Peripheral nerve repair with cultured schwann cells: getting closer to the clinics.

Peripheral nerve injuries are a frequent and disabling condition, which affects 13 to 23 per 100.000 persons each year. Severe cases, with structural disruption of the nerve, are associated with poor functional recovery. The experimental treatment using nerve grafts to replace damaged or shortened axons is limited by technical difficulties, invasiveness, and mediocre results. Other therapeutic choices include the adjunctive application of cultured Schwann cells and nerve conduits to guide axonal growth. The bone marrow is a rich source of mesenchymal cells, which can be differentiated in vitro into Schwann cells and subsequently engrafted into the damaged nerve. Alternatively, undifferentiated bone marrow mesenchymal cells can be associated with nerve conduits and afterward transplanted. Experimental studies provide evidence of functional, histological, and electromyographical improvement following transplantation of bone-marrow-derived cells in animal models of peripheral nerve injury. This paper focuses on this new therapeutic approach highlighting its direct translational and clinical utility in promoting regeneration of not only acute but perhaps also chronic cases of peripheral nerve damage.

Toward personalized cell therapies: autologous menstrual blood cells for stroke.

Cell therapy has been established as an important field of research with considerable progress in the last years. At the same time, the progressive aging of the population has highlighted the importance of discovering therapeutic alternatives for diseases of high incidence and disability, such as stroke. Menstrual blood is a recently discovered source of stem cells with potential relevance for the treatment of stroke. Migration to the infarct site, modulation of the inflammatory reaction, secretion of neurotrophic factors, and possible differentiation warrant these cells as therapeutic tools. We here propose the use of autologous menstrual blood cells in the restorative treatment of the subacute phase of stroke. We highlight the availability, proliferative capacity, pluripotency, and angiogenic features of these cells and explore their mechanistic pathways of repair. Practical aspects of clinical application of menstrual blood cells for stroke will be discussed, from cell harvesting and cryopreservation to administration to the patient.

Permeating the blood brain barrier and abrogating the inflammation in stroke: implications for stroke therapy.

Cell therapy has been shown as a potential treatment for stroke and other neurological disorders. Human umbilical cord blood (HUCB) may be a promising source of stem cells for cell therapy. The most desired outcomes occur when stem cells cross the blood brain barrier (BBB) and eventually reach the injured brain site. We propose, from our previous studies, that mannitol is capable of disrupting the BBB, allowing the transplanted cells to enter the brain from the periphery. However, when the BBB is compromised, the inflammatory response from circulation may also be able to penetrate the brain and thus may actually exacerbate the stroke rather than afford therapeutic effects. We discuss how an NF-kB decoy can inhibit the inflammatory responses in the stroke brain thereby reducing the negative effects associated with BBB disruption. In this review, we propose the combination of mannitol-induced BBB permeation and NF-kB decoy for enhancing the therapeutic benefits of cell therapy in stroke.

Immediate, but not delayed, microsurgical skull reconstruction exacerbates brain damage in experimental traumatic brain injury model.

Moderate to severe traumatic brain injury (TBI) often results in malformations to the skull. Aesthetic surgical maneuvers may offer normalized skull structure, but inconsistent surgical closure of the skull area accompanies TBI. We examined whether wound closure by replacement of skull flap and bone wax would allow aesthetic reconstruction of the TBI-induced skull damage without causing any detrimental effects to the cortical tissue. Adult male Sprague-Dawley rats were subjected to TBI using the controlled cortical impact (CCI) injury model. Immediately after the TBI surgery, animals were randomly assigned to skull flap replacement with or without bone wax or no bone reconstruction, then were euthanized at five days post-TBI for pathological analyses. The skull reconstruction provided normalized gross bone architecture, but 2,3,5-triphenyltetrazolium chloride and hematoxylin and eosin staining results revealed larger cortical damage in these animals compared to those that underwent no surgical maneuver at all. Brain swelling accompanied TBI, especially the severe model, that could have relieved the intracranial pressure in those animals with no skull reconstruction. In contrast, the immediate skull reconstruction produced an upregulation of the edema marker aquaporin-4 staining, which likely prevented the therapeutic benefits of brain swelling and resulted in larger cortical infarcts. Interestingly, TBI animals introduced to a delay in skull reconstruction (i.e., 2 days post-TBI) showed significantly reduced edema and infarcts compared to those exposed to immediate skull reconstruction. That immediate, but not delayed, skull reconstruction may exacerbate TBI-induced cortical tissue damage warrants a careful consideration of aesthetic repair of the skull in TBI.

A Step-up Approach for Cell Therapy in Stroke: Translational Hurdles of Bone Marrow-Derived Stem Cells.

Stroke remains a significant unmet condition in the USA and throughout the world. To date, only approximately 3% of the population suffering an ischemic stroke benefit from the thrombolytic drug tissue plasminogen activator, largely due to the drug's narrow therapeutic window. The last decade has witnessed extensive laboratory studies suggesting the therapeutic potential of cell-based therapy for stroke. Limited clinical trials of cell therapy in stroke patients are currently being pursued. Bone marrow-derived stem cells are an attractive, novel transplantable cell source for stroke. There remain many unanswered questions in the laboratory before cell therapy can be optimized for transplantation in the clinical setting. Here, we discuss the various translational hurdles encountered in bringing cell therapy from the laboratory to the clinic, using stem cell therapeutics as an emerging paradigm for stroke as a guiding principle. In particular, we focus on the preclinical studies of cell transplantation in experimental stroke with emphasis on a better understanding of mechanisms of action in an effort to optimize efficacy and to build a safety profile for advancing cell therapy to the clinic. A forward looking strategy of combination therapy involving stem cell transplantation and pharmacologic treatment is also discussed.

Cerebral aneurysm as an exacerbating factor in stroke pathology and a therapeutic target for neuroprotection.

Stroke remains a major cause of death in the US and around the world. Despite major scientific advances in our understanding of stroke pathology, the only FDA-approved drug for ischemic stroke is tissue plasminogen activator (tPA). Moreover, the therapeutic window for tPA is confined to the acute phase of stroke, thereby greatly limiting its benefits to less than 3% of ischemic stroke patients. Many treatment strategies for stroke have targeted the subacute or chronic phase in an effort to abrogate the secondary cell death that ensues after the initial stroke insult. Here, we advance the hypothesis that blood vessel disruption, or aneurysm, in the brain is an exacerbating factor for stroke, especially in the evolution of the penumbra or peri-infarct area. A better understanding of aneurysm, specifically its dynamic onset and juxtaposition to the ischemic brain tissue should facilitate the development of novel strategies for attenuating the secondary cell death associated with stroke. To this end, we discuss the laboratory and clinical evidence implicating aneurysm formation in stroke and also provide insights on how stem cell therapy may prove efficacious in combating aneurysm and stroke.

Cell therapy for stroke: emphasis on optimizing safety and efficacy profile of endothelial progenitor cells.

Endothelial progenitor cells (EPCs) correspond to a population of cells with novel properties capable of angiogenesis and vasculogenesis, thus they are likely to display unique role in the reconstitution of the blood brain barrier (BBB) after stroke. Laboratory evidence supports safety and efficacy of cell therapy for stroke, with limited clinical trials recently initiated. This lab-to-clinic ascent of cell-based therapeutics has been aided by the establishment of consortium consisting of thought-leaders from academia, industry, National Institutes of Health (NIH) and the United States Food and Drug Administration (FDA). However, there remain unanswered questions prior to realization of large-scale application of cell transplantation in patients. This review article discusses translational challenges associated in cell therapy, emphasizing the need for optimizing both safety and efficacy profiles for advancing the clinical applications of EPC transplantation for stroke patients.

Intravenous grafts of amniotic fluid-derived stem cells induce endogenous cell proliferation and attenuate behavioral deficits in ischemic stroke rats.

We recently reported isolation of viable rat amniotic fluid-derived stem (AFS) cells [1]. Here, we tested the therapeutic benefits of AFS cells in a rodent model of ischemic stroke. Adult male Sprague-Dawley rats received a 60-minute middle cerebral artery occlusion (MCAo). Thirty-five days later, animals exhibiting significant motor deficits received intravenous transplants of rat AFS cells or vehicle. At days 60-63 post-MCAo, significant recovery of motor and cognitive function was seen in stroke animals transplanted with AFS cells compared to vehicle-infused stroke animals. Infarct volume, as revealed by hematoxylin and eosin (H&E) staining, was significantly reduced, coupled with significant increments in the cell proliferation marker, Ki67, and the neuronal marker, MAP2, in the dentate gyrus (DG) [2] and the subventricular zone (SVZ) of AFS cell-transplanted stroke animals compared to vehicle-infused stroke animals. A significantly higher number of double-labeled Ki67/MAP2-positive cells and a similar trend towards increased Ki67/MAP2 double-labeling were observed in the DG and SVZ of AFS cell-transplanted stroke animals, respectively, compared to vehicle-infused stroke animals. This study reports the therapeutic potential of AFS cell transplantation in stroke animals, possibly via enhancement of endogenous repair mechanisms.

Menstrual blood transplantation for ischemic stroke: Therapeutic mechanisms and practical issues.

Cerebrovascular diseases are a major cause of death and long-term disability in developed countries. Tissue plasmin activator (tPA) is the only approved therapy for ischemic stroke, strongly limited by the short therapeutic window and hemorrhagic complications, therefore excluding most patients from its benefits. The rescue of the penumbra area of the ischemic infarct is decisive for functional recovery after stroke. Inflammation is a key feature in the penumbra area and it plays a dual role, improving injury in early phases but impairing neural survival at later stages. Stem cells can be opportunely used to modulate inflammation, abrogate cell death and, therefore, preserve neural function. We here discuss the possible role of stem cells derived from menstrual blood as restorative treatment for stroke. We highlight the availability, proliferative capacity, pluripotentiality and angiogenic features of these cells and explore their present and future experimental and clinical applications.

Nestin overexpression precedes caspase-3 upregulation in rats exposed to controlled cortical impact traumatic brain injury.

Our understanding of biological mechanisms and treatment options for traumatic brain injury (TBI) is limited. Here, we employed quantitative real-time PCR (QRT-PCR) and immunohistochemical analyses to determine the dynamic expression of cell proliferation and apoptosis in an effort to provide insights into the therapeutic window for developing regenerative strategies for TBI. For this purpose, young adult Sprague-Dawley rats were subjected to experimental TBI using a controlled cortical impactor, then euthanized 1-48 hours after TBI for QRT-PCR and immunohistochemistry. QRT-PCR revealed that brains from TBI exposed rats initially displayed nestin mRNA expression that modestly increased as early as 1-hour post-TBI, then significantly peaked at 8 hours, but thereafter reverted to pre-TBI levels. On the other hand, caspase-3 mRNA expression was slightly elevated at 8 hours post-TBI, which did not become significantly upregulated until 48 hours. Immunofluorescent microscopy revealed a significant surge in nestin immunoreactive cells in the cortex, corpus callosum, and subventricular zone at 24 hours post-TBI, whereas a significant increase in the number of active caspase-3 immunoreactive cells was only found in the cortex and not until 48 hours. These results suggest that the injured brain attempts to repair itself via cell proliferation immediately after TBI, but that this endogenous regenerative mechanism is not sufficient to abrogate the secondary apoptotic cell death. Treatment strategies designed to amplify cell proliferation and to prevent apoptosis are likely to exert maximal benefits when initiated at the acute phase of TBI.

The great migration of bone marrow-derived stem cells toward the ischemic brain: therapeutic implications for stroke and other neurological disorders.

Accumulating laboratory studies have implicated the mobilization of bone marrow (BM)-derived stem cells in brain plasticity and stroke therapy. This mobilization of bone cells to the brain is an essential concept in regenerative medicine. Over the past ten years, mounting data have shown the ability of bone marrow-derived stem cells to mobilize from BM to the peripheral blood (PB) and eventually enter the injured brain. This homing action is exemplified in BM stem cell mobilization following ischemic brain injury. Various BM-derived cells, such as hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs) and very small embryonic-like cells (VSELs) have been demonstrated to exert therapeutic benefits in stroke. Here, we discuss the current status of these BM-derived stem cells in stroke therapy, with emphasis on possible cellular and molecular mechanisms of action that mediate the cells' beneficial effects in the ischemic brain. When possible, we also discuss the relevance of this therapeutic regimen in other central nervous system (CNS) disorders.