Second-degree Burn Wounds Research Articles

Mouse Mast Cell Proteases 4 and 5 Mediate Epidermal Injury through Disruption of Tight Junctions

We previously established a mast cell (MC)-dependent thermal injury model in mice with ulceration and scar formation that depended on nonredundant functions of mouse MC protease (mMCP)4 and mMCP5. We hypothesized that MC activation is an early event and now find by histology that exocytosis of granule contents occurred by 2 min after thermal injury in wild-type (WT) C57BL/6 mice and in the mMCP4- or mMCP5-deficient mice. The degranulation was equivalent for MCs in the dermis and hypodermis of all three strains, but only the WT mice showed an appreciable increase in epidermal thickness. There was no loss of total MCs, partially degranulated plus intact, during the 4 h of observation. By electron microscopy, MCs in all strains showed early zonal degranulation at 30 s with marked progression in magnitude by 120 s and no mitochondrial injury or cellular necrosis. Concomitantly there was an increase in intercellular spaces indicative of tight junction (TJ) disruption in WT mice but not in the mMCP4- or mMCP5-deficient strains. The desmosomes were intact in all strains. Immunodetection of the TJ protein claudin 4 in WT and mMCP5-deficient mice indicated a significant reduction after scald injury whereas mMCP4(-/-) mice showed no significant changes. Taken together, these findings reveal that a second-degree burn injury can initiate an immediate novel zonal degranulation of MCs throughout all skin layers and a disruption of the epidermal TJs dependent on the nonredundant presence of mMCP4 and mMCP5.

A Randomized and Controlled Multicenter Prospective Study of the Chinese Medicinal Compound Fufang Xuelian Burn Ointment for the Treatment of Superficial and Deep Second-Degree Burn Wounds

The objective of this study was to evaluate the efficacy and safety of a traditional Chinese medicine, Fufang Xuelian Burn Ointment (FXBO), to treat superficial and deep second-degree burn wounds. A four-center, randomized, controlled, and prospective study was conducted. Overall, 240 patients with either superficial or deep second-degree burn wounds were enrolled consecutively in this study. Patients who were randomly assigned to the control group (superficial: 72, deep: 48) underwent common burn wound therapy, whereas those randomized to the treatment group (superficial: 72, deep: 48) received common burn wound therapy plus topical FXBO. The healing rate, healing time, effective rate, and safety data were compared between the two groups. The baseline characteristics were comparable for the two groups. The healing rate was 94.79(±7.50) in the control group and 98.60(±5.69) in the FXBO group after 14 days for patients with superficial second-degree burn wounds (P = 0.000), and 95.17(±9.68) versus 97.44(±9.81) at 28 for deep second-degree burn wounds (P = 0.025). The median healing time in the FXBO group were 9 and 21 days for superficial and deep second-degree burns, respectively, compared to 10.5 and 22.5 days, respectively, in control group (P(superficial) = 0.000 and P(deep) = 0.009). The results of the effective rate showed that comprehensive efficacy of the FXBO group was improved compared to the control group for either superficial or deep second-degree burns (P(superficial) = 0.035 and P deep = 0.003). There were no reported drug-related adverse events in both groups. Therefore, FXBO was well tolerated and more effective than control group for treating superficial and deep second-degree burn wounds.

Burn injury-induced mechanical allodynia is maintained by Rac1-regulated dendritic spine dysgenesis

Although nearly 11million individuals yearly require medical treatment due to burn injuries and develop clinically intractable pain, burn injury-induced pain is poorly understood, with relatively few studies in preclinical models. To elucidate mechanisms of burn injury-induced chronic pain, we utilized a second-degree burn model, which produces a persistent neuropathic pain phenotype. Rats with burn injury exhibited reduced mechanical pain thresholds ipsilateral to the burn injury. Ipsilateral WDR neurons in the spinal cord dorsal horn exhibited hyperexcitability in response to a range of stimuli applied to their hindpaw receptive fields. Because dendritic spine morphology is strongly associated with synaptic function and transmission, we profiled dendritic spine shape, density, and distribution of WDR neurons. Dendritic spine dysgenesis was observed on ipsilateral WDR neurons in burn-injured animals exhibiting behavioral and electrophysiological evidence of neuropathic pain. Heat hyperalgesia testing produced variable results, as expected from previous studies of this model of second-degree burn injury in rats. Administration of Rac1-inhibitor, NSC23766, attenuated dendritic spine dysgenesis, decreased mechanical allodynia and electrophysiological signs of burn-induced neuropathic pain. These results support two related implications: that the presence of abnormal dendritic spines contributes to the maintenance of neuropathic pain, and that therapeutic targeting of Rac1 signaling merits further investigation as a novel strategy for pain management after burn injury.

Laboratory Evaluation of Thermal Protective Clothing Performance Upon Hot Liquid Splash

This study provides an understanding of heat and mass transfer through materials exposed to hot liquid splash, a relatively unexplored hazard in the safety clothing industry. Selected fabrics and layered systems were exposed to three hot liquids to study the effects of hot liquids and configuration. To explore the energy transfer mechanisms, a modified apparatus (based on ASTM F 2701-08) was developed to assess the protection performance provided by a fabric when exposed to a hot liquid. The modified test method allows measurement of the energy absorbed by the sensor, and with the use of a skin model, the time required to produce a second-degree burn injury was predicted. The preliminary testing demonstrated that mass transfer of the hot liquid through the fabric is the main factor contributing to burn injury. Key factors that determine the level of protection that a fabric system provides are summarized.

Silk sericin ameliorates wound healing and its clinical efficacy in burn wounds

The aim of this study was to evaluate the effect of silk sericin, a protein from silkworm cocoon, on scratch wound healing in vitro. For applicable result in clinical use, we also study the efficacy of sericin added to a standard antimicrobial cream, silver zinc sulfadiazine, for open wound care in the treatment of second-degree burn wounds. In vitro scratch assays show that sericin at concentration 100μg/mL can promote the migration of fibroblast L929 cells similar to epidermal growth factor (positive control) at 100μg/mL. After 1 day of treatment, the length of scratch in wounds treated with sericin was significantly shorter than the length of negative control wounds (culture medium without sericin). For clinical study, a total of 29 patients with 65 burn wounds which covered no less than 15% of total body surface area were randomly assigned to either control (wounds treated with silver zinc sulfadiazine cream) or treatment (wounds treated with silver zinc sulfadiazine with added sericin cream) group in this randomized, double-blind, standard-controlled study. The results showed that the average time to reach 70% re-epithelialization of the burned surface and complete healing in the treatment group was significantly shorter, approximately 5-7days, than in the control group. Regarding time for complete healing, control wounds took approximately 29.28±9.27days, while wounds treated with silver zinc sulfadiazine with added sericin cream took approximately 22.42±6.33days, (p=0.001). No infection or severe reaction was found in any wounds. This is the first clinical study to show that silk sericin is safe and beneficial for burn wound treatment when it is added to silver sulfadiazine cream.

Management of Paediatric Second-degree Burn in a Developing Country: With or Without Closed Dressing?

Objective: Our objective was to observe whether second-degree burn wound management can be done without using any occlusive dressing than conventional occlusive dressing in children. The purpose of this study was to evaluate our experience and to see the results of open dressing versus closed dressing in management of second-degree burn in children. Methods : A prospective comparative study was done on children (0–12 years) presented with second-degree burn during the period of August 2009 to December 2010. More than 10% total burn surface area (TBSA ) involving any region of the body and any percentage of TBSA involving the hands, feet, face, and perineum were included. Patients arrived only after 24 hours after burn; burn with other systemic illnesses were excluded. By randomized controlled trial (RCT) sampling technique, study population was divided into two groups—group A and group B. In group A, exposure or without dressing technique was followed and in group B, occlusive dressing technique was followed. Results: 125 patients were treated in each group. Age range was from 2 months 15 days to10 years. The range of mean length of stay (LOS) in the hospital in group A was 5 to 26 days and in group B, 7 to 43 days. In group B, 42% (52) patients had wound infection, but in group A, it was only 15%. Pseudomonas infection in group B was found in 40 cases. In group A it was only in 5 patients. In group B, 94% patients needed cleaning and dressing under general anesthesia and in group A it was only 12%. Eleven patients from group B needed skin grafting, but none from group A needed it. Mean total costs of management was USD 111.13 in group A, it was USD 182.85 in group B. Conclusion: The present study demonstrated that the open or exposure or without dressing method is suitable and effective in reducing patients’ morbidity when compared to the closed or with occlusive dressing method for the management of second-degree burn wound in children. This method is also significantly cost effective. DOI: http://dx.doi.org/10.11566/cmoshmcj.v12i2.37 Chatt Maa Shi Hosp Med Coll J 2013; 12(2): 35-40

Investigation of the skin repair and healing mechanism of N‐carboxymethyl chitosan in second‐degree burn wounds

N-carboxymethyl chitosan (NCMC) was synthesized with the modification of chitosan; the substitution degree was measured by titration. The biocompatibility and degradability of the NCMC were studied in vivo and the results showed that the NCMC was nontoxic and biocompatible. The in vivo degradation rate of NCMC in musculature was faster than that in subcutaneous tissue due to the relatively high lysozyme concentration. The NCMC was used as biomaterial to heal deep second-degree burn wounds. The wound size reduction, histological examination, and the quantification of transforming growth factor-β(1) , tumor necrosis factor-α and interleukin-8 protein levels, and Smad3 gene expression were measured to evaluate the healing effects. The results demonstrated that the NCMC was efficient in accelerating wound healing via activating transforming growth factor-β(1) /Smad3 signaling pathway.

Sodium Channel Nav1.7 Is Essential for Lowering Heat Pain Threshold after Burn Injury

Marked hypersensitivity to heat and mechanical (pressure) stimuli develop after a burn injury, but the neural mechanisms underlying these effects are poorly understood. In this study, we establish a new mouse model of focal second-degree burn injury to investigate the molecular and cellular basis for burn injury-induced pain. This model features robust injury-induced behavioral effects and tissue-specific altered cytokine profile, but absence of glial activation in spinal dorsal horn. Three voltage-gated sodium channels, Na(v)1.7, Na(v)1.8, and Na(v)1.9, are preferentially expressed in peripheral somatosensory neurons of the dorsal root ganglia (DRGs) and have been implicated in injury-induced neuronal hyperexcitability. Using knock-out mice, we provide evidence that Na(v)1.7 selectively contributes to burn-induced hypersensitivity to heat, but not mechanical, stimuli. After burn model injury, wild-type mice display increased sensitivity to heat stimuli, and a normally non-noxious warm stimulus induces activity-dependent Fos expression in spinal dorsal horn neurons. Strikingly, both effects are absent in Na(v)1.7 conditional knock-out (cKO) mice. Furthermore, burn injury increases density and shifts activation of tetrodotoxin-sensitive currents in a hyperpolarized direction, both pro-excitatory properties, in DRG neurons from wild-type but not Na(v)1.7 cKO mice. We propose that, in sensory neurons damaged by burn injury to the hindpaw, Na(v)1.7 currents contribute to the hyperexcitability of sensory neurons, their communication with postsynaptic spinal pain pathways, and behavioral thresholds to heat stimuli. Our results offer insights into the molecular and cellular mechanisms of modality-specific pain signaling, and suggest Na(v)1.7-blocking drugs may be effective in burn patients.

Recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) could accelerate burn wound healing in hamster skin

Burns are one of the most devastating forms of trauma and wound healing is a complex and multicellular process, which is executed and regulated by signaling networks involving numerous growth factors, cytokines, and chemokines. Recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) was specifically produced from rice cell culture through use of a recombinant technique in our laboratory. The effect of rhGM-CSF on promotion of deep second-degree burn wound healing on the back skin of a hamster model was evaluated through a randomized and double-blind trial. As macroscopic results, hamster skins of the experimental groups showed earlier recovery by new epidermis than the control groups. Immunohistochemical reactions of proliferating cell nuclear antigen and transforming growth factor-β1, which are indicators of cell proliferation, were more active in the experimental group, compared with the control group. On electron microscopy, basal cells in the epidermis of the experimental group showed oval nuclei, prominent nucleoli, numerous mitochondria and abundant free ribosomes. In addition, fibroblasts contained well-developed rough endoplasmic reticulum with dilated cisternae. Bundles of collagen fibrils filled the extracellular spaces. Particularly, ultrastructural features indicating active metabolism for regeneration of injured skin at 15 days after burn injury, including abundant euchromatin, plentiful free ribosomes, and numerous mitochondria, were observed. These findings suggest that use of rhGM-CSF could result in accelerated deep second-degree burn wound healing in animal models.

Prospective Randomized Phase II Trial of Accelerated Reepithelialization of Superficial Second-Degree Burn Wounds Using Extracorporeal Shock Wave Therapy

As extracorporeal shock wave therapy (ESWT) can enhance healing of skin graft donor sites, this study focused on shock wave effects in burn wounds. A predefined cohort of 50 patients (6 with incomplete data or lost to follow-up) with acute second-degree burns from a larger study of 100 patients were randomly assigned between December 2006 and December 2007 to receive standard therapy (burn wound debridement/topical antiseptic therapy) with (n = 22) or without (n = 22) defocused ESWT (100 impulses/cm at 0.1 mJ/mm) applied once to the study burn, after debridement. Randomization sequence was computer-generated, and patients were blinded to treatment allocation. The primary endpoint, time to complete burn wound epithelialization, was determined by independent, blinded-observer. A worst case scenario was applied to the missing cases to rule out the impact of withdrawal bias. Patient characteristics across the 2 study groups were balanced (P > 0.05) except for older age (53 ± 17 vs. 38 ± 13 years, P = 0.002) in the ESWT group. Mean time to complete (≥95%) epithelialization (CE) for patients that did and did not undergo ESWT was 9.6 ± 1.7 and 12.5 ± 2.2 days, respectively (P < 0.0005). When age (continuous variable) and treatment group (binary) were examined in a linear regression model to control the baseline age imbalance, time to CE, age was not significant (P = 0.33) and treatment group retained significance (P < 0.0005). Statistical significance (P = 0.001) was retained when ESWT cases with missing follow-up were assigned the longest time to CE and when controls with missing follow-up were assigned the shortest time to CE. In this randomized phase II study, application of a single defocused shock wave treatment to the superficial second-degree burn wound after debridement/topical antiseptic therapy significantly accelerated epithelialization. This finding warrants confirmation in a larger phase III trial (ClinicalTrials.gov identifier: NCT01242423).

Prospective Randomized Phase II Trial of Accelerated Reepithelialization of Superficial Second-Degree Burn Wounds Using Extracorporeal Shock Wave Therapy

Prospective Randomized Phase II Trial of Accelerated Reepithelialization of Superficial Second-Degree Burn Wounds Using Extracorporeal Shock Wave Therapy

Burn Injury Caused by Unexpected Ignition of Rifle Cartridge Gunpowder

It is known that modern cartridges of firearms or rifles consist of gunpowder as a propellant. Because of its burning properties, it produces a large amount of heat and expanding gas such as nitrogen and carbon dioxide. Gunpowder is a mixture of sulfur, charcoal, and potassium nitrate. When the composition is ignited, the sulfur and charcoal act as fuel, and the potassium nitrate works as an oxidizer. The sulfur also makes the powder easier to ignite and lowers the temperature of the burning material.1 Potassium nitrate is also important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients.1 The case presented here is a recruit who was burned with the flame caused by unexpected ignition of rifle cartridge gunpowder. He was trying to open the bullet portion of a cartridge which was not ignited during shooting training. The accidental ignition and explosion of the rifle cartridge gunpowder caused a second-degree burn injury to his face which was fully epithelized after 7 days of treatment.

Effect of Poloxamer 188 on deepening of deep second-degree burn wounds in the early stage

Objective To discuss the effect of Poloxamer 188 (P188) on deepening of deep second-degree burn wounds in the early stage after burn. Methods We divided Wistar rats with deep second-degree burn wounds on the backs thereof into two groups, then intravenously injected P188 for the treatment group and intravenously injecting physiological saline for the control group, detecting the activity of Na +–K +–adenosine triphosphatase (Na +–K +–ATPase), myeloperoxidase (MPO) and the content of malonaldehyde (MDA) and succinic dehydrogenase (SDH) in the burn wound, and showing the degree of necrosis in the wound by haematoxylin–eosin (HE) and proliferating cell nuclear antigen (PCNA) immunohistochemical staining. Results In the control group and treatment group, the activity of SDH and Na +–K +–ATPase dropped to the lowest point 24 h after the burn took place, and then increased gradually, but was still far lower than the normal level at the furthest time point. At 24 h after burn, activity of SDH and Na +–K +–ATPase in the treatment group was higher than that of the control group ( P < 0.05); the activity of MPO of the control group reached the highest point at 24 h while that of MPO of the treatment group reached the highest point after 48 h; later, that of MPO of both groups decreased, but was still higher than the normal level. Compared with the highest values of the activity of MPO of both groups, that of the control group was higher than that of the treatment group ( p < 0.05); the contents of MDA of both groups kept increasing after the burn; 72 h later, that of the control group was higher than that of the treatment group ( p < 0.05). HE and PCNA staining showed progressive damage of the wound in the treatment group, which was decreased with treatment, particularly at the early stages. Conclusion Systemic application of P188 on deep second-degree burn wounds at the early stage may alleviate wound deepening, whose mechanism may be related to timely sealing up the damaged cell membrane and inhibiting the inflammatory reaction.

Evaluation of chitosan gel containing liposome-loaded epidermal growth factor on burn wound healing

The objective of this study is to develop a chitosan gel formulation containing liposomes loaded with epidermal growth factor (EGF) and to evaluate their effects on the healing of second-degree burn wounds in rats by immunohistochemical, histochemical and histological methods. EGF-containing multilamellar liposomes which were carried in chitosan gel, EGF gel and EGF-loaded liposome formulations were prepared. The in vivo experiments were performed on female Sprague Dawley rats. Second-degree standard burn wounds were formed on rats and liposomes containing 10 µg/ml EGF in 2% chitosan gel, EGF-chitosan gel and EGF-loaded liposome formulations were applied daily to the burn wounds and biopsies were taken at the 3rd, 7th and 14th day of the treatment. When the results were evaluated immunohistochemically, there were significant increases in cell proliferation observed in the EGF-containing liposome in chitosan gel (ELJ) formulation applied group (P < 0·001). The histochemical results showed that the epithelisation rate in the ELJ group was the highest compared with the other group results (P < 0·001). The histological results indicated and supported these findings and faster epithelisation was observed in the ELJ group compared with the other groups.

Collagen-based films containing liposome-loaded usnic acid as dressing for dermal burn healing.

The aim of this study was assess the effect of collagen-based films containing usnic acid as a wound dressing for dermal burn healing. Second-degree burn wounds were performed in forty-five Wistar rats, assigned into nine groups: COL—animals treated with collagen-based films; PHO—animals treated with collagen films containing empty liposomes; UAL—animals treated with collagen-based films containing usnic acid incorporated into liposomes. After 7, 14, and 21 days the animals were euthanized. On 7th day there was a moderate infiltration of neutrophils, in UAL, distributed throughout the burn wounds, whereas in COL and PHO, the severity of the reaction was slighter and still limited to the margins of the burn wounds. On the 14th day, the inflammatory reaction was less intense in UAL, with remarkable plasma cells infiltration. On the 21st day, there was reduction of the inflammation, which was predominantly composed of plasma cells in all groups, particularly in UAL. The use of the usnic acid provided more rapid substitution of type-III for type-I collagen on the 14th day, and improved the collagenization density on the 21st day. It was concluded that the use of reconstituted bovine type-I collagen-based films containing usnic acid improved burn healing process in rats.

Minocycline Attenuates Mechanical Allodynia and Central Sensitization Following Peripheral Second-Degree Burn Injury

Burn injury induces severe pain that can be refractory to existing pharmacotherapies. The underlying mechanism of burn pain remains unclear. We previously established an animal model and reported that unilateral burn injury induces chronic and bilateral mechanical allodynia, which is associated with central sensitization and microglial activation in the spinal cord dorsal horn. Modulation of the activity of microglia and p38 mitogen-activated protein kinase (MAPK) has been shown to ameliorate neuropathic pain in several nerve-injury pain models. In the present study, we show in this rat model that daily treatment with the microglial inhibitor minocycline (10 mg/kg), administered at the time of burn injury and for 7 days thereafter, significantly attenuates ipsilateral and contralateral allodynia as assessed up to 1 month following burn injury. These sensory changes are paralleled by significant suppression of evoked hyperexcitability of dorsal-horn neurons and of the expression of phosphorylated p38 (phospho-p38) in OX42+ microglial cells within the dorsal horn. Our results suggest that modulation of inflammation at early times after burn injury may have long-lasting effects, attenuating central neuropathic mechanisms which contribute to pain after burn injury. We demonstrate, in a rodent model of burn-associated pain, that the microglial inhibitor minocycline, delivered at the time of burn injury and for 1 week thereafter, has long-lasting effects, attenuating microglial activation and neuronal hyperresponsiveness in the dorsal horns, and ameliorating allodynia for at least 1 month.

The effect of dressing with fresh kiwifruit on burn wound healing

This study was designed to evaluate the wound healing effects of kiwifruit in the treatment of second-degree burn wounds in rats. Sixty rats were each randomly assigned to 1 of 3 groups. A deep second-degree burn was created on the lateral flank of each rat with a standard burning procedure in the form of applying a heated plaque. In the control group (group C; n = 20) burns were dressed with Vaseline sterile gauze after normal saline irrigation. In group S (n = 20), the lesions were treated with silver sulfadiazine cream after normal saline irrigation. In the third group (group K; n = 20), the burn wounds were dressed with kiwifruit. The dressings were changed twice a day in all groups. The response to treatments was assessed histologically at day 21 postburn and microbiologically on days 7 and 21. Macroscopic evaluation was performed every day to determine wound closure rate, measure burn wound area, and investigate macroscopic edema, hyperemia, and epithelialization. Histopathologic evaluation included monitoring of epithelialization, vascularization, granulation tissue formation, and inflammatory cell response. On day 21, the wounds in the group K healed completely in comparison to other groups (P < .0001). There was significant reduction in wound area size in the group K in all evaluation days as compared with groups S and C (P < .0001). Microscopic evaluation revealed a high grade of neovascularization in group K lesions in contrast with groups S and C (P < .0001). Wound infection was dramatically less common in the group K compared with the other 2 groups (P < .05). We suggest that the dramatic antibacterial, debridement, wound contracture, and angiogenic effect of kiwifruit induced a significant wound healing in burn ulcers and might be useful in treating chronic ulcers, such as bedsores.

Human lactoferrin stimulates skin keratinocyte function and wound re-epithelialization

Human lactoferrin (hLF), a member of the transferrin family, is known for its antimicrobial and anti-inflammatory effects. Recent studies on various nonskin cell lines indicate that hLF may have a stimulatory effect on cell proliferation. To study the potential role of hLF in wound re-epithelialization. The effects of hLF on cell growth, migration, attachment and survival were assessed, with a rice-derived recombinant hLF (holo-rhLF), using proliferation analysis, scratch migration assay, calcein-AM/propidium iodide staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) method, respectively. The mechanisms of hLF on cell proliferation and migration were explored using specific pathway inhibitors. The involvement of lactoferrin receptor low-density lipoprotein receptor-related protein 1 (LRP1) was examined with RNA interference technique. An in vivo swine second-degree burn wound model was also used to assess wound re-epithelialization. Studies revealed that holo-rhLF significantly stimulated keratinocyte proliferation which could be blocked by mitogen-activated protein kinase (MAPK) kinase 1 inhibitor. Holo-rhLF also showed strong promoting effects on keratinocyte migration, which could be blocked by either inhibition of the MAPK, Src and Rho/ROCK pathways, or downregulation of the LRP1 receptor. With cells under starving or 12-O-tetradecanoylphorbol-13-acetate exposure, the addition of holo-rhLF was found greatly to increase cell viability and inhibit cell apoptosis. Additionally, holo-rhLF significantly increased the rate of wound re-epithelialization in swine second-degree burn wounds. Our studies demonstrate the direct effects of holo-rhLF on wound re-epithelialization including the enhancement of keratinocyte proliferation and migration as well as the protection of cells from apoptosis. The data strongly indicate its potential therapeutic applications in wound healing.

Evaluation of a new type of wound dressing made from recombinant spider silk protein using rat models

This study investigates the feasibility of recombinant spider silk protein as a wound-dressing material for coverage of deep second-degree burn wounds using an animal model. Sixty Sprague–Dawley (SD) rats were randomly divided into four groups (15 rats in each group). Two types of recombinant spider silk proteins, pNSR-16 and pNSR-32, as well as collagen (as a control) were applied on the wound; the fourth group was left untreated as a negative control. Each group was evaluated on the 3rd, 5th, 7th, 14th and 21st days for wound-healing rate, histological test, levels of hydroxyproline synthesis and the samples were stained for immunohistochemical detection of the basic fibroblast growth factor (bFGF). The results of implantation testing showed that wound healing in the treatment groups – recombinant spider silk protein pNSR-16 and pNSR-32 – was much better than that in the control group ( p < 0.01). On the 7th, 14th and 21st days, higher expression of bFGF and the increase of hydroxyproline content of the skin indicated good regeneration of wound skin in the treatment groups. Preliminarily, we conclude that the recombinant spider silk protein membrane promotes the recovery of wound skin by increasing the expression and secretion of the growth factor bFGF and hydroxyproline.

A multicenter clinical trial of recombinant human GM‐CSF hydrogel for the treatment of deep second‐degree burns

Wound healing is a complex and dynamic biological process. The efficacy and safety of a recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) hydrogel to promote deep-second-degree burn wound healing is evaluated in this study. In this multicenter, randomized, double-blind, and placebo-controlled clinical trial, 90 patients with deep second-degree burns were randomly assigned into two groups. Complete healing time and percentage of wound healing at different time points were observed and side effects were recorded. A statistically significant difference was noted at each time point (p<0.01). No side effects were observed. These results suggest that rhGM-CSF hydrogel can significantly accelerate deep second-degree burn wound healing and is considered to be safe.