Effects of glutamine on wound healing

A pro-reparative bioelectronic device for controlled delivery of ions and biomolecules

Wound healing is a complex physiological process that requires precise control and modulation of many parameters. Therapeutic ion and biomolecule delivery has the capability to regulate the wound healing process beneficially. However, achieving controlled delivery through a compact device with the ability to deliver multiple therapeutic species can be a challenge. Bioelectronic devices have emerged as a promising approach for therapeutic delivery. Here, we present a pro-reparative bioelectronic device designed to deliver ions and biomolecules for wound healing applications. The device incorporates ion pumps for the targeted delivery of H+ and zolmitriptan to the wound site. In vivo studies using a mouse model further validated the device's potential for modulating the wound environment via H+ delivery that decreased M1/M2 macrophage ratios. Overall, this bioelectronic ion pump demonstrates potential for accelerating wound healing via targeted and controlled delivery of therapeutic agents to wounds. Continued optimization and development of this device could not only lead to significant advancements in tissue repair and wound healing strategies but also reveal new physiological information about the dynamic wound environment.

Wound Healing Effect of 20(S)-Protopanaxadiol of Ginseng Involves VEGF-ERK Pathways in HUVECs and Diabetic Mice

Wound healing is the process of skin and soft tissue repair following an injury. Angiogenesis is an essential process in wound healing and plays an important role in tissue regeneration. Ginseng is mainly composed of saponins and protopanaxadiol-based ginsenosides, namely Rb1, Rb2, Rc, Re, Rg1, and Rf. 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT) are aglycones of ginsenosides produced by metabolic processes and heat treatment. This study aimed to investigate the wound healing effects of active ingredients of ginseng, namely ginsenosides and aglycones, in various cellular and animal skin wound models. The angiogenic effects of ginsenosides were investigated in human umbilical vein endothelial cells (HUVECs). All experiments were conducted at increased intracellular glucose concentrations and the induction of angiogenesis through tube formation was evaluated. Among the ginsenosides and aglycones used in this study, PPD showed the strongest wound-healing activity. Cell scratch experiments confirmed that PPD increased intracellular proliferation and cell migration at high glucose concentrations, and western blotting of HUVECs showed that phosphorylated ERK, Akt, and p38 were regulated. We observed accelerated wound healing with PPD treatment in STZ-treated mice. Overall, the findings suggested that PPD could possibly help improve skin wound healing in patients with diabetes, although further research is recommended.

Commensal microbiome promotes hair follicle regeneration by inducing keratinocyte HIF-1α signaling and glutamine metabolism

Tissue injury induces metabolic changes in stem cells, which likely modulate regeneration. Using a model of organ regeneration called wound-induced hair follicle neogenesis (WIHN), we identified skin-resident bacteria as key modulators of keratinocyte metabolism, demonstrating a positive correlation between bacterial load, glutamine metabolism, and regeneration. Specifically, through comprehensive multiomic analysis and single-cell RNA sequencing in murine skin, we show that bacterially induced hypoxia drives increased glutamine metabolism in keratinocytes with attendant enhancement of skin and hair follicle regeneration. In human skin wounds, topical broad-spectrum antibiotics inhibit glutamine production and are partially responsible for reduced healing. These findings reveal a conserved and coherent physiologic context in which bacterially induced metabolic changes improve the tolerance of stem cells to damage and enhance regenerative capacity. This unexpected proregenerative modulation of metabolism by the skin microbiome in both mice and humans suggests important methods for enhancing regeneration after injury.

Oral glutamine dipeptide or oral glutamine free amino acid reduces burned injury progression in rats

This study was carried out to evaluate the effect of Glutamine, as a dipeptide or a free amino acid form, on the progression of burn injuries in rats. Thirty male Wistar rats were burned with a comb metal plate heated in boiling water (98 °C) for three minutes, creating four rectangular full-thickness burn areas separated by three unburned interspaces (zone of stasis) in both dorsum sides. The animals were randomized into three groups (n=10): saline solution (G1-Control) and treated groups that orally received Glutamine as dipeptide (G2-Dip) or free amino acid (G3-FreeAA). Two and seven days after burn injury, lesions were photographed for unburned interspaces necrosis evolution assessment. Seven days after injury, glutathione seric was measured and histopathological analysis was performed. By photographs, there was a significant reduction in necrosis progression in G3-Free-AA between days two and seven. Histopathological analysis at day 7 showed a significantly higher stasis zone without necrosis and a higher number of fibroblasts in G2-Dip and G3-FreeAA compared with G1-Control. Also, glutathione serum dosage was higher in G2-Dip. The plasmatic glutathione levels were higher in the G2-Dip than the G1-Control, and there was a trend to higher levels in G3-FreeAA. The reduction in histological lesions, greater production of fibroblasts, and greater amounts of glutathione may have benefited the evolution of burn necrosis, which showed greater preservation of interspaces.

Proline Precursors and Collagen Synthesis: Biochemical Challenges of Nutrient Supplementation and Wound Healing

Wound healing is a complex process marked by highly coordinated immune fluxes into an area of tissue injury; these are required for re-establishment of normal tissue integrity. Along with this cascade of cellular players, wound healing also requires coordinated flux through a number of biochemical pathways, leading to synthesis of collagen and recycling or removal of damaged tissues. The availability of nutrients, especially amino acids, is critical for wound healing, and enteral supplementation has been intensely studied as a potential mechanism to augment wound healing-either by increasing tensile strength, decreasing healing time, or both. From a practical standpoint, although enteral nutrient supplementation may seem like a reasonable strategy to augment healing, a number of biochemical and physiologic barriers exist that limit this strategy. In this critical review, the physiology of enteral amino acid metabolism and supplementation and challenges therein are discussed in the context of splanchnic physiology and biochemistry. Additionally, a review of studies examining various methods of amino acid supplementation and the associated effects on wound outcomes are discussed.

The effect of glutamine intake on complications of colorectal and colon cancer treatment: A systematic review

Background:

Improvement in complications of antitumor agents and surgery is important to enhance life quality and survival among patients with colon and colorectal cancer. It has been reported that some dietary components such as glutamine (Gln) have beneficial effects on these complications of cancer therapies. However, the results of studies are inconsistent in this area. We performed a review on randomized controlled trials (RCTs) evaluating the effects of Gln intake on complications related to therapeutic strategies of the colon and colorectal cancer.

Materials and Methods:

A systematic search was conducted in PubMed, Google Scholar, Cochrane Library, and SID databases to find the relevant literature, published before July 2015.

Results:

Nine RCTs of 217 screened articles were included in this systematic review. The results of the present review suggested that Gln intake among colon and colorectal cancer patients could reduce some complications induced by chemotherapy such as gut mucositis and diarrhea and improve nitrogen balance, immune system and wound healing after surgery, whereas benefits role of Gln on radiochemotherapy side effects were not provided.

Conclusion:

The role of Gln intake on some improvement of complications induced by cancer therapeutic methods and shorten the length of hospital stay may be promising and one that is worthy of further exploration.

Targeted amino acid supplementation in diabetic foot wounds: pilot data and a review of the literature

BACKGROUND

Diabetic foot wounds are a highly morbid and costly complication of diabetes mellitus. Targeted amino acid supplementation, by increasing tissue hydroxyproline concentrations, has been implicated in improved wound outcomes in surgical incisions and chronic wounds, and after radiation injury. A major component of collagen, hydroxyproline is a surrogate marker used commonly for tissue collagen concentrations. This paper reviews the literature pertaining to amino acid supplementation and wound healing, and also evaluates our pilot data relating to supplementation with arginine, glutamine, and beta-hydroxy-beta-methylbutyrate (HMB) in the treatment of diabetic foot ulcers.

METHODS

For the pilot study, nine patients scheduled to undergo wound debridement for diabetic foot ulcers were randomized prospectively to be a part of either a placebo group or a treatment group that received supplementation twice daily for 2 wks. Tissue samples were collected both before and after 2 wk of supplementation. The results of assay of the samples for hydroyproline were then analyzed via a one tailed Student t-test to evaluate tissue concentrations of hydroxyproline. For the literature review in the study, the MEDLINE/PubMed database was reviewed, using search terms contained in the Medical Subject Headings (MeSH).

RESULTS

The treatment group in the study exhibited a significantly greater hydroxyproline concentration after supplementation than before it (p=0.03). The mean percent change in the tissue hydroxyproline concentration for arginine, glutamine, and HMB group was +67.8%, with a standard deviation (SD) of 129.89. The mean percent change for the corresponding amino acids in the placebo group was -78.4%, with an SD of 20.55. The review of the MEDLINE/PubMed literature revealed only two human studies of amino acid supplementation in patients with diabetic foot wounds, one of which found a significant improvement in wound-depth and wound-appearance scores.

CONCLUSIONS

Given the results of our pilot study, and on the basis of a review of the literature, the administration of a simple amino acid supplement may improve the healing of diabetic foot wounds via increased collagen production.