Early born neurons are abnormally positioned in the doublecortin knockout hippocampus

Human doublecortin (DCX) mutations are associated with severe brain malformations leading to aberrant neuron positioning (heterotopia), intellectual disability and epilepsy. The Dcx protein plays a key role in neuronal migration, and hippocampal pyramidal neurons in Dcx knockout (KO) mice are disorganized. The single CA3 pyramidal cell layer observed in wild type (WT) is present as two abnormal layers in the KO, and CA3 KO pyramidal neurons are more excitable than WT. Dcx KO mice also exhibit spontaneous epileptic activity originating in the hippocampus. It is unknown, however, how hyperexcitability arises and why two CA3 layers are observed.Transcriptome analyses were performed to search for perturbed postnatal gene expression, comparing Dcx KO CA3 pyramidal cell layers with WT. Gene expression changes common to both KO layers indicated mitochondria and Golgi apparatus anomalies, as well as increased cell stress. Intriguingly, gene expression analyses also suggested that the KO layers differ significantly from each other, particularly in terms of maturity. Layer-specific molecular markers and BrdU birthdating to mark the final positions of neurons born at distinct timepoints revealed inverted layering of the CA3 region in Dcx KO animals. Notably, many early-born 'outer boundary' neurons are located in an inner position in the Dcx KO CA3, superficial to other pyramidal neurons. This abnormal positioning likely affects cell morphology and connectivity, influencing network function. Dissecting this Dcx KO phenotype sheds light on coordinated developmental mechanisms of neuronal subpopulations, as well as gene expression patterns contributing to a bi-layered malformation associated with epilepsy.

Organelle and cellular abnormalities associated with hippocampal heterotopia in neonatal doublecortin knockout mice

Heterotopic or aberrantly positioned cortical neurons are associated with epilepsy and intellectual disability. Various mouse models exist with forms of heterotopia, but the composition and state of cells developing in heterotopic bands has been little studied. Dcx knockout (KO) mice show hippocampal CA3 pyramidal cell lamination abnormalities, appearing from the age of E17.5, and mice suffer from spontaneous epilepsy. The Dcx KO CA3 region is organized in two distinct pyramidal cell layers, resembling a heterotopic situation, and exhibits hyperexcitability. Here, we characterized the abnormally organized cells in postnatal mouse brains. Electron microscopy confirmed that the Dcx KO CA3 layers at postnatal day (P) 0 are distinct and separated by an intermediate layer devoid of neuronal somata. We found that organization and cytoplasm content of pyramidal neurons in each layer were altered compared to wild type (WT) cells. Less regular nuclei and differences in mitochondria and Golgi apparatuses were identified. Each Dcx KO CA3 layer at P0 contained pyramidal neurons but also other closely apposed cells, displaying different morphologies. Quantitative PCR and immunodetections revealed increased numbers of oligodendrocyte precursor cells (OPCs) and interneurons in close proximity to Dcx KO pyramidal cells. Immunohistochemistry experiments also showed that caspase-3 dependent cell death was increased in the CA1 and CA3 regions of Dcx KO hippocampi at P2. Thus, unsuspected ultrastructural abnormalities and cellular heterogeneity may lead to abnormal neuronal function and survival in this model, which together may contribute to the development of hyperexcitability.

Modulation of inflammation by Cicaderma ointment accelerates skin wound healing

Skin wound healing is a natural and intricate process that takes place after injury, involving different sequential phases such as hemostasis, inflammatory phase, proliferative phase, and remodeling that are associated with complex biochemical events. The interruption or failure of wound healing leads to chronic nonhealing wounds or fibrosis-associated diseases constituting a major health problem where, unfortunately, medicines are not very effective. The objective of this study was to evaluate the capacity of Cicaderma ointment (Boiron, Lyon, France) to accelerate ulcer closure without fibrosis and investigate wound healing dynamic processes. We used a necrotic ulcer model in mice induced by intradermal doxorubicin injection, and after 11 days, when the ulcer area was maximal, we applied Vaseline petroleum jelly or Cicaderma every 2 days. Topical application of Cicaderma allowed a rapid recovery of mature epidermal structure, a more compact and organized dermis and collagen bundles compared with the Vaseline group. Furthermore, the expression of numerous cytokines/molecules in the ulcer was increased 11 days after doxorubicin injection compared with healthy skin. Cicaderma rapidly reduced the level of proinflammatory cytokines, mainly tumor necrosis factor (TNF)-α and others of the TNF pathway, which can be correlated to a decrease of polymorphonuclear recruitment. It is noteworthy that the modulation of inflammation through TNF-α, macrophage inflammatory protein-1α, interleukin (IL)-12, IL-4, and macrophage-colony-stimulating factor was maintained 9 days after the first ointment application, facilitating the wound closure without affecting angiogenesis. These cytokines seem to be potential targets for therapeutic approaches in chronic wounds. Our results confirm the use of Cicaderma for accelerating skin wound healing and open new avenues for sequential treatments to improve healing.