The cellular proliferative phase of the wound repair process

Effect of Helichrysum italicum in Promoting Collagen Deposition and Skin Regeneration in a New Dynamic Model of Skin Wound Healing

Natural products have many healing effects on the skin with minimal or no adverse effects. In this study, we analyzed the regenerative properties of a waste product (hydrolate) derived from Helichrysum italicum (HH) on scratch-tested skin cell populations seeded on a fluidic culture system. Helichrysum italicum has always been recognized in the traditional medicine of Mediterranean countries for its wide pharmacological activities. We recreated skin physiology with a bioreactor that mimics skin stem cell (SSCs) and fibroblast (HFF1) communication as in vivo skin layers. Dynamic culture models represent an essential instrument for recreating and preserving the complex multicellular organization and interactions of the cellular microenvironment. Both cell types were exposed to two different concentrations of HH after the scratch assay and were compared to untreated control cells. Collagen is the constituent of many wound care products that act directly on the damaged wound environment. We analyzed the role played by HH in stimulating collagen production during tissue repair, both in static and dynamic culture conditions, by a confocal microscopic analysis. In addition, we performed a gene expression analysis that revealed the activation of a molecular program of stemness in treated skin stem cells. Altogether, our results indicate a future translational application of this natural extract to support skin regeneration and define a new protocol to recreate a dynamic process of healing.

Enhanced burn wound healing by controlled-release 3D ADMSC-derived exosome-loaded hyaluronan hydrogel

Adipose mesenchymal stem cell (ADMSC)-derived exosomes (ADMSC-Exos) have shown great potential in regenerative medicine and been evidenced benefiting wound repair such as burns. However, the low yield, easy loss after direct coating, and no suitable loading system to improve their availability and efficacy hinder their clinical application for wound healing. And few studies focused on the comparison of biological functions between exosomes derived from different culture techniques, especially in exosome-releasing hydrogel system. Therefore, we designed a high-performance exosome controllable releasing hydrogel system for burn wound healing, namely loading 3D-printed microfiber culture-derived exosomes in a highly biocompatible hyaluronic acid (HA). In this project, we compared the biological functions in vitro and in a burn model among exosomes derived from the conventional two-dimensional (2D) plate culture (2D-Exos), microcarrier culture (2.5D-Exos), and 3D-printed microfiber culture (3D-Exos). Results showed that compared with 2D-Exos and 2.5D-Exos, 3D-Exos promoted HACATs and HUVECs cell proliferation and migration more significantly. Additionally, 3D-Exos had stronger angiogenesis-promoting effects in tube formation of (HUVECs) cells. Moreover, we found HA-loaded 3D-Exos showed better burn wound healing promotion compared to 2D-Exos and 2.5D-Exos, including accelerated burn wound healing rate and better collagen remodeling. The study findings reveal that the HA-loaded, controllable-release 3D-Exos repair system distinctly augments therapeutic efficacy in terms of wound healing, while concurrently introducing a facile application approach. This system markedly bolsters the exosomal loading efficiency, provides a robust protective milieu, and potentiates the inherent biological functionalities of the exosomes. Our findings provide a rationale for more efficient utilization of high-quality and high-yield 3D exosomes in the future, and a novel strategy for healing severe burns.

The Effect of Oxidative Stress on the Human Voice

The vocal fold vibrates in high frequency to create voice sound. The vocal fold has a sophisticated histological "layered structure" that enables such vibration. As the vibration causes fricative damage to the mucosa, excessive voicing can cause inflammation or injury to the mucosa. Chronic inflammation or repeated injury to the vocal fold occasionally induces scar formation in the mucosa, which can result in severe dysphonia, which is difficult to treat. Oxidative stress has been proven to be an important factor in aggravating the injury, which can lead to scarring. It is important to avoid excessive oxidative stress during the wound healing period. Excessive accumulation of reactive oxygen species (ROS) has been found in the injured vocal folds of rats during the early phase of wound healing. Antioxidants proved to be useful in preventing the accumulation of ROS during the period with less scar formation in the long-term results. Oxidative stress is also revealed to contribute to aging of the vocal fold, in which the mucosa becomes thin and stiff with a reduction in vibratory capacity. The aged voice can be characterized as weak and breathy. It has been confirmed that ROS gradually increases in rat vocal fold mucosa with age, which may cause further damage to the vocal fold. Antioxidants have also proved effective in avoiding aging of the vocal fold in rat models. Recently, human trials have shown significant effects of the antioxidant Twendee X for maintaining the voice of professional opera singers. In conclusion, it is suggested that oxidative stress has a great impact on the damage or deterioration of the vocal folds, and the use of antioxidants is effective for preventing damage of the vocal fold and maintaining the voice.

Nutritional factors and pressure injury risk in hospitalised patients post-stroke

OBJECTIVE

This study aimed to analyse the nutritional factors and pressure injury (PI) risk in hospitalised patients post-stroke.

METHOD

The research employed a descriptive observational method in which patients ≥18 years of age were followed for six days. Nutritional evaluation was based on anthropometric and dietary factors. The nutritional risk was assessed via anthropometric measurements, Braden nutrition subscale and daily dietary intake. PI risk was evaluated through the Braden Scale. The Wilcoxon test, paired t-test, and Kruskal-Wallis test were applied and corrected with Bonferroni correction or analysis of variance, followed by the post hoc Tukey test.

RESULTS

During their hospital stays, the participating 59 patients had an increase in sensory perception (p=0.02) and nutrition (p=0.005) scores. It was observed that patients at high risk of PI did not meet daily nutritional recommendations for calories, proteins, carbohydrates, lipids and micronutrients (zinc, selenium and copper) compared with patients at low-to-moderate risk. Weight (p<0.001), body mass index (p<0.001), calf (p=0.01) and arm (p=0.04) circumferences, and subscapular (p=0.003) and triceps (p<0.001) skinfolds decreased during the six days of hospitalisation.

CONCLUSION

From the findings of this study, it was concluded that nutritional factors, such as unmet recommended daily nutritional requirements of macronutrients and micronutrients, and nutritional status are associated with a higher risk of developing a PI.

Screening Plasma Proteins for the Putative Drug Targets for Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is one of the most common work-related musculoskeletal disorders. The present study sought to identify putative causal proteins for CTS. We conducted a two-sample Mendelian randomization (MR) analysis to evaluate the causal association between 2859 plasma proteins (N = 35,559) and CTS (N = 1,239,680) based on the published GWAS summary statistics. Then we replicated the significant associations using an independent plasma proteome GWAS (N = 10,708). Sensitivity analyses were conducted to validate the robustness of MR results. Multivariate MR and mediation analyses were conducted to evaluate the mediation effects of body mass index (BMI), type 2 diabetes (T2D), and arm tissue composition on the association between putative causal proteins and CTS. Colocalization analysis was used to examine whether the identified proteins and CTS shared causal variant(s). Finally, we evaluated druggability of the identified proteins. Ten plasma proteins were identified as putative causal markers for CTS, including sCD14, PVR, LTOR3, CTSS, SIGIRR, IFNL3, ASPN, TM11D, ASIP, and ITIH1. Sensitivity analyses and reverse MR analysis validated the robustness of their causal effects. Arm tissue composition, BMI, and T2D may play a fully/partial mediating role in the causal relationships of ASIP, TM11D, IFNL3, PVR, and LTOR3 with CTS. The association of ASPN and sCD14 with CTS were supported by colocalization analysis. Druggability assessment demonstrated that sCD14, CTSS, TM11D, and IFNL3 were potential drug therapeutic targets. The present study identified several potential plasma proteins that were causally associated with CTS risk, providing new insights into the pathogenesis of protein-mediated CTS and offering potential targets for new therapies.

Stem cell therapy for vocal fold regeneration after scarring: a review of experimental approaches

This review aims at becoming a guide which will help to plan the experimental design and to choose adequate methods to assess the outcomes when testing cell-based products in the treatment of the damaged vocal folds. The requirements to preclinical trials of cell-based products remain rather hazy and dictated by the country regulations. Most parameters like the way the cells are administered, selection of the cell source, selection of a carrier, and design of in vivo studies are decided upon by each research team and may differ essentially between studies. The review covers the methodological aspects of preclinical studies such as experimental models, characterization of cell products, assessment of the study outcome using molecular, morphological and immunohistochemical analyses, as well as measuring the tissue physical properties. The unified recommendations to perform preclinical trials could significantly facilitate the translation of cell-based products into the clinical practice.

Design and Development of Naringin Loaded Proposomal Gel for Wound Healing

BACKGROUND

The injuries or wounds caused by various means will impact human lives severely. An increase in the demand for wounds or burns was observed. For better wound healing and to combat the free radical effect on the healing process, wounds must be treated with multifunctional or multipurpose dressing or gel or any other type of biomaterial.

OBJECTIVES

The study aims to develop, optimize, and evaluate the naringin-loaded proposomal gel (PPG) for quick wound healing.

METHODS

The central composite design was employed for the optimization of proposomes. Naringin-loaded proposomes were evaluated for percentage entrapment efficiency (EE), the particle size of proposomes (PsP), and the zeta potential of proposomes (ZpP). The change in drug release profile was studied by dissolution. Furthermore, naringin and naringin-loaded proposomes, antioxidant activity was determined by 2,2- diphenyl-1-picrylhydrazyl hydrate (DPPH) reagent and ascorbic acid as a reference standard. Different gel bases were prepared, and based on various parameters, the G2 (0.6 % Carbopol 974) gel base was selected for naringin proposomes loading. The naringin-loaded PPG was evaluated for various in vitro and in vivo wound healing properties.

RESULTS

The optimized naringin-loaded proposomes showed extended drug release (90.78 ± 2.19%) for 72 h. The naringin-loaded PPG improved the permeability of naringin, which showed 28.91 ± 2.81% of drug release after 96 h, and the drug solution showed 9.05 ± 0.92%. IC50 values of antioxidant activity of naringin and naringin proposomes were found to be 337.31 μg/ mL and 201.86 μg/ mL, respectively. The naringin-loaded PPG showed better-wound closure on the 15^th day (3.32%) compared to proposomal solution (4.75%) or naringin topical gel (4.2%).

CONCLUSION

Based on the obtained results, we conclude naringin-loaded PPG can be an alternative strategic approach to deliver the naringin for quick wound healing.

The application of mesenchymal stromal cells (MSCs) and their derivative exosome in skin wound healing: a comprehensive review

Recently, mesenchymal stromal cells (MSCs) and also their exosome has become a game-changing tool in the context of tissue engineering and regenerative medicine. MSCs due to their competencies to establish skin cells, such as fibroblast and keratinocyte, and also their unique attribute to suppress inflammation in wound site has attracted increasing attention among scholars. In addition, MSC's other capabilities to induce angiogenesis as a result of secretion of pro-angiogenic factors accompanied with marked anti-fibrotic activities, which mainly mediated by the releases matrix metalloproteinase (MMPs), make them a rational and effective strategy to accelerate wound healing with a small scar. Since the chief healing properties of the MSCs depend on their paracrine effects, it appears that MSCs-derived exosomes also can be an alternative option to support wound healing and skin regeneration as an innovative cell-free approach. Such exosomes convey functional cargos (e.g., growth factor, cytokine, miRNA, etc.) from MSCs to target cells, thereby affecting the recipient skin cells' biological events, such as migration, proliferation, and also secretion of ECM components (e.g., collagen). The main superiorities of exosome therapy over parental MSCs are the diminished risk of tumor formation and also lower immunogenicity. Herein, we deliver an overview of recent in vivo reports rendering the therapeutic benefits of the MSCs-based therapies to ease skin wound healing, and so improving quality of life among patients suffering from such conditions.

Nanotechnology Development for Formulating Essential Oils in Wound Dressing Materials to Promote the Wound-Healing Process: A Review

Wound healing refers to the replacement of damaged tissue through strongly coordinated cellular events. The patient’s condition and different types of wounds complicate the already intricate healing process. Conventional wound dressing materials seem to be insufficient to facilitate and support this mechanism. Nanotechnology could provide the physicochemical properties and specific biological responses needed to promote the healing process. For nanoparticulate dressing design, growing interest has focused on natural biopolymers due to their biocompatibility and good adaptability to technological needs. Polysaccharides are the most common natural biopolymers used for wound-healing materials. In particular, alginate and chitosan polymers exhibit intrinsic antibacterial and anti-inflammatory effects, useful for guaranteeing efficient treatment. Recent studies highlight that several natural plant-derived molecules can influence healing stages. In particular, essential oils show excellent antibacterial, antifungal, antioxidant, and anti-inflammatory properties that can be amplified by combining them with nanotechnological strategies. This review summarizes recent studies concerning essential oils as active secondary compounds in polysaccharide-based wound dressings.

Scarring and wound healing

Following injury, the skin undergoes a wound healing process culminating in the formation of a mature scar. Millions of patients worldwide are left with scars every year as a result of trauma or surgery. Scars can be painful, disfiguring and disabling, yet patients report that clinicians are often dismissive of their concerns, unable to identify pathological scars and unaware of treatment options. The normal wound healing process comprises three overlapping stages: inflammation, proliferation and remodelling. In some patients this process is deranged, resulting in the formation of hypertrophic or keloid scars. Clinicians can minimize the risk of these pathological scars developing with good surgical technique and wound aftercare. If pathological scars do form, they should be identified early and patients referred for treatment, most often topical or intralesional corticosteroids. In resistant cases, pathological scars may be treated with phototherapy, radiotherapy or surgical resection.

The effect of Korean Red Ginseng on full-thickness skin wound healing in rats

BACKGROUND

Panax ginseng is regarded as one of the best compounds for promoting health, and it has been used traditionally as a medicinal herb. Recently, Korean Red Ginseng (RG) has been shown to protect skin from aging and wrinkling; it can also relieve atopic dermatitis and allergy symptoms. This study aimed to evaluate RG's effects on the regeneration of the full-thickness skin wounds in rat.

METHODS

Full-thickness skin wounds were generated in rats, and then RG was administered either orally or topically. The wound-healing effects of RG were investigated by assessing wound size, mRNA expression patterns of genes related to wound healing, histological staining, and measurements of lipid, moisture, and elasticity in skin tissues.

RESULTS

The wound size was smaller, and tissue regeneration rate was faster in the RG-treated group than that in the control group on days 15 and 20 after initiating treatment. On postoperative day 20, skin lipid and moisture content had increased significantly in the RG-treated group. Significant increases in the gene expression levels of transforming growth factor-β1 and vascular endothelial growth factor were found in the RG group during the early stages of wound healing. Matrix metalloproteinase-1 and matrix metalloproteinase-9 showed significant increases in gene expression levels on day 20.

CONCLUSION

The results suggested that RG may promote healing of full-thickness skin wounds in rats. They also provided basic insights into the effects of RG on skin regeneration, supporting its use as a dressing material for wound treatment and its development as a functional food.

The effects of cryotherapy on vocal fold healing in a rabbit model

OBJECTIVES/HYPOTHESIS

Cryotherapy has been shown to be a scarless treatment modality for dermal lesions; however, there are limited data addressing the effect of cryotherapy on vocal fold tissue. The aim of this study was to clarify the effectiveness of cryotherapy for prevention of postsurgical vocal fold scarring.

STUDY DESIGN

Prospective animal study in rabbits.

METHODS

The lamina propria of 20 rabbit vocal folds was bilaterally stripped, followed by randomized unilateral cryotherapy. Five larynges were harvested for real-time polymerase chain reaction (RT-PCR) analysis at 1 day, 3 days, and 7 days postinjury. The remaining five were harvested for histologic analysis at 3 months. Images of the healing phase were recorded by laryngoscopy. Analyses of RT-PCR for cyclooxygenase (COX)-2, interleukin (IL)-6, collagen I, collagen III, matrix metallopeptidase 1 (MMP1), transforming growth factor β (TGFβ1), α smooth muscle actin (α-SMA), and hyaluronan synthase 1 (HAS1) were completed. Histological samples were completed for collagen and hyaluronic acid analysis.

RESULTS

RT-PCR results revealed that higher expressions of HAS1 and MMP1 and lower expressions of COX-2, IL-6, collagen I, collagen III, TGFβ1, and α-SMA were observed, and histological examination showed significantly increased hyaluronic acid, decreased deposition, and more organized configuration of collagen in injury with the cryotherapy cohort compared with the injury cohort.

CONCLUSIONS

Cryotherapy can inhibit the inflammatory reaction and simulate a fetal healing environment in extracellular matrix synthesis to regenerate vocal fold tissue with less fibrosis. Histological results showed that cryotherapy achieves a mature healing result with less scar, which tends to return to normal. In summary, the findings of this study suggest that administration of cryotherapy at the time of injury has the potential to minimize vocal fold scarring.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E151-E157, 2019.

Pressure Ulcer and Nutrition

Pressure ulcers can diminish global life quality, contribute to rapid mortality in some patients and pose a significant cost to health-care organizations. Accordingly, their prevention and management are highly important. Nutritional deprivation and insufficient dietary intake are the key risk factors for the development of pressure ulcers and impaired wound healing. Unplanned weight loss is a major risk factor for malnutrition and pressure ulcer development. Suboptimal nutrition interferes with the function of the immune system, collagen synthesis, and tensile strength. No laboratory test can exactly define an individual's nutritional status. Although serum albumin, prealbumin, transferrin, and retinol-binding protein as well as anthropometric measures such as height, weight, and body mass index and the other laboratory values may be suitable to establish the overall prognosis, still they might not well represent the nutritional status. Although the ideal nutrient intake to encourage wound healing is unknown, increased needs for energy, protein, zinc, and Vitamins A, C, and E and also amino acids such as arginine and glutamine have been documented. Hydration plays a vital role in the preservation and repair of skin integrity. Dehydration disturbs cell metabolism and wound healing. Adequate fluid intake is necessary to support the blood flow to wounded tissues and to prevent additional breakdown of the skin. The main aim of the present article is to review the current evidence related to hydration and nutrition for bedsore prevention and management in adults.

Histologic Characterization of Rat Vocal Fold Scarring

This study aimed to clarify the characteristics of rat vocal fold scarring by examining the alteration of key components in the extracellular matrix: hyaluronic acid, collagen, and fibronectin. Under monitoring with a 1.9-mm-diameter telescope, unilateral vocal fold stripping was performed, and larynges were harvested at 2, 4, 8, and 12 weeks after operation. The vocal folds were histologically analyzed with Alcian blue stain, trichrome stain, and immunofluorescence of collagen type I, collagen type III, and fibronectin. The scarred vocal folds showed less hyaluronic acid and more collagen types I and III than did the controls at all time points. Type III was stable for 12 weeks, while type I declined until 8 weeks and thereafter remained unchanged. Fibronectin increased for 4 weeks and then decreased; it was close to the control level at 8 and 12 weeks. These results suggest that the tissue remodeling process in scarred vocal folds slows down around 2 months after wounding.

Homeostasis of hyaluronic acid in normal and scarred vocal folds

OBJECTIVES/HYPOTHESIS

Vocal fold scarring is one of the most challenging laryngeal disorders to treat. Hyaluronic acid (HA) is the main component of lamina propria, and it plays an important role in proper vocal fold vibration and is also thought to be important in fetal wound healing without scarring. Although several animal models of vocal fold scarring have been reported, little is known about the way in which HA is maintained in vocal folds. The purpose of this study was to clarify the homeostasis of HA by examining the expression of hyaluronan synthase (Has) and hyaluronidase (Hyal), which produce and digest HA, respectively.

STUDY DESIGN

Experimental prospective animal study.

METHODS

Vocal fold stripping was performed on 38 Sprague-Dawley rats. Vocal fold tissue was collected at five time points (3 days-2 months). Expression of HA was examined by immunohistochemistry, and messenger RNA (mRNA) expression of Has and Hyal was examined by real-time polymerase chain reaction and in-situ hybridization.

RESULTS

In scarred vocal folds, expression of Has1 and Has2 increased at day 3 together with expression of HA and returned to normal at 2 weeks. At 2 months, Has3 and Hyal3 mRNA showed higher expressions than normal.

CONCLUSIONS

Expression patterns of Has and Hyal genes differed between normal, acute-scarred, and chronic-scarred vocal folds, indicating the distinct roles of each enzyme in maintaining HA. Continuous upregulation of Has genes in the acute phase may be necessary to achieve scarless healing of vocal folds.

Biocompatibility and efficacy of collagen/gelatin sponge scaffold with sustained release of basic fibroblast growth factor on vocal fold fibroblasts in 3-dimensional culture

OBJECTIVE

Treatment of vocal fold scarring remains challenging. We have previously reported the therapeutic effects of local injection of basic fibroblast growth factor (bFGF) in animal models and humans. A novel collagen/gelatin sponge (CGS) is capable of sustained release of bFGF, which compensates for its quick absorption in vivo, avoiding multiple injections. This study aimed to evaluate the biocompatibility and efficacy of the CGS in rat vocal fold fibroblasts prior to human trials.

METHODS

Fibroblasts extracted from Sprague-Dawley rat vocal folds were seeded onto a CGS and then cultivated with bFGF at concentrations of 0, 10, and 100 ng/mL. Vocal fold fibroblast morphology, adhesion, proliferation, and gene expression were measured under these 3-dimensional conditions.

RESULTS

Cells adhered to the CGS from day 1. Although no significant differences in cell morphology were detected, cell proliferation was accelerated by bFGF administration. Expression of endogenous bFGF and hepatocyte growth factor was significantly up-regulated at 10 ng/mL bFGF. The expression of procollagen I and procollagen III was significantly suppressed, whereas HAS-1 and HAS-2 were up-regulated at 10 and 100 ng/mL bFGF.

CONCLUSION

The collagen/gelatin sponge is biocompatible with vocal fold fibroblasts and may be useful as a bFGF drug delivery system for the treatment of scarred vocal folds.

Therapeutic effect of total ginseng saponin on skin wound healing

In this study, we investigated the effects of total ginseng saponin (TGS) on the cutaneous wound healing process using histological analysis. A total of 24 ICR mice, 5-weeks-old, were used for all in vivo experiments. Mice were divided into control and TGS-treated groups and four equidistant 1-cm full-thickness dorsal incisional wounds were created. The wounds were extracted at days 1, 3, 5, and 7 post-injury for histomorphometrical analysis including wound area and contracture measurements, keratinocyte migration rate, and calculation of infiltrating inflammatory cells. The results showed that the wound area was smaller and keratinocyte migration rate was higher in the TGS-treated group than that of the control group from days 3 to 7. Inflammatory cells in the TGS-treated group at days 1 and 3 were reduced compared to the control group. Wound contraction in the TGS-treated group was greater than in the control group on days 3 to 5, and collagen deposition in the TGS-treated group was higher than in the control group during wound healing. The results indicate a beneficial effect of TGS when used to treat skin wounds.

Extracts from Radix Astragali and Radix Rehmanniae promote keratinocyte proliferation by regulating expression of growth factor receptors

Chinese herbal medicine has long been used as a treatment for wounds. However, the underlying cellular and molecular mechanisms remain largely unknown. In this study it was shown that the proliferation of keratinocytes, which is known to play an important role in wound healing as the major cell type in the epidermis, was promoted by three herbal extracts/natural compounds: NF3 (an extract from the mixture of Radix Astragali (RA) and Radix Rehmanniae (RR) in the ratio of 2:1), stachyose (an isolated compound from Radix Rehmanniae) and extract P2-2 (a sub-fraction from the extract of Radix Astragali). The effect of the herbal extracts/natural compounds on the growth of keratinocytes was not influenced by a high glucose level, a condition similar to diabetic patients who usually suffer from diabetic foot ulcers. Real time RT-PCR results showed that the expression of epidermal growth factor (EGF) receptor, but not transforming growth factor-β (TGF-β) receptor, was up-regulated by NF3. Moreover, treatments with the EGF receptor kinase inhibitor AG1478 and the MEK inhibitor U0126 resulted in the diminishment of the effect of the three herbal extracts/natural compounds on keratinocyte proliferation, indicating that EGF receptor might have a significant role in this action. This study has further elucidated the molecular mechanism under which herbal extracts/natural compounds exert their effects on the wound healing process.

Morphological and extracellular matrix changes following vocal fold injury in mice

Mouse experimental models are commonly utilized tools in biomedical research but remain underrepresented in vocal fold biology, presumably due to the small size of the larynx and limited description of the anatomical, cellular and extracellular composition of the vocal folds. In this study, we provide a whole-mount serial section-based histological description of vocal fold morphology of wild-type FVB strain mice, alongside a histological and immunohistochemical (IHC)-based quantitative analysis of extracellular matrix (ECM) alteration 1, 7, 14, 28, 42 and 56 days following unilateral vocal fold injury. IHC was specific for procollagen type I, collagen type I, collagen type III, collagen type IV, elastin, decorin, fibronectin and hyaluronic acid binding protein 2. The histological description confirmed the presence of a laryngeal alar structural complex in the mouse, which appears to be a morphological feature unique to rodents. The lamina propria appeared uniform without evidence of a distinct layer structure as has been reported in larger animals and humans. Time-dependent alterations in vocal fold morphology, ECM organization and ECM protein/glycoconjugate abundance were observed in injured vocal folds compared to control. The presence of a mature scar was observed between 28 and 42 days postinjury. Morphological and ECM changes following vocal fold injury in the mouse were generally consistent with those reported in other animal models, particularly the rat, although wound repair in the mouse appears to occur at a faster rate.

Copyright © 2010 S. Karger AG, Basel

Extracellular matrix gene expression after vocal fold injury in a rabbit model

OBJECTIVES

We determined the expression of matrix metalloproteinase (MMP)-1, MMP-9, collagen types I and III, and fibronectin from rabbit vocal folds after injury.

METHODS

Thirty rabbits were involved in this study. Five animals were assigned to each time period. Noninjured vocal fold specimens were collected as a control. Gene expression was analyzed at 2, 4, 8, 24, 48, and 72 hours after injury by use of real-time polymerase chain reaction.

RESULTS

Compared to 2 hours after injury, MMP-1 expression was increased at 4, 8, 24, 48, and 72 hours. Compared to 4 hours, MMP-1 expression was increased at 8, 24, 48, and 72 hours. Compared to the control specimens, MMP-9 expression was increased at 4, 8, 24, 48, and 72 hours. Compared to 2 hours, MMP-9 expression was increased at 4, 8, 24, 48, and 72 hours. Compared to 2 and 4 hours, collagen type I expression was increased at 72 hours. Collagen type III expression was increased at 72 hours compared to 2, 4, and 8 hours. Compared to 2 hours, fibronectin expression was increased at 24, 48, and 72 hours.

CONCLUSIONS

Results revealed time-dependent changes in expression of MMP-1, MMP-9, collagen types I and III, and fibronectin from rabbit vocal folds after injury. Future experiments are planned to investigate the effects of phonation on expression of these genes after injury.

Roles of vitamin A and macula flava in maintaining vocal folds

OBJECTIVES

Vitamin A plays important roles in development, growth, and regeneration. Vitamin A-storing stellate cells have been identified in several organs. The functional roles of vitamin A in the vocal folds are still unknown, although vitamin A-storing vocal fold stellate cells have been observed in the macula flava of human and rat vocal folds. The purpose of this study was to investigate the roles of vitamin A in vocal folds.

METHODS

Vitamin A-deficient rats were generated, and the vocal folds were examined histologically. Messenger RNA was extracted from the vocal folds and analyzed by real-time polymerase chain reaction.

RESULTS

Immunohistochemical analysis of normal vocal folds revealed expression of retinoic acid receptor a in vocal fold stellate cells. The cells in the macula flava of vitamin A-deficient rats showed a larger nucleus/cytoplasm ratio than did those of vitamin A-sufficient rats, but messenger RNA expression of major extracellular matrix components in the macula flava of vitamin A-deficient rats did not present a remarkable change except for procollagen type I. Expression of hyaluronic acid, collagen types I and III, and elastin did not show a significant change in vitamin A-deficient rat vocal folds.

CONCLUSIONS

These results indicate that vitamin A is not essential to maintaining the extracellular matrix of normal adult vocal folds, although vocal fold stellate cells participate in vitamin A storage.

Histological study of acute vocal fold injury in a rat model

OBJECTIVES

We used an acute vocal fold injury in a rat model to characterize vocal fold wound healing by studying the expression pattern of the extracellular matrix components in the vocal fold lamina propria.

METHODS

Vocal fold stripping was performed unilaterally in 27 Sprague-Dawley rats. The vocal folds were harvested at 5 time points (1, 3, 5, 7, and 14 days) and histologically analyzed by Alcian blue stain, trichrome stain, and immunofluorescence with antibodies to collagen type I, collagen type III, and fibronectin.

RESULTS

Re-epithelialization occurred by day 3 and was complete by day 14. Granulation tissue was formed by day 3. Hyaluronic acid and collagen type I appeared in injured vocal folds by day 3, peaked at day 5, and thereafter decreased. Collagen type III and fibronectin appeared by day 1 and continued to be intense at all time points after day 3.

CONCLUSIONS

These results suggest that the expression of these extracellular matrix components peaks in the period around days 3 to 5, and that the characteristics of wound healing in the vocal fold are similar to those in the skin in the early phases, but differ during the subsequent remodeling phase.

Healing responses of skin and muscle in critical illness

OBJECTIVE

Many aspects of the care and underlying pathologies in patients suffering critical illness can detrimentally influence the normal healing processes of skin and soft tissues. Although a great diversity of pathologies exists, some aspects of the diseases and their treatments are common in critically ill patients. We aimed to identify some features, both common and specific, that could influence wound healing and the mechanisms by which they may do so.

DESIGN

In this review, we first outline the biology of normal skin and muscle healing and then explore how critical illness may influence the normal healing cascade.

FINDINGS

The healing of skin and skeletal muscle in critical illness is influenced by both underlying disease processes and the intensive care environment. Local and systemic factors can contribute to impaired healing, with the potential to prolong functional disability and increase the likelihood of wound complications. The frequency and number of soft tissue injuries derived from accidental injury, surgical intervention, and the need for invasive monitoring and therapies in the intensive care unit setting are likely to compromise the innate immunity and potentially further jeopardize the patient's ability to heal. Alterations in coagulation, tissue perfusion, inflammation, immune functioning, metabolism, nutrition, and drug therapies will influence healing responses by modifying the biological responses to tissue disruption. Locally, wound contamination, sepsis, tissue hypoxia, edema, and excessive or prolonged local pressure all have the potential to compromise soft tissue healing. One or more of these factors may be present at any time.

CONCLUSION

The skin and soft tissues are vulnerable to both injury and compromised healing when a patient is critically ill and exposed to a critical care environment. The identification of risk factors may aid in forming and modifying treatment strategies when caring for the critically ill patient with soft tissue injuries.

Wound remodelling and scarring

Wound healing usually results in a scar. No therapy currently exists for removing scars, so treatments focus on making them less obvious. Research is investigating how to prevent scars forming, inspired by what happens to foetuses in the womb.