Mast cells: an unexpected finding in the modulation of cutaneous wound repair by charged beads

Clinical and Histological Outcomes of Negatively Charged Polystyrene Microspheres Applied Daily Versus Three Times per Week in Hard-to-Heal Diabetic Foot Ulcers: A Randomized Blinded Controlled Trial

Negatively charged polystyrene microspheres (NCMs) have been demonstrated as a novel and effective therapy for managing hard-to-heal diabetic foot ulcers (DFUs). However, one limitation of this therapy is that the protocol is based on daily application, which sometimes does not fit local protocols of wound care. Thus, we aimed to analyze the safety and efficacy of a new dose regimen. We conducted a randomized blinded controlled trial in a specialized diabetic foot unit between May 2019 and February 2021 with a total of 30 patients who had neuropathic or neuroischemic DFUs that had not responded after four weeks of standard treatment. Patients were randomized consecutively into a group that received daily application (control) or one that received applications three times per week (experimental). The clinical outcomes were evaluated using the Wollina score and wound-area reduction (WAR) weekly during a treatment period of 28 days. The histological outcomes were assessed using a soft-tissue punch biopsy (3 mm) at 0, 14, and 28 days to evaluate cellular proliferation. The Wollina scores were higher at the end of treatment by week 4 in both groups, but the differences were not significant between groups. The averages were 6 (5, 7) points in Experimental group (EG) and 6 (6,7) points in Control group (CG) (p = 0.848). Wound area reduction at day 28 was 53.57 [37.43, 79.16] % in the CG and 79.37 [42.74, 93.57] % in the EG, without differences among groups (p = 0.305). Cellular proliferation was similar in both groups at day 28. Application three times per week showed similar clinical and histological outcomes to those of daily application, both dose regimens demonstrated significant improvement of granulation tissue formation and WAR during the treatment.

Cryosurgery as a Single Agent and in Combination with Intralesional Corticosteroids Is Effective on Young, Small Keloids and Induces Characteristic Histological and Immunohistological Changes: A Prospective Randomized Trial

BACKGROUND

As the pathogenesis of keloids is poorly understood, there is no sound biological basis of keloid management. Few controlled therapeutic studies have been published, and recurrences are a major reason for treatment failure.

OBJECTIVE

To detect efficacy and safety of cryosurgery regimens on keloids and the occurring biological changes caused by the treatment.

METHODS

This prospective randomized study compared efficacy and tolerability as well as histological/immunohistochemical effects of liquid nitrogen contact cryosurgery as a single regimen (group A) and combined with intralesional corticosteroids (group B) on young (<2 years old), small (≤10 cm2) keloids in 40 patients (2-sided effect, α-error 1%, power 95%).

RESULTS

Marked flattening of the lesions was achieved by both regimens. Median lesional volumes decreased from 106 to 7 mm3 in group A (p = 0.001) and from 138 to 6 mm3 in group B (p < 0.0001; ns, between groups). Good to excellent responses were registered in 83.3 and 90% of patients in groups A and B, respectively, by evaluating the lesional volume, in 80 and 95% of patients by the physician's evaluation and in 95% of patients in either group by the patient's assessment. Follow-up of 6-36 months revealed no further significant changes. Cryosurgery was generally well tolerated, with minor pain during treatment not requiring (27.5%) or requiring local anaesthesia (5%) - but not analgesics -, and hypopigmentation (25%). Histological examination showed increased vessel number and lumen dilatation after treatment in group B and reduction of rete ridge length in both groups with more prominent changes in group A. Tenascin C staining demarcated keloids from normal skin before therapy, while after therapy the entire treated tissue was labelled. Interferon-γ expression was significantly decreased after therapy both regarding positively stained cells and intensity in both groups.

CONCLUSION

Cryosurgery without and with intralesional corticosteroids is effective and safe on young, small keloids not only as a destructive physical procedure, but also by inducing biochemical and immunological scar rejuvenation.

Cost-effectiveness of using Polyheal compared with surgery in the management of chronic wounds with exposed bones and/or tendons due to trauma in France, Germany and the UK

The objective of this study was to assess the cost-effectiveness of Polyheal compared with surgery in treating chronic wounds with exposed bones and/or tendons (EB&T) due to trauma in France, Germany and the UK, from the perspective of the payers. Decision models were constructed depicting the management of chronic wounds with EB&T and spanned the period up to healing or up to 1 year. The models considered the decision by a plastic surgeon to treat these wounds with Polyheal or surgery and was used to estimate the relative cost-effectiveness of Polyheal at 2010/2011 prices. Using Polyheal instead of surgery is expected to increase the probability of healing from 0·93 to 0·98 and lead to a total health-care cost of €7984, €7517 and €8860 per patient in France, Germany and the UK, respectively. Management with surgery is expected to lead to a total health-care cost of €12 300, €18 137 and €11 330 per patient in France, Germany and the UK, respectively. Hence, initial treatment with Polyheal instead of surgery is expected to lead to a 5% improvement in the probability of healing and a substantial decrease in health-care costs of 35%, 59% and 22% in France, Germany and the UK, respectively. Within the models' limitations, Polyheal potentially affords the public health-care system in France, Germany and the UK a cost-effective treatment for chronic wounds with EB&T due to trauma, when compared with surgery. However, this will be dependent on Polyheal's healing rate in clinical practice when it becomes routinely available.

Wound 'dechronification' with negatively-charged polystyrene microspheres: a double-blind RCT

OBJECTIVE

To compare the efficacy and safety of negatively-charged polystyrene microspheres (NCM)with controls (saline soaks) in the treatment of hard-to-heal wounds of various aetiologies.

METHOD

Patients with one or more hard-to-heal wounds, defined as refractory to healing for at least 4 weeks, or those with exposed bone, tendon or ligament, were eligible for inclusion and were randomised to either NCM (PolyHeal; MediWound Ltd.) or controls, both applied twice daily for 4 weeks. Patients were monitored bi-weekly for an additional 8 weeks, while treated by standard wound care, at the investigators' discretion, and were re-evaluated 2 years after inclusion. The primary endpoint was defined as coverage of> 75% of the wound area by light-red granulation tissue after 4 weeks of treatment.

RESULTS

Fifty-eight patients completed the study, 32 in the NCM group and 26 in the control group. The two most common wound types were those with primary etiologies of venous insufficiency and postoperative/post trauma. In the NCM group 47% of patients achieved > 75% light red granulation tissue after 4 weeks compared with 15% of patients in the control group (p=O.O I). The mean wound surface area in the NCM group was reduced by 39.0% after 4 weeks compared with 14.9% in the control group (p=0.02).The achievement of> 75% light red granulation tissue and reduction of mean wound surface area was also observed in the two main sub-groups (venous insufficiency and postoperative/post trauma), although it was not statistically significant, possibly due to the small sample size in each sub-group.

CONCLUSION

This study demonstrates that compared to control treatment, NCM treatment of hard to-heal and chronic wounds improves formation of healthy granulation tissue and reduces wound size thus in fact 'kick-starting' the healing process and 'dechronifying' chronic wounds.

Post-facelift flap necrosis treatment using charged polystyrene microspheres

BACKGROUND

Flap necrosis following facial rhytidectomy constitutes a vexing and grievous complication to the patient and the surgeon. Treatment modalities that can expedite wound healing and re-epithelialization rates are highly desired.

OBJECTIVES

To assess wound healing and re-epithelialization rates of open wounds following postrhytidectomy flap necrosis treated with commercially available charged polystyrene microspheres (Polyheal-1, Polyheal Ltd, Israel).

METHODS

Flap necrosis following rhytidectomy with open wounds in three female patients were treated using dressings soaked with Polyheal-1. Wound closure rates were documented.

RESULTS

The wounds demonstrated both accelerated granulation tissue formation and rapid re-epithelialization rates. No complications or side effects were encountered.

CONCLUSIONS

Charged polystyrene microspheres may offer a new and efficacious way to treat open wounds due to flap necrosis following facial rhytidectomy. Further research with larger patient numbers is still needed to verify these findings.

Structural changes in the skin of hairless mice following exposure to sulfur mustard correlate with inflammation and DNA damage

Sulfur mustard (SM, bis(2-chloroethyl)sulfide) is a bifunctional alkylating agent that causes dermal inflammation, edema and blistering. To investigate the pathogenesis of SM-induced injury, we used a vapor cup model which provides an occlusive environment in which SM is in constant contact with the skin. The dorsal skin of SKH-1 hairless mice was exposed to saturated SM vapor or air control. Histopathological changes, inflammatory markers and DNA damage were analyzed 1-14 days later. After 1 day, SM caused epidermal thinning, stratum corneum shedding, basal cell karyolysis, hemorrhage and macrophage and neutrophil accumulation in the dermis. Cleaved caspase-3 and phosphorylated histone 2A.X (phospho-H2A.X), markers of apoptosis and DNA damage, respectively, were increased whereas proliferating cell nuclear antigen (PCNA) was down-regulated after SM exposure. By 3 days, epithelial cell hypertrophy, edema, parakeratosis and loss of epidermal structures were noted. Enzymes generating pro-inflammatory mediators including myeloperoxidase and cyclooxygenase-2 were upregulated. After 7 days, keratin-10, a differentiation marker, was evident in the stratum corneum. This was associated with an underlying eschar, as neoepidermis began to migrate at the wound edges. Trichrome staining revealed increased collagen deposition in the dermis. PCNA expression in the epidermis was correlated with hyperplasia, hyperkeratosis, and parakeratosis. By 14 days, there was epidermal regeneration with extensive hyperplasia, and reduced expression of cleaved caspase-3, cyclooxygenase-2 and phospho-H2A.X. These findings are consistent with the pathophysiology of SM-induced skin injury in humans suggesting that the hairless mouse can be used to investigate the dermatoxicity of vesicants and the potential efficacy of countermeasures.

Rat mast cells enhance fibroblast proliferation and fibroblast-populated collagen lattice contraction through gap junctional intercellular communications

BACKGROUND

Mast cells' association with fibrosis is known, but the mechanics of that association are unclear. The hypothesis is that mast cells promote fibroblast profibrotic activities through heterocellular gap junctional intercellular communications. Casting populated collagen lattices with both human mastocytoma cell line (HMC-1), an established mast cell line, and fibroblasts enhances lattice contraction via gap junctional intercellular communications. Unfortunately, in monolayer culture, HMC-1 cells and fibroblasts do not form heterocellular gap junctional intercellular communications. Freshly isolated rat peritoneal mast cells, however, establish these communications with fibroblasts in monolayer culture. Isolated rat peritoneal mast cells, however, survive only 7 days. Establishing a rat mast cell line that grows in the same medium as fibroblasts advances the study of mast cell-fibroblast interactions. HMC-1 cells thrive without supplements, suggesting that they release the factor(s) necessary for their viability. Spent HMC-1 medium may contain the factor(s) that generate a viable rat mast cell line.

METHODS

Rat peritoneal-isolated mast cells grew in culture medium containing spent HMC-1 medium for 4 weeks. At 4 weeks, rat mast cells (RMC-1) were successfully maintained in Dulbecco's Modified Eagle Medium with 10% serum.

RESULTS

RMC-1 cells formed heterocellular gap junctional intercellular communications with fibroblasts, enhancing both fibroblast proliferation and co-cultured RMC-1/fibroblast/populated collagen lattice contraction. Enhanced fibroblast proliferation and lattice contraction failed to occur by including RMC-1 cells unable to establish gap junctional intercellular communications with fibroblasts, but cell proliferation was not affected by including degranulated RMC-1 cells.

CONCLUSION

Heterocellular gap junctional intercellular communications with mast cells increase in fibroblast proliferation and fibroblast PCL contraction, two hypertrophic scar fibroblast activities.

Effect of low-level treatment with an 80-Hz pulsed infrared diode laser on mast-cell numbers and degranulation in a rat model of third-degree burn

BACKGROUND DATA

Low-level laser therapy (LLLT) has been reported to be capable of changing mast cell numbers and degranulation in experimental burns in rats.

OBJECTIVE

We conducted a study of the influence of LLLT on mast cells in a rat model of third-degree burn.

METHODS

In this study we divided 48 rats equally into two groups of 24 rats each. Third-degree burns were inflicted at three different locations on each rat in each group. The first burn site on rats in group I was treated with 890-nm pulsed laser, 75W peak, 80 Hz, 180 ns, average power 1mW, illuminated area 1 cm(2), 1 mW/cm(2), 856 sec, 0.924 J/cm(2). The second burn site on both groups of rats was treated with 0.2% nitrofurazone cream. Mast cell numbers and degranulation at each burn site on each group of rats were then assessed at 4, 8, 13, and 20 days after the infliction of burns.

RESULTS

Analysis of variance on day 4 showed that the total numbers of mast cells were significantly lower at the laser-treated burn sites than at other burn sites on both groups of rats. On day 8 the total numbers of mast cells were again significantly lower at the laser-treated burn sites than at other burn sites, and on day 13, the numbers of both types 1 and 2 mast cells were significantly lower at the laser-treated burn sites than at other burn sites.

CONCLUSIONS

We conclude that LLLT can significantly decrease total numbers of mast cells during the proliferation and remodeling phases of healing in a rat model of third-degree burn.

Poly(methacrylic acid-co-methyl methacrylate) beads promote vascularization and wound repair in diabetic mice

Topical application of beads made from poly(methacrylic acid-co-methyl methacrylate) (45 mol % methacrylic acid, MAA) increased the number of blood vessels and improved 1.5 x 1.5 cm full thickness wound closure in a diabetic mouse (db/db) model. Three groups were compared: MAA beads, control poly(methyl methacrylate) beads (PMMA), and no bead blanks. MAA bead treatment significantly increased percent wound closure at all timepoints (7, 14, and 21 days) with MAA bead-treated wounds almost closed at day 21 (91 +/- 5.4% MAA vs. 79 +/- 3.2% PMMA or 76 +/- 4.8% no beads; p < 0.05). This was consistent with the expected significant increase in vascularity in the MAA group at days 7 and 14. For example at day 14, MAA bead-treated wounds had a vascular density of 22.7 +/- 2.6 vessels/hpf compared with 17.0 +/- 2.0 vessels/hpf in the PMMA bead group (p < 0.05). Epithelial gap and migration measurements suggested that the increased vascularity leads to enhanced epithelial cell migration as a principal means of wound closure. Although studies are underway to elucidate the mechanism of this angiogenic response, the results presented here support the notion that such materials, perhaps in other forms, may be useful in wound care or in other situations where vascularity is to be enhanced without the use of exogenous growth factors.

Keloids: pathogenesis, clinical features, and management

Cutaneous wound healing is a complex response to skin injury. Deregulation of this process can lead to excessive scar formation, as seen in keloids. Keloids are common skin lesions that are difficult to treat and are associated with high recurrence rates despite the large number of available treatment options. With increased knowledge of the disease process and further scientific advancements, future approaches will hopefully improve keloid treatment. In this article, we review the epidemiology, genetic basis, etiology, clinical features, pathogenesis, and management of keloids.

Antagonists of CD117 (cKit) signaling inhibit mast cell accumulation in healing skin wounds

Mast cells (MCs) have important functional roles in leukocyte recruitment, pain, and wound healing, and increased tissue resident MC function has been associated with several fibrotic diseases. Consequently, the study of MCs in situ can be a direct approach to studying the pharmacodynamic impact of MC-directed therapeutics in tissues. Here we describe an automated laser scanning cytometry assay that was used to characterize the kinetics of MC accumulation in healing skin wounds and to study the effect of inhibiting CD117 (cKit) signaling. The number of tryptase-positive MCs approximately doubled 14 days after cutaneous injury in nonhuman primates. Treatment of animals with anti-CD117 or imatinib mesylate (Gleevec) reduced MC accumulation at the edge of healing wounds in mice and nonhuman primates, respectively. In translating this MC assay to become a biomarker for human studies, no differences in dermal MC numbers were evident between genders, ages or body mass index from 20 healthy donors. These data suggest that skin is a practical and useful tissue for tracking pharmacodynamic effects of MC-directed therapies.

Pharmacological modulation of wound healing in experimental burns

Factors involved in wound healing and their interdependence are not yet fully understood; nevertheless, new prospects for therapy to favor speedy and optimal healing are emerging. Reports about wound healing modulation by local application of simple and natural agents abound even in the recent literature, however, most are anecdotal and lack solid scientific evidence. We describe the effect of silver sulfadiazine and moist exposed burn ointment (MEBO), a recently described burn ointment of herbal origin, on mast cells and several wound healing cytokines (bFGF, IL-1, TGF-beta, and NGF) in the rabbit experimental burn model. The results demonstrate that various inflammatory cells, growth factors and cytokines present in the wound bed may be modulated by application of local agents with drastic effects on their expression dynamics with characteristic temporal and spatial regulation and changes in the expression pattern. Such data are likely to be important for the development of novel strategies for wound healing since they shed some light on the potential formulations of temporally and combinatory optimized therapeutic regimens.

Rat mast cells communicate with fibroblasts via gap junction intercellular communications

Usually mast cells (MCs) modulate other cellular activities through the release of their cytoplasmic granules. Recently, gap junctional intercellular communication (GJIC) between an established human MC cell line (HMC-1) co-cultured with human dermal fibroblasts in fibroblast populated collagen lattices (FPCLs), enhanced the rate and degree of FPCL contraction. However, HMC-1 cells were unable to generate GJIC with human neonatal fibroblasts in monolayer culture. Here freshly isolated rat peritoneal MCs are co-cultured with fibroblasts in collagen lattices and in monolayer culture in vitro and introduced into rat polyvinyl alcohol (PVA) sponge implants in vivo. Co-cultured MC-FPCL contracted faster and to a greater degree. Loading Calcein AM green fluorescent dye into red fluorescent Dil tagged MC generates MC-paratroopers. When MC-paratroopers form GJIC with fibroblasts, some green dye is passed into the fibroblast, while the MC-paratrooper retains both its red and green fluorescence. MC-paratroopers passed green fluorescent dye into both human and rat dermal fibroblasts in monolayer culture. In rats 7-day-old subcutaneous PVA sponge implants, which received an injection of MC-paratroopers, exhibited auto-fluorescent green fibroblasts, when harvested 24 h later. MC-paratroopers pretreated with a long-acting GJIC inhibitor prior to their introduction into PVA sponge implants, failed to pass dye into fibroblasts. It is proposed that GJIC between granulation tissue fibroblasts and MCs can modulate some aspects of wound repair and fibrosis.

Effect of low-level laser therapy on the healing of second-degree burns in rats: a histological and microbiological study

This paper presents the results of a study on the effects of two different doses of low-level laser therapy on healing of deep second-degree burns. Sixty rats were randomly allocated to one of four groups. A deep second-degree burn was inflicted in each rat. In the control group burns remained untreated; in two laser treated groups the burns were irradiated daily with low-level helium-neon laser with energy densities of 1.2 and 2.4 J/cm2, respectively. In the fourth group the burns were treated topically with 0.2% nitrofurazone cream every day. The response to treatments was assessed histologically at 7, 16 and 30 days after burning, and microbiologically at Day 15. The number of macrophages at day 16, and the depth of new epidermis at day 30, was significantly less in the laser treated groups in comparison with control and nitrofurazone treated groups (P=0.000). Staphylococcus epidermidis was found in the 70% of rat wounds in the laser treated groups in comparison with 100% of rats in the control group. S. aureus was found in the 40% rat wounds in the nitrofurazone treated group, but there was not found in the wounds of laser treated, and control groups. It is concluded that low-level laser therapy of deep second-degree burn caused significant decrease in the number of macrophage and depth of new epidermis. In addition, it decreased incidence of S. epidermidis and S. aureus.

Keloid or Hypertrophic Scar

Keloid and hypertrophic scars are 2 types of excessive scarring observed clinically that require different therapeutic approaches. The clinical course and physical appearance define keloids and hypertrophic scars as separate entities; however, they are often confused because of an apparent lack of morphologic differences. Nevertheless, clinical differences between hypertrophic scars and keloids have long been recognized by plastic surgeons and dermatologists. Yet, translating these differences into morphologic or biochemical distinctions has prompted much conflict in the literature. The present report is an attempt to clarify the longstanding controversy regarding these 2 similar yet separate and nonidentical entities by highlighting the reported points of differentiation as well as the similarities.

Possible involvement of mast cells in collagen remodeling in the late phase of cutaneous wound healing in mice

We examined possible roles of mast cells in cutaneous wound healing using mast cell deficient (W/Wv) mice and their normal littermates (+/+). A round full-thickness wound was made on the back skin of these mice. The wounds closed completely within 20 days, and there was no difference in wound contraction between +/+ and W/Wv mice during the wound healing. While either chymase or tryptase activities were hardly detectable in W/Wv mice, chymase activities decreased at the impaired sites and recovered to the control level within 20 days in +/+ mice. Tryptase activities were higher than the control level on day 15 and day 20 in +/+ mice. Histological observations on day 15 and day 20 in +/+ mice revealed that mast cells were abundant at the wound edges but absent at the center. The latent and the active forms of MMP-2 and MMP-9 increased on day 10 and day 15 but recovered nearly to control levels on day 20 in both mice groups. The hydroxyproline contents in W/Wv mice were significantly higher than those in +/+ mice on day 15 and day 20. Furthermore, histological observations revealed that the collagen aggregation at the wound edges was tighter and less interwoven in W/Wv mice compared with +/+ mice. These results suggest that mast cells accumulated at the wound edge may participate in tissue remodeling in the late phase of wound healing.