The collagen structure of C1q induces wound healing by engaging discoidin domain receptor 2

Low-temperature plasma jet suppresses bacterial colonisation and affects wound healing through reactive species

An argon-based low-temperature plasma jet (LTPJ) was used to treat chronically infected wounds in Staphylococcus aureus-laden mice. Based on physicochemical property analysis and in vitro antibacterial experiments, the effects of plasma parameters on the reactive nitrogen and oxygen species (RNOS) content and antibacterial capacity were determined, and the optimal treatment parameters were determined to be 4 standard litre per minute and 35 W. Additionally, the plasma-treated activation solution had a bactericidal effect. Although RNOS are related to the antimicrobial effect of plasma, excess RNOS may be detrimental to wound remodelling. In vivo studies demonstrated that medium-dose LTPJ promoted MMP-9 expression and inhibited bacterial growth during the early stages of healing. Moreover, LTPJ increased collagen deposition, reduced inflammation, and restored blood vessel density and TGF-β levels to normal in the later stages of wound healing. Therefore, when treating chronically infected wounds with LTPJ, selecting the medium dose of plasma is more advantageous for wound recovery. Overall, our study demonstrated that low-temperature plasma jets may be a potential tool for the treatment of chronically infected wounds.

Proangiogenic properties of complement protein C1q can contribute to endometriosis

Endometriosis (EM) is defined as the engraftment and proliferation of functional endometrial-like tissue outside the uterine cavity, leading to a chronic inflammatory condition. While the precise etiology of EM remains elusive, recent studies have highlighted the crucial involvement of a dysregulated immune system. The complement system is one of the predominantly altered immune pathways in EM. Owing to its involvement in the process of angiogenesis, here, we have examined the possible role of the first recognition molecule of the complement classical pathway, C1q. C1q plays seminal roles in several physiological and pathological processes independent of complement activation, including tumor growth, placentation, wound healing, and angiogenesis. Gene expression analysis using the publicly available data revealed that C1q is expressed at higher levels in EM lesions compared to their healthy counterparts. Immunohistochemical analysis confirmed the presence of C1q protein, being localized around the blood vessels in the EM lesions. CD68+ macrophages are the likely producer of C1q in the EM lesions since cultured EM cells did not produce C1q in vitro. To explore the underlying reasons for increased C1q expression in EM, we focused on its established pro-angiogenic role. Employing various angiogenesis assays on primary endothelial endometriotic cells, such as migration, proliferation, and tube formation assays, we observed a robust proangiogenic effect induced by C1q on endothelial cells in the context of EM. C1q promoted angiogenesis in endothelial cells isolated from EM lesions (as well as healthy ovary that is also rich in C1q). Interestingly, endothelial cells from EM lesions seem to overexpress the receptor for the globular heads of C1q (gC1qR), a putative C1q receptor. Experiments with siRNA to silence gC1qR resulted in diminished capacity of C1q to perform its angiogenic functions, suggesting that C1q is likely to engage gC1qR in the pathophysiology of EM. gC1qR can be a potential therapeutic target in EM patients that will disrupt C1q-mediated proangiogenic activities in EM.

Hydrogels in Gene Delivery Techniques for Regenerative Medicine and Tissue Engineering

Hydrogels are 3D networks swollen with water. They are biocompatible, strong, and moldable and are emerging as a promising biomedical material for regenerative medicine and tissue engineering to deliver therapeutic genes. The excellent natural extracellular matrix simulation properties of hydrogels enable them to be co-cultured with cells or enhance the expression of viral or non-viral vectors. Its biocompatibility, high strength, and degradation performance also make the action process of carriers in tissues more ideal, making it an ideal biomedical material. It has been shown that hydrogel-based gene delivery technologies have the potential to play therapy-relevant roles in organs such as bone, cartilage, nerve, skin, reproductive organs, and liver in animal experiments and preclinical trials. This paper reviews recent articles on hydrogels in gene delivery and explains the manufacture, applications, developmental timeline, limitations, and future directions of hydrogel-based gene delivery techniques.

Laminin mimetic angiogenic and collagen peptide hydrogel for enhance dermal wound healing

Laminins are essential in basement membrane architecture and critical in re-epithelialization and angiogenesis. These processes and collagen deposition are vital in skin wound healing. The role of angiogenic peptides in accelerating the wound-healing process has been known. The bioactive peptides could be a potential approach due to their similar effects as growth factors and inherent biocompatible and biodegradable nature with lower cost. They can also recognize ligand-receptor interaction and mimic the extracellular matrix. Here, we report novel angiogenic DYVRLAI, CDYVRLAI, angiogenic-collagen PGPIKVAV, and Ac-PGPIKVAV peptides conjugated sodium carboxymethyl cellulose hydrogel, which was designed from laminin. The designed peptide exhibits a better binding with the α3β1, αvβ3, and α5β1 integrins and CXCR2 receptor, indicating their angiogenic and collagen binding efficiency. The peptides were evaluated to stimulate wound healing in full-thickness excision wounds in normal and diabetic mice (type II). They demonstrated their efficacy in terms of angiogenesis (CD31), re-epithelialization through regeneration of the epidermis (H&E), and collagen deposition (MT). The synthesized peptide hydrogel (DYVRLAI and CDYVRLAI) showed enhanced wound contraction up to 10.1 % and 12.3 % on day 7th compared to standard becaplermin gel (49 %) in a normal wound model. The encouraging results were also observed with the diabetic model, where these peptides showed a significant decrease of 5.20 and 5.17 % in wound size on day 10th compared to the commercial gel (9.27 %). These outcomes signify that the modified angiogenic peptide is a cost effective, novel peptide motif to promote dermal wound healing in both models.

The role of human extracellular matrix proteins in defining Staphylococcus aureus biofilm infections

Twenty to forty one percent of the world's population is either transiently or permanently colonized by the Gram-positive bacterium, Staphylococcus aureus. In 2017, the CDC designated methicillin-resistant S. aureus (MRSA) as a serious threat, reporting ∼300 000 cases of MRSA-associated hospitalizations annually, resulting in over 19 000 deaths, surpassing that of HIV in the USA. S. aureus is a proficient biofilm-forming organism that rapidly acquires resistance to antibiotics, most commonly methicillin (MRSA). This review focuses on a large group of (>30) S. aureus adhesins, either surface-associated or secreted that are designed to specifically bind to 15 or more of the proteins that form key components of the human extracellular matrix (hECM). Importantly, this includes hECM proteins that are pivotal to the homeostasis of almost every tissue environment [collagen (skin), proteoglycans (lung), hemoglobin (blood), elastin, laminin, fibrinogen, fibronectin, and fibrin (multiple organs)]. These adhesins offer S. aureus the potential to establish an infection in every sterile tissue niche. These infections often endure repeated immune onslaught, developing into chronic, biofilm-associated conditions that are tolerant to ∼1000 times the clinically prescribed dose of antibiotics. Depending on the infection and the immune response, this allows S. aureus to seamlessly transition from colonizer to pathogen by subtly manipulating the host against itself while providing the time and stealth that it requires to establish and persist as a biofilm. This is a comprehensive discussion of the interaction between S. aureus biofilms and the hECM. We provide particular focus on the role of these interactions in pathogenesis and, consequently, the clinical implications for the prevention and treatment of S. aureus biofilm infections.

ECM-Focused Proteomic Analysis of Ear Punch Regeneration in Acomys Cahirinus

In mammals, significant injury is generally followed by the formation of a fibrotic scar which provides structural integrity but fails to functionally restore damaged tissue. Spiny mice of the genus Acomys represent the first example of full skin autotomy in mammals. Acomys cahirinus has evolved extremely weak skin as a strategy to avoid predation and is able to repeatedly regenerate healthy tissue without scar after severe skin injury or full-thickness ear punches. Extracellular matrix (ECM) composition is a critical regulator of wound repair and scar formation and previous studies have suggested that alterations in its expression may be responsible for the differences in regenerative capacity observed between Mus musculus and A. cahirinus , yet analysis of this critical tissue component has been limited in previous studies by its insolubility and resistance to extraction. Here, we utilize a 2-step ECM-optimized extraction to perform proteomic analysis of tissue composition during wound repair after full-thickness ear punches in A. cahirinus and M. musculus from weeks 1 to 4 post-injury. We observe changes in a wide range of ECM proteins which have been previously implicated in wound regeneration and scar formation, including collagens, coagulation and provisional matrix proteins, and matricryptic signaling peptides. We additionally report differences in crosslinking enzyme activity and ECM protein solubility between Mus and Acomys. Furthermore, we observed rapid and sustained increases in CD206, a marker of pro-regenerative M2 macrophages, in Acomys, whereas little or no increase in CD206 was detected in Mus. Together, these findings contribute to a comprehensive understanding of tissue cues which drive the regenerative capacity of Acomys and identify a number of potential targets for future pro-regenerative therapies.

Allele-specific expression reveals genetic drivers of tissue regeneration in mice

In adult mammals, skin wounds typically heal by scarring rather than through regeneration. In contrast, "super-healer" Murphy Roths Large (MRL) mice have the unusual ability to regenerate ear punch wounds; however, the molecular basis for this regeneration remains elusive. Here, in hybrid crosses between MRL and non-regenerating mice, we used allele-specific gene expression to identify cis-regulatory variation associated with ear regeneration. Analyzing three major cell populations (immune, fibroblast, and endothelial), we found that genes with cis-regulatory differences specifically in fibroblasts were associated with wound-healing pathways and also co-localized with quantitative trait loci for ear wound-healing. Ectopic treatment with one of these proteins, complement factor H (CFH), accelerated wound repair and induced regeneration in typically fibrotic wounds. Through single-cell RNA sequencing (RNA-seq), we observed that CFH treatment dramatically reduced immune cell recruitment to wounds, suggesting a potential mechanism for CFH's effect. Overall, our results provide insights into the molecular drivers of regeneration with potential clinical implications.

Extracellular matrix-induced signaling pathways in mesenchymal stem/stromal cells

The extracellular matrix (ECM) is a crucial component of the stem cell microenvironment, or stem-cell niches, and contributes to the regulation of cell behavior and fate. Accumulating evidence indicates that different types of stem cells possess a large variety of molecules responsible for interactions with the ECM, mediating specific epigenetic rearrangements and corresponding changes in transcriptome profile. Signals from the ECM are crucial at all stages of ontogenesis, including embryonic and postnatal development, as well as tissue renewal and repair. The ECM could regulate stem cell transition from a quiescent state to readiness to perceive the signals of differentiation induction (competence) and the transition between different stages of differentiation (commitment). Currently, to unveil the complex networks of cellular signaling from the ECM, multiple approaches including screening methods, the analysis of the cell matrixome, and the creation of predictive networks of protein-protein interactions based on experimental data are used. In this review, we consider the existing evidence regarded the contribution of ECM-induced intracellular signaling pathways into the regulation of stem cell differentiation focusing on mesenchymal stem/stromal cells (MSCs) as well-studied type of postnatal stem cells totally depended on signals from ECM. Furthermore, we propose a system biology-based approach for the prediction of ECM-mediated signal transduction pathways in target cells. Video Abstract.

Extracellular matrix and synapse formation

The extracellular matrix (ECM) is a complex molecular network distributed throughout the extracellular space of different tissues as well as the neuronal system. Previous studies have identified various ECM components that play important roles in neuronal maturation and signal transduction. ECM components are reported to be involved in neurogenesis, neuronal migration, and axonal growth by interacting or binding to specific receptors. In addition, the ECM is found to regulate synapse formation, the stability of the synaptic structure, and synaptic plasticity. Here, we mainly reviewed the effects of various ECM components on synapse formation and briefly described the related diseases caused by the abnormality of several ECM components.

C1q and central nervous system disorders

C1q is a crucial component of the complement system, which is activated through the classical pathway to perform non-specific immune functions, serving as the first line of defense against pathogens. C1q can also bind to specific receptors to carry out immune and other functions, playing a vital role in maintaining immune homeostasis and normal physiological functions. In the developing central nervous system (CNS), C1q functions in synapse formation and pruning, serving as a key player in the development and homeostasis of neuronal networks in the CNS. C1q has a close relationship with microglia and astrocytes, and under their influence, C1q may contribute to the development of CNS disorders. Furthermore, C1q can also have independent effects on neurological disorders, producing either beneficial or detrimental outcomes. Most of the evidence for these functions comes from animal models, with some also from human specimen studies. C1q is now emerging as a promising target for the treatment of a variety of diseases, and clinical trials are already underway for CNS disorders. This article highlights the role of C1q in CNS diseases, offering new directions for the diagnosis and treatment of these conditions.

Single-cell mapping of regenerative and fibrotic healing responses after musculoskeletal injury

After injury, a cascade of events repairs the damaged tissue, including expansion and differentiation of the progenitor pool and redeposition of matrix. To guide future wound regeneration strategies, we compared single-cell sequencing of regenerative (third phalangeal element [P3]) and fibrotic (second phalangeal element [P2]) digit tip amputation (DTA) models as well as traumatic heterotopic ossification (HO; aberrant). Analyses point to a common initial response to injury, including expansion of progenitors, redeposition of matrix, and activation of transforming growth factor β (TGF-β) and WNT pathways. Surprisingly, fibrotic P2 DTA showed greater transcriptional similarity to HO than to regenerative P3 DTA, suggesting that gene expression more strongly correlates with healing outcome than with injury type or cell origin. Differential analysis and immunostaining revealed altered activation of inflammatory pathways, such as the complement pathway, in the progenitor cells. These data suggests that common pathways are activated in response to damage but are fine tuned within each injury. Modulating these pathways may shift the balance toward regenerative outcomes.

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Regenerative and fibrotic injuries share common early response mechanisms

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Transcriptomes correlate with healing outcome more than injury type or cell source

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Matrix composition after injury-induced tissue repair is highly injury type dependent

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Inflammatory cascades are activated in immune and mesenchymal cells

Macrophage-Specific, Mafb-Deficient Mice Showed Delayed Skin Wound Healing

Macrophages play essential roles throughout the wound repair process. Nevertheless, mechanisms regulating the process are poorly understood. MAFB is specifically expressed in the macrophages in hematopoietic tissue and is vital to homeostatic function. Comparison of the skin wound repair rates in macrophage-specific, MAFB-deficient mice (Mafb^f/f::LysM-Cre) and control mice (Mafb^f/f) showed that wound healing was significantly delayed in the former. For wounded GFP knock-in mice with GFP inserts in the Mafb locus, flow cytometry revealed that their GFP-positive cells expressed macrophage markers. Thus, macrophages express Mafb at wound sites. Immunohistochemical (IHC) staining, proteome analysis, and RT-qPCR of the wound tissue showed relative downregulation of Arg1, Ccl12, and Ccl2 in Mafb^f/f::LysM-Cre mice. The aforementioned genes were also downregulated in the bone marrow-derived, M2-type macrophages of Mafb^f/f::LysM-Cre mice. Published single-cell RNA-Seq analyses showed that Arg1, Ccl2, Ccl12, and Il-10 were expressed in distinct populations of MAFB-expressing cells. Hence, the MAFB-expressing macrophage population is heterogeneous. MAFB plays the vital role of regulating multiple genes implicated in wound healing, which suggests that MAFB is a potential therapeutic target in wound healing.

Adipose-derived stem cells-derived exosomes facilitate cutaneous wound healing by delivering XIST and restoring discoidin domain receptor 2

BACKGROUND

Adipose-derived stem cells (ADSCs) and their derived exosomes (ADSC-Exos) have shown potential functions in tissue repair. This study focuses on the effects of ADSCs-Exos on cutaneous wound healing and the potential involvement of the long non-coding RNA (lncRNA) XIST/microRNA-96-5p (miR-96-5p)/discoidin domain receptor 2 (DDR2) axis.

METHODS

Exos were isolated from the ADSCs and identified. A mouse model of full-thickness skin wounds was established. The mice were treated with ADSC-Exos to evaluate the function of ADSC-Exos in wound healing. Mouse dermal fibroblasts (MDFs) were co-cultured with the ADSC-Exos for in vitro experiments. The most differentially expressed lncRNAs in mouse skin tissues after ADSC-Exo treatment were screened by microarray analysis. The downstream molecules were analyzed by bioinformatics tools. Gain- and loss-of-function studies were performed to examine the functions of the XIST/miR-96-5p/DDR2 axis in wound healing.

RESULTS

ADSC-Exos facilitated wound healing in mice, reduced inflammatory infiltration, and increased collagen deposition in the wound skin tissues. In vitro, the ADSC-Exos promoted proliferation, migration of the MDFs. XIST was the most upregulated lncRNA in MDFs after ADSC-Exo treatment. Downregulation of XIST suppressed the promoting role of ADSC-Exos in wound healing. XIST bound to miR-96-5p to restore the expression of DDR2 mRNA. Either silencing of miR-96-5p or overexpression of DDR2 restored the promoting functions of ADSC-Exos in proliferation and migration of MDFs.

CONCLUSION

This study demonstrates that ADSC-Exos-carried XIST accelerates cutaneous wound healing through suppressing miR-96-5p and restoring the DDR2 expression.

Understanding the contextual functions of C1q and LAIR-1 and their applications

The importance of the complement component C1q has been highlighted by its involvement in autoimmunity, infection, inflammatory diseases, and tumors. The unique tulip-like structure of C1q has both a collagen-like stalk (C1q tail) and heterotrimeric globular head (gC1q), each with different binding specificities, and the binding of these components to their respective receptors leads to functional complexities in the body and bridges innate and adaptive immunity. This review describes the fundamental roles of C1q in various microenvironments and focuses on the importance of the interactions of C1q and its receptors with the inhibitory receptor LAIR-1 in maintaining homeostasis. Current therapeutic opportunities modulating LAIR-1 are also discussed.

Research into the activities of the protein C1q, involved in a cascade of molecular interactions of the immune response called complement activation, is revealing new details of the protein’s role and opening up possible new therapeutic opportunities. Myoungsun Son at Feinstein Institutes for Medical Research in Manhasset, USA, reviews the involvement of C1q in infection, autoimmunity, inflammatory diseases and tumors. The interaction of C1q with a receptor protein called LAIR-1 seems to be particularly significant. LAIR-1 is present in the membrane of most blood-forming cells and is involved in maintaining the healthy balance of cellular activities referred to as homeostasis. Emerging research suggests that targeting the interactions between C1q and LAIR-1 could enable the development of new treatments for many diseases, including inflammatory diseases, the autoimmune condition lupus, a variety of cancers, and possibly Covid-19.