining chronic inflammation particularly at the very early stages of cancer.

A murine model of xenotransplantation of human glioblastoma with immunosuppression by orogastric cyclosporin

Several animal experimental models have been used in the study of malignant gliomas. The objective of the study was to test the efficacy of a simple, reproducible and low cost animal model, using human cells of glioblastoma multiforme (GBM) xenotransplantated in subcutaneous tissue of Wistar rats, immunosuppressed with cyclosporin given by orogastric administration, controlled by nonimunosuppressed rats. The animals were sacrificed at weekly intervals and we have observed gradual growth of tumor in the immunosuppressed group. The average tumor volume throughout the experiment was 4.38 cm(3) in the immunosuppressed group, and 0.27 cm(3) in the control one (p<0.001). Tumors showed histopathological hallmarks of GBM and retained its glial identity verified by GFAP and vimentin immunoreaction. Immunosuppression of rats with cyclosporin was efficient in allowing the development of human glioblastoma cells in subcutaneous tissues. The model has demonstrated the maintenance of most of the histopathological characteristics of human glioblastoma in an heterotopic site and might by considered in research of molecular and proliferative pathways of malignant gliomas.

Isolation of human multipotent neural progenitors from adult filum terminale

Stem cells have been isolated from several CNS regions, including the spinal cord. However, the terminal end of the spinal cord, filum terminale, has been referred to as a fibrovascular tag without neurogenic potential and of no clinical significance. Recently, we were fortunate to acquire some samples of this tissue. We show for the first time that progenitor cells exhibiting the hallmarks of stem cells can be isolated from adult human filum terminale (FTNPs). More specifically, FTNPs self-renew and proliferate to form neurospheres, and exhibit tripotent differentiation into neurons, astrocytes, and oligodendrocytes. Equally important, FTNPs develop the electrophysiological profile of neurons and glia. Whole-cell patch-clamp recordings show beta-III-tubulin(+) neurons exhibiting overshooting action potentials, displaying both the fast inactivating TTX-sensitive sodium current as well as 4-AP and TEA sensitive potassium currents. To assess potency in vivo, FTNPs were transplanted into the posterior periventricular region of control or ischemic rat brains. Despite a vigorous immune response against the xenograft, FTNPs survived and were found not only in the graft area but had also migrated to the lesioned CA1 region. Notwithstanding the immune response, FTNPs differentiated into astrocytes, but no neuronal differentiation was observed in the transplant milieu tested. However, neuronal differentiation in vivo cannot be ruled out and assessment of the conditions necessary to promote neurogenesis in vivo requires more research. Significantly, no tumor formation or aberrant cell morphology was seen in or adjacent to the graft area. Thus, filum terminale provides a novel source of adult human neural progenitor cells that develop into functional neurons with possible clinical applications.

Transplantation of stem cells from the adult human brain to the adult rat brain

OBJECTIVE

To investigate the migration, proliferation, and differentiation of stem cells and neural progenitor cells (NPCs) from the adult human brain after transplantation into adult rodent brains.

METHODS

Adult human NPCs were obtained from temporal lobe specimens removed because of medical intractable epilepsy. The cells were transplanted into the posterior periventricular region above the hippocampus in the brains of either healthy adult rats (control) or rats with selective injury of the hippocampal CA1 region (global ischemia).

RESULTS

In the control animals, grafted cells were mainly distributed from the site of transplantation toward the midline along white matter tracts. The density of transplanted cells elsewhere, including the hippocampus, was low and apparently random. In animals with CA1 damage, NPCs showed targeted migration into the injured area. Cell survival at 10 weeks was 4.7 +/- 0.3% (control, n = 3) and 3.7 +/- 1.1% (ischemia, n = 3); at 16 weeks, cell survival was 3.4 +/- 0.6% (control, n = 2) and 7.2 +/- 1.5% (ischemia, n = 2), i.e., comparable to what has been observed earlier when transplanting embryonic tissue into the human brain or progenitor cells between inbred rats. The number of dividing cells decreased with time. Sixteen weeks after transplantation, 4 +/- 1% (n = 4) of the cells showed proliferative activity. We did not observe signs of tumor formation or aberrant cell morphology. Neuronal differentiation was much slower than what has been observed earlier in vitro or after transplantation to the developing nervous system, and 16 weeks after transplantation many surviving cells were still in maturation.

CONCLUSION

The present study shows that adult human NPCs survive, show targeted migration, proliferate, and differentiate after grafting into the adult rat brain.

Sustained survival of xenografted human neural stem/progenitor cells in experimental brain trauma despite discontinuation of immunosuppression

Neural stem cells have emerged as a promising therapeutic tool in CNS disease and injuries. In the clinical setting, cultured human neural stem/progenitor cells (hNSC) are an attractive possibility for transplantation to the damaged brain. However, transplantation of hNSC requires toxic immunosuppressive treatment to avoid rejection. The aim of the current study was to evaluate if shortening the duration of immunosuppression by cyclosporin A would affect hNSC survival and differentiation after transplantation to the site of a focal brain injury in the rat. hNSC were xenografted to the hippocampus and the medial limit of an experimentally induced cortical contusion. The animals received immunosuppression for either 6 or 3 weeks or no immunosuppression. The status of the grafted human cells was analysed by immunohistochemistry. No statistically significant differences were observed between the two immunosuppressed groups regarding graft survival, migration or proliferation at 6 weeks post-transplantation. In contrast, the graft survival was extremely poor in the non-immunosuppressed group. Furthermore, the expression of the differentiation markers nestin, neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) in the transplanted cells did not differ significantly between the two immunosuppressed groups. Moreover, a fourth group of eight animals that were immunosuppressed for 3 weeks were allowed to survive for 6 months. Five of these rats demonstrated robust graft survival in the hippocampus and scattered cells in the cortex. This study demonstrates the importance of immunosuppression but also the possibility of shortening immunosuppression without impacting on the phenotype of the grafted hNSC.

Proliferation, migration, and differentiation of human neural stem/progenitor cells after transplantation into a rat model of traumatic brain injury

Object. Cultures containing human neural stem and progenitor cells (neurospheres) have the capacity to proliferate and differentiate into the major phenotypes of the adult brain. These properties make them candidates for therapeutic transplantation in cases of neurological diseases that involve cell loss. In this study, long-term cultured and cryopreserved cells were transplanted into the traumatically injured rat brain to evaluate the potential for human neural stem/progenitor cells to survive and differentiate following traumatic injury.

Methods. Neural stem/progenitor cell cultures were established from 10-week-old human forebrain. Immunosuppressed adult rats received a unilateral parietal cortical contusion injury, which was delivered using the weight-drop method. Immediately following the injury, these animals received transplants of neural stem/progenitor cells, which were placed close to the site of injury. Two or 6 weeks after the procedure, these animals were killed and their brains were examined by immunohistochemical analysis.

At both 2 and 6 weeks postoperatively, the transplanted human cells were found in the perilesional zone, hippocampus, corpus callosum, and ipsilateral subependymal zone of the rats. Compared with the 2-week time point, an increased number of HuN-positive cells was observed at 6 weeks. In addition, at 6 weeks post—injury/transplantation, the cells were noted to cross the midline to the contralateral corpus callosum and into the contralateral cortex. Double labeling demonstrated neuronal and astrocytic, but not oligodendrocytic differentiation. Moreover, the cortex appeared to provide an environment that was less hospitable to neuronal differentiation than the hippocampus.

Conclusions. This study shows that expandable human neural stem/progenitor cells survive transplantation, and migrate, differentiate, and proliferate in the injured brain. These cells could potentially be developed for transplantation therapy in cases of traumatic brain injury.

Neuroprotection by human neural progenitor cells after experimental contusion in rats

Neural progenitor/stem cells (HNPC) have been suggested to contribute essential trophic factors and promote survival of degenerating neurons after traumatic brain injury. For these reasons we hypothesize that the addition of HNPC to a post-injury region could possibly protect injured neurons. Experimental brain contusions were carried out in 18 rats. Immediately post-injury, rats were injected with 0.1 ml of medium (n=8), dead cells (n=4), or live cells (n=6) in the medial border of the lesion. The rats were sacrificed 6 days post-surgery and evaluated by immunohistochemistry using a human nuclear marker (huN), hematoxylin and Fluoro-Jade (FJ). Human neural stem cells showed engraftment detectable by positive huN staining in 5/6 animals. The non-grafted animal was excluded from further analyses. Those given dead HNPC or medium showed no detectable huN immunoreactivity. A statistical comparison between the numbers of FJ positive degenerating endogenous neurons was made between rats receiving vehicle and dead cells to evaluate whether the presence of human cells would increase neuronal degeneration in comparison to vehicle alone. The rats receiving vehicle had a median of 117.5 FJ positive cells and dead progenitor cell recipients 175.0 per counted section (P<0.05, Mann-Whitney). Consequently, the animals receiving dead human cells were chosen as controls to the animals receiving live progenitor cells. The rats that received live HNPC demonstrated significantly fewer FJ positive cells per counted section than controls (58.0 vs. 175.0, P<0.01, Mann-Whitney). The post-traumatic perilesional environment allowed for the engraftment of live HNPC. The stepwise analysis indicated that host neuronal degeneration was higher in animals transplanted with non-viable human neuronal progenitor cells than in those receiving vehicle, indicating a bystander effect from introducing foreign antigen. In contrast, transplantation of viable progenitor cells attenuated neuronal degeneration, indicating that a potentially beneficial effect in progenitor cell transplantation is not limited to restoration by transplanted cells, but also improving survival of host cells.