1 Introduction
The skin, as the heaviest and largest organ in our body, constitutes approximately 15% of the total body mass and encompasses a surface area of about 1.5–2 m2 in adults (Richardson, 2003; Lai-Cheong and McGrath, 2017). It acts as a pivotal interface between the internal and external environments and acts as a protective barrier to protect the body against various environmental damages and infections. Additionally, it plays a crucial role in homeostasis, thermoregulation, metabolic, neurosensory, and immunologic functions (Naseri-Nosar et al., 2018; Heidari et al., 2019). Wounds emerge as a significant factor that disrupts the skin’s defensive capacity and exposes the body to protein and water depletion as well as infection. Wounds can occur due to scratching, burn, surgery, exposure to chemicals, abrasion, drug reactions, cold, and pressure, or as a consequence of diseases like psoriasis, eczema, and carcinomas, which can notably affect patients’ quality of life (Enoch and Price, 2004; Lai-Cheong and McGrath, 2017; Shpichka et al., 2019). Burn injury occurs subsequent to the skin being harmed by elevated temperature, electricity, chemical substances, or radiation. Severe complications from extensive or deep burns may occur, such as sepsis caused by bacterial infection, contraction of scar tissue after improper wound healing, or shock due to hypovolemia (Shpichka et al., 2019). The skin has also developed efficient, rapid, multifaceted, and dynamic mechanisms to close breaches in its protective barrier, which is collectively referred to as the wound healing response. Overall, this process involves four interconnected yet distinct biological processes including hemostasis, inflammation, proliferation, and remodeling. These phases collectively form the cascade of wound healing, and any deficiency within these phases can impede the body’s ability to heal wounds (Wilkinson and Hardman, 2020; Almadani et al., 2021). This intricate process encompasses a sequence of occurrences, diverse types of tissue, cells, and mediators including platelets, various growth factors (e.g., platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β), etc.), oxidative stress factors (e.g., reactive oxygen species (ROS), catalase (CAT), glutathione peroxidase (GPx), nitric oxide (NO), etc.), inflammatory cells and mediators (e.g., macrophages, interleukins (ILs), tumor necrosis factor-α (TNF-α) interferons (IFNs), etc.), angiogenesis, cell proliferation, granulation, extracellular matrix (ECM) formation (e.g., proteoglycans, vitronectin, fibronectin, thrombospondin, and collagen III), and ultimately the formation of a scar, all working in harmony (Kurahashi and Fujii, 2015; Tottoli et al., 2020; Wilkinson and Hardman, 2020; Shaygan et al., 2021). In addition, growing evidence emphasizes the significance of targeting oxidative stress and inflammatory mediators to facilitate the process of wound recovery (Kurahashi and Fujii, 2015; Wilkinson and Hardman, 2020; Lopez et al., 2022; Wang et al., 2023).
Various strategies have been utilized for wound healing, encompassing methodologies such as cell therapy, chemical and herbal medicines, wound dressings, as well as laser therapy. The overall goal of all these treatment approaches is to facilitate prompt healing with minimal complications and simultaneously ensure cost-effectiveness (Pereira and Bártolo, 2016; Kolimi et al., 2022). In the context of wound healing, the selection of an ideal dressing plays a critical role. Effective wound dressing should prevent bacterial infiltration, have antibacterial properties, sufficient oxygen permeability, absorb wound secretions, and exhibit biological and structural characteristics similar to the extracellular matrix to accelerate wound healing (Selig et al., 2012; Dhivya et al., 2015; Connelly and McColl, 2016; Omar et al., 2017; Vowden and Vowden, 2017; Li et al., 2019). In creating new dressings, adding features such as anti-inflammatory effects, preventing cell death, even helping to heal cells, repairing nerve cells, and reacting quickly and intelligently to wound infection can be helpful (Dhivya et al., 2015). Conventional dressings (e.g., gauze, silver ion dressing, alginate dressing, hydrogel, etc.) have been used to cover wounds, prevent contamination, and create a suitable environment for wound healing (Naseri-Nosar et al., 2017; Alves et al., 2024). Recently, researchers have been trying to provide biocompatible and biodegradable nanofiber dressings that have unprecedented properties such as high surface area and high porosity to boost wound healing (Jeong et al., 2012). Nanofibers can be obtained through various techniques (Chen et al., 2017). The electrospinning process is the most common method due to its simplicity, cost-effectiveness, and flexibility (Barnes et al., 2007). Electrospinning nanofibers have attracted substantial attention due to their unique properties, such as exceptional strength, high surface area to volume ratio, controllable pore size, and high porosity (Haider et al., 2018; Al-Abduljabbar and Farooq, 2022). These exceptional properties make nanofibers highly appealing and significant. Given that nanofiber scaffolds exhibit behavior comparable to the extracellular matrix, they emerge as promising candidates for functional wound dressing materials and tissue engineering (Owida et al., 2022; Flores-Rojas et al., 2023; Jiang et al., 2023). Several agents have long been used to produce electrospun nanofibers as wound dressings such as polyvinyl alcohol (PVA), poly-ethylene oxide (PEO), gelatin, chitosan (CS), collagen, polycaprolactone, fibrinogen, and poly-lactic acid (Powell et al., 2008; Guo et al., 2020; Stojanov and Berlec, 2020). PVA is a water-soluble, non-toxic, and biodegradable synthetic polymer with good mechanical properties. The presence of hydroxyl groups in the PVA structure gives it the ability to form a gel network that facilitates the electrospinning process (Fahami and Fathi, 2018). Natural polymers such as tree gums (e.g., gum arabic, gum karaya, and gum kondagogu), gellan gum, alginate, tragacanth gum, guar gum, and CS have been reported to be successfully electrospun and mixed with PEO or PVA are important resources, and comprehensive reports on electrospinning of these polymers have been presented in various studies. The principal challenges facing electrospinning of these tree gums are high molecular weight, reduced solubility, swelling properties, and proper selection of solvent electrospinning systems (Bonino et al., 2011; Elsabee et al., 2012; Vashisth et al., 2014; Padil et al., 2016).
Traditional and ethnomedicine from different countries are highly regarded as valuable resources for discovering new drugs. Additionally, the plant kingdom has shown great potential in providing alternative treatments with fewer side effects and lower costs for the management or treating different diseases like skin disorders. This is due to the extensive variety of phytochemicals found in plants, which possess anti-inflammatory, antioxidant, and immunomodulatory effects (Bahramsoltani et al., 2017; Heidari et al., 2019). Wild pistachio (Pistacia) is a genus of the Anacardiaceae family. Pistacia atlantica Desf. subspecies kurdica (Zohary) Rech. f. (PAK), also known as the “Baneh” in Iran, is one of the Pistacia species that grow naturally in some countries such as Iran, Turkey, and Iraq (Bahramnejad, 2014; Gharazi et al., 2021). In the inner tissues of the “Baneh” tree, sap is present and is commonly collected from the bark pores during the summer season. This sap is frequently found in the western regions of Iran, including Kurdistan and Kermanshah. This sap is called Pistacia atlantica oleo-gum-resin and is locally known as “Saqez gum” (Gharazi et al., 2021). Different parts of Pistacia, including essential oils, oleo-gum-resin, and leaves are chemically identified and used to treat various human diseases (Gourine et al., 2010; Peksel et al., 2010; Gharazi et al., 2021). In Traditional Persian Medicine (TPM), PAK is utilized in the treatment of different diseases like skin wounds, eczema, peptic ulcer, dyspepsia, asthma, and kidney diseases (Amin, 2005; Aghili, 2009; Bozorgi et al., 2013). Moreover, PAK represented significant anti-inflammatory, antioxidant, wound healing, antibacterial, and antifungal activities in recent reports (Tohidi et al., 2011; Haghdoost et al., 2013; Hatamnia et al., 2014; Farahpour et al., 2015; Minaiyan et al., 2015; Shialy et al., 2015).
Therefore, the purpose of this study was to assess the efficacy of the nanofibers containing PVA/PAK oleo-gum-resin in promoting wound healing in two rat models of burn and excision wound repair. Additionally, the potential antioxidative and tissue regenerative impacts of the prepared nanofibers were also examined.
2 Material and methods
2.1 Chemicals and reagents
Acetic acid, Polyvinyl alcohol (PVA), ammonium molybdate, hydrogen peroxide (H2O2), 5, 5′-dithiobis-(2-nitrobenzoic acid) (DTNB), and xylazine were purchased from Merck Company (Germany). Ketamine was procured from Alfasan (Woerden, Netherlands). Phenytoin cream via Behvazan Company (Irán) and silver sulfadiazine 1% cream was provided by Sobhan Darou Company (Irán). All used compounds and chemicals were of analytical grade.
2.2 Plant material
The gum of P. atlantica Desf. subsp. kurdica (Zohary) Rech. f. [Anacardiaceae] was collected in June 2020 from the Kermanshah province, Iran. The plant was approved by Department of Pharmacognosy, Faculty of Pharmacy, Tehran University of Medical Science, and a voucher specimen (No. PMP-818) was deposited at the Herbarium of Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. 0.4 g of gum was suspended in 9.6 mL of acetic acid, and then it was filtered using Whatman No. 1 filter paper to obtain the gum solution (PKA gum).
2.3 Preparation of polymeric solution
To prepare a PVA solution, 0.8 g of the polymer was added to 9.2 mL of distilled water and stirred for 12 h. PKA gum was then added to the PVA solution at 30:70, 40:60, and 50:50 w/v and stirred at room temperature for 24 h.
2.4 Preparation of nanofibers by electrospinning method
After preparing polymer solutions containing PKA gum with concentrations of 30:70, 40:60, and 30:70 w/v, the desired experiments were conducted to achieve the desired nanofibers using an electrospinning device. In order to obtain the optimal nanofibers, various parameters of the electrospinning process, including material concentration (mentioned above), the distance between the nozzle and the collector, and the voltage applied were thoroughly examined. The electrospinning solutions were loaded into a 1 mL syringe (inner diameter of the needle = 0.8 mm) and fixed in a horizontal position on the syringe pump. Electrospinning was performed in ambient conditions (25°C and 30% relative humidity) using the following parameters: distances of 10, 15, and 20 cm and voltages of 15, 18, and 20 kV were investigated. A light microscope (Olympus CX23 light microscope, Dino-Lite camera, and DinoCapture 2.0 software) was employed to identify the most suitable fiber. The best nanofibers were obtained when the nozzle was positioned 15 cm away from the collector, with a working voltage of 15 kV, and an injection rate of 0.5 mm per hour, using the 30:70 w/v PKA gum.
2.5 Scanning electron microscope analysis
The diameter distribution and morphology of nanofibers were assessed using a scanning electron microscope (SEM), FEI Model Quanta 450 FEG, Hillsboro, OR, United States, with an operating voltage of 25 kV. To prepare the samples, they were fixed to an aluminum stub and subsequently coated with a thin layer of gold under an argon atmosphere. The diameter range of nanofibers was analyzed with ImageJ (National Institutes of Health, United States). The average diameter of nanofibers was determined by measuring the diameter of 100 randomly selected fibers.
2.6 Release test
In order to determine the quantity of PAK released from the proper nanofiber, 100 mg of nanofiber was measured and placed within a cellulose membrane (Merck Millipore, Dialysis sacks, Avg. flat width 35 mm (1.4 in), MWCO 12,000 Da), containing 2 mL of phosphate buffer. This membrane was then submerged in a 50 mL solution of phosphate buffer at pH 7.2, which served as the release medium, and put in a shaker incubator (100 rpm at 25°C). This procedure was repeated three times and samples were collected at various intervals up to 72 h. The absorbance of the collected samples was subsequently measured using a UV-visible apparatus at a wavelength of 260 nm. Then, the average absorption of the samples was plotted at different times, and based on that, the PAK release curve was obtained.
2.7 Mechanical properties of nanofibers
The mechanical properties of the PVA and PVA/PAK gum were assessed using a mechanical tensile testing device (STM-1 DBBP-100, South Korea). The nanofibers were cut to dimensions of 40 mm × 10 mm and related mechanical properties were examined at room temperature. The tensioning speed was 1 mm/min.
2.8 Animals and ethical considerations
Adult male Wistar rats (weighing 200 ± 20 g) that were free from any skin disorders and infections were obtained from the pet of Kermanshah University of Medical Sciences, School of Pharmacy. The rats were maintained under specific conditions including a temperature of 22–25°C, a 12:12 h light/dark cycle, free access to rodent food, and tap water. The cages were cleaned once per week. Tissue samples were obtained by sacrificing the animals. All animal procedures were approved by the animal ethics committee of Kermanshah University of Medical Sciences, Iran (IIR.KUMS.REC.1398.1048), and were carried out in compliance with relevant guidelines and regulations for the care and use of laboratory animals at the Institute.
2.9 Creation of excision wound and burn injury
The rats were anesthetized via intraperitoneal (i.p.) injection of a combination of ketamine (80 mg/kg) and xylazine (10 mg/kg). Following this, the dorsal surface of the rats was shaved and sterilized. To create an excision wound, a section of skin was removed with a scalpel blade to create a 20 mm diameter excision wound on the back of each rat. A burn wound was created by applying an aluminum rod (20 mm diameter) on the shaved area of rats which was heated to 100°C for 10 s. Animals were housed individually (one in a cage) and treatment started 24 h after the introduction of wounds and continued to day 10, and 21 for excision and burn models, respectively.
2.10 <italic>In vivo</italic> assessment of wound healing activity of PVA/<italic>PAK</italic> gum nanofibers
Forty-eight male Wistar rats, weighing 200 ± 20 g, were randomly allocated into eight different groups of six (n = 6).
2.10.1 Excision wound healing activity
The animals were randomly segregated into four groups of six: (1) Control (negative control group, normal saline, 1 mL for each rat), (2) Phenytoin cream 1% (positive control group, 1 g for each rat), (3) PVA nanofibers (polymer only group), and (4) PVA + Extract (PVA/PAK gum nanofibers). All groups were treated once daily for 10 days and nanofibers were applied topically in the volume to fully cover the 20 mm wounds on the back of each rat. The wound was dressed by a regular dressing and changed every 24 h. On the 11th day, the rats were sacrificed, and prior to their sacrifice, blood samples were collected from their aorta to evaluate the serum levels of the CAT and GSH, which are indicative of oxidative stress.
2.10.2 Burn wound healing activity
The animals were randomly segregated into four groups of six: (1) Control (negative control group, normal saline, 1 mL for each rat), (2) silver sulfadiazine cream 1% (positive control group, 1 g for each rat), (3) PVA nanofibers (polymer only group), and (4) PVA + Extract (PVA/PAK gum nanofibers). Rats were treated once daily for 10 days and nanofibers were applied topically in the volume to fully cover the 20 mm wounds. The nanofibers served as a topical patch or dressing and were directly applied in the appropriate dimensions onto the wound area. The wound dressed by a regular dressing and changed every 24 h. On the 22nd day, the rats were sacrificed, and prior to their sacrifice, blood samples were collected to evaluate the serum levels of the CAT and GSH, which are indicative of oxidative stress.
2.11 Wound size assessment
To assess wound contraction, a digital camera was employed to capture photographs. The acquired images underwent analysis utilizing ImageJ software to determine the size of the wound area. The rate of wound closure was subsequently expressed as a percentage, reflecting the reduction in size compared to the initial measurement on day zero. This rate was computed using the following formula (Shaygan et al., 2021):
Wound contraction
%
=
wound size of the induction day
−
wound
size
of the specific day
days after treatment
)
/
wound size of the induction day
×
100
.
2.12 Histopathological analysis
For histopathological assessments, the rats underwent anesthesia by i.p. administration of thiopental sodium. Skin tissue samples from the wound areas were collected and fixed with a 10% formalin. After tissue preparation, 7 μm thick tissue sections were stained with hematoxylin and eosin (H&E). The samples were visualized using the Olympus CX23 light microscope, Dino-Lite camera, and DinoCapture 2.0 software. The histopathological investigations were carried out by an experimenter who was blinded to the study.
2.13 Catalase assay
CAT activity was assessed in order to evaluate the level of antioxidants, following the procedure outlined by Aebi (1984). In brief, 20 µL of serum samples were combined with 100 µL of H2O2 (65 mM) in 96-well plate wells. The mixture was then incubated at room temperature for 4 min. To stop the reaction, 100 µL of ammonium molybdate (32.4 mM) was added, resulting in the formation of a yellow molybdate and H2O2 complex. The absorbance of the sample was subsequently measured at a wavelength of 405 nm using an ELISA reader (Iranpanah et al., 2024). Each assay was conducted in triplicate based on the following formula:
Concentration difference
%
=
C
Health
‐
C
Sample
/
C
Health
×
100
2.14 Glutathione assay
The antioxidant level was assessed by measuring the reduced GSH levels using the Ellman method established in 1959. This method involves the oxidation of GSH through DTNB, resulting in the formation of the yellow derivative 5′-thio-2-nitrobenzoic acid (TNB), which can be measured at a wavelength of 412 nm. To perform the assay, 40 μL of serum samples were mixed with 50 μL of phosphate-buffered saline (PBS, 0.1 M) with a pH of 7.2 in each well. Subsequently, 100 μL of the Ellman or reagent 5′-dithiobis-(2-nitrobenzoic acid) (DTNB) was added. The plate was then incubated at a temperature of 37°C for 10 min. Following the incubation period, the optical density (OD) of the mixture was measured at a wavelength of 412 nm using an ELISA reader (Iranpanah et al., 2024). Each assay was conducted in triplicate to ensure the accuracy and consistency of the results (Rahman et al., 2006). Each assay was conducted in triplicate based on the following formula:
Concentration difference
%
=
C
Health
−
C
Sample
/
C
Health
×
100
2.15 Statistical analysis
All data were presented as mean ± standard error of the mean (SEM) and mean ± standard deviation (SD) for formulation evaluations. Repeated measures of one-way and two-way analysis of variance (ANOVA) were conducted, followed by Tukey’s post hoc analysis. In all analyses, a difference with p < 0.05 was regarded as significance.
4 Discussion
In the current study, PVA/PKA nanofibers were synthesized by the electrospinning method, and PAK gum was loaded on the surface of nanofibers in different concentrations (30:70, 40:60, and 50:50 w/v). According to the results, the best nanofiber with PAK gum was obtained (30:70 w/v) and were used for wound healing in rats. Other concentrations led to the production of irregular and unsuitable nanofibers. Based on the SEM images, PAK gum has been successfully loaded on optimal nanofiber. High tensile strength, ease of use, and handling of materials used for wound dressing are very important features of these nanofibers. For this reason, the tensile strength of the prepared nanofiber was investigated, and based on the results, the tensile strength of this nanofiber is high and acceptable. We exhibited the wound-healing efficacy of the PAK gum nanofibers in a rat model of excision and burn wound injury. According to wound closure results, PAK gum nanofibers have the potential to speed up the wound healing process in comparison to the negative (untreated) and positive (phenytoin and silver) controls, in both excision and burn wound injuries. Histopathological evaluation confirmed wound healing activity of PAK gum nanofibers, as well through regeneration of the epidermal layer, higher density of dermal collagen fibers, and lower presence of inflammatory cells. Additionally, we showed the antioxidant capabilities of the PAK gum nanofibers through CAT and GSH assay. Our study displayed that PAK gum nanofibers could enhance levels of serum GSH and CAT, indicating its systemic antioxidant activity that contributes to the promotion of wound repair.
From the mechanistic point of view, the wound-healing activity of PAK gum nanofibers could be attributed to the presence of diverse constituents like phenolic compounds and terpenoids that are able to speed up wound healing and exhibited antioxidant properties. According to our results, Haghdoost et al. (2013) demonstrated the wound healing potential of the P. atlantica resin extract by improving the angiogenesis and enhancing FGF and PDGF concentration, in the rat model of skin burn injury. They also presented α-pinene as one of the active compounds of essential oil of resin. By targeting VEGF, the resin oil of P. atlantica showed antioxidant effects in treating skin burn (Shahouzehi et al., 2018). In another study by Hamidi and colleagues, the cutaneous wound-healing activity of the topical P. atlantica gel was investigated. The gel with a concentration of 10%, decreased the total lymphocyte count and improved total fibrocyte count, number of blood vessels, and re-epithelialization. These effects were observed in terms of wound closure, histological analysis, and oxidative stress biomarkers (Hamidi et al., 2015; 2017). To evaluate the anti-inflammatory effect of P. atlantica volatile oil, alpha-pinene was found as the main constituent and reduced colitis and myeloperoxidase activity in rats (Minaiyan et al., 2015). Furthermore, some studies represented notable wound healing, antimicrobial and antifungal effects of P. atlantica extracts and found to be effective in scavenging and decreasing the superoxide anions in vitro (Benhammou et al., 2008; Tohidi et al., 2011). In another in vitro study P. atlantica was also presented as a natural anti-fungal agent against different fungal species (Shialy et al., 2015). Employing high-performance liquid chromatography method, Hatamnia et al. showed that the highest antioxidant activity of PAK was attributed to related phenolic content, including vanillic acid, sinapic acid, and p-hydroxybenzoic acid (Hatamnia et al., 2014). In another study, topical administration of P. atlantica increased upregulated mast cells infiltration and hydroxylproline content, accelerated proliferation phase, while lowered RNA damage (Farahpour et al., 2015). Similarly, the antioxidant activity of PAK provided by Rahman in 2018 (Rahman, 2018). Therefore, these effects could be another reason for the wound healing effects of P. atlantica. Considering the antioxidant, anti-inflammatory and antimicrobial effects of PAK, as well as the advantages of using nanofiber wound dressings, the PVA/PAK gum nanofibers can serve as a natural treatment for the treatment of different types of wounds. In line with our results, Rajati et al. (2023) showed that a nanofiber-hydrogel composite from green synthesized Ag nanoparticles embedded to PVA hydrogel and P. atlantica gum nanofiber had the therapeutic potential in wound dressing.
Generally, PVA has shown potential and is widely used for wound healing because of its small-molecule permeability, soft consistency, transparency, low interfacial tension, and antibiotic release control (Saraiva et al., 2023). However, tacky mechanical properties restrict their potential as wound dressings (Song et al., 2021). Studies have shown that PVA can be cross-linked with Ca2+ or other agents, thereby improving biological and physicochemical properties in wound healing. In similar studies, the anti-bacterial effects of formulations containing PVA provided for wound healing with a high biocompatibility (Song et al., 2021).
In terms of pathology, wounds present a formidable clinical challenge due to the primary and secondary lesions that give rise to disease and high mortality rates (Natarajan et al., 2000; Panuncialman and Falanga, 2010). The healing process of wounds is characterized by its complexity and dynamic nature. It comprises four stages, namely, inflammation, proliferation (including re-epithelialization, granulation tissue formation, and neovascularization), hemostasis, and remodeling, that ultimately lead to the repair of dermis and epidermis tissues (Rousselle et al., 2019; Knoedler et al., 2023). Furthermore, recent reports have shed light on the importance of modulating inflammatory and oxidative stress mediators to facilitate the process of wound healing. Oxidative stress refers to an internal imbalance between the body’s prooxidants and antioxidants. During oxidative stress, the production of ROS increases, and these play a crucial role in wound healing. Low levels of ROS are involved in the regulation of numerous signal transduction pathways within cells (Dunnill et al., 2017; Qiu et al., 2021). Moreover, ROS modulates the wound-healing process through affecting inflammation, angiogenesis, extracellular matrix formation, and cell proliferation (Wang et al., 2023). To counter excessive oxidation reactions, the body produces antioxidant enzymes like superoxide dismutase (SOD), CAT, and GPx that neutralize ROS. For complex wounds that prove difficult to heal, the supplementation of antioxidants can aid in the protection of cells against oxidative damage and can enhance the process of wound healing (García-Sánchez et al., 2020; Qiu et al., 2021). The inflammatory response, which occurs shortly after an injury, primarily starts with the infiltration of PMN leukocytes or granulocytes and gives rise to the generation of free radicals at the site of inflammation. These free radicals can cause cellular damage and delay the healing process (Heidari et al., 2019).
Achieving faster wound healing with the least side effects is one of the main therapeutic aims of recent investigations. Wounds, as one of the main issues in the world, have long captivated the attention of medical researchers (Nuutila et al., 2014; Shaygan et al., 2021). Extensive investigation has been conducted, employing various treatment methods including chemical and medicinal therapies, herbal remedies, as well as physical approaches like laser therapy. The ultimate aims of recent studies are to discover effective, cost-efficient, less toxic, and rapid treatments for wound healing (Reinke and Sorg, 2012; Shaygan et al., 2021; Kolimi et al., 2022). The utilization of nanotechnology systems for delivering natural compounds holds great potential for enhancing the effectiveness of wound treatments. Various research groups worldwide are presently engaged in designing and manufacturing novel wound dressings (Ajith et al., 2023; Amutha Gokul et al., 2024; Nandhini et al., 2024). Nanofiber structures possess the ability to interact effectively with skin cells and their environment, expediting the wound-healing process (Liu et al., 2021; Ajith et al., 2023). Wound dressings play a pivotal role in managing wound healing by shielding the wound from external hazards and enhancing the healing process. The current market offers a range of common dressings including hydrogel, film, foam, sponge, and nanofiber membranes (Gupta et al., 2019; Hawthorne et al., 2021; Liu et al., 2021). Among these, electrospun nanofiber membranes illustrate a novel category of materials, characterized by their high surface-to-volume ratio, density, remarkable microporosity, and notable versatility (Fadil et al., 2021; Liu et al., 2021; Al-Abduljabbar and Farooq, 2022). These unique properties enable their utilization in various biomedical applications such as wound dressings, tissue engineering scaffolds, and drug delivery. Electrospun nanofiber wound dressings offer some advantages, including a structure and biological function that closely resemble the natural ECM, creating an optimal microenvironment for cell proliferation, migration, and differentiation (Liu et al., 2021; Ajith et al., 2023; Nandhini et al., 2024). Moreover, the extensive surface area and specific structure of the nanofiber membrane facilitate the effective loading of phytochemicals, antibacterial drugs, vitamins, growth hormones, and other biologically active ingredients (Ajith et al., 2023; Amutha Gokul et al., 2024). Therefore, the development and production of advanced and smart wound dressings capable of preventing wound infection and providing full support for wound healing can significantly reduce treatment costs and enhance patient wellbeing. Despite the availability of different topical preparations in the market, there is a noticeable lack of suitable medication for this purpose. Additionally, most of the currently available topical preparations or medications have negative adverse effects, toxicity, and primarily possess antimicrobial properties rather than wound repair effects (Heidari et al., 2019; Oliveira and Almeida, 2023). Modern medicine allocates nearly 1%–3% of its resources to wound repair, while traditional medicine proposed about 30% of its preparations to skin disorders, highlighting the high potential of traditional medicine in suggesting new drugs for wound care (Heidari et al., 2019). Natural products have the ability to induce wound-healing effects due to their diverse range of phytochemicals, such as phenolic compounds, terpenoids, alkaloids, fatty acids, and saponins (Vitale et al., 2022; Cedillo-Cortezano et al., 2024). These phytochemicals exert their effects at various stages of the healing process through a range of mechanisms, including the regulation of PMN, macrophages, ILs, IFNs, and TNF-α to induce an anti-inflammatory response and modulate ROS, CAT, SOD, and GSH levels to act as antioxidants. Additionally, they promote cell proliferation, enhance angiogenesis by upregulating TGF-β and VEGF levels, exhibit antimicrobial properties, and stimulate collagen synthesis (Vitale et al., 2022; Cedillo-Cortezano et al., 2024).
The most famous species of Pistacia [Anacardiaceae], namely, P. atlantica Desf., Pistacia vera L., Pistacia khinjuk Stocks, Pistacia lentiscus L., and Pistacia terebinthus L., are widely distributed in the Mediterranean and Middle Eastern regions (Mahjoub et al., 2018; Pekacar and Deliorman Orhan, 2022). The species P. atlantica, also known as wild pistachio, holds the most economical species and can be found in Iran, and has thee subspecies, kurdica, mutica, and cabulica. In Persian, P. atlantica is known as “Baneh,” Mt. Atlas mastic tree in English, Butm in Arabic, and Melengic in Turkish. In Iran, the oleo-gum-resin of P. atlantica is known as “Saqez gum” (Mahjoub et al., 2018). Extensive phytochemical studies on oleo-gum-resin of P. atlantica have revealed the presence of volatile compounds with α-pinene and β-pinene as the main components (Delazar et al., 2004; Barrero et al., 2005; Sharifi and Hazell, 2011; Benabderrahmane et al., 2016; Benabdallah et al., 2017; Ellahi et al., 2019). In addition, analysis of the monosaccharides has reported the majority presence of arabinose, galactose, glucose, rhamnose and xylose, while the most abundant aminoacids are aspartic acid, glutamic acid, histidine, proline and serine (Mirahmadi et al., 2019). Finally, triterpenoids like morolic acid, oleanonic acid, oleanolic acid, isomasticadienonic acid, 3-epi-isomasticadienolic acid, masticadienonic acid, dihydromasticadienonic acid, 3-O-acetyl-3epi (iso)masticadienolic acid, masticadienolic acid, dihydromasticadienolic acid, 3-acetoxy-3-epiisomasticadienolic acid, and 3-acetoxy-3-epimasticadienolic acid, ursonic acid) have also been identified (Sharifi, 2006).
In the TPM, various parts of P. atlantica have been utilized for the management of various skin disorders (like skin wounds, eczema, scabies, and lip fissures), gastrointestinal diseases (dyspepsia, peptic ulcer, esophagitis, and anal fissures), seizure, tremor, headache, asthma, pneumonia, hepatitis, and kidney diseases (Amin, 2005; Aghili, 2009; Bozorgi et al., 2013; Mahjoub et al., 2018). Recent reports have showed the extensive pharmacological and biological properties exhibited by different parts of P. atlantica, encompassing wound-healing, anti-inflammatory, antioxidant, nipple fissure healing, antimicrobial, antifungal, analgesic, anticancer, anticholinesterase, antidiabetic, hepatoprotective, antihypertensive, and antihyperlipidemic activities (Mahjoub et al., 2018; Pekacar and Deliorman Orhan, 2022).
Despite the critical role of novel preclinical studies in providing novel formulations and therapeutic agents in wound healing, there are some limitations. For instance, there are physiological and anatomical differences between animals and humans. Additionally, no study can recapitulate the complexity and heterogeneity of chronic wounds in humans. The lack of procedure standardization and translation of preclinical data into clinical models remains a crucial challenge (Grada et al., 2018).
Providing other preclinical models could confirm our findings in different models of burn and other scars. Preclinical reports could not only evaluate the wound healing potential of PAK, but also assess related scar vanishing effects. Future reports are needed to provide well-controlled clinical trials regarding evaluating the effectiveness of PVA/PAK in humans. In line, the development of PAK-based nanofiber dressings in humans could pave the road to wound healing. Further studies are also needed to provide other novel topical formulations to introduce products with a higher efficacy and a lower side effect.