Traumatic brain injury promotes neurogenesis at the cost of astrogliogenesis in the adult hippocampus of male mice.

Traumatic brain injury (TBI) can result in long-lasting changes in hippocampal function. The changes induced by TBI on the hippocampus contribute to cognitive deficits. The adult hippocampus harbors neural stem cells (NSCs) that generate neurons (neurogenesis), and astrocytes (astrogliogenesis). While deregulation of hippocampal NSCs and neurogenesis have been observed after TBI, it is not known how TBI may affect hippocampal astrogliogenesis. Using a controlled cortical impact model of TBI in male mice, single cell RNA sequencing and spatial transcriptomics, we assessed how TBI affected hippocampal NSCs and the neuronal and astroglial lineages derived from them. We observe an increase in NSC-derived neuronal cells and a concomitant decrease in NSC-derived astrocytic cells, together with changes in gene expression and cell dysplasia within the dentate gyrus. Here, we show that TBI modifies NSC fate to promote neurogenesis at the cost of astrogliogenesis and identify specific cell populations as possible targets to counteract TBI-induced cellular changes in the adult hippocampus.

Circadian glucocorticoid oscillations preserve a population of adult hippocampal neural stem cells in the aging brain.

A decrease in adult hippocampal neurogenesis has been linked to age-related cognitive impairment. However, the mechanisms involved in this age-related reduction remain elusive. Glucocorticoid hormones (GC) are important regulators of neural stem/precursor cells (NSPC) proliferation. GC are released from the adrenal glands in ultradian secretory pulses that generate characteristic circadian oscillations. Here, we investigated the hypothesis that GC oscillations prevent NSPC activation and preserve a quiescent NSPC pool in the aging hippocampus. We found that hippocampal NSPC populations lacking expression of the glucocorticoid receptor (GR) decayed exponentially with age, while GR-positive populations decayed linearly and predominated in the hippocampus from middle age onwards. Importantly, GC oscillations controlled NSPC activation and GR knockdown reactivated NSPC proliferation in aged mice. When modeled in primary hippocampal NSPC cultures, GC oscillations control cell cycle progression and induce specific genome-wide DNA methylation profiles. GC oscillations induced lasting changes in the methylation state of a group of gene promoters associated with cell cycle regulation and the canonical Wnt signaling pathway. Finally, in a mouse model of accelerated aging, we show that disruption of GC oscillations induces lasting changes in dendritic complexity, spine numbers and morphology of newborn granule neurons. Together, these results indicate that GC oscillations preserve a population of GR-expressing NSPC during aging, preventing their activation possibly by epigenetic programming through methylation of specific gene promoters. Our observations suggest a novel mechanism mediated by GC that controls NSPC proliferation and preserves a dormant NSPC pool, possibly contributing to a neuroplasticity reserve in the aging brain.

Cardiac transplantation from a carbon monoxide intoxicated donor.

Heart transplantation is a demonstrated successful and life-saving treatment for an increasing number of patients. The growth of heart transplantation surgery is limited by the relative lack of suitable donors, and the increasing demand has lead to the expansion of acceptance criteria. Patients succumbing to carbon monoxide (CO) poisoning are usually considered not suitable organ donors and they are routinely rejected in many centers. Although organs from CO poisoning donors have been occasionally used, cardiac transplantation in this scenario remains very uncommon. We report the successful heart transplantation from a CO intoxicated donor, who was previously refused by two other transplantation teams. Standard donor evaluation criteria, transplantation techniques and management were used. Limited cases are described in literature. The present case may increase awareness among emergency department physicians, as well as transplantations teams, that patients dying of CO exposure may be acceptable cardiac donors.

Heart transplantation in patients with Emery-Dreifuss muscular dystrophy: case reports.

Emery-Dreifuss muscular dystrophy (EDMD) is an hereditary syndrome characterized by slow but progressive locomotor involvement and cardiomyopathy. Cardiac impairment is often the life-limiting feature of the illness. Only a few cases of cardiac transplantation have been reported previously in muscular dystrophy, and only 4 cases of end-stage disease due to EDMD have been treated previously with heart transplantation. Herein we have reported our experince with 2 consecutive patients who underwent heart transplantation for EDMD cardiomyopathy.

Amyloid deposition as a cause of atrial remodelling in persistent valvular atrial fibrillation.

AIM: The spectrum of histological alterations, namely atrial amyloidosis, in the right and left atria of patients with chronic persistent atrial fibrillation (AF) and rheumatic heart disease is not completely known. METHODS AND RESULTS: One hundred and twenty-eight atrial appendages (66 left and 62 right), obtained from 72 patients with rheumatic valve disease and chronic AF undergoing cardiac surgery for valve replacement or repair and AF treatment were histologically evaluated for the presence of amyloid deposits. One hundred and four specimens of left and right auricles from 52 patients in sinus rhythm with severe chronic heart failure undergoing heart transplant were also analyzed (controls). Amyloid was found in 33 (46%) valvular patients with chronic persistent AF and in 6 (12%) controls. Amyloid was related to the presence and duration of AF, was more frequently found in left atrial samples and was independent of age. On stepwise logistic regression analysis, AF duration and female gender were independently related to amyloid deposition. CONCLUSIONS: Patients with long-standing AF and rheumatic heart disease have a very high prevalence of atrial amyloidosis. Amyloid deposition is more frequent in left than in right atrial appendage and correlates with AF duration and female gender. Amyloid deposition could constitute an additional histological feature in the structural remodeling of atria during long-standing AF, at least in rheumatic valve disease. Persistence of AF might play a pivotal role in promoting amyloid deposition.