Introduction

The process of wound healing in any type of tissue follows a predictable sequence of cellular and molecular events leading to the repair of injured tissue [1]. The healing process of acute wounds consists of four different consecutive phases (haemostasis, inflammation, proliferation/ migration and remodelling) [2]. However, certain wounds exhibit a failure in this sequential process of wound healing and are generally categorized as chronic or hard-to-heal wounds [3]. Wound chronicity is attributed to a confluence of local wound related factors including prolonged inflammation, infection [4], impaired immune response, reduced cellular proliferation and migration, hindered extracellular and intracellular matrix synthesis, as well as compromised secretion of growth factors and perturbed cellular metabolism [5]. In addition, there are also host related factors (overall health status) which impact the wound healing process including age [6] (especially elevated age is a significant risk factor for delayed wound healing), nutritional status (especially malnutrition or specific nutritional shortages have a profound impact on wound healing), vascular insufficiency, hypoxia, comorbidities e.g. coronary heart disease and diabetes mellitus [7].

What is needed for optimal wound healing?

Adequate and total wound care involves:

-         Local wound management:

• cleanse and debride the wound
• cover and protect the wound
• monitor wound healing

-         Supporting the host:

• identify and treat the cause of the wound
• optimize disease management
• optimize frail and compromised health status

The overall goal is to create a well-vascularized wound bed, free from non-viable tissue and excess exudate and with a low bacterial burden, that is optimal for the development of healthy granulation tissue and epithelializing towards closing wound edges.

Wound bed preparation is represented by the acronym TIME [8,9]:

-         Tissue management: removing devitalized and necrotic tissue and its bacterial burden by adequate cleansing and debridement,

-         Infection and inflammation control: antiseptic and antimicrobial cleaning [10],

-         Moisture balance: promoting a warm and moist wound bed + control of excessive moisture; appropriate use of suitable wound dressing [11,12],

-         Epithelial edge advancement: promoting well-advancing wound edges by adequate epithelialization [13].

What are important requirements of wound dressings?

Wound dressings should meet the following requirements to ensure an optimal wound healing process during all phases: preserving a moist wound environment [11], prevention of dressing adherence [14], acting anti-microbial [15], providing peri-wound protection [16], maceration control [17,18] and strengthening the skin’s barrier function [19,20].

Besides that, dressings that lead to a reduction in number of dressing changes, a reduction in the number of debridement episodes [21], a reduction in the number of wound cleansing episodes with antiseptic solutions [21], and which are easy-to-use and enable self-care (patient or family) are favourite.

Positioning of a novel wound dressing spray.

Today, a large variety of hydrocolloid, hydrogel, alginate, polymeric and foam wound dressings exists of which all fulfil some, though not all requirements to support a good wound healing process in a feasible, cost-effective and patient/ professional friendly way.

The novel treatment studied in this article involves the application of a wound dressing spray based on St John’s wort oil and Neem oil [22]. The spray acts as a primary wound dressing and is applied from a distance of 5-10 cm directly onto the wound surface and peri-wound skin, after which it creates a thin layer of oil covering the wound bed and the surrounding skin.

The spray can be used for acute and chronic wounds and in all health care settings including the patients’ home. Application can not only be done by wound care professionals but also by patients themselves and or their informal caregivers.

Mechanism of action.

• The spray creates a non-adherent wound coverage. The usage of non-adherent wound dressings supports wound healing since damage of the granulation tissue and regenerating epithelium during dressing change is prevented. This leads to improved epithelization and decrease of pain during dressing change.
• The spray creates a continuous moist wound environment due to reduced water evaporation (barrier function). The thin oil film on the wound surface executes a barrier function, preventing water evaporation from the wound due to the hydrophobic nature of the oil. A moist environment is known to support wound healing by facilitating cell migration and diffusion of signalling molecules and nutrients into the wound area [11].
• The spray exerts an antimicrobial effect based on a physical mode of action due to its high content of unsaturated fatty acids. Several publications have described antimicrobial effects of unsaturated fatty acids such as oleic and linoleic acid, which is caused by their surface activity [10,23].
• The spray protects the skin area around the wound and supports a healthy skin barrier function due to the high content of unsaturated fatty acids [19].

The mechanism of the wound dressing spray is depicted in (Figure 1).

Figure 1: Primary effect of a wound dressing spray* based on St John’s wort oil and Neem oil. *This wound dressing spray is currently available as WOUND. (https://www.bap-medical.com/brands/wound/).

Aim of this study

As this innovative wound dressing spray appears to meet most relevant requirements needed for an optimal wound healing process, we performed a narrative review to evaluate:

-         the effects of this wound dressing spray on wound healing in acute and chronic wounds,

-         its’ feasibility for use in daily wound care practice,

-         and patients’ and professionals’ satisfaction with the product.

Methods

Search Strategy

Potentially relevant articles were obtained by performing a broad systematic search in three electronic databases: PubMed, Web of Science and Google Scholar.

Search Terms

The following terms were combined with AND and OR:

“St John’s wort oil” AND “Neem oil” AND “wound spray” AND “patients” AND “wounds” AND “2000/01/01” – “2024/12/31” AND “English” OR “German”.

Articles were eligible for inclusion if they met the following inclusion criteria:

1. written in English or German
2. clinical trial (RCT or CT) or case study or review or expert opinion/ clinical expertise
3. treatment of acute and/ or chronic wounds
4. with a dressing spray based on St John’s wort oil and Neem oil
5. describing the effect of both plant preparations as a primary wound dressing
6. describing the feasibility for daily wound care practice
7. describing patients’ and/ or professionals’ satisfaction about the wound spray
8. describing cost effectiveness of the application of the spray in the treatment of acute and/ or chronic wounds
9. no age nor health restrictions for patients

In the first phase, all potentially relevant articles were reviewed based on title by JN and JS. In the second phase, abstract assessment of the initially retrieved articles was performed by JN and JS and articles not meeting the inclusion criteria were excluded. In the third phase, full text assessment was done by JN and JS of all articles included after the second phase. Finally, after full text analysis combined with searching the reference lists of the included articles for relevant additional articles, the final article selection for this narrative review was achieved by both assessors.

Search results

The combined search in PubMed, Web of Science and Google

Scholar yielded 264 potentially relevant articles. Based on the title, 249 articles were excluded because they had another outcome than wound healing, did not contain St John’s wort oil together with Neem oil in the form of a spray as primary wound dressing, or were not treatment studies. Additionally, 3 articles were excluded because they did not involve human studies. Twelve full text publications remained for review. Thereafter, 4 reviews were excluded because 1 did not meet the inclusion criteria and 3 revealed duplicates of already included potentially relevant articles. After searching the reference lists of the 8 remaining articles, 1 relevant article was added. Finally, 9 articles were included in this narrative review.

The flow chart of the selection process is depicted in (Figure 2).

Results

The 9 included studies in this review were published between 2012 and 2024. They were conducted in different care settings: University Hospital (N=3), Hospital (N=5) and Long-Term Care (N=1). All studies evaluated a plant-derived primary wound dressing spray, based on St John’s wort oil and Neem oil, in the treatment of acute wounds, chronic wounds or both.

Eight out of 9 studies are case series studies of which 7 retrospective and 1 prospective. The 9th study is a single-blinded RCT. The study characteristics (type, (N), settings, wound types and participants’ age), study aims as reported, and outcomes are summarized in (Table 1), organized by first author and year of publication.

Figure 2: Flow chart of the selection process of the specific literature search.

Table 1: Study characteristics and outcomes.