Role of adenosine signaling in coordinating cardiomyocyte function and coronary vascular growth in chronic fetal anemia.

Fetal anemia causes rapid and profound changes in cardiac structure and function, stimulating proliferation of the cardiac myocytes, expansion of the coronary vascular tree, and impairing early contraction and relaxation. Although hypoxia-inducible factor-1α is sure to play a role, adenosine, a metabolic byproduct that increases coronary flow and growth, is implicated as a major stimulus for these adaptations. We hypothesized that genes involved in myocardial adenosine signaling would be upregulated in chronically anemic fetuses and that calcium-handling genes would be downregulated. After sterile surgical instrumentation under anesthesia, gestationally timed fetal sheep were made anemic by isovolumetric hemorrhage for 1 wk (16% vs. 35% hematocrit). At 87% of gestation, necropsy was performed to collect heart tissue for PCR and immunohistochemical analysis. Anemia increased mRNA expression levels of adenosine receptors ADORA 1, ADORA2A, and ADORA2B in the left and right ventricles (adenosine receptor ADORA3 was unchanged). In both ventricles, anemia also increased expression of ectonucleoside triphosphate diphosphohydrolase 1 and ecto-5'-nucleotidase. The genes for both equilibrative nucleoside transporters 1 and 2 were expressed more abundantly in the anemic right ventricle but were not different in the left ventricle. Neither adenosine deaminase nor adenosine kinase cardiac levels were significantly changed by chronic fetal anemia. Chronic fetal anemia did not significantly change cardiac mRNA expression levels of the voltage-dependent L-type calcium channel, ryanodine receptor 1, sodium-calcium exchanger, sarcoplasmic/endoplasmic reticulum calcium transporting ATPase 2, phospholamban, or cardiac calsequestrin. These data support local metabolic integration of vascular and myocyte function through adenosine signaling in the anemic fetal heart.

CCL20 Is Associated with Neurodegeneration Following Experimental Traumatic Brain Injury and Promotes Cellular Toxicity In Vitro.

Traumatic brain injury (TBI) is complex and involves multiple processes that contribute to functional decline. Progressive neuropathies result from delayed cellular death following the initial impact. Although the precise mechanisms responsible for delayed injury are unknown, numerous data implicate a role for the peripheral immune system in perpetuating neuroinflammation after TBI. A previous report demonstrated that splenic CCL20 chemokine expression was upregulated 24 h after lateral fluid percussive impact (LFPI), prior to neuronal expression but consistent with neurodegeneration. Here, we expand on those data to report increased CCL20 protein expression in white matter 48 h after LFPI and demonstrate that CCL20 is directly toxic to primary neurons and oligodendrocytes subjected to oxygen glucose deprivation. The temporal expression profile of CCL20, coupled with in vitro toxicity to primary cells, suggests that this chemokine exerts deleterious effects on cell viability following TBI. These findings warrant further investigations into the use of CCL20 as a potential biomarker and/or therapeutic target.

Increased neuronal proliferation in the dentate gyrus of aged rats following neural stem cell implantation.

It is now well accepted that the brain is able to generate newborn neurons from a population of resident multipotential neural stem cells (NSCs) located in two discrete regions of the brain. The capacity for neurogenesis appears to diminish over the lifespan of an organism. Methods to potentiate the proliferation of new neuronal or glial cells within the central nervous system from resident NSCs could have therapeutic potential following an insult, such as stroke, or to replace lost cells as a result of a neurodegenerative disease. We implanted cells from a human NSC cell line, CTX0E03, originally derived from fetal cortical tissue directly into the ventricles of aged rats. CTX0E03 cells have angiogenic properties via secretion of growth factors, so we investigated if the implanted cells would stimulate proliferation of NSCs within the subgranular zone (SGZ) of the dentate gyrus. Bromodeoxyuridine staining demonstrated significantly increased proliferation in the SGZ. Absence of double labeling for human nuclear antigen suggested that the increased proliferation was from endogenous neural progenitor cells. The acute treatment also led to an increased number of immature neurons as demonstrated by immunohistochemical staining for the immature neuronal marker doublecortin. The data suggest that implants of exogenous NSCs may promote regeneration in aging organisms through stimulation of endogenous neurogenesis.

Methodological study investigating long term laser Doppler measured cerebral blood flow changes in a permanently occluded rat stroke model.

Cerebral blood flow is impaired during middle cerebral artery occlusion in the rat model of stroke. However, the long term effects on cerebral blood flow following occlusion have received little attention. We examined cerebral blood flow in both sides at multiple time points following middle cerebral artery occlusion of the rat. The bilateral cerebral blood flow in young male Sprague Dawley rats was measured at the time of occlusion, as well as 4, 10 and 16 weeks after occlusion. Under the present experimental conditions, the difference between the left and right side's cerebral blood flow was observed to appear to switch in direction in a visual oscillatory fashion over time in the sham-treated group, whereas the occluded animals consistently showed left side dominance. One group of rats was intraparenchymally transplanted with a human neural stem cell line (CTX0E03 cells) known to have benefit in stroke models. Cerebral blood flow in the lesioned side of the cell-treated group was observed to be improved compared to the untreated rats and to demonstrate a similar oscillatory nature as that observed in sham-treated animals. These findings suggest that multiple bilateral monitoring of cerebral blood flow over time can show effects of stem cell transplantation efficiently as well as functional tests in an animal stroke model.

Inflammation and stem cell migration to the injured brain in higher organisms.

Current treatments of neurological disorders such as Parkinson's disease and stroke are only partially effective. Consequently new therapies such as cell transplantation are of great interest. Cell therapy has shown promising results in animal models and in limited clinical trials. This form of treatment does have its own concerns, such as what factors control the survival and/or migration of the transplanted cells and how do they exert their benefit. Recent studies on tracking the transplants, such as prelabeling of the cells prior to transplant, and those elucidating the role of chemokines, as well as microglial and inflammatory responses, that may initiate the movement and survival of these cells are discussed in this review. A better understanding of these mechanism-driven pathways of neural repair will facilitate the clinical application of cell therapy for neurological disorders.