[Current state on development of neuroprotective agents for cerebral ischemia]

A Novel Cell Therapy Method for Recovering after Brain Stroke in Rats

BACKGROUND

Nowadays, stroke leads to a significant part of the adult mortality and morbidity and also it could result in some neurological deficits in the patients' lives. Cell therapy has opened a new approach to treat the brain ischemia and reduce its terrible effects on the patients' lives. There are several articles which show that the cell therapy could be beneficial for treating brain stroke. In this study, we have planned to present a new cell therapy method for stroke by administration of Mesenchymal stem cells and differentiated neural stem cells without astrocytes.

METHOD AND MATERIALS

The Mesenchymal stem cells were isolated from tibia and femur of a 250~300 g rat and they were cultured in DMEM/F12, 10% fetal bovine serum, 1% Pen/Strep. Neural stem cells were isolated from 14 days rat embryo ganglion eminence and were cultured in NSA media containing Neurobasal, 2% B27, bFGF 10 ng/ml and EGF 20 ng/ml after 5 days they formed some neurospheres. The isolated neural stem cells were differentiated to neural lineages by adding 5% fetal bovine serum to their culture media. After 48 hours the astrocytes were depleted by using MACS kit.

RESULTS

The group that received Mesenchymal stem cells systemically and differentiated neural stem cells without astrocytes had the best neurological outcomes and the least infarct volume and apoptosis. It could be understood that this cell therapy method might cause almost full recovery after brain stoke.

CONCLUSION

Using combination cell therapy with Mesenchymal stem cells and differentiated neural stem cells with removed astrocyte could provide a novel method for curing brain stroke.

Mesenchymal autologous stem cells

The use of cell-based therapies for spinal cord injuries has recently gained prominence as a potential therapy or component of a combination strategy. Experimental and clinical studies have been performed using mesenchymal stem cell therapy to treat spinal cord injuries with encouraging results. However, there have been reports on the adverse effects of these stem cell-based therapies, especially in the context of tumor modulation. This article surveys the literature relevant to the potential of mesenchymal autologous stem cells for spinal cord injuries and their clinical implications.

Morphological changes in rat hippocampus after brain injury

We performed morphological analysis of the structure of rat hippocampus after ablation of the left sensorimotor cortex. Four experimental groups were formed: two control groups (intravenous and intracerebral injections of the culture medium) and two experimental groups (intravenous and intracerebral transplantation of MSC). Ten weeks after surgery, disturbed cytoarchitectonics and great number of dead neurons were found in all zones of the hippocampus in animals of the control groups. In animals receiving cell therapy, no pathological changes in the structure of the hippocampus were found: hyperchromatic neurons were absent and the cells had regular shape and closely adjoined to each other.

Neural stem cells enhance nerve regeneration after sciatic nerve injury in rats

With the development of tissue engineering and the shortage of autologous nerve grafts in nerve reconstruction, cell transplantation in a conduit is an alternative strategy to improve nerve regeneration. The present study evaluated the effects and mechanism of brain-derived neural stem cells (NSCs) on sciatic nerve injury in rats. At the transection of the sciatic nerve, a 10-mm gap between the nerve stumps was bridged with a silicon conduit filled with 5 × 10(5) NSCs. In control experiments, the conduit was filled with nerve growth factor (NGF) or normal saline (NS). The functional and morphological properties of regenerated nerves were investigated, and expression of hepatocyte growth factor (HGF) and NGF was measured. One week later, there was no connection through the conduit. Four or eight weeks later, fibrous connections were evident between the proximal and distal segments. Motor function was revealed by measurement of the sciatic functional index (SFI) and sciatic nerve conduction velocity (NCV). Functional recovery in the NSC and NGF groups was significantly more advanced than that in the NS group. NSCs showed significant improvement in axon myelination of the regenerated nerves. Expression of NGF and HGF in the injured sciatic nerve was significantly lower in the NS group than in the NSCs and NGF groups. These results and other advantages of NSCs, such as ease of harvest and relative abundance, suggest that NSCs could be used clinically to enhance peripheral nerve repair.

A subpopulation of endothelial progenitor cells with low aldehyde dehydrogenase activity attenuates acute ischemic brain injury in rats

Previous studies have examined the therapeutic effect of endothelial progenitor cells (EPCs) during the chronic phase of cerebral infarction in rats; however, few studies have investigated the effects of EPCs during the acute phase of infarction. In this study, we evaluated the therapeutic effect of EPCs with low aldehyde dehydrogenase activity (Alde-Low EPCs) in rats with acute cerebral infarction, and our results provide insight that may help to identify a therapeutic mechanism of EPCs for acute cerebral infarction. The administration of Alde-Low EPCs into rats with acute cerebral infarction results in the accumulation and migration of the Alde-Low EPCs into the infarct area and the subsequent decrease of infarct volume. Moreover, we found that the stromal cell-derived factor-1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) signaling pathway may regulate the accumulation of Alde-Low EPCs. The transplantation of Alde-Low EPCs may represent a potential treatment strategy for acute cerebral infarction.

Intravenous administration of mesenchymal stem cells derived from bone marrow after contusive spinal cord injury improves functional outcome

Transplantation of mesenchymal stem cells (MSCs) derived from bone marrow has been shown to improve functional outcome in spinal cord injury (SCI). Systemic delivery of MSCs results in therapeutic benefits in a number of experimental central nervous system disorders. In the present study we intravenously administered rat MSCs derived from bone marrow at various time points after induction of a severe contusive SCI in rat to study their therapeutic effects. MSCs were systemically delivered at varied time points (6h to 28 days after SCI). The spinal cords were examined histologically 6 weeks after SCI. Stereological quantification was performed on the spinal cords to determine donor cell (MSCs transduced with the LacZ gene) density in the lesions. Light microscopic examination revealed that cavitation in the contused spinal cords was less in the MSC-treated rats. A limited number of cells derived from MSCs (LacZ(+)) in the injury site expressed neural or glial markers. Functional outcome measurements using the Basso-Beattie-Bresnehan (BBB) score were performed periodically up to 6 weeks post-SCI. Locomotor recovery improvement was greater in the MSC-treated groups than in sham controls with greatest improvement in the earlier post-contusion infusion times. The availability of autologous MSCs in large number and the potential for systemically delivering cells to target lesion areas without neurosurgical intervention suggests the potential utility of intravenous cell delivery as a prospective therapeutic approach in acute and subacute SCI.

Therapeutic benefits of human mesenchymal stem cells derived from bone marrow after global cerebral ischemia

Although intravenous delivery of mesenchymal stem cells (MSCs) prepared from adult bone marrow reduces infarction size and ameliorates functional deficits in rat middle cerebral artery occlusion models, there are few reports of MSC treatment in global cerebral ischemia. We utilized a global cerebral ischemia model induced by arresting the heart with a combination of hypovolemia and intracardiac injections of a cold potassium chloride solution in order to study the potential therapeutic benefits of human mesenchymal stem cells (hMSCs) on global cerebral ischemia. hMSCs were intravenously injected into the rats 3 h after resuscitation from cardiac arrest. The effects on structural and functional outcome of hMSC were assessed at 5 h and 1, 3, and 7 days using magnetic resonance spectroscopy (MRS), histology, and cognitive functional analysis. Intravenous delivery of hMSCs reduced the Lac/Cr ratios, nuclear DNA fragmentation, neuronal loss, and elicited functional improvement compared with the control sham group. Enzyme-linked immunosorbent assay (ELISA) of the hippocampus revealed an increase in BDNF in hMSC-treated group. These data suggest that intravenous delivery of hMSC may have a therapeutic effect in global cerebral ischemia.

Chapter 22: Transplantation of olfactory ensheathing cells for peripheral nerve regeneration

Peripheral nerve injury is a common clinical problem, and the development of novel strategies to enhance peripheral nerve regeneration is important. Traumatic events, including motor vehicle accidents, sports-related injuries, violence, and falls, lead to significant numbers of peripheral nerve lesions. Traumatic nerve injuries are often associated with life-threatening injuries, which must be treated first. During the delay in nerve repair, the transected nerves undergo Wallerian degeneration. Therefore, delay before surgical treatment is critical, but care must also be taken to ensure that nerve reapposition is performed in a manner that will result in a therapeutic benefit. Peripheral nerve repair after transection injury combined with transplantation of myelin-forming glia cells, for example, Schwann cells (SCs) or olfactory ensheathing cells (OECs), may facilitate the regenerative process. Cell-based therapies are being considered in clinical trials for a number of neurological diseases, including multiple sclerosis, spinal cord injury, Parkinson's disease, and stroke. The rationale is that transplanted cells may provide neuroprotection by production of chemokines and neurotrophins or could serve as a replacement therapy. A number of cells derived from adult peripheral tissues for cell therapies are also being actively investigated. These cells include SCs from peripheral nerve, olfactory OECs from the olfactory system, and stromal cells from bone marrow (mesenchymal stem cells, MSCs). In principle, these cells could be derived autologously, and used acutely or expanded in culture and used for cell-based therapies. Here, we review experimental work demonstrating the potential of one of these cells, the OEC, as an experimental tool for promoting recovery in peripheral nerve injury.

Optimization of a therapeutic protocol for intravenous injection of human mesenchymal stem cells after cerebral ischemia in adult rats

The systemic injection of human mesenchymal stem cells (hMSCs) prepared from adult bone marrow has therapeutic benefits after cerebral artery occlusion in rats, and may have multiple therapeutic effects at various sites and times within the lesion as the cells respond to a particular pathological microenvironment. However, the comparative therapeutic benefits of multiple injections of hMSCs at different time points after cerebral artery occlusion in rats remain unclear. In this study, we induced middle cerebral artery occlusion (MCAO) in rats using intra-luminal vascular occlusion, and infused hMSCs intravenously at a single 6 h time point (low and high cell doses) and various multiple time points after MCAO. From MRI analyses lesion volume was reduced in all hMSC cell injection groups as compared to serum alone injections. However, the greatest therapeutic benefit was achieved following a single high cell dose injection at 6 h post-MCAO, rather than multiple lower cell infusions over multiple time points. Three-dimensional analysis of capillary vessels in the lesion indicated that the capillary volume was equally increased in all of the cell-injected groups. Thus, differences in functional outcome in the hMSC transplantation subgroups are not likely the result of differences in angiogenesis, but rather from differences in neuroprotective effects.

Mesenchymal stem cells derived from peripheral blood protects against ischemia

Intravenous delivery of mesenchymal stem cells (MSCs) prepared from bone marrow (BMSCs) reduces infarction volume and ameliorates functional deficits in a rat cerebral ischemia model. MSC-like multipotent precursor cells (PMSCs) have also been suggested to exist in peripheral blood. To test the hypothesis that treatment with PMSCs may have a therapeutic benefit in stroke, we compared the efficacy of systemic delivery of BMSCs and PMSCs. A permanent middle cerebral artery occlusion (MCAO) in rat was induced by intraluminal vascular occlusion with a microfilament. Rat BMSCs and PMSCs were prepared in culture and intravenously injected into the rats 6 h after MCAO. Lesion size was assessed at 6 h, and 1, 3, and 7 days using MR imaging and histology. The hemodynamic change of cerebral blood perfusion on stroke was assessed the same times using perfusion-weighted image (PWI). Functional outcome was assessed using the treadmill stress test. Both BMSCs and PMSCs treated groups had reduced lesion volume, improved regional cerebral blood flow, and functional improvement compared to the control group. The therapeutic benefits of both MSC-treated groups were similar. These data suggest that PMSCs derived from peripheral blood could be an important cell source of cell therapy for stroke.

Intravenous infusion of immortalized human mesenchymal stem cells protects against injury in a cerebral ischemia model in adult rat

Intravenous infusion of bone marrow cells has demonstrated therapeutic efficacy in animal models of cerebral ischemia and spinal cord injury. We intravenously delivered human mesenchymal stem cells (SH2+, SH3+, CD34-, and CD45-) immortalized with a human-telomerase gene (hTERT-MSCs) and transfected with eGFP or LacZ into rats 12 h after induction of transient middle cerebral artery occlusion (MCAO), to study their potential therapeutic benefit. hTERT-MSCs were delivered at 12 h after lesion induction. Lesion size was assessed using MR imaging and spectroscopy, and histological methods. Functional outcome was assessed using the Morris water maze and a treadmill test. Intravenous delivery of hTERT-MSCs reduced lesion volume and the magnitude of the reduction and functional improvement was positively correlated with the number of cells injected. The reduction of lesion size could be assessed in vivo with MRI and MRS and was correlated with subsequent histological examination of the brain. This work demonstrates that highly purified hTERT-MSCs reduce cerebral infarction volume and improve functional outcome.

A therapeutic window for intravenous administration of autologous bone marrow after cerebral ischemia in adult rats

The primary objective of this study was to test the hypothesis that intravenous administration of autologous bone marrow cells could improve functional recovery after middle cerebral artery occlusion (MCAO) for 45 min in the rat and to determine specific time windows for efficacy. Mononuclear cells from autologous bone marrow were transfected with the LacZ reporter gene, and injected intravenously into rats at 3-72 h after induction of MCAO. Histological analysis of the ischemic lesion at 14 days after transplantation revealed reduced ischemic lesion volume. Lesion volume was 250+/-45 mm(3) (n=6) after MCAO without cell transplantation. Lesions were minimally detected by absence of 2,3,5-triphenyltetrazolium chloride (TTC) staining when bone marrow cells were infused 3 h after lesion induction. Lesions were clearly detected beginning with the 6-h postlesion group and became progressively larger at 12, 24 and 72 h (80+/-25, 140+/-18, and 180+/-22 mm(3), respectively; n=6 for each group). Transplanted LacZ(+) bone marrow cells accumulated extensively in and around the ischemic lesions, and immunohistochemistry suggests some neuronal and glial lineage differentiation. Behavioral testing (Morris water maze and Treadmill stress test) indicated greater functional recovery in the treated group. These findings suggest that early intervention with intravenous administration of autologous mononuclear cells from bone marrow can reduce lesion size in the MCAO model in the rat, and improve functional outcome.