RESUMO
BACKGROUND: Preclinical data and adult studies have showed an endogenous regeneration process following brain damage that involves mobilization of progenitor cells. This process is not well described in preterm neonates. The present study aims to investigate the mobilization of Circulating Progenitor Cells (CPCs) and their relation to biomarkers of brain injury in preterm neonates. METHODS: This is a prospective cohort study of preterm infants with gestational age (GA) <34 weeks. Serial cranial ultrasounds scans were performed in all neonates. Brain injury was defined by the presence of intraventricular hemorrhage grade III/IV, cystic periventricular leukomalacia or infarct. Peripheral blood samples were collected from all neonates on days(d) 1, 3, 9, 18 and 45 of life for the measurement of levels of CPCs [early and late Endothelial Progenitor Cells (EPCs), Haematopoietic Stem Cells (HSCs) and Very Small Embryonic-Like Stem Cells (VSELs)], Neuron-Specific Enolase (NSE), S100b, Erythropoietin (EPO) and Stromal Cell-Derived Factor-1 (SDF-1) . RESULTS: Ten out of the 23 preterm infants included in the study developed brain injury; the remaining thirteen infants served as controls. In the brain injury group a significant increase of HSCs (d9, d45), early EPCs (d3, d9, d18) and late EPCs (d1, d3, d9, d18, d45) was observed compared to controls. VSELs on d45 were significantly higher in controls. S100b on d1, EPO on d1, SDF-1 on d3 and NSE on d18 were significantly increased in the brain injury group. Moreover, CPCs were significantly related to S100b, NSE, EPO and SDF-1 levels at multiple time points. CONCLUSIONS: The observed pattern of CPCs mobilization and its association with biomarkers following brain injury in preterm neonates indicate the existence of an endogenous brain regeneration process. Enhancement of this process with exogenous progenitor cell transplantation might be a powerful therapeutic strategy to restore brain damage and improve the neurodevelopmental outcome in premature infants. Hippokratia 2015; 19 (2):141-147.
RESUMO
BACKGROUND: The diagnosis of Alzheimer's disease (AD) during life remains difficult and a definite diagnosis of AD relies on histopathological confirmation at post-mortem or by cerebral biopsy. It is well known that levels of tau proteins are consistently and significantly increased in the cerebrospinal fluid (CSF) of Alzheimer's patients versus levels in normal controls. However, the sole use of this biochemical marker as a test for AD is hampered by mediocre specificity, since tau concentrations may also be elevated in certain other neurological disorders (OND). Studies of the regional cerebral blood flow (rCBF) are widely performed because of their convenience and usefulness in a variety of neurological disorders. Most studies have reported high diagnostic accuracy for brain perfusion single-photon emission tomography (SPECT) in Alzheimer's disease. METHODS: In order to improve specificity, in this study, correlation of 99mTc-HMPAO SPECT scanning and CSF tau protein levels was made in 117 patients with AD, 67 patients with OND (26 of which had other dementias), and 23 age-matched controls. Means and standard deviations of tau protein levels were 297, 42 +/- 221, 12 in AD patients and 78, 07 +/- 98, 51 in patients with OND (p = 0.0006). No correlation was noted between CSF tau protein levels and age, duration of the disease, and neuropsychological scores of mini-mental state examination (MMSE), Cambridge Cognitive Examination (CAMCOG), and Functional Rating Scale for Symptoms of Dementia (FRSSD). FINDINGS: There was a bilateral parietal and temporal hypoperfusion in patients with AD in SPECT in comparison to normal subjects (p < 0.05) and there was a statistical correlation between this hypoperfusion and neuropsychological tests, such as MMSE and CAMCOG (p < 0.01). There was no correlation between tau protein levels and hypoperfusion in SPECT. INTERPRETATION: Conclusively, the correlation between elevated levels of tau proteins and hypoperfusion in SPECT in AD patients therefore cannot improve the specificity of tests in AD and this means that the determination of CSF tau proteins levels is not a specific diagnostic test for AD.