Endocannabinoid system and wound healing

Cannabinoids in Integumentary Wound Care: A Systematic Review of Emerging Preclinical and Clinical Evidence

This systematic review critically evaluates preclinical and clinical data on the antibacterial and wound healing properties of cannabinoids in integument wounds. Comprehensive searches were conducted across multiple databases, including CINAHL, Cochrane library, Medline, Embase, PubMed, Web of Science, and LILACS, encompassing records up to May 22, 2024. Eighteen studies met the inclusion criteria. Eleven were animal studies, predominantly utilizing murine models (n = 10) and one equine model, involving 437 animals. The seven human studies ranged from case reports to randomized controlled trials, encompassing 92 participants aged six months to ninety years, with sample sizes varying from 1 to 69 patients. The studies examined the effects of various cannabinoid formulations, including combinations with other plant extracts, crude extracts, and purified and synthetic cannabis-based medications administered topically, intraperitoneally, orally, or sublingually. Four animal and three human studies reported complete wound closure. Hemp fruit oil extract, cannabidiol (CBD), and GP1a resulted in complete wound closure in twenty-three (range: 5-84) days with a healing rate of 66-86% within ten days in animal studies. One human study documented a wound healing rate of 3.3 cm2 over 30 days, while three studies on chronic, non-healing wounds reported an average healing time of 54 (21-150) days for 17 patients by oral oils with tetrahydrocannabinol (THC) and CBD and topical gels with THC, CBD, and terpenes. CBD and tetrahydrocannabidiol demonstrated significant potential in reducing bacterial loads in murine models. However, further high-quality research is imperative to fully elucidate the therapeutic potential of cannabinoids in the treatment of bacterial skin infections and wounds. Additionally, it is crucial to delineate the impact of medicinal cannabis on the various phases of wound healing. This study was registered in PROSPERO (CRD42021255413).

Antimicrobial and Immunomodulatory Activity of Herb Extracts Used in Burn Wound Healing: "San Huang Powder"

"San Huang Powder," a nonsterile milled herb powder, is frequently used to treat burn wounds in traditional Chinese herbal medicine. However, treating a wound with a nonsterile dressing or reagent is not compatible with the current guidelines in modern medicine. Therefore, we investigated the bactericidal and anti-inflammatory activities of four herb extracts used in "San Huang Powder" in vitro. Meanwhile, an in vivo porcine model with superficial second-degree burns was used for the experiments since the size and skin composition of pigs are the closest to that of the human body. The minimal bactericidal concentration (MBC) of the herb extracts was determined. The in vitro assay indicated that Rhubarb and Phellodendron bark extracts decreased the levels of inflammatory cytokines, IL-8, and GM-CSF on LPS-induced HMEC-1 cells. In accordance with this result, the histopathological evaluation results showed that the efficacy of "San Huang Powder" containing both herb materials was much better than the group without Rhubarb. Our results not only provide a basis to understand why "San Huang Powder" has been used to clinically treat wounds without sterilization directly since ancient times but also show the advantages of using multiple herb materials simultaneously on wound sites to prevent infection during treatment. Rhubarb is the recommended ingredient involved in the preparation of "San Huang Powder" to ensure the healing efficacy of burn wounds.

Red Maca (Lepidium meyenii), a Plant from the Peruvian Highlands, Promotes Skin Wound Healing at Sea Level and at High Altitude in Adult Male Mice

Nuñez, Denisse, Paola Olavegoya, Gustavo F. Gonzales, and Cynthia Gonzales-Castañeda. Red maca (Lepidium meyenii), a plant from the Peruvian highlands, promotes skin wound healing at sea level and at high altitude in adult male mice. High Alt Med Biol 18:373-383, 2017.-Wound healing consists of three simultaneous phases: inflammation, proliferation, and remodeling. Previous studies suggest that there is a delay in the healing process in high altitude, mainly due to alterations in the inflammatory phase. Maca (Lepidium meyenii) is a Peruvian plant with diverse biological properties, such as the ability to protect the skin from inflammatory lesions caused by ultraviolet radiation, as well as its antioxidant and immunomodulatory properties. The aim of this study was to determine the effect of high altitude on tissue repair and the effect of the topical administration of the spray-dried extract of red maca (RM) in tissue repair. Studies were conducted in male Balb/c mice at sea level and high altitude. Lesions were inflicted through a 10 mm-diameter excisional wound in the skin dorsal surface. Treatments consisted of either (1) spray-dried RM extract or (2) vehicle (VH). Animals wounded at high altitude had a delayed healing rate and an increased wound width compared with those at sea level. Moreover, wounding at high altitude was associated with an increase in inflammatory cells. Treatment with RM accelerated wound closure, decreased the level of epidermal hyperplasia, and decreased the number of inflammatory cells at the wound site. In conclusion, RM at high altitude generate a positive effect on wound healing, decreasing the number of neutrophils and increasing the number of macrophages in the wound healing at day 7 postwounding. This phenomenon is not observed at sea level.

Systems-Level Lipid Analysis Methodologies for Qualitative and Quantitative Investigation of Lipid Signaling Events During Wound Healing

OBJECTIVE

Accumulating evidence implicates a prominent role for lipid signaling molecules in the regulation of wound healing. These lipids regulate hemostasis, onset and resolution of inflammation, migration and proliferation cells, angiogenesis, epithelialization, and remodeling of collagen. The objective of this overview is to demonstrate the applicability of systems level lipid analyses to identify and quantify lipid involved in events leading to wound healing.

APPROACH

Current advances in liquid chromatography coupled to tandem mass spectrometry have provided the means for carrying out quantitative and qualitative analysis of lipids at a systems level. This emerging field is collectively referred to as lipidomics and its potential in wound healing research is largely ignored.

RESULTS

While comprehensive applications of lipidomics in wound healing are limited, studies carried out by the authors as well as others demonstrate distinct changes in the lipidome during the wound healing process.

INNOVATION

Until recently, investigations into lipids were limited to the study of a few lipids at a time. Lipidomics approaches provide the capability to quantitatively and qualitatively assay almost the full complement of lipid signaling circuits at the same time. This allows obtaining a system level understanding of changes to the entire lipidome during the wound healing process.

CONCLUSION

The technology provides promising approach to understanding new signaling pathways based on lipids involved in wound healing. The understanding gained from such studies has the potential for the development of novel lipid based treatment strategies to promote wound healing.

Bioactive lipid mediators in skin inflammation and immunity

The skin is the primary barrier from the outside environment, protecting the host from injury, infectious pathogens, water loss and solar ultraviolet radiation. In this role, it is supported by a highly organized system comprising elements of innate and adaptive immunity, responsive to inflammatory stimuli. The cutaneous immune system is regulated by mediators such as cytokines and bioactive lipids that can initiate rapid immune responses with controlled inflammation, followed by efficient resolution. However, when immune responses are inadequate or mounted against non-infectious agents, these mediators contribute to skin pathologies involving unresolved or chronic inflammation. Skin is characterized by active lipid metabolism and fatty acids play crucial roles both in terms of structural integrity and functionality, in particular when transformed to bioactive mediators. Eicosanoids, endocannabinoids and sphingolipids are such key bioactive lipids, intimately involved in skin biology, inflammation and immunity. We discuss their origins, role and influence over various cells of the epidermis, dermis and cutaneous immune system and examine their function in examples of inflammatory skin conditions. We focus on psoriasis, atopic and contact dermatitis, acne vulgaris, wound healing and photodermatology that demonstrate dysregulation of bioactive lipid metabolism and examine ways of using this insight to inform novel therapeutics.