Neutrophils and natural killer T cells as negative regulators of wound healing

Advances in Immunomodulatory Mechanisms of Mesenchymal Stem Cells-Derived Exosome on Immune Cells in Scar Formation

Pathological scars are the result of over-repair and excessive tissue proliferation of the skin injury. It may cause serious dysfunction, resulting in psychological and physiological burdens on the patients. Currently, mesenchymal stem cells-derived exosomes (MSC-Exo) displayed a promising therapeutic effect on wound repair and scar attenuation. But the regulatory mechanisms are opinions vary. In view of inflammation has long been proven as the initial factor of wound healing and scarring, and the unique immunomodulation mechanism of MSC-Exo, the utilization of MSC-Exo may be promising therapeutic for pathological scars. However, different immune cells function differently during wound repair and scar formation. The immunoregulatory mechanism of MSC-Exo would differ among different immune cells and molecules. Herein, this review gave a comprehensive summary of MSC-Exo immunomodulating different immune cells in wound healing and scar formation to provide basic theoretical references and therapeutic exploration of inflammatory wound healing and pathological scars.

In-silico engineering of RNA nanoplatforms to promote the diabetic wound healing

One of the most notable required features of wound healing is the enhancement of angiogenesis, which aids in the acceleration of regeneration. Poor angiogenesis during diabetic wound healing is linked to a shortage of pro-angiogenic or an increase in anti-angiogenic factors. As a result, a potential treatment method is to increase angiogenesis promoters and decrease suppressors. Incorporating microRNAs (miRNAs) and small interfering RNAs (siRNAs), two forms of quite small RNA molecules, is one way to make use of RNA interference. Several different types of antagomirs and siRNAs are now in the works to counteract the negative effects of miRNAs. The purpose of this research is to locate novel antagonists for miRNAs and siRNAs that target multiple genes to promote angiogenesis and wound healing in diabetic ulcers.In this context, we used gene ontology analysis by exploring across several datasets. Following data analysis, it was processed using a systems biology approach. The feasibility of incorporating the proposed siRNAs and miRNA antagomirs into polymeric bioresponsive nanocarriers for wound delivery was further investigated by means of a molecular dynamics (MD) simulation study. Among the three nanocarriers tested (Poly (lactic-co-glycolic acid) (PLGA), Polyethylenimine (PEI), and Chitosan (CTS), MD simulations show that the integration of PLGA/hsa-mir-422a is the most stable (total energy = -1202.62 KJ/mol, Gyration radius = 2.154 nm, and solvent-accessible surface area = 408.416 nm2). With values of -25.437 KJ/mol, 0.047 nm for the Gyration radius, and 204.563 nm2 for the SASA, the integration of the second siRNA/ Chitosan took the last place. The results of the systems biology and MD simulations show that the suggested RNA may be delivered through bioresponsive nanocarriers to speed up wound healing by boosting angiogenesis.

Autologous Platelet-Rich Plasma in Clitoral Reconstructive Surgery After Female Genital Mutilation/Cutting: A Pilot Case Study

BACKGROUND

Postoperative healing after clitoral reconstruction (CR) for female genital mutilation/cutting can be long and painful due to prolonged clitoral re-epithelialization time (up to 3 months). Autologous platelet-rich plasma (A-PRP) might reduce postoperative clitoral epithelialization time and pain.

OBJECTIVES

The authors assessed postoperative clitoral re-epithelialization time and pain after intraoperative clitoral administration of A-PRP.

METHODS

Five consecutive women underwent CR (Foldès technique) followed by the administration of A-PRP Regen Lab SA (Le Mont-sur-Lausanne, Switzerland) plasma and glue, injected inside and applied above the re-exposed clitoris, respectively. We recorded surgical complications, postoperative clitoral pain (visual analogue scale), painkiller intake, time to complete re-epithelialization, and the experienced subjective changes in sexual response and perception of their own body image referred by women.

RESULTS

Sexual distress/dysfunction as well as the desire to be physically and symbolically "repaired" were the reasons behind women's requests for surgery. None of the women suffered from chronic vulvar or non-vulvar pain. All women achieved complete clitoral epithelialization by day 80, 3 women between day 54 and 70, and only 1 woman was still taking 1 g of paracetamol twice a day at 2 months postoperative. She had stopped it before the 3-month control. There were no short- or long-term complications. All women described easier access and stimulation of their clitoris as well as improved sexual arousal, lubrication, and pleasure and claimed to be satisfied with their restored body image.

CONCLUSIONS

A-PRP could expedite postoperative clitoral epithelialization and reduce postoperative pain after CR after female genital mutilation/cutting.

LEVEL OF EVIDENCE: 4

Therapeutic Properties of Honey for the Management of Wounds; Is There a Role in the Armamentarium of Diabetic Foot Ulcer Treatment? Results From In vitro and In vivo Studies

Diabetic foot ulcers are one of the most dreadful complications of diabetes mellitus and efforts to accelerate diabetic wound healing are of paramount importance to prevent ulcer infections and subsequent lower-limb amputations. There are several treatment approaches for the management of diabetic foot ulcers and honey seems to be a safe and cost-effective therapeutic approach on top of standard of care. The aim of this review was to summarize the therapeutic properties of honey and the data regarding its possible favorable effects on diabetic wound healing. A literature search of articles from 1986 until April 2021 was performed using MEDLINE, EMBASE, and the Cochrane Library to assess for studies examining the therapeutic wound healing properties of honey, it's in vitro effect, and the efficacy and/or mechanism of action of several types of honey used for the treatment of diabetic animal wounds. Honey has antioxidant, anti-inflammatory, and antibacterial properties and in vitro studies of keratinocytes and fibroblasts, as well as studies in diabetic animal models show that treatment with honey is associated with increased re-epithelialization and collagen production, higher wound contraction, and faster wound healing. The use of honey could be a promising approach for the management of diabetic foot ulcers.

Similarities between Tumour Immune Response and Chronic Wound Microenvironment: Influence of Mesenchymal Stromal/Stem Cells

Tumours are characterized by a state of chronic inflammation and are regarded as wounds that never heal. Mesenchymal stromal/stem cells (MSCs) are being considered as a possible treatment option. While MSCs can regulate the immune system, migrate to sites of inflammation, and are naturally immune-privileged, there have been contradictory reports on the role of these cells in the tumour microenvironment (TME). Some studies have suggested that MSCs promote tumourigenesis while others have suggested the contrary. To better evaluate the role of MSCs in the TME, it may be helpful to understand the role of MSCs in chronic wounds. Here, we discuss the role of MSCs in chronic wounds and extrapolate this to the TME. Chronic wounds are stuck in the inflammatory phase of wound healing, while in the case of the TME, both the inflammatory and proliferative phases are exploited. MSCs in chronic wounds promote a switch in macrophage phenotype from proinflammatory (M1) to anti-inflammatory (M2), thereby suppressing T, B, and natural killer cells, consequently promoting wound healing. In the case of the TME, MSCs are reported to promote tumorigenesis by suppressing T, B, and natural killer cells in addition to dendritic cells, cytotoxic T cells, and Th1-associated cytokines, thereby promoting tumour growth. Some studies have however suggested that MSCs inhibit tumourigenesis, depending on the source of the MSCs and the specific mediators involved. Therefore, the role of MSCs in the TME appears to be complex and may result in variable outcomes. Compelling evidence to suggest that MSCs are an effective treatment option against tumour progression is lacking.

The optimal platelet concentration in platelet-rich plasma for proliferation of human cells in vitro-diversity, biases, and possible basic experimental principles for further research in the field: A review

BACKGROUND

In the last decades, several in vitro studies have tested the effect of plate-rich plasma (PRP) on the proliferation of human cells in search of a wizard for the use of PRP in a clinical setting. However, the literature displays striking differences regarding this question despite the relatively similar experimental design. The aim of this review is twofold: describe and explain this diversity and suggest basic principles for further in vitro studies in the field. The optimal platelet concentration in vivo will also be discussed.

METHODS

A search in mainly EMBASE and PubMed was performed to identify in vitro studies that investigate the effect of different PRP concentrations on human cell proliferation. The assessment of bias was based on the principles of "Good Cell Culture Practice" and adapted.

RESULTS

In total, 965 in vitro studies were detected. After the initial screening, 31 studies remained for full-text screening. A total of 16 studies met the criteria of final inclusion and appeared relatively sound. In general, the studies state consistently that PRP stimulates the proliferation of the human cell. Two main types of experimental techniques were detected: 1. The Fixed PRP Concentration Group using a fixed PRP concentration throughout the experiment, which leads to a substantial decrease in nutrition available at higher concentrations. 2. The Fixed PRP Volume Group using a fixed PRP-to-media ratio (Vol/Vol) throughout the experiment. A general tendency was observed in both groups: when the PRP to media ratio increased (Vol/Vol), the proliferation rate decreased. Further, The Low Leukocyte group observed a substantial higher optimal PRP concentration than The High leukocyte group. No prominent tendencies was seen regarding anticoagulants, activation methods, and blood donor (age or sex).

DISCUSSION

Two major biases regarding optimal proliferation in vitro is pointed out: 1. Too high PRP volume. It is speculated that the techniques used by some studies led to an adverse growth condition and even cell starvation at higher concentrations. 2. High leukocyte levels. Reduced proliferation rate due to proinflammatory substances released during degranulation of leukocytes.

CONCLUSIONS

The two main biases may explain the bell-shaped effect of PRP and the detrimental effects at higher platelet concentrations observed in several studies. These biases may also explain the low optimal PRP concentration observed in some studies. Even if one universal optimal PRP concentration does not exist, the review indicates that PRP concentrations in the upper parts of the scale is optimal or at least beneficial. Finally, following basic experimental principles are suggested. 1: The PRP/media ratio (Vol/Vol) should be kept as constant. 2: The PRP/media ratio should provide a sufficient nutrition supply, that is, PRP ≤ 10% (Vol/Vol). 3: The cell density per well (cells/mL) should be defined. 4: Leukocyte level should be kept low, preferable depleted (< 0.1 PLT/µL).

Targeted inhibition of endothelial calpain delays wound healing by reducing inflammation and angiogenesis

Wound healing is a multistep phenomenon that relies on complex interactions between various cell types. Calpains are a well-known family of calcium-dependent cysteine proteases that regulate several processes, including cellular adhesion, proliferation, and migration, as well as inflammation and angiogenesis. CAPNS1, the common regulatory subunit of Calpain-1 and 2, is indispensable for catalytic subunit stabilization and activity. Calpain inhibition has been shown to reduce organ damage in various disease models. Here, we report that endothelial calpain-1/2 is crucially involved in skin wound healing. Using a mouse genetic model where Capns1 is deleted only in endothelial cells, we showed that calpain-1/2 disruption is associated with reduced injury-activated inflammation, reduced CD31⁺ blood vessel density, and delayed wound healing. Moreover, in cultured HUVECs, inhibition of calpain reduced TNF-α-induced proliferation, migration, and tube formation. Deletion of Capns1 was associated with elevated levels of IκB and downregulation of β-catenin expression in endothelial cells. These observations delineate a novel mechanistic role for calpain in the crosstalk between inflammation and angiogenesis during skin repair.

Current Approaches Targeting the Wound Healing Phases to Attenuate Fibrosis and Scarring

Cutaneous fibrosis results from suboptimal wound healing following significant tissue injury such as severe burns, trauma, and major surgeries. Pathologic skin fibrosis results in scars that are disfiguring, limit normal movement, and prevent patient recovery and reintegration into society. While various therapeutic strategies have been used to accelerate wound healing and decrease the incidence of scarring, recent studies have targeted the molecular regulators of each phase of wound healing, including the inflammatory, proliferative, and remodeling phases. Here, we reviewed the most recent literature elucidating molecular pathways that can be targeted to reduce fibrosis with a particular focus on post-burn scarring. Current research targeting inflammatory mediators, the epithelial to mesenchymal transition, and regulators of myofibroblast differentiation shows promising results. However, a multimodal approach addressing all three phases of wound healing may provide the best therapeutic outcome.

Physical plasma and leukocytes - immune or reactive?

Leukocytes are professionals in recognizing and removing pathogenic or unwanted material. They are present in virtually all tissues, and highly motile to enter or leave specific sites throughout the body. Less than a decade ago, physical plasmas entered the field of medicine to deliver their delicate mix of reactive species and other physical agents for mainly dermatological or oncological therapy. Plasma treatment thus affects leukocytes via direct or indirect means: immune cells are either present in tissues during treatment, or infiltrate or exfiltrate plasma-treated areas. The immune system is crucial for human health and resolution of many types of diseases. It is therefore vital to study the response of leukocytes after plasma treatment in vitro and in vivo. This review gathers together the major themes in the plasma treatment of innate and adaptive immune cells, and puts these into the context of wound healing and oncology, the two major topics in plasma medicine.

An Increasing Neutrophil-to-Lymphocyte Ratio Trajectory Predicts Organ Failure in Critically-Ill Male Trauma Patients. An Exploratory Study

Background: Although the association of neutrophil proportions with mortality in trauma patients has recently been shown, there is a paucity of research on the association with other outcomes. We sought to investigate the association of neutrophil proportions with organ failure in critically-ill trauma patients. Methods: We reviewed a randomly-selected group of trauma patients admitted to our level-1 trauma intensive care unit between July 2007 and December 2016. Data collected included demographics, injury mechanism and severity (ISS), neutrophil-to-lymphocyte ratio (NLR) at admission and at 24 and 48 hours and organ failure data. NLR patterns during the first 48 hours were divided into two trajectories identified by applying factor and cluster analysis to longitudinal measures. Logistic regression was performed for the association between NLR trajectories and any organ failure; negative binomial regression was used to model the number of organ failures and stage of kidney failure measured by KDIGO classification. Results: 207 patients had NLR data at all three time points. The average age was 44.9 years with mean ISS of 20.6. Patients were 72% male and 23% had penetrating trauma. The 74 patients (36%) with Trajectory 1 had a mean NLR at admission of 3.6, which increased to 14.7 at 48 hours. The 133 (64%) patients in Trajectory 2 had a mean NLR at admission of 8.5 which decreased to 6.6 at 48 hours. Mean NLR was different between the two groups at all three time points (all p < 0.01). There was no significant difference in ISS, age or gender between the two trajectory groups. Models adjusted for age, gender and ISS showed that relative to those with trajectory 2, patients with the trajectory 1 were more likely to have organ failure OR 2.96 (1.42⁻6.18; p < 0.01), higher number of organ failures IRR 1.50 (1.13⁻2.00, p < 0.01), and degree of AKI IRR 2.06 (1.04⁻4.06, p = 0.04). In all cases, the estimated associations were higher among men vs. women, and all were significant among men, but not women. Conclusions: Trauma patients with an increasing NLR trajectory over the first 48 hours had increased risk, number and severity of organ failures. Further research should focus on the mechanisms behind this difference in outcome.

Immune Regulation of Skin Wound Healing: Mechanisms and Novel Therapeutic Targets

Significance: The immune system plays a central role in orchestrating the tissue healing process. Hence, controlling the immune system to promote tissue repair and regeneration is an attractive approach when designing regenerative strategies. This review discusses the pathophysiology of both acute and chronic wounds and possible strategies to control the immune system to accelerate chronic wound closure and promote skin regeneration (scar-less healing) of acute wounds. Recent Advances: Recent studies have revealed the key roles of various immune cells and immune mediators in skin repair. Thus, immune components have been targeted to promote chronic wound repair or skin regeneration and several growth factors, cytokines, and biomaterials have shown promising results in animal models. However, these novel strategies are often struggling to meet efficacy standards in clinical trials, partly due to inadequate drug delivery systems and safety concerns. Critical Issues: Excess inflammation is a major culprit in the dysregulation of normal wound healing, and further limiting inflammation effectively reduces scarring. However, current knowledge is insufficient to efficiently control inflammation and specific immune cells. This is further complicated by inadequate drug delivery methods. Future Directions: Improving our understanding of the molecular pathways through which the immune system controls the wound healing process could facilitate the design of novel regenerative therapies. Additionally, better delivery systems may make current and future therapies more effective. To promote the entry of current regenerative strategies into clinical trials, more evidence on their safety, efficacy, and cost-effectiveness is also needed.

Harmful Effects of Leukocyte-Rich Platelet-Rich Plasma on Rabbit Tendon Stem Cells In Vitro

BACKGROUND

Platelet-rich plasma (PRP) is now widely used as a promising treatment for patients with tendinopathy. However, the efficacy of PRP treatment for tendinopathy is controversial mainly because of inconsistent results from human clinical trials and particularly because the concentration and effect of leukocytes in PRP remain largely unknown.

HYPOTHESIS

Leukocyte-rich PRP (L-PRP) inhibits growth factor release, decreases proliferation, and induces nontenocyte differentiation of tendon stem cells (TSCs); increases catabolic cytokine concentrations; and causes inflammation and apoptosis. Thus, L-PRP has a detrimental effect on tendon stem/progenitor cells, which impairs injured tendon healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Pure PRP (P-PRP) and L-PRP were prepared from the same individual rabbit blood, and platelet numbers in each PRP product were adjusted to reach the same level. The leukocyte level in L-PRP was 4 and 8 times higher than those in whole blood and P-PRP, respectively. The growth factors in both P-PRP and L-PRP were measured by enzyme-linked immunosorbent assay kits. The morphology, stemness, proliferation, and differentiation of TSCs grown in L-PRP and P-PRP were examined by microscopy, immunocytochemistry, population doubling time, quantitative real-time polymerase chain reaction, and histological analysis.

RESULTS

L-PRP produced lower levels of growth factors, such as vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), transforming growth factor (TGF)-β1, and platelet-derived growth factor (PDGF), than did P-PRP. TSC proliferation was significantly decreased in L-PRP in a concentration-dependent manner. Furthermore, TSCs cultured in P-PRP produced more collagen and formed tendon-like tissue; however, TSCs grown in L-PRP differentiated into nontenocytes and produced more inflammatory factors such as membrane-associated prostaglandin synthase (mPGES) and interleukin (IL)-1β. Moreover, L-PRP was associated with increased apoptosis.

CONCLUSION

L-PRP has harmful effects on TSCs.

CLINICAL RELEVANCE

This study revealed the direct effects of different compositions of PRP on TSCs and provided basic scientific data to help understand the cellular and molecular mechanisms of the efficacy of PRP treatment in clinical use.

Neutrophil extracellular trap formation is elicited in response to cold physical plasma

Cold physical plasma is an ionized gas with a multitude of components, including hydrogen peroxide and other reactive oxygen and nitrogen species. Recent studies suggest that exposure of wounds to cold plasma may accelerate healing. Upon wounding, neutrophils are the first line of defense against invading microorganisms but have also been identified to play a role in delayed healing. In this study, we examined how plasma treatment affects the functions of peripheral blood neutrophils. Plasma treatment induced oxidative stress, as assessed by the oxidation of intracellular fluorescent redox probes; reduced metabolic activity; but did not induce early apoptosis. Neutrophil oxidative burst was only modestly affected after plasma treatment, and the killing of Pseudomonas aeruginosa and Staphylococcus aureus was not significantly affected. Intriguingly, we found that plasma induced profound extracellular trap formation. This was inhibited by the presence of catalase during plasma treatment but was not replicated by adding an equivalent concentration of hydrogen peroxide. Plasma-induced neutrophil extracellular trap formation was not dependent on the activity of myeloperoxidase or NADPH oxidase 2 but seemed to involve short-lived molecules. The amount of DNA release and the time course after plasma treatment were similar to that with the common neutrophil extracellular trap inducer PMA. After neutrophil extracellular traps had formed, concentrations of IL-8 were also significantly increased in supernatants of plasma-treated neutrophils. Both neutrophil extracellular traps and IL-8 release may aid antimicrobial activity and spur inflammation at the wound site. Whether this aids or exacerbates wound healing needs to be tested.

PKM2 released by neutrophils at wound site facilitates early wound healing by promoting angiogenesis

Neutrophils infiltration/activation following wound induction marks the early inflammatory response in wound repair. However, the role of the infiltrated/activated neutrophils in tissue regeneration/proliferation during wound repair is not well understood. Here, we report that infiltrated/activated neutrophils at wound site release pyruvate kinase M2 (PKM2) by its secretive mechanisms during early stages of wound repair. The released extracellular PKM2 facilitates early wound healing by promoting angiogenesis at wound site. Our studies reveal a new and important molecular linker between the early inflammatory response and proliferation phase in tissue repair process.

Immunomodulator 'mushroom beta glucan' induces Wnt/β catenin signalling and improves wound recovery in tilapia and rat skin: a histopathological study

The present study aims to investigate the effects of mushroom beta glucan (MBG) on wound recovery in partial hepatectomy (PH) in Nile tilapia (Oreochromis niloticus) and in rat skin wound healing examination. Following PH, we focussed on the effects on liver repair ability using in vitro and in vivo tests. In vitro, we examined whether the MBG has an impact on liver cell proliferation, mainly through 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assays and bromodeoxyuridine (BrdU) cell proliferation assay detection method. Results showed that MBG treatment was remarkable in enhancing cell proliferation of hepatocytes and in maintaining the cellular viability. Immunohistochemical staining to analyse Wnt/β-catenin signalling also showed that MBG has the effect of promoting cell proliferation of liver tissues after PH surgery.

Complement deficiency promotes cutaneous wound healing in mice

Wound healing is a complex homeostatic response to injury that engages numerous cellular activities, processes, and cell-to-cell interactions. The complement system, an intricate network of proteins with important roles in immune surveillance and homeostasis, has been implicated in many physiological processes; however, its role in wound healing remains largely unexplored. In this study, we employ a murine model of excisional cutaneous wound healing and show that C3(-/-) mice exhibit accelerated early stages of wound healing. Reconstitution of C3(-/-) mice with serum from C3(+/+) mice or purified human C3 abrogated the accelerated wound-healing phenotype. Wound histology of C3(-/-) mice revealed a reduction in inflammatory infiltrate compared with C3(+/+) mice. C3 deficiency also resulted in increased accumulation of mast cells and advanced angiogenesis. We further show that mice deficient in the downstream complement effector C5 exhibit a similar wound-healing phenotype, which is recapitulated in C5aR1(-/-) mice, but not C3aR(-/-) or C5aR2(-/-) mice. Taken together, these data suggest that C5a signaling through C5aR may in part play a pivotal role in recruitment and activation of inflammatory cells to the wound environment, which in turn could delay the early stages of cutaneous wound healing. These findings also suggest a previously underappreciated role for complement in wound healing, and may have therapeutic implications for conditions of delayed wound healing.

Recent advances on the association of apoptosis in chronic non healing diabetic wound

Generally, wounds are of two categories, such as chronic and acute. Chronic wounds takes time to heal when compared to the acute wounds. Chronic wounds include vasculitis, non healing ulcer, pyoderma gangrenosum, and diseases that cause ischemia. Chronic wounds are rapidly increasing among the elderly population with dysfunctional valves in their lower extremity deep veins, ulcer, neuropathic foot and pressure ulcers. The process of the healing of wounds has several steps with the involvement of immune cells and several other cell types. There are many evidences supporting the hypothesis that apoptosis of immune cells is involved in the wound healing process by ending inflammatory condition. It is also involved in the resolution of various phases of tissue repair. During final steps of wound healing most of the endothelial cells, macrophages and myofibroblasts undergo apoptosis or exit from the wound, leaving a mass that contains few cells and consists mostly of collagen and other extracellular matrix proteins to provide strength to the healing tissue. This review discusses the various phases of wound healing both in the chronic and acute wounds especially during diabetes mellitus and thus support the hypothesis that the oxidative stress, apoptosis, connexins and other molecules involved in the regulation of chronic wound healing in diabetes mellitus and gives proper understanding of the mechanisms controlling apoptosis and tissue repair during diabetes and may eventually develop therapeutic modalities to fasten the healing process in diabetic patients.

Stereological quantification of immune-competent cells in baseline biopsy specimens from achilles tendons: results from patients with chronic tendinopathy followed for more than 4 years

BACKGROUND

Limited data exist on the presence and function of immune-competent cells in chronic tendinopathic tendons and their potential role in inflammation and tissue healing as well as in predicting long-term outcome.

PURPOSE

To quantify subtypes of immune-competent cells in biopsy specimens from nonruptured chronic tendinopathic Achilles tendons and healthy control tendons. In addition, to examine whether findings in baseline cell biopsy specimens can predict the long-term presence of Achilles tendon symptoms.

STUDY DESIGN

Cross-sectional and case-control study; Level of evidence, 3.

METHODS

Fifty patients with nonruptured chronic Achilles tendinopathy and 15 healthy participants were included. At time of inclusion, an ultrasound examination was performed immediately before an ultrasound-guided Achilles tendon biopsy specimen was obtained. Tissue samples were evaluated immunohistochemically by quantifying the presence of macrophages (CD68-PGM1(+), CD68-KP1(+)), hemosiderophages (Perls blue), T lymphocytes (CD2(+), CD3(+), CD4(+), CD7(+), CD8(+)), B lymphocytes (CD20(+)), natural killer cells (CD56(+)), mast cells (NaSDCl(+)), Schwann cells (S100(+)), and endothelial cells (CD34(+)) using a stereological technique. A follow-up examination was conducted more than 4 years (range, 4-9 years) after the biopsy procedure to evaluate the long-term presence of Achilles tendon symptoms.

RESULTS

Macrophages, T lymphocytes, mast cells, and natural killer cells were observed in the majority (range, 52%-96%) of biopsy specimens from nonruptured chronic tendinopathic Achilles tendons. CD68-KP1(+) macrophages (0.29% vs 0; P = .005) and CD34(+) endothelial cells (3% vs 0.97%; P = .04) were significantly more numerous in tendinopathic tendons compared with healthy tendons. The presence of iron(+) hemosiderophages was more frequently observed in biopsy specimens obtained from the group who was asymptomatic at follow-up compared with the symptomatic group (42% vs 5%; P = .02).

CONCLUSION

This study provides evidence for the presence of immune-competent cells in the majority of biopsy specimens from nonruptured chronic tendinopathic Achilles tendons. Macrophages and endothelial cells were significantly more numerous in tendinopathic tendons than in healthy tendons. The presence of iron(+) hemosiderophages in baseline biopsy specimens was associated with a good prognosis.

CLINICAL RELEVANCE

New insight into the role of immune-competent cells in chronic Achilles tendinopathy.

Apoptotic cell: linkage of inflammation and wound healing

We consider that from the wound to the healing process, the physiology point key to linkage of the process is still unclear. The process from inflammation to the wound healing is divided into three phases: (1) inflammation process, (2) tissue formation, and (3) tissue remodeling. The inflammation program includes cell produced related factors and immune cells infiltration. We thought the inflammation factors that may be also involved in the followed healing process. But the question is "what kind of factor is the major key involved in the end of the inflammation then to initiate the healing." We suspect that the apoptosis of immune cell may be the major key to end of inflammation and to initiate the healing.

Reduced neutrophil chemotaxis and infiltration contributes to delayed resolution of cutaneous wound infection with advanced age

Advanced age is associated with alterations in innate and adaptive immune responses, which contribute to an increased risk of infection in elderly patients. Coupled with this immune dysfunction, elderly patients demonstrate impaired wound healing with elevated rates of wound dehiscence and chronic wounds. To evaluate how advanced age alters the host immune response to cutaneous wound infection, we developed a murine model of cutaneous Staphylococcus aureus wound infection in young (3-4 mo) and aged (18-20 mo) BALB/c mice. Aged mice exhibit increased bacterial colonization and delayed wound closure over time compared with young mice. These differences were not attributed to alterations in wound neutrophil or macrophage TLR2 or FcγRIII expression, or age-related changes in phagocytic potential and bactericidal activity. To evaluate the role of chemotaxis in our model, we first examined in vivo chemotaxis in the absence of wound injury to KC, a neutrophil chemokine. In response to a s.c. injection of KC, aged mice recruited fewer neutrophils at increasing doses of KC compared with young mice. This paralleled our model of wound infection, where diminished neutrophil and macrophage recruitment was observed in aged mice relative to young mice despite equivalent levels of KC, MIP-2, and MCP-1 chemokine levels at the wound site. This reduced leukocyte accumulation was also associated with lower levels of ICAM-1 in wounds from aged mice at early time points. These age-mediated defects in early neutrophil recruitment may alter the dynamics of the inflammatory phase of wound healing, impacting macrophage recruitment, bacterial clearance, and wound closure.

Topical application of aminopeptidase N-neutralizing antibody accelerates wound closure

Upon release from keratinocytes, 14-3-3 sigma (also known as stratifin) acts on the dermal fibroblast and modulates its production of extracellular matrix proteins. Subsequent to the recent identification as a receptor responsible for stratifin-mediated matrix turnover in dermal fibroblasts, aminopeptidase N has been implicated in the regulation of epidermal-dermal communication and expression of key matrix proteases and adhesion molecules. In light of the growing importance of aminopeptidase N in modulation of the fibroblast phenotype, the present study evaluates the potential of targeting the ectoenzyme in cutaneous repair, and demonstrates that neutralization of aminopeptidase N led to acceleration of wound closure. This was attributed to at least in part an increase of collagen deposition and fibroblast contractility in the granulation tissue. These findings confirmed the important role of aminopeptidase N in post-injury tissue remodeling and wound contraction.

Effects of hydrogen peroxide on wound healing in mice in relation to oxidative damage

It has been established that low concentrations of hydrogen peroxide (H₂O₂) are produced in wounds and is required for optimal healing. Yet at the same time, there is evidence that excessive oxidative damage is correlated with poor-healing wounds. In this paper, we seek to determine whether topical application of H₂O₂ can modulate wound healing and if its effects are related to oxidative damage. Using a C57BL/6 mice excision wound model, H₂O₂ was found to enhance angiogenesis and wound closure at 10 mM but retarded wound closure at 166 mM. The delay in closure was also associated with decreased connective tissue formation, increased MMP-8 and persistent neutrophil infiltration. Wounding was found to increase oxidative lipid damage, as measured by F₂-isoprostanes, and nitrative protein damage, as measured by 3-nitrotyrosine. However H₂O₂ treatment did not significantly increase oxidative and nitrative damage even at concentrations that delay wound healing. Hence the detrimental effects of H₂O₂ may not involve oxidative damage to the target molecules studied.

An improved cell isolation method for flow cytometric and functional analyses of cutaneous wound leukocytes

Isolation of leukocytes from full-thickness excisional wounds has proven to be a difficult process that results in poor cell yield and holds significant limitations for functional assays. Given the increased interest in the isolation, characterization and functional measurements of wound-derived cell populations, herein we describe a method for preparing wound cell suspensions with an improved yield that enables both phenotypic and functional assessments.