Macrophages and inflammation play a beneficial role during wound repair with macrophages regulating a wide range of processes, such as removal of dead cells, debris and pathogens, through to extracellular matrix deposition re-vascularisation and wound re-epithelialisation. To perform this range of functions, these cells develop distinct phenotypes over the course of wound healing. They can present with a pro-inflammatory M1 phenotype, more often found in the early stages of repair, through to anti-inflammatory M2 phenotypes that are pro-repair in the latter stages of wound healing. There is a continuum of phenotypes between these ranges with some cells sharing phenotypes of both M1 and M2 macrophages. One of the less pleasant consequences of quick closure, namely the replacement with scar tissue, is also regulated by macrophages, through their promotion of fibroblast proliferation, myofibroblast differentiation and collagen deposition. Alterations in macrophage number and phenotype disrupt this process and can dictate the level of scar formation. It is also clear that dysregulated inflammation and altered macrophage phenotypes are responsible for hindering closure of chronic wounds. The review will discuss our current knowledge of macrophage phenotype on the repair process and how alterations in the phenotypes might alter wound closure and the final repair quality.

There is a vast number of treatments on the market for the management of wounds and burns, representing a multi-billion dollar industry worldwide. These include conventional wound dressings, dressings that incorporate growth factors to stimulate and facilitate the wound healing process, and skin substitutes that incorporate patient-derived cells. This article will review the more established, and the recent advances in the use of biomaterials for wound healing therapies, and their future direction.

Macrophage migration into injured or infected tissue is a key aspect in the pathophysiology of many diseases where inflammation is a driving factor.Membrane-type-1 matrix metalloproteinase (MT1-MMP) cleaves extracellular matrix components to facilitate invasion. Here we show that, unlike the constitutive MT1-MMP surface recycling seen in cancer cells, unactivated macrophages express low levels of MT1-MMP. Upon lipopolysaccharide (LPS) activation, MT1-MMP synthesis dramatically increases 10-fold at the surface by 15 hours. MT1-MMP is trafficked from the Golgi complex to the surface via late endosomes/lysosomes in a pathway regulated by the late endosome/lysosome R-SNAREs VAMP7 and VAMP8. These form two separate complexes with the surface Q-SNARE complex Stx4/SNAP23 to regulate MT1-MMP delivery to the plasma membrane. Loss of either one of these SNAREs leads to a reduction in surface MT1-MMP, gelatinase activity and reduced invasion. Thus, inhibiting MT1-MMP transport through this pathway could reduce macrophage migration and the resulting inflammation. K E Y W O R D S late endosome, macrophage, migration, MT1-MMP, SNAP23, SNARE, Stx4, VAMP7, VAMP8

The L-type voltage-gated Ca2+ channel gene CACNA1C is a risk gene for various psychiatric conditions, including schizophrenia and bipolar disorder. However, the cellular mechanism by which CACNA1C contributes to psychiatric disorders has not been elucidated. Here, we report that the embryonic deletion of Cacna1c in neurons destined for the cerebral cortex using an Emx1-Cre strategy disturbs spontaneous Ca2+ activity and causes abnormal brain development and anxiety. By combining computational modeling with electrophysiological membrane potential manipulation, we found that neural network activity was driven by intrinsic spontaneous Ca2+ activity in distinct progenitor cells expressing marginally increased levels of voltage-gated Ca2+ channels. MRI examination of the Cacna1c knockout mouse brains revealed volumetric differences in the neocortex, hippocampus, and periaqueductal gray. These results suggest that Cacna1c acts as a molecular switch and that its disruption during embryogenesis can perturb Ca2+ handling and neural development, which may increase susceptibility to psychiatric disease.

Whole-brain three-dimensional (3D) imaging is desirable to obtain a comprehensive and unbiased view of architecture and neural circuitry. However, current spatial analytic methods for brain RNAs are limited to thin sections or small samples. Here, we combined multiple new techniques to develop TRIC-DISCO, a new pipeline that allows imaging of RNA spatial distributions in whole adult mouse brains. First, we developed Tris-mediated retention of in situ hybridization signal during clearing (TRIC), which produces highly transparent tissue while maintaining the RNA signal intensities. We then combined TRIC with DISCO clearing (TRIC-DISCO) by controlling temperature during the in situ hybridization chain reaction (isHCR) to ensure uniform whole-brain staining. This pipeline eliminates the requirements for both strict RNase-free environments and workflow-compatible RNase inhibitors. Our TRIC-DISCO pipeline enables simple and robust, single-cell, whole-brain, 3D imaging of transcriptional signatures, cell-identity markers, and noncoding RNAs across the entire brain.