Wound healing reaction: A switch from gestation to senescence

Brain Injury: Response to Injury Wound-Healing Mechanisms and Enlarged Perivascular Spaces in Obesity, Metabolic Syndrome, and Type 2 Diabetes Mellitus

Embryonic genetic mechanisms are present in the brain and ready to be placed into action upon cellular injury, termed the response to injury wound-healing (RTIWH) mechanism. When injured, regional brain endothelial cells initially undergo activation and dysfunction with initiation of hemostasis, inflammation (peripheral leukocytes, innate microglia, and perivascular macrophage cells), proliferation (astrogliosis), remodeling, repair, and resolution phases if the injurious stimuli are removed. In conditions wherein the injurious stimuli are chronic, as occurs in obesity, metabolic syndrome, and type 2 diabetes mellitus, this process does not undergo resolution and there is persistent RTIWH with remodeling. Indeed, the brain is unique, in that it utilizes its neuroglia: the microglia cell, along with peripheral inflammatory cells and its astroglia, instead of peripheral scar-forming fibrocytes/fibroblasts. The brain undergoes astrogliosis to form a gliosis scar instead of a fibrosis scar to protect the surrounding neuropil from regional parenchymal injury. One of the unique and evolving remodeling changes in the brain is the development of enlarged perivascular spaces (EPVSs), which is the focus of this brief review. EPVSs are important since they serve as a biomarker for cerebral small vessel disease and also represent an impairment of the effluxing glymphatic system that is important for the clearance of metabolic waste from the interstitial fluid to the cerebrospinal fluid, and disposal. Therefore, it is important to better understand how the RTIWH mechanism is involved in the development of EPVSs that are closely associated with and important to the development of premature and age-related cerebrovascular and neurodegenerative diseases with impaired cognition.

Natural TEMPO oxidized cellulose nano fiber/alginate/dSECM hybrid aerogel with improved wound healing and hemostatic ability

Natural biopolymers have attracted considerable attention in a variety of biomedical applications. Herein, tempo-oxidized-cellulose nanofibers (T) were incorporated into sodium alginate/chitosan (A/C) to reinforce the physicochemical properties and further modified with decellularized skin extracellular matrix (E). A unique ACTE aerogel was successfully prepared, and its nontoxic behavior was validated using mouse fibroblast L929 cells. In vitro hemolysis results revealed excellent platelet adhesion and fibrin network formation abilities of the obtained aerogel. A high speed of homeostasis was attained based on the quick clotting in <60 s. Skin regeneration in vivo experiments were conducted using the ACT1E0 and ACT1E10 groups. In comparison to ACT1E0 samples, ACT1E10 samples demonstrated enhanced skin wound healing with increased neo-epithelialization, increased collagen deposition, and extracellular matrix remodeling. ACT1E10 was found to be a promising aerogel for skin defect regeneration due to its improved wound-healing ability.

Transcriptomic analyses of gastrulation-stage mouse embryos with differential susceptibility to alcohol

Genetics are a known contributor to differences in alcohol sensitivity in humans with fetal alcohol spectrum disorders (FASDs) and in animal models. Our study profiled gene expression in gastrulation-stage embryos from two commonly used, genetically similar mouse substrains, C57BL/6J (6J) and C57BL/6NHsd (6N), that differ in alcohol sensitivity. First, we established normal gene expression patterns at three finely resolved time points during gastrulation and developed a web-based interactive tool. Baseline transcriptional differences across strains were associated with immune signaling. Second, we examined the gene networks impacted by alcohol in each strain. Alcohol caused a more pronounced transcriptional effect in the 6J versus 6N mice, matching the increased susceptibility of the 6J mice. The 6J strain exhibited dysregulation of pathways related to cell death, proliferation, morphogenic signaling and craniofacial defects, while the 6N strain showed enrichment of hypoxia and cellular metabolism pathways. These datasets provide insight into the changing transcriptional landscape across mouse gastrulation, establish a valuable resource that enables the discovery of candidate genes that may modify alcohol susceptibility that can be validated in humans, and identify novel pathogenic mechanisms of alcohol. This article has an associated First Person interview with the first author of the paper.

Metabolism in Acute-On-Chronic Liver Failure: The Solution More than the Problem

Chronic inflammatory liver disease with an acute deterioration of liver function is named acute-on-chronic inflammation and could be regulated by the metabolic impairments related to the liver dysfunction. In this way, the experimental cholestasis model is excellent for studying metabolism in both types of inflammatory responses. Along the evolution of this model, the rats develop biliary fibrosis and an acute-on-chronic decompensation. The acute decompensation of the liver disease is associated with encephalopathy, ascites, acute renal failure, an acute phase response and a splanchnic increase of pro- and anti-inflammatory cytokines. This multiorgan inflammatory dysfunction is mainly associated with a splanchnic and systemic metabolic switch with dedifferentiation of the epithelial, endothelial and mesothelial splanchnic barriers. Furthermore, a splanchnic infiltration by mast cells occurs, which suggests that these cells could carry out a compensatory metabolic role, especially through the modulation of hepatic and extrahepatic mitochondrial-peroxisome crosstalk. For this reason, we propose the hypothesis that mastocytosis in the acute-on-chronic hepatic insufficiency could represent the development of a survival metabolic mechanisms that mitigates the noxious effect of the hepatic functional deficit. A better understanding the pathophysiological response of the mast cells in liver insufficiency and portal hypertension would help to find new pathways for decreasing the high morbidity and mortality rate of these patients.

Alginate in Wound Dressings

Alginate is a biopolymer used in a variety of biomedical applications due to its favourable properties, such as biocompatibility and non-toxicity. It has been particularly attractive in wound healing applications to date. It can be tailored to materials with properties suitable for wound healing. Alginate has been used to prepare different forms of materials for wound dressings, such as hydrogels, films, wafers, foams, nanofibres, and in topical formulations. The wound dressings prepared from alginate are able to absorb excess wound fluid, maintain a physiologically moist environment, and minimize bacterial infections at the wound site. The therapeutic efficacy of these wound dressings is influenced by the ratio of other polymers used in combination with alginate, the nature of cross linkers used, the time of crosslinking, nature of excipients used, the incorporation of nanoparticles, and antibacterial agents. This review provides a comprehensive overview of the different forms of wound dressings containing alginate, in vitro, and in vivo results.

Cellular senescence and liver disease: Mechanisms and therapeutic strategies

Cellular senescence is a fundamental cell fate caused by several cellular injuries which results in irreversible cell cycle arrest yet remaining metabolically active across all species. Cellular senescence not only can prevent tumor occurrence by inhibiting the proliferation of injured cells, but also can affect the surrounding cells through the senescence-associated secretory phenotype (SASP). Attractively, accumulating evidence shows that cellular senescence is closely related to various liver diseases. Therapeutic opportunities based on targeting senescent cells and the SASP are considered to be potential strategy for liver diseases. However, although research on cell senescence has attracted widespread attention, the overview on detailed mechanism and biological function of cell senescence in liver disease is still largely unknown. The present review summarizes the specific role of cell senescence in various liver diseases, and updates the molecular mechanisms underlying cell senescence. Moreover, the review also explores new strategies for prevention and treatment of liver disease through promoting senescence or counteracting excessive pathological senescence.

The gestational power of mast cells in the injured tissue

The inflammatory response expressed after wound healing would be the recapitulation of systemic extra-embryonic functions, which would focus on the interstitium of the injured tissue. In the injured tissue, mast cells, provided for a great functional heterogeneity, could play the leading role in the re-expression of extra-embryonic functions, i.e., coelomic-amniotic and trophoblastic-vitelline. Moreover, mast cells would favor the production of a gastrulation-like process, which in certain tissues and organs would induce the regeneration of the injured tissue. Therefore, the engraftment of mesenchymal stem cells and mast cells, both with an extra-embryonic regenerative phenotype, would achieve a blastema, from the repaired and regenerated injured tissue, rather than by fibrosis, which is commonly made through wound-healing.

Biologic scaffolds for regenerative medicine: mechanisms of in vivo remodeling

Successful regenerative medicine strategies for functional tissue reconstruction include the in situ placement of acellular materials composed of the extracellular matrix (ECM) or individual components of the ECM. The composition and ultrastructure of these materials vary depending on multiple factors including the tissue source and species from which the materials are harvested, the methods of manufacture, the efficiency of decellularization, post-processing modifications such as chemical cross-linking or solubilization, and the methods of terminal sterilization. Appropriately configured materials have the ability to modulate different stages of the healing response by inducing a shift from a process of inflammation and scar tissue formation to one of constructive remodeling and functional tissue restoration. The events that facilitate such a dramatic change during the biomaterial-host interaction are complex and necessarily involve both the immune system and mechanisms of stem cell recruitment, growth, and differentiation. The present manuscript reviews the composition of biologic scaffolds, the methods and recommendations for manufacture, the mechanisms of the biomaterial-host interaction, and the clinical application of this regenerative medicine approach.