Macrophage-induced neutrophil apoptosis

Autologous platelet-rich fibrin enhances skin wound healing in a feline trauma model

Trauma is a common cause of cutaneous surgical disease with an increased risk of secondary infection in cat clinics. Platelet-rich fibrin (PRF), a platelet and leukocyte concentrate containing multiple cytokines and growth factors, is known to accelerate the healing of wounds. However, how PRF affects wound healing in the cat trauma model has not been fully investigated. The study aimed to examine the impact of PRF on skin wound healing in the cat trauma model. In this study, PRF from cats was successfully produced for our investigation. The models of feline trauma were effectively established. A total of 18 cats were randomly divided into 3 groups (n = 6): (1) Control group (CON); (2) PRF group; (3) Manuka honey group (MAN, as a positive control). Experiments were performed separately on days 7, 14, 21, and 28. Our results showed that PRF was a safe and efficient method of wound healing that did not influence the cat's body temperature, respiration rate, and heart rate (HR). PRF accelerated skin wound healing in the cat trauma model based on the rate and histological observation of wound healing. In addition, PRF promoted the production of growth factors and suppressed inflammation during wound healing. PRF accelerated wound healing by increasing the formation of collagen fibers, as shown by Masson-trichrome staining. The outcomes of the PRF and MAN groups were comparable. In conclusion, PRF improves the healing of skin wounds in cats by boosting the synthesis of growth factors, reducing inflammation, and enhancing the synthesis of collagen fibers.

A Systematic Review on Biochemical Perspectives on Natural Products in Wound Healing: Exploring Phytochemicals in Tissue Repair and Scar Prevention

Wound healing is a critical process in tissue repair following injury, and traditional herbal therapies have long been utilized to facilitate this process. This review delves into the mechanistic understanding of the significant contribution of pharmacologically demonstrated natural products in wound healing. Natural products, often perceived as complex yet safely consumed compared to synthetic chemicals, play a crucial role in enhancing the wound-healing process. Drawing upon a comprehensive search strategy utilizing databases such as PubMed, Scopus, Web of Science, and Google Scholar, this review synthesizes evidence on the role of natural products in wound healing. While the exact pharmacological mechanisms of secondary metabolites in wound healing remain to be fully elucidated, compounds from alkaloids, phenols, terpenes, and other sources are explored here to delineate their specific roles in wound repair. Each phytochemical group exerts distinct actions in tissue repair, with some displaying multifaceted roles in various pathways, potentially enhancing their therapeutic value, supported by reported safety profiles. Additionally, these compounds exhibit promise in the prevention of keloids and scars. Their potential alongside economic feasibility may propel them towards pharmaceutical product development. Several isolated compounds, including chlorogenic acid, thymol, and eugenol from natural sources, are undergoing investigation in clinical trials, with many reaching advanced stages. This review provides mechanistic insights into the significant role of pharmacologically demonstrated natural products in wound healing processes.

Fibroblasts in Diabetic Foot Ulcers

Fibroblasts are stromal cells ubiquitously distributed in the body of nearly every organ tissue. These cells were previously considered to be "passive cells", solely responsible for ensuring the turnover of the extracellular matrix (ECM). However, their versatility, including their ability to switch phenotypes in response to tissue injury and dynamic activity in the maintenance of tissue specific homeostasis and integrity have been recently revealed by the innovation of technological tools such as genetically modified mouse models and single cell analysis. These highly plastic and heterogeneous cells equipped with multifaceted functions including the regulation of angiogenesis, inflammation as well as their innate stemness characteristics, play a central role in the delicately regulated process of wound healing. Fibroblast dysregulation underlies many chronic conditions, including cardiovascular diseases, cancer, inflammatory diseases, and diabetes mellitus (DM), which represent the current major causes of morbidity and mortality worldwide. Diabetic foot ulcer (DFU), one of the most severe complications of DM affects 40 to 60 million people. Chronic non-healing DFU wounds expose patients to substantial sequelae including infections, gangrene, amputation, and death. A complete understanding of the pathophysiology of DFU and targeting pathways involved in the dysregulation of fibroblasts are required for the development of innovative new therapeutic treatments, critically needed for these patients.

The Synergistic Effects of Hyaluronic Acid and Platelet-Rich Plasma for Patellar Chondropathy

Musculoskeletal disorders are increasingly prevalent worldwide, causing significant socioeconomic burdens and diminished quality of life. Notably, patellar chondropathy (PC) is among the most widespread conditions affecting joint structures, resulting in profound pain and disability. Hyaluronic acid (HA) and platelet-rich plasma (PRP) have emerged as reliable, effective, and minimally invasive alternatives. Continuous research spanning from laboratory settings to clinical applications demonstrates the numerous advantages of both products. These encompass lubrication, anti-inflammation, and stimulation of cellular behaviors linked to proliferation, differentiation, migration, and the release of essential growth factors. Cumulatively, these benefits support the rejuvenation of bone and cartilaginous tissues, which are otherwise compromised due to the prevailing degenerative and inflammatory responses characteristic of tissue damage. While existing literature delves into the physical, mechanical, and biological facets of these products, as well as their commercial variants and distinct clinical uses, there is limited discussion on their interconnected roles. We explore basic science concepts, product variations, and clinical strategies. This comprehensive examination provides physicians with an alternative insight into the pathophysiology of PC as well as biological mechanisms stimulated by both HA and PRP that contribute to tissue restoration.

Pigmented skin exhibits accelerated wound healing compared to the nonpigmented skin in Guinea pig model

This study investigated and compared the wound healing kinetics of pigmented (PG) and non-pigmented (NP) skin in guinea pigs, focusing on histological and transcriptional changes. Full-thickness wounds created on PG and NP skin were evaluated at various time points post-injury. Fontana-Masson staining and ultrastructural analysis suggested the presence of melanin and melanosomes in PG skin, which coincided with an upregulation of melanogenic genes cKIT, TYR, and DCT. On day 9 post-wound, PG skin exhibited a rapid transition from the inflammatory to proliferative phase, which correlated with the reappearance of epidermal pigmentation whereas the NP skin exhibited a delayed neo-epidermis formation. Furthermore, the study revealed that melanocyte-derived growth factors (conditioned media) positively regulated keratinocyte migration while inhibiting fibroblast differentiation. These effects were more prominent in tyrosine-treated (hyperpigmented) melanocyte-CM as was TGF- β expression. These findings provide valuable insights into the mechanisms underlying skin repair and pigmentation.

Mechanisms and applications of adipose-derived stem cell-extracellular vesicles in the inflammation of wound healing

Wound healing is a sophisticated process consisting of serial phases with overlaps, including hemostasis, inflammation, proliferation, and remodeling. The inflammation response is an early response that plays a crucial role in eliminating microbes and clearing damaged cell debris. However, in some pathological circumstances, such as diabetes mellitus, ischemia, trauma, deep burn, etc., abnormal inflammation can cause impaired wound healing. Adipose-derived stem cells (ADSCs) belong to the mesenchymal stem cell (MSC) family and exhibit prospective applications in tissue regeneration and dermatological repairs. ADSC-secreted extracellular vesicles (ADSC-EVs) mimic the functions of ADSCs without the concerns of cell survival, immune response, or ethical issues. Studies have revealed that ADSC-EVs can inhibit abnormal inflammation responses and accelerate wound healing through various mechanisms. Moreover, some studies explored modifications in the cargo components of ADSC-EVs to enhance their therapeutic efficacy. Given the increasing studies focusing on the potential of ADSC-EVs in wound healing, how they interfere with different phases of this process has been investigated in pieces. In this review, we summarized all up-to-date evidence to map a clearer picture of the underlying mechanisms of ADSC-EVs in inflammation response. The applications of ADSC-EVs aiming at inflammation in the healing process were also reviewed to provide therapeutic strategies for future investigators.

Platelet-Rich Plasma Power-Mix Gel (ppm)-An Orthobiologic Optimization Protocol Rich in Growth Factors and Fibrin

Platelet- and fibrin-rich orthobiologic products, such as autologous platelet concentrates, have been extensively studied and appreciated for their beneficial effects on multiple conditions. Platelet-rich plasma (PRP) and its derivatives, including platelet-rich fibrin (PRF), have demonstrated encouraging outcomes in clinical and laboratory settings, particularly in the treatment of musculoskeletal disorders such as osteoarthritis (OA). Although PRP and PRF have distinct characteristics, they share similar properties. The relative abundance of platelets, peripheral blood cells, and molecular components in these orthobiologic products stimulates numerous biological pathways. These include inflammatory modulation, augmented neovascularization, and the delivery of pro-anabolic stimuli that regulate cell recruitment, proliferation, and differentiation. Furthermore, the fibrinolytic system, which is sometimes overlooked, plays a crucial role in musculoskeletal regenerative medicine by regulating proteolytic activity and promoting the recruitment of inflammatory cells and mesenchymal stem cells (MSCs) in areas of tissue regeneration, such as bone, cartilage, and muscle. PRP acts as a potent signaling agent; however, it diffuses easily, while the fibrin from PRF offers a durable scaffolding effect that promotes cell activity. The combination of fibrin with hyaluronic acid (HA), another well-studied orthobiologic product, has been shown to improve its scaffolding properties, leading to more robust fibrin polymerization. This supports cell survival, attachment, migration, and proliferation. Therefore, the administration of the "power mix" containing HA and autologous PRP + PRF may prove to be a safe and cost-effective approach in regenerative medicine.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

Continuous infiltration of small peritoneal macrophages in the mouse peritoneum through CCR2-dependent and -independent routes during fibrosis and mesothelioma development induced by a multiwalled carbon nanotube, MWNT-7

Although toxicities of multiwalled carbon nanotube (MWCNT) have been found to be related with activities of macrophages phagocytosing the fibers, the exact relationship between macrophage population and pathogenesis of fibrosis and mesotheliomas induced by MWCNTs is largely unknown. CCL2-CCR2 axis, a major monocyte/macrophage infiltration route, is thought to be involved in not only acute inflammation but also the formation of tumor microenvironment. We therefore described a time-course of alteration of macrophage population in an attempt to clarify the contribution of the Ccr2 gene to mesotheliomagenesis. Wild-type (WT) C57BL/6 mice and Ccr2-knockout (KO) mice were intraperitoneally administered with MWNT-7 and were sequentially necropsied at 1, 7, 28, 90, and 245 day(s) after the injection. Peritoneal fibrosis was prominent in all MWCNT-treated mice, with a lower severity in the KO mice. No differences were observed in the incidences of neoplastic lesions of mesothelia between WT and KO mice. A flow cytometric analysis revealed that after gross disappearance of macrophages after MWCNT exposure, small peritoneal macrophages (SPMs) were exclusively refurbished by the CCR2-dependent route at day 1 (as Ly-6C+MHC class II- cells), followed by additional CCR2-independent routes (as Ly-6C-MHC class II- cells); i.e., the only route in KO mice; with a delay of 1-7 days. The SPMs derived from both routes appeared to differentiate into maturated cells as Ly-6C-MHC class II+, whose ratio increased in a time-dependent manner among the total SPM population. Additionally, most macrophages expressed M1-like features, but a small fraction of macrophages exhibited an M1/M2 mixed status in MWCNT-treated animals. Our findings demonstrate a long-persistent activation of the CCL2-CCR2 axis after MWCNT exposure and enable a better understanding of the participation and potential roles of SPMs in fibrous material-induced chronic toxicities.

Advances in surface modifications of the silicone breast implant and impact on its biocompatibility and biointegration

Silicone breast implants are commonly used for cosmetic and oncologic surgical indications owing to their inertness and being nontoxic. However, complications including capsular contracture and anaplastic large cell lymphoma have been associated with certain breast implant surfaces over time. Novel implant surfaces and modifications of existing ones can directly impact cell-surface interactions and enhance biocompatibility and integration. The extent of foreign body response induced by breast implants influence implant success and integration into the body. This review highlights recent advances in breast implant surface technologies including modifications of implant surface topography and chemistry and effects on protein adsorption, and cell adhesion. A comprehensive online literature search was performed for relevant articles using the following keywords silicone breast implants, foreign body response, cell adhesion, protein adsorption, and cell-surface interaction. Properties of silicone breast implants impacting cell-material interactions including surface roughness, wettability, and stiffness, are discussed. Recent studies highlighting both silicone implant surface activation strategies and modifications to enhance biocompatibility in order to prevent capsular contracture formation and development of anaplastic large cell lymphoma are presented. Overall, breast implant surface modifications are being extensively investigated in order to improve implant biocompatibility to cater for increased demand for both cosmetic and oncologic surgeries.

The effect of expressive writing on wound healing: Immunohistochemistry analysis of skin tissue two weeks after punch biopsy wounding

OBJECTIVE

To investigate the effects of expressive writing and its timing (pre or post wounding) on re-epithelialisation and leucocyte subsets within healing tissue. We previously showed expressive writing pre-wounding improved re-epithelialisation. Here we investigate cellular processes in the wound.

METHODS

In a 2(writing content) x 2(writing timing) randomized trial, 122 participants were randomized to perform either expressive or control writing, before or after a 4 mm punch biopsy wound. On day 14 post-wounding, participants had a 5 mm punch biopsy of the initial wound. Seven of 16 primary registered outcomes were analysed, including re-epithelialisation from two photographs of the 4 mm biopsy (previously reported). This paper reports immunohistochemistry analysis of five primary outcomes - Langerhans cells, immune cell activation (HLA and CD3+), and macrophages (CD68 and MPO) - in the 5 mm biopsies in a random sample of 96 participants.

RESULTS

Participants who performed either writing task pre-wounding had greater Langerhans cell infiltration, than those who wrote post-wounding (F_(1,85) = 7.86, p = .006, η_p² = 0.08). Those who performed expressive writing also had greater Langerhans cell infiltration than those who performed control writing (F_(1,85) = 4.00, p = .049, η_p² = 0.04). There were no significant group or interaction effects on immune cell activation or macrophages. Healed wounds on day 10 had lower levels of macrophages (z = -1.96, p = .050), and CD3+ cells (z = -1.99, p = .046) than non-healed wounds.

CONCLUSION

Langerhans cells in the healing skin are affected by the timing and topic of writing. More research is needed to further explore timing and corroborate these results.

CLINICAL TRIALS REGISTRATION

Registered at https://www.anzctr.org.au/ (Trial ID: ACTRN12614000971639).

Therapeutic delivery of nucleic acids for skin wound healing

Though wound care has advanced, treating chronic wounds remains a challenge and there are many clinical issues that must be addressed. Gene therapy is a recent approach to treating chronic wounds that remains in its developmental stage. The limited reports available describe the therapeutic applications of various forms of nucleic acid delivery for treating chronic wounds, including DNA, mRNA, siRNA, miRNA and so on. Though these bioactive molecules represent great therapeutic potential, sustaining their bioactivity in the wound bed is a challenge. To overcome this hurdle, delivery systems are also being widely investigated. In this review, nucleic acid-based therapy and its delivery for treating chronic wounds is discussed in detail.

Neutrophil-Derived Tumor Necrosis Factor Drives Fungal Acute Lung Injury in Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) results from deficiency of nicotinamide adenine dinucleotide phosphate(NADPH) oxidase and impaired reactive oxygen species (ROS) generation. This leads to impaired killing of Aspergillus and, independently, a pathologic hyperinflammatory response to the organism. We hypothesized that neutrophil-derived ROS inhibit the inflammatory response to Aspergillus and that acute lung injury in CGD is due to failure of this regulation. Mice with gp91phox deficiency, the most common CGD mutation, had more severe lung injury, increased neutrophilinfiltration, and increased lung tumor necrosis factor (TNF) after Aspergillus challenge compared with wild-types. Neutrophils were surprisingly the predominant source of TNF in gp91phox-deficient lungs. TNF neutralization inhibited neutrophil recruitment in gp91phox-deficient mice and protected from lung injury. We propose that, in normal hosts, Aspergillus stimulates TNF-dependent neutrophil recruitment to the lungs and neutrophil-derived ROS limit inflammation. In CGD, in contrast, recruited neutrophils are the dominant source of TNF, promoting further neutrophil recruitment in a pathologic positive-feedback cycle, resulting in progressive lung injury.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Toward a Better Regeneration through Implant-Mediated Immunomodulation: Harnessing the Immune Responses

Tissue repair/regeneration, after implantation or injury, involves comprehensive physiological processes wherein immune responses play a crucial role to enable tissue restoration, amidst the immune cells early-stage response to tissue damages. These cells break down extracellular matrix, clear debris, and secret cytokines to orchestrate regeneration. However, the immune response can also lead to abnormal tissue healing or scar formation if not well directed. This review first introduces the general immune response post injury, with focus on the major immune cells including neutrophils, macrophages, and T cells. Next, a variety of implant-mediated immunomodulation strategies to regulate immune response through physical, chemical, and biological cues are discussed. At last, various scaffold-facilitated regenerations of different tissue types, such as, bone, cartilage, blood vessel, and nerve system, by harnessing the immunomodulation are presented. Therefore, the most recent data in biomaterials and immunomodulation is presented here in a bid to shape expert perspectives, inspire researchers to go in new directions, and drive development of future strategies focusing on targeted, sequential, and dynamic immunomodulation elicited by implants.

The regenerative mechanisms of platelet-rich plasma: A review

Orthobiologics continue to gain popularity in many areas of medical science, especially in the field of regenerative medicine. Platelet-rich plasma derivatives are orthobiologic tools of particular interest. These biologic products can be obtained via centrifugation of a patient's whole blood and the components can then be subsequently isolated, concentrated and ultimately administered into injured tissues, particularly in areas where standard healing is disrupted. The elevated concentration of platelets above the basal value enables accelerated growth of various tissues with minimal side effects. The application of autologous orthobiologics is a relatively new biotechnology undergoing expansion which continues to reveal optimistic results in the stimulation and enhanced healing of various sorts of tissue injuries. The local release of growth factors and cytokines contained in platelet alpha granules accelerates and ameliorates tissue repair processes, mimicking and supporting standard wound healing. This effect is greatly enhanced upon combination with the fibrinolytic system, which are essential for complete regeneration. Fibrinolytic reactions can dictate proper cellular recruitment of certain cell populations such as mesenchymal stem cells and other immunomodulatory agents. Additionally, these reactions also control proteolytic activity in areas of wound healing and regenerative processes of mesodermal tissues including bone, cartilage, and muscle, which makes it particularly valuable for musculoskeletal health, for instance. Although many investigations have demonstrated significant results with platelet-rich plasma derivatives, further studies are still warranted.

Monocyte phenotype as a predictive marker for wound healing in diabetes-related foot ulcers

AIMS

Delayed healing of diabetes-related foot ulcers (DRFUs) is associated with increased macrophage and matrix metalloproteinases (MMPs) at the wound site. Whether circulating monocyte phenotype and/or MMPs are altered in association with wound healing outcome is unknown, and was investigated in this study.

METHODS

Blood was obtained from 21 participants with DRFU, at initial visit (V1), week-4 (V2), and week-8 (V3) for measurement of monocyte number (CD14⁺), phenotype (CD16, CD163) and chemokine receptors (CCRs) by flow cytometry, and circulating MMPs and TIMP-1 by ELISA.

RESULTS

Six wounds healed during the study. At V1, non-classical CD16⁺⁺ monocytes and MMP-3 were higher in healed vs unhealed (both p < 0.05). At V3, the increased %CD16⁺⁺ persisted and %CCR2⁺ was decreased in healed, but no other monocyte markers nor MMP/TIMP differed between groups. Increased wound closure rate (WCR) at V3 correlated with increased %CD16⁺⁺ monocytes and decreased MMP-2 at V1 or V1 + V2. Receiver operating characteristic (ROC) curves yielded an area-under-the-curve of %CD16⁺⁺ at V1 of 0.78 to predict ulcer healing at V3.

CONCLUSIONS

These results indicate that circulating monocyte phenotype and MMPs alter as DRFUs heal. The relationship of %CD16⁺⁺ monocytes with WCR and ROC curve suggest a predictive role of %CD16⁺⁺ monocytes for ulcer healing.

Allogeneic Platelet-Rich Plasma: Is It Safe and Effective for Wound Repair?

BACKGROUND

Platelet-rich plasma (PRP) and its derivatives are an emerging biotechnology whereby concentrated platelets provide damaged tissue with growth factors, cytokines, and other mediators to improve healing outcomes. Although there is strong evidence in the benefits of autologous PRP for both acute and chronic wounds, allogeneic PRP has been studied far less in comparison.

SUMMARY

In this mini-review, we discuss critical steps of allogenic PRP (and its derivatives) preparation. We performed a non-systematic review of the literature to identify animal and human subject studies testing allogenic PRP for wound treatment. We searched OVID Medline and PubMed for articles using the keywords "wound, ulcer, lesion, skin, and cutaneous" and "PRP, or platelet-rich plasma, or platelet-rich fibrin, or PRF, or platelet releasate" and "homologous, allogeneic or allogenic," which were limited to non-review articles and English language. Two studies in animal models and 8 studies in patients were reviewed. There were inconsistencies in preparation methods, treatment regimens, and some lacked a control group in their studies. Despite these variations, none of the studies identified any major side effects or adverse events. The treatment resulted in a reduced time to heal and/or reduced wound size in most cases. Key Messages: In situations where autologous PRP is not available or suitable, allogeneic PRP appears to provide a safe alternative. Its efficacy, however, requires larger-scale studies with appropriate controls. Standardization in PRP preparation and treatment regime are also needed to be able to interpret allogenic PRP efficacy.

Nanomaterials Versus The Microbial Compounds With Wound Healing Property

Age and diabetes related slow-healing or chronic wounds may result in morbidity and mortality through persistent biofilms infections and prolonged inflammatory phase. Nano-materials [metal/metal oxide NPs (39%), lipid vehicles (21%), polymer NPs (19%), ceramic nanoparticles (NPs) (14%), and carbon nanomaterials (NMs) (7%)] can be introduced as a possible next-generation therapy because of either their intrinsic wound healing activity or via carrying bioactive compounds including, antibiotics, antioxidants, growth factor or stem cell. The nanomaterials have been shown to implicate in all four stages of wound healing including hemostasis (polymer NPs, ceramic NPs, nanoceria-6.1%), inflammation (liposome/vesicles/solid lipid NPs/polymer NPs/ceramic NPs/silver NPs/gold NPs/nanoceria/fullerenes/carbon-based NPs-32.7%), proliferation (vesicles/liposome/solid lipid NPs/gold NPs/silver NPs/iron oxide NPs/ceramic NPs/copper NPs/self-assembling elastin-like NPs/nanoceria/micelle/dendrimers/polymer NPs-57.1%), remodeling (iron oxide NPs/nanoceria-4.1%). Natural compounds from alkaloids, flavonoids, retinoids, volatile oil, terpenes, carotenoids, or polyphenolic compounds with proven antioxidant, anti-inflammatory, immunomodulatory, or antimicrobial characteristics are also well known for their potential to accelerate the wound healing process. In the current paper, we survey the potential and properties of nanomaterials and microbial compounds in improving the process of wound and scar healing. Finally, we review the potential biocompounds for incorporation to nano-material in perspective to designate more effective or multivalent wound healing natural or nano-based drugs.

Molecular Mechanisms for Regulation of Neutrophil Apoptosis under Normal and Pathological Conditions

Neutrophils are one of the main cells of innate immunity that perform a key effector and regulatory function in the development of the human inflammatory response. Apoptotic forms of neutrophils are important for regulating the intensity of inflammation and restoring tissue homeostasis. This review summarizes current data on the molecular mechanisms of modulation of neutrophil apoptosis by the main regulatory factors of the inflammatory response-cytokines, integrins, and structural components of bacteria. Disturbances in neutrophil apoptosis under stress are also considered, molecular markers of changes in neutrophil lifespan associated with various diseases and pathological conditions are presented, and data on pharmacological agents for modulating apoptosis as potential therapeutics are also discussed.

Primary Ciliary Signaling in the Skin-Contribution to Wound Healing and Scarring

Primary cilia (PC) are solitary, post-mitotic, microtubule-based, and membrane-covered protrusions that are found on almost every mammalian cell. PC are specialized cellular sensory organelles that transmit environmental information to the cell. Signaling through PC is involved in the regulation of a variety of cellular processes, including proliferation, differentiation, and migration. Conversely, defective, or abnormal PC signaling can contribute to the development of various pathological conditions. Our knowledge of the role of PC in organ development and function is largely based on ciliopathies, a family of genetic disorders with mutations affecting the structure and function of PC. In this review, we focus on the role of PC in their major signaling pathways active in skin cells, and their contribution to wound healing and scarring. To provide comprehensive insights into the current understanding of PC functions, we have collected data available in the literature, including evidence across cell types, tissues, and animal species. We conclude that PC are underappreciated subcellular organelles that significantly contribute to both physiological and pathological processes of the skin development and wound healing. Thus, PC assembly and disassembly and PC signaling may serve as attractive targets for antifibrotic and antiscarring therapies.

In Vitro and In Vivo Wound Healing and Anti-Inflammatory Activities of Babassu Oil (Attalea speciosa Mart. Ex Spreng., Arecaceae)

Babassu (Attalea speciosa Mart. ex Spreng., Arecaceae) is a palm tree endemic to Brazil and found mainly in the borders of Amazon forest, where the harvesting of its fruits is an important source of income for more than 300,000 people. Among the communities of coconut breakers women, babassu oil is used in culinary, as fuel, and mostly as medicinal oil for the treatment of skin wounds and inflammation. This study aimed to evaluate in vitro and in vivo the wound healing effects of babassu oil. In vitro, babassu oil increased the migration of L929 fibroblasts, inhibited the production of nitric oxide by LPS-stimulated peritoneal macrophages, and increased the levels of INF-γ and IL-6 cytokines production. In vivo, babassu oil accelerated the healing process in a full-thickness splinted wound model, by an increase in the fibroblasts number, blood vessels, and collagen deposition in the wounds. The babassu oil also increased the recruitment of inflammatory cells into the wound site and showed an anti-inflammatory effect in a chronic ear edema model, reducing ear thickness, epidermal hyperplasia, and myeloperoxidase activity. Thus, these data corroborate the use of babassu oil in folk medicine as a remedy to treat skin wounds.

Role of Inflammatory Cell Responses in Stimulating Fibroblasts in Diabetic Oral Ulcer after Treatment with Liquid Smoke of Coconut Endocarp: A Histological Assessment

Objective  The liquid smoke of coconut endocarp (LS-CE) contains high antioxidants that promote oral ulcer healing in diabetics. This study reveals the profile of inflammatory cell responses to oral ulcer healing in diabetics under treatment with LS-CE.

Materials and Methods  A diabetic model was induced with alloxan. Treatment with LS-CE was performed on oral ulcer at a dose of 1 μL/g weight for 3, 5, and 7 days. The anti-inflammatory effect was tested on animal’s oral ulcer model by measuring the inflammatory cell responses of the neutrophils, macrophages, lymphocytes, and fibroblasts through histological assessment.

Results  The LS-CE stimulated the healing by simultaneously increasing the inflammatory cell responses. The numbers of neutrophils, macrophages, and fibroblasts after treatment for 7 days are higher than that after 3 days and 5 days ( p < 0.01), but not for neutrophils. The LS-CE shows increase in the fibroblasts by hastening responses of macrophage recruitment by five times, but not neutrophil and lymphocyte recruitment. The higher phenolic compounds in LS-CE are responsible for increase in the proliferation of fibroblasts, as it hastens cellular responses of macrophages.

Conclusions  The application of LS-CE enables hastening of the healing of diabetic oral ulcer by stimulating the macrophages.

Bacteria and Antibiotics in Wound Healing

This review of the literature concerning bacteria, antibiotics and tissue repair shows there are extensive data supporting microbial interference with wound healing once bacterial burden exceeds 104 CFU per unit of measure, The mechanism of bacterial interference lies largely in prolonging the inflammatory phase of tissue repair. Reducing the microbial bioburden allows tissue repair to continue. Systemic and topical antimicrobials appear critical to reducing the bioburden and facilitating repair. The current controversy over the use of antimicrobials in patients with chronically infected wounds, in particular, revolves around the definition of infection. The reliance on classic clinical signs of inflammation to support antimicrobial use in these patients is tenuous due to the lack of correlation of these signs with the microbial burden known to impair tissue repair.

Electromedical devices in wound healing management: a narrative review

Wound healing is the sum of physiological sequential steps, leading to skin restoration. However, in some conditions, such as diabetes, pressure ulcers (PU) and venous legs ulcers (VLU), healing is a major challenge and requires multiple strategies. In this context, some electromedical devices may accelerate and/or support wound healing, modulating the inflammatory, proliferation (granulation) and tissue-remodelling phases. This review describes some helpful electromedical devices including: ultrasonic-assisted wound debridement; electrotherapy; combined ultrasound and electric field stimulation; low-frequency pulsed electromagnetic fields; phototherapy (for example, laser therapy and light-emitting diode (LED) therapy); biophotonic therapies, and pressure therapies (for example, negative pressure wound therapy, and high pressure and intermittent pneumatic compression) The review focuses on the evidence-based medicine and adequate clinical trial design in relation to these devices.

Macrophage Dysregulation and Impaired Skin Wound Healing in Diabetes

Monocytes (Mo) and macrophages (Mϕ) play important roles in normal skin wound healing, and dysregulation of wound Mo/Mϕ leads to impaired wound healing in diabetes. Although skin wound Mϕ originate both from tissue resident Mϕ and infiltrating bone marrow-derived Mo, the latter play dominant roles during the inflammatory phase of wound repair. Increased production of bone marrow Mo caused by alterations of hematopoietic stem and progenitor cell (HSPC) niche and epigenetic modifications of HSPCs likely contributes to the enhanced number of wound Mϕ in diabetes. In addition, an impaired transition of diabetic wound Mϕ from “pro-inflammatory” to “pro-healing” phenotypes driven by the local wound environment as well as intrinsic changes in bone marrow Mo is also thought to be partly responsible for impaired diabetic wound healing. The current brief review describes the origin, heterogeneity and function of wound Mϕ during normal skin wound healing followed by discussion of how dysregulated wound Mϕ numbers and phenotype are associated with impaired diabetic wound healing. The review also highlights the possible links between altered bone marrow myelopoiesis and increased Mo production as well as extrinsic and intrinsic factors that drive wound macrophage dysregulation leading to impaired wound healing in diabetes.

The Local and Peripheral Immune Responses to Stroke: Implications for Therapeutic Development

The immune response to stroke is an exciting target for future stroke therapies. Stroke is a leading cause of morbidity and mortality worldwide, and clot removal (mechanical or pharmacological) to achieve tissue reperfusion is the only therapy currently approved for patient use. Due to a short therapeutic window and incomplete effectiveness, however, many patients are left with infarcted tissue that stimulates inflammation. Although this is critical to promote repair, it can also damage surrounding healthy brain tissue. In addition, acute immunodepression and subsequent infections are common and are associated with worse patient outcomes. Thus, the acute immune response is a major focus of researchers attempting to identify ways to amplify its benefits and suppress its negative effects to improve short-term recovery of patients. Here we review what is known about this powerful process. This includes the role of brain resident cells such as microglia, peripherally activated cells such as macrophages and neutrophils, and activated endothelium. The role of systemic immune activation and subsequent immunodepression in the days after stroke is also discussed, as is the chronic immune responses and its effects on cognitive function. The biphasic role of inflammation, as well as complex timelines of cell production, differentiation, and trafficking, suggests that the relationship between the acute and chronic phases of stroke recovery is complex. Gaining a more complete understanding of this intricate process by which inflammation is initiated, propagated, and terminated may potentially lead to therapeutics that can treat a larger population of stroke patients than what is currently available. The immune response plays a critical role in patient recovery in both the acute and chronic phases after stroke. In patients, the immune response can be beneficial by promoting repair and recovery, and also detrimental by propagating a pro-inflammatory microenvironment. Thus, it is critical to understand the mechanisms of immune activation following stroke in order to successfully design therapeutics.

Macrophage mediation in normal and diabetic wound healing responses

PURPOSE

The failure in timely healing of wounds is a central feature in chronic wounds that leads to physiological, psychological and economic burdens. Macrophages have been demonstrated to have various functions in wounds including host defense, the promotion and resolution of inflammation, the removal of apoptotic cells and tissue restoration following injury. Accumulated evidence suggests that macrophage dysfunction is a component of the pathogenesis of non-healing wounds. While the overall signaling cascades have been well understood, their complex interplay and a detailed characterization of events that are disrupted in chronic wounds have still not emerged satisfactorily.

METHODS

The existing literature was reviewed to summarize the regulation of macrophage polarization in wound closure and dysregulation in non-healing wounds. Further, the review also underscored the role of Nrf2 in promoting macrophage-mediated regulation in wound responses and in particular, macrophage involvement in iron homeostasis that is impaired in chronic wounds such as in diabetes.

RESULTS

The mechanisms involved in the reprogramming of macrophage subtypes in chronic wounds are still emerging. Furthermore, treating non-healing wounds has increasingly been shifting focus from generic treatments to the development of targeted therapies. Increasing evidence suggests the need for modeling wound tissue in vitro which may very well serve a critical aspect to characterize the relevant factors that sustain chronic wounds in vivo such as the constant iron overload at the wound site from recurrent infection and bleeding.

CONCLUSION

The development of targeted therapies and also developing a reliable means to monitor assisted healing of chronic wounds are two major goals to be pursued. In addition, identifying molecular targets that can regulate macrophages to aid tissue restoration in chronic wounds would serve the crucial step in realizing both aforementioned goals.

Insights Into Mechanisms of Tumor and Immune System Interaction: Association With Wound Healing

A large number of studies have presented a great deal of information about tumor and immune system interaction. Nevertheless, the problem of tumor evasion from the immune reaction is still difficult to resolve. Understanding the ways in which immunosuppressive tumor microenvironment develops and maintains its potential is of utmost importance to ensure the best use of the suppressed immune functions. The study presents a review covering the data on tumor-associated antigens, mechanisms of tumor evasion from the immune reactions, and search for common immunosuppressive processes of tumor growth and normal wound healing. The study discusses the important role of monocytes/macrophages in the regulation of immune system reactions. We suggest that the simultaneous actions of growth factors and pro-inflammatory cytokines may result in the suppression of the immune system. The study describes intracellular signaling molecules that take part in the regulation of the myeloid cell functions. If the hypothesis is proved correct, the indicated interaction of cytokines could be regarded as a prospective target for antitumor therapy.

Innate immune cell-epithelial crosstalk during wound repair

Skin and intestinal epithelial barriers play a pivotal role in protecting underlying tissues from harsh external environments. The protective role of these epithelia is, in part, dependent on a remarkable capacity to restore barrier function and tissue homeostasis after injury. In response to damage, epithelial wounds repair by a series of events that integrate epithelial responses with those of resident and infiltrating immune cells including neutrophils and monocytes/macrophages. Compromise of this complex interplay predisposes to development of chronic nonhealing wounds, contributing to morbidity and mortality of many diseases. Improved understanding of crosstalk between epithelial and immune cells during wound repair is necessary for development of better pro-resolving strategies to treat debilitating complications of disorders ranging from inflammatory bowel disease to diabetes. In this Review we focus on epithelial and innate immune cell interactions that mediate wound healing and restoration of tissue homeostasis in the skin and intestine.

Limiting angiogenesis to modulate scar formation

Angiogenesis, the process of new blood vessel formation from existing blood vessels, is a key aspect of virtually every repair process. During wound healing an extensive, but immature and leaky vascular plexus forms which is subsequently reduced by regression of non-functional vessels. More recent studies indicate that uncontrolled vessel growth or impaired vessel regression as a consequence of an excessive inflammatory response can impair wound healing, resulting in scarring and dysfunction. However, in order to elucidate targetable factors to promote functional tissue regeneration we need to understand the molecular and cellular underpinnings of physiological angiogenesis, ranging from induction to resolution of blood vessels. Especially for avascular tissues (e.g. cornea, tendon, ligament, cartilage, etc.), limiting rather than boosting vessel growth during wound repair potentially is beneficial to restore full tissue function and may result in favourable long-term healing outcomes.

TRIM33 deficiency in monocytes and macrophages impairs resolution of colonic inflammation

BACKGROUND

Mature myeloid cells play a crucial role in Crohn's disease (CD) but the molecular players that regulate their functions in CD are not fully characterized. We and others have shown that TRIM33 is involved in the innate immune response and in the inflammatory response but TRIM33 role in intestinal inflammation is not known. In this study, we investigated the role of TRIM33 in myeloid cells during dextran sulfate sodium (DSS)-induced colitis.

METHODS

We study the role of TRIM33 during DSS-induced colitis which mimics intestinal inflammation using mice deleted for Trim33 only in mature myeloid cells (Trim33-/- mice) FINDINGS: We first show that Trim33 mRNA level is decreased in CD patient's blood monocytes suggesting a role of TRIM33 in CD. Using Trim33-/- mice, we show that these mice display an impaired resolution of colonic inflammation with an increased number of blood and colon monocytes and a decreased number of colonic macrophages. Trim33-/- monocytes are less competent for recruitment and macrophage differentiation. Finally, during resolution of inflammation, Trim33-/- colonic macrophages display an impaired M1/M2 switch and express a low level of membrane-bound TNF that is associated with an increased number of colonic neutrophils.

INTERPRETATION

Our study shows an important role of TRIM33 in monocytes/macrophages during DSS-induced colitis and suggests that the decreased expression of TRIM33 in CD patient's blood monocytes might not be a consequence but might be involved in CD progression. FUND: La Ligue contre le Cancer (équipe labelisée), INSERM, CEA, Université Paris-Diderot, Université Paris-Sud.

Contribution of platelets, the coagulation and fibrinolytic systems to cutaneous wound healing

Wound healing is a complex process that consists of multiple phases, each of which are indispensable for adequate repair. Timely initiation and resolution of each of these phases namely, hemostasis, inflammation, proliferation and tissue remodeling, is critical for promoting healing and avoiding excess scar formation. While platelets have long been known to influence the healing process, other components of blood particularly coagulation factors and the fibrinolytic system also contribute to efficient wound repair. This review aims to summarize our current understanding of the role of platelets, the coagulation and fibrinolytic systems in cutaneous wound healing, with a focus on how these components communicate with immune and non-immune cells in the wound microenvironment. We also outline current and potential therapeutic strategies to improve the management of chronic, non-healing wounds.

Cytotoxic Necrotizing Factor 1 Downregulates CD36 Transcription in Macrophages to Induce Inflammation During Acute Urinary Tract Infections

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) induce cystitis, pyelonephritis, and can cause kidney scarring and failure if inflammation is not under control. The detailed effects of cytotoxic necrotizing factor 1 (CNF1), the key UPEC toxin, on the pathogenicity of UPEC remain unclear. CD36 is an important scavenger receptor, responsible for pathogen and apoptotic cell clearance, and plays an essential role in host immune defense and homeostasis. Regulation of CD36 by bacterial toxins has not been reported. In this study, using a pyelonephritis mouse model, CNF1 was observed to contribute to increasing neutrophils and bacterial titers in infected bladder and kidney tissues, resulting in severe inflammation and tissue damage. CD36 expression in macrophages was found to be decreased by CNF1 in vitro and in vivo. We demonstrated that CNF1 attenuated CD36 transcription by decreasing expressions of its upstream transcription factors LXRβ and C/EBPα and their recruitment to the CD36 promotor. In addition, Cdc42 was found to be involved in CNF1-mediated downregulation of LXRβ. Our study investigated the pathogenesis of cnf1-carrying UPEC, which affected host innate immune defenses and homeostasis through regulation of CD36 in macrophages during acute UTIs.

Cone-beam computed tomographic and histological investigation of regenerative endodontic procedure in an immature mandibular second premolar with chronic apical abscess

AIM

The aim of the present study was to investigate the tissue generated after regenerative endodontic procedure (REP) in the root canal space of an immature mandibular second premolar with pulp necrosis and chronic apical abscess using cone-beam computed tomographic (CBCT) and histological methods.

METHODS

REP was performed in an immature mandibular second premolar. At the 3-year follow up, CBCT scans were taken to evaluate the outcome of treatment. As the tooth was not restorable to function, it was extracted and processed for histological examination.

RESULTS

CBCT showed a reduction in size of the periradicular radiolucency, with a marginal increase in root length. Apical closure and thickening of the root canal walls were apparent. Histologically, the root canal space was filled with minimally-inflamed fibrous connective tissue. Some cementum-like mineralized connective tissue was evident on the internal canal walls. The apical third showed cementum-like deposits at the apex and the outer canal walls, without dentin formation.

CONCLUSIONS

The present study of a structurally-failed tooth with prior REP demonstrates that the tissue formed within the root canal space was fibrous connective tissue with cementum-like deposition in the canal space. No evidence of dentin- or pulp-like tissue was found.

Extracellular vesicles as modulators of wound healing

Impaired healing of cutaneous wounds and ulcers continues to have a major impact on the quality of life of millions of people. In recent years, the capacity for stem and progenitor cells to promote wound repair has been investigated with evidence that secreted factors are responsible for the observed therapeutic benefits. This review addresses current evidence in support of stem/progenitor cell-derived extracellular vesicles (EVs) as a regenerative therapy for acceleration of wound healing. Encouraging results for local or systemic administration of EVs have been reported in a range of clinically-relevant animal models of cutaneous wounds. Furthermore, a number of plausible mechanisms involving EV-mediated transfer of proteins and RNAs that trigger pro-repair pathways in target cells have been demonstrated experimentally. However, for successful clinical translation in the coming years, further emphasis on standardized experimental protocols, detailed methodological reporting and clear definition of EV-based therapeutic products will be required.

Discovering Macrophage Functions Using In Vivo Optical Imaging Techniques

Macrophages are an important component of host defense and inflammation and play a pivotal role in immune regulation, tissue remodeling, and metabolic regulation. Since macrophages are ubiquitous in human bodies and have versatile physiological functions, they are involved in virtually every disease, including cancer, diabetes, multiple sclerosis, and atherosclerosis. Molecular biological and histological methods have provided critical information on macrophage biology. However, many in vivo dynamic behaviors of macrophages are poorly understood and yet to be discovered. A better understanding of macrophage functions and dynamics in pathogenesis will open new opportunities for better diagnosis, prognostic assessment, and therapeutic intervention. In this article, we will review the advances in macrophage tracking and analysis with in vivo optical imaging in the context of different diseases. Moreover, this review will cover the challenges and solutions for optical imaging techniques during macrophage intravital imaging.

Microparticles to enhance delivery of drugs and growth factors into wound sites

Microparticles with controlled size and morphology are of significant interest in the field of drug delivery. Although advanced nanoparticles have been the object of a substantial number of reviews, fewer have focused on microparticles, especially for the delivery of drugs and growth factors to the wound site. Microparticles show distinct advantages, including ease of production and characterization, extended release properties, high drug loading and little concern about the toxicity as compared with the nanosized systems. This review presents an introduction to the pathophysiology of wound healing and provides an overview of some of the recent advances in microparticle-based drugs and growth factors delivery to wound sites.

Accelerated Healing of Diabetic Wounds Treated with L-Glutamic acid Loaded Hydrogels Through Enhanced Collagen Deposition and Angiogenesis: An In Vivo Study

We have developed L-glutamic acid (LG) loaded chitosan (CS) hydrogels to treat diabetic wounds. Although literature reports wound healing effects of poly(glutamic acid)-based materials, there are no studies on the potential of L-glutamic acid in treating diabetic wounds. As LG is a direct precursor for proline synthesis, which is crucial for collagen synthesis, we have prepared CS + LG hydrogels to accelerate diabetic wound healing. Physiochemical properties of the CS + LG hydrogels showed good swelling, thermal stability, smooth surface morphology, and controlled biodegradation. The addition of LG to CS hydrogels did not alter their biocompatibility significantly. CS + LG hydrogel treatment showed rapid wound contraction compared to control and chitosan hydrogel. Period of epithelialization is significantly reduced in CS + LG hydrogel treated wounds (16 days) compared to CS hydrogel (20 days), and control (26 days). Collagen synthesis and crosslinking are also significantly improved in CS + LG hydrogel treated diabetic rats. Histopathology and immunohistochemistry results revealed that the CS + LG hydrogel dressing accelerated vascularization and macrophage recruitment to enhance diabetic wound healing. These results demonstrate that incorporation of LG can improve collagen deposition, and vascularization, and aid in faster tissue regeneration. Therefore, CS + LG hydrogels could be an effective wound dressing used to treat diabetic wounds.

Current and Emerging Treatments for Postsurgical Cleft Lip Scarring: Effectiveness and Mechanisms

Cleft lip with or without cleft palate is the most common congenital malformation of the head and the third-most common birth defect. Surgical repair of the lip is the only treatment and is usually performed during the first year of life. Hypertrophic scar (HTS) formation is a frequent postoperative complication that impairs soft tissue form, function, or movement. Multiple lip revision operations are often required throughout childhood, attempting to optimize aesthetics and function. The mechanisms guiding HTS formation are multifactorial and complex. HTS is the result of dysregulated wound healing, where excessive collagen and extracellular matrix proteins are deposited within the wound area, resulting in persistent inflammation and resultant fibrosis. Many studies support the contribution of dysregulated, exaggerated inflammation in scar formation. Fibrosis and scarring result from chronic inflammation that interrupts tissue remodeling in normal wound healing. Failure of active resolution of inflammation pathways has been implicated. The management of HTS has been challenging for clinicians, since current therapies are minimally effective. Emerging evidence that specialized proresolving mediators of inflammation accelerate wound healing by preventing chronic inflammation and allowing natural uninterrupted tissue remodeling suggests new therapeutic opportunities in the prevention and management of HTS.

Cellular Stress Response and Immune Signaling in Retinal Ischemia-Reperfusion Injury

Ischemia–reperfusion injury is a well-known pathological hallmark associated with diabetic retinopathy, glaucoma, and other related retinopathies that ultimately can lead to visual impairment and vision loss. Retinal ischemia pathogenesis involves a cascade of detrimental events that include energy failure, excitotoxic damage, calcium imbalance, oxidative stress, and eventually cell death. Retina for a long time has been known to be an immune privileged site; however, recent investigations reveal that retina, as well as the central nervous system, elicits immunological responses during various stress cues. Stress condition, such as reperfusion of blood supply post-ischemia results in the sequestration of different immune cells, inflammatory mediators including cytokines, chemokines, etc., to the ischemic region, which in turn facilitates induction of inflammatory conditions in these tissues. The immunological activation during injury or stress per se is beneficial for repair and maintenance of cellular homeostasis, but whether the associated inflammation is good or bad, during ischemia–reperfusion injury, hitherto remains to be explored. Keeping all these notions in mind, the current review tries to address the immune response and host stress response mechanisms involved in ischemia–reperfusion injury with the focus on the retina.

Transition from inflammation to proliferation: a critical step during wound healing

The ability to rapidly restore the integrity of a broken skin barrier is critical and is the ultimate goal of therapies for hard-to-heal-ulcers. Unfortunately effective treatments to enhance healing and reduce scarring are still lacking. A deeper understanding of the physiology of normal repair and of the pathology of delayed healing is a prerequisite for the development of more effective therapeutic interventions. Transition from the inflammatory to the proliferative phase is a key step during healing and accumulating evidence associates a compromised transition with wound healing disorders. Thus, targeting factors that impact this phase transition may offer a rationale for therapeutic development. This review summarizes mechanisms regulating the inflammation-proliferation transition at cellular and molecular levels. We propose that identification of such mechanisms will reveal promising targets for development of more effective therapies.

Roles of Proteoglycans and Glycosaminoglycans in Wound Healing and Fibrosis

A wound is a type of injury that damages living tissues. In this review, we will be referring mainly to healing responses in the organs including skin and the lungs. Fibrosis is a process of dysregulated extracellular matrix (ECM) production that leads to a dense and functionally abnormal connective tissue compartment (dermis). In tissues such as the skin, the repair of the dermis after wounding requires not only the fibroblasts that produce the ECM molecules, but also the overlying epithelial layer (keratinocytes), the endothelial cells, and smooth muscle cells of the blood vessel and white blood cells such as neutrophils and macrophages, which together orchestrate the cytokine-mediated signaling and paracrine interactions that are required to regulate the proper extent and timing of the repair process. This review will focus on the importance of extracellular molecules in the microenvironment, primarily the proteoglycans and glycosaminoglycan hyaluronan, and their roles in wound healing. First, we will briefly summarize the physiological, cellular, and biochemical elements of wound healing, including the importance of cytokine cross-talk between cell types. Second, we will discuss the role of proteoglycans and hyaluronan in regulating these processes. Finally, approaches that utilize these concepts as potential therapies for fibrosis are discussed.

Macrophage activation in human diseases

It is becoming increasingly accepted that macrophages play a crucial role in many diseases associated with chronic inflammation, including atherosclerosis, obesity, diabetes, cancer, skin diseases, and even neurodegenerative diseases. It is therefore not surprising that macrophages in human diseases have gained significant interest during the last years. Molecular analysis combined with more sophisticated murine disease models and the application of genome-wide technologies has resulted in a much better understanding of the role of macrophages in human disease. We highlight important gain of knowledge during the last years for tumor-associated macrophages, and for macrophages in atherosclerosis, obesity and wound healing. Albeit these exciting findings certainly pave the way to novel diagnostics and therapeutics, several hurdles still need to be overcome. We propose a general outline for future research and development in disease-related macrophage biology based on integrating (1) genome-wide technologies, (2) direct human sampling, and (3) a dedicated use of in vivo model systems.

Emerging roles for macrophages in cardiac injury: cytoprotection, repair, and regeneration

The mammalian heart contains a population of resident macrophages that expands in response to myocardial infarction through the recruitment of monocytes. Infarct macrophages exhibit high phenotypic diversity and respond to microenvironmental cues by altering their functional properties and secretory profile. In this issue of the JCI, de Couto and colleagues demonstrate that infiltrating macrophages can be primed to acquire a cardioprotective phenotype in ischemic heart and exert this proactive effect through activation of an antiapoptotic program in cardiomyocytes. This study supports the growing body of evidence that suggests that macrophage subpopulations can be modulated to mediate cytoprotective, reparative, and even regenerative functions in the infarcted heart. The cellular mechanisms and molecular signals driving these macrophage phenotypes are yet unknown; however, harnessing the remarkable potential of the macrophage in regulating cell survival and tissue regeneration may hold therapeutic promise for myocardial infarction.

The Effect of Bone Marrow-Derived Mesenchymal Stem Cells and Their Conditioned Media Topically Delivered in Fibrin Glue on Chronic Wound Healing in Rats

Bone marrow-derived mesenchymal stem cells (BM-MSCs) represent a modern approach for management of chronic skin injuries. In this work, we describe BM-MSCs application versus their conditioned media (CM) when delivered topically admixed with fibrin glue to enhance the healing of chronic excisional wounds in rats. Fifty-two adult male rats were classified into four groups after induction of large-sized full-thickness skin wound: control group (CG), fibrin only group (FG), fibrin + MSCs group (FG + SCs), and fibrin + CM group (FG + CM). Healing wounds were evaluated functionally and microscopically. Eight days after injury, number of CD68+ macrophages infiltrating granulation tissue was considerably higher in the latter two groups. Although--later--none of the groups depicted a substantially different healing rate, the quality of regenerated skin was significantly boosted by the application of either BM-MSCs or their CM both (1) structurally as demonstrated by the obviously increased mean area percent of collagen fibers in Masson's trichrome-stained skin biopsies and (2) functionally as supported by the interestingly improved epidermal barrier as well as dermal tensile strength. Thus, we conclude that topically applied BM-MSCs and their CM-via fibrin vehicle--could effectively improve the quality of healed skin in chronic excisional wounds in rats, albeit without true acceleration of wound closure.

Fetal and early neonatal interleukin-6 response

In 1998, a systemic fetal cytokine response, defined as a plasma interleukin-6 (IL-6) value above 11 pg/mL, was reported to be a major independent risk factor for the subsequent development of neonatal morbid events even after adjustments for gestational age and other confounders. Since then, the body of literature investigating the use of blood concentrations of IL-6 as a hallmark of the fetal inflammatory response syndrome (FIRS), a diagnostic marker of early-onset neonatal sepsis (EONS) and a risk predictor of white matter injury (WMI), has grown rapidly. In this article, we critically review: IL-6 biological functions; current evidence on the association between IL-6, preterm birth, FIRS and EONS; IL-6 reference intervals and dynamics in the early neonatal period; IL-6 response during the immediate postnatal period and perinatal confounders; accuracy and completeness of IL-6 diagnostic studies for EONS (according to the Standards for Reporting of Diagnostic Accuracy statement); and recent breakthroughs in the association between fetal blood IL-6, EONS, and WMI.

The significance of macrophage polarization subtypes for animal models of tissue fibrosis and human fibrotic diseases

The systemic and organ-specific human fibrotic disorders collectively represent one of the most serious health problems world-wide causing a large proportion of the total world population mortality. The molecular pathways involved in their pathogenesis are complex and despite intensive investigations have not been fully elucidated. Whereas chronic inflammatory cell infiltration is universally present in fibrotic lesions, the central role of monocytes and macrophages as regulators of inflammation and fibrosis has only recently become apparent. However, the precise mechanisms involved in the contribution of monocytes/macrophages to the initiation, establishment, or progression of the fibrotic process remain largely unknown. Several monocyte and macrophage subpopulations have been identified, with certain phenotypes promoting inflammation whereas others display profibrotic effects. Given the unmet need for effective treatments for fibroproliferative diseases and the crucial regulatory role of monocyte/macrophage subpopulations in fibrogenesis, the development of therapeutic strategies that target specific monocyte/macrophage subpopulations has become increasingly attractive. We will provide here an overview of the current understanding of the role of monocyte/macrophage phenotype subpopulations in animal models of tissue fibrosis and in various systemic and organ-specific human fibrotic diseases. Furthermore, we will discuss recent approaches to the design of effective anti-fibrotic therapeutic interventions by targeting the phenotypic differences identified between the various monocyte and macrophage subpopulations.