Cortisone, vitamin A, and wound healing: the importance of measuring wound surface area

Functional characterisation of bioactive peptide derived from terrestrial snail Cryptozona bistrialis and its wound-healing property in normal and diabetic-induced Wistar albino rats

A peptide might be an exciting biomaterial or template for the development of novel wound-healing agents. In this report, it was isolated from the terrestrial snail Cryptozona bistrialis by enzymatic digestion and was evaluated for its in vitro wound-healing activity in NIH/3T3 mouse fibroblasts cell line and in vivo wound-healing activity in normal and diabetic-induced Wistar albino rats. The C. bistrialis protein was digested by the papain enzyme, and 21.79 kDa peptide (Cb-peptide) was purified by reversed-phase high-performance liquid chromatography and identified by MALDI (matrix-assisted laser desorption/ionization)-TOF analysis. The isolated Cb-peptide was characterised by various analytical methods. The peptide demonstrated a capacity to prevent the development of pathogenic bacterial and fungal cultures and proved that it promotes significant wound-healing activity in the wound scratch assay method by rapid cell migration and closure of wound. Isolated Cb-peptide was lyophilised and formulated to ointment and analysed for in vivo wound-healing activity in normal and diabetic (alloxan monohydrate)-induced Wistar albino rats. Cb-peptide ointment-treated groups showed a greater degree of wound healing and early and complete period of epithelialisation in normal and diabetic-induced Wistar albino rats. Cb-peptide ointment-treated groups showed significant excision and incision wound-healing activity. A conclusion was reached that the peptide isolated from C. bistrialis showed greater wound-healing activity compared with vehicle control and standard control.

The in vivo and in vitro diabetic wound healing effects of a 2-herb formula and its mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

The herbs Radix Astragali (RA) and Radix Rehmanniae (RR) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating diabetic foot ulcer.

AIM OF STUDY

Diabetic complications, such as foot ulcer, impose major public health burdens worldwide. In our previous clinical studies, two Chinese medicine formulae F1 and F2 have achieved over 80% limb salvage. A simplified 2-herb formula (NF3) comprising of RA and RR in the ratio of 2:1 was used for further study. NF3 was examined for the ulcer healing effect in diabetic rats, and its potential mechanisms of action in fibroblast proliferation, angiogenesis and anti-inflammation in vitro.

MATERIALS AND METHODS

A chemically induced diabetic foot ulcer rat model was used for studying the wound healing effect. In the in vitro mechanistic studies, human fibroblast cells (Hs27), human umbilical vein endothelial cells (HUVEC) and mouse macrophage cells (RAW264.7) were assessed for tissue regeneration, angiogenesis and anti-inflammatory activities, respectively.

RESULTS

Our in vivo results demonstrated a significant reduction of wound area at day 8 in NF3 (0.98g/kg) group as compared to control (p<0.01). NF3 could significantly stimulate Hs27 proliferation in a dose dependent manner (p<0.05). Besides, NF3 could significantly increase the cell migration and tube formation (p<0.05-0.001) of HUVEC in the angiogenesis study. Furthermore, significant inhibition of nitric oxide production (p<0.01) was found in NF3-treated macrophage cells, suggesting its anti-inflammatory activity.

CONCLUSIONS

Our study presents for the first time scientific evidence towards the efficacy of the two-herb formula NF3 in enhancing diabetic wound healing through the actions of tissue regeneration, angiogenesis and anti-inflammation.

The effect of topical tretinoin on tissue strength and skin components in a murine incisional wound model

BACKGROUND

Vitamin A derivatives modulate the inflammatory phase in wound healing. Retinoic acid can restore decreased tensile strength and collagen content in steroid- or diabetes-impaired wounds. It is hypothesized that retinoic acid can lead to accelerated healing with improved breaking strength in unimpaired incisional wounds.

MATERIALS AND METHODS

Skin incisions were made in 45 CD-1 mice. The sutured wounds were treated once daily with topical all-trans-retinoic acid 0.1% (n = 15), vehicle ointment (n = 15), or left untreated (n = 15). Skin biopsies at 1-, 2-, and 3-week intervals were examined using hematoxylin and eosin (H&E), Masson's trichrome, and immunoperoxidase staining methods. Wound breaking strength was determined by biomechanical analysis.

RESULTS

Incisions treated with retinoic acid exhibited a significantly reduced breaking strength at week 1 when compared to the vehicle and control group. Histologic examination showed a prolonged inflammatory reaction with abundant deposition of granulation tissue. Despite an increased fibroplastic proliferation in the tretinoin-treated wounds, the production of collagen was diminished.

CONCLUSIONS

Topical retinoic acid does not enhance the healing of unimpaired incisional wounds. The inadequate tensile strength in the early phase of the healing process is possibly the result of an increased dermal inflammatory response and the decreased collagen content. Although these adverse effects disappeared by 3 weeks postwounding, we found no discernible benefit of supplemental retinoic acid in unimpaired wounds.

The importance of patients' nutritional status in wound healing

Good nutritional status is essential for wound healing to take place. Ignoring nutritional status may compromise the patient's ability to heal and subsequently prolong the stages of wound healing. Glucose provides the body with its power source for wound healing and this give energy for angiogenesis and the deposition of new tissue. Therefore, it is vital that the body receives adequate amounts of glucose to provide additional energy for wound healing. Fatty acids are essential for cell structure and have an important role in the inflammatory process. Wound healing is dependent on good nutrition and the presence of suitable polyunsaturated fatty acids in the diet. Protein deficiency has been demonstrated to contribute to poor healing rates with reduced collagen formation and wound dehiscence. High exudate loss can result in a deficit of as much as 100g of protein in one day. This subsequently needs to be replaced with a high protein diet. Vitamins are also important in wound healing. Vitamin C deficiency contributes to fragile granulation tissue. There is a correlation between low serum albumin and body mass index (BMI) and the development of pressure ulcers. Also, low serum albumin and high Waterlow score have a positive association. The body automatically renews tissue while we are asleep but this does not mean that protein synthesis does not take place during our wakeful hours. Holistic assessment of nutrition and early detection of malnutrition are essential to promote effective wound healing.

Physiology of wound healing and surgical wound care

Wound healing is a systemic process, which occurs stepwise and involves the stages of hemostasis, inflammation, and repair. Hemostasis with fibrin formation creates a protective wound scab. The scab provides a surface beneath which cell migration and movement of the wound edges can occur. Inflammation brings nutrients to the area of the wound, removes debris and bacteria, and provides chemical stimuli for wound repair. Repair begins immediately after wounding and proceeds rapidly through the processes of epithelialization, fibroplasia, and capillary proliferation into the healing area. Different tissues have their own normal rates of growth during the process of healing. The optimal rate of healing is approached when factors advantageous to healing are present and factors having the ability to disturb or retard the healing processes are controlled or absent. These factors are discussed.

Glucocorticoid-dependent impairment of wound healing in experimental diabetes: amelioration by adrenalectomy and RU 486

BACKGROUND

Failure of wounds to heal represents one of the major diabetic complications. Emerging evidence favors the involvement of glucocorticoids (GCs) in the pathogenesis of impaired wound healing in diabetes mellitus.

OBJECTIVE

The purpose of this study was to examine wound healing potential in diabetics under conditions in which the hypercortisolemic state is normalized.

DESIGN AND INTERVENTION

Linear skin incision and polyvinyl alcohol (PVA) sponge were used as wound healing models. Six groups of rats matched with respect to age, sex, and strain were included in this study. Animals in groups 1 and 6 were injected with citrate buffer, whereas rats in groups 2,3,4, and 5 received streptozotocin (STZ, 55 mg/kg iv in citrate buffer). Five days later animals in groups 4,5, and 6 received insulin (group 4) and subcutaneous implantation of slow-releasing pellets containing either the GC receptor blocker RU 486 (group 5) or a high dose of GC (group 6).

MAIN OUTCOME MEASUREMENTS

Skin wound tensile strength and PVA sponge collagen metabolism were determined using tensiometric, spectrosphotometric, and polymerase chain reaction-based assays. In addition, cell infiltration and granulation tissue growth were assessed using a well-established histochemical technique.

RESULTS

Wound-related parameters including fibroplasia, neovascularization, and inflammatory cell numbers were reduced as a function of diabetes. Similarly, skin wound tensile strength, PVA sponge hydroxyproline content, and the levels of mRNA transcripts for type I and III collagen were also decreased in this disease state. This diabetes-related deficit in wound healing potential was ameliorated by subjecting diabetic animals to insulin treatment or by counteracting the excessive actions of GCs using both pharmacological (RU 486) and endocrinological (ADX) paradigms.

CONCLUSION

The current study supports the notion that GCs are implicated in the wound healing deficit of diabetics. Moreover, it illuminates the therapeutic potential of the GC receptor blocker (e. g., RU 486) in promoting wound repair under hypercortisolemic conditions including diabetes and Cushing's syndrome.

Uses of vitamins A, C, and E and related compounds in dermatology: a review

Vitamins have been increasingly used as prophylactic and therapeutic agents in the management of skin disorders. The current literature is replete with studies that promote the potential benefits of these compounds and attempt to elucidate their mechanisms of action. We review the literature and discuss the roles, safety, and efficacy of vitamins A, C, and E and related compounds in cutaneous health and disease.

Assessment of healing kinetics through true color image processing

A quantitative method of skin healing assessment using true color image processing is presented. The method was developed during a clinical trial using healthy volunteers, the goal of which was to study a drug for accelerating healing. Photographic images of the skin were sequentially acquired between day 1 and day 12 after pure painless epidermal wounds. The images were digitized in controlled conditions using a color video camera connected to a computer system. A color threshold based segmentation was developed to provide an operator-independent delineation of the wound. Two healing indexes were built measuring, the wound area and the wound color. The method was implemented in a software system allowing a fully automated determination of the healing indexes. The method provides a new quantitative global assessment of healing kinetics. It is noninvasive and well suited for multicentric clinical trials.

Preoperative corticosteroids. A contraindication to lung transplantation?

Regular preoperative application of corticosteroids has been considered as a contraindication to lung transplantation for fear of an increased risk of postoperative morbidity and mortality. Recently, however, we have accepted patients for transplantation in whom treatment with steroid medication could not be terminated preoperatively. Up to February 1991, 27 unilateral and bilateral transplantations in 26 patients were analyzed. Corticosteroid therapy was discontinued at least three months prior to transplantation in 13 patients (group 1), whereas in 14 cases, the patients continued their daily corticosteroid therapy to the time of transplantation (prednisolone, 0.1 to 0.3 mg/kg/day; group 2). There were no significant differences between the groups with respect to sex, age, diagnosis, or type of transplantation. One limited bronchial dehiscence occurred; the incidence of postoperative bronchial stenosis was identical in both cohorts; one patient died in each group. In conclusion, no increased morbidity or mortality could be found following lung transplantation with regular preoperative administration of prednisolone up to 0.3 mg/kg/day. Thus, patients who cannot be weaned from their steroid medication but who otherwise are acceptable candidates should not be excluded from lung transplantation.

The reversibility of UV-altered wound tensile strength in the hairless guinea pig following a 90-day recovery period

Investigations in our laboratory showed that exposure to ultraviolet radiation significantly diminishes wound tensile strength in hairless guinea pigs. A recurring question is whether changes in wound tensile strength are reversible. The present project addresses whether wound tensile strength in irradiated and control animals differs following a 90-day healing period after irradiation and wounding. Group 1 animals (n = 10) served as nonirradiated controls. Group 2 animals (n = 10) were irradiated with a UVA/B source receiving a cumulative dose of 8,960 joules/cm2 over a 16-week period. Following completion of the irradiation schedule, a standard 6 cm midline incision was made on the dorsum of each animal and then allowed to heal for 90 days. At this time, wound tensile strength measurements were performed. The mean wound tensile strength value for the control group (4.62 +/- 0.16) was not significantly different compared to the irradiated animals (4.23 +/- 0.24). The alteration in wound tensile strength observed at 21 days in animals irradiated with a UVA/B light source is reversible after a 90-day recovery period.

Wound tensile strength in the hairless guinea pig following irradiation with pure ultraviolet-A light

Ultraviolet light in the wavelength range of 315-400 nm (UVA) is known to penetrate the epidermis more readily than UVB and to result in significant dermal damage. Fibroblasts within the dermis are responsible for the production of collagen, which is the chief determinant of wound tensile strength during the third week of wound healing. The present study assesses the effects of UV radiation limited to the UVA wavelength on wound tensile strength in the hairless guinea pig. Twenty female hairless guinea pigs were randomly divided into two equal groups (n = 10). Group 1 animals served as controls. Group 2 animals were irradiated with 120 J/cm2 from a pure UVA fluorescent light source every other day for a period of 21.3 weeks (cumulative dose = 8960 J/cm2). Upon completion of the irradiation schedule, a standard 6 cm linear full-thickness surgical wound was created on the dorsum of all animals and allowed to heal for 21 days. The wounds were excised and wound tensile strength was assessed by determining breaking strength and dividing by the breaking-point surface area. Wound tensile strength was significantly lower (p less than 0.0017) in irradiated animals (0.99 +/- 0.12) than in controls (1.54 +/- 0.08). Therefore, UVA at this dose significantly decreased wound tensile strength in this model and raises further concern regarding exposure to this wavelength of ultraviolet radiation.

A dose-related curve of wound tensile strength following ultraviolet irradiation in the hairless guinea pig

A dose-related curve of wound tensile strength was derived following exposure to three doses of predominantly UVA (Ultraviolet A) radiation (98.3% between 315 nm and 400 nm, 1.7% less than 315 nm). Forty female hairless guinea pigs were divided into four equal groups: Group 1 (controls); Group 2 (40 J[Joules]/cm2/day); Group 3 (80 J/cm2); and Group 4 (160 J/cm2). Preoperatively, the experimental groups were irradiated on alternate days for 16 weeks. Serial dorsal punch biopsies (4 mm) were taken prior to the initial exposure and subsequently at 2, 4, 8, 12, and 16 weeks and examined histologically and microscopically. Then, standard 6 cm midline dorsal surgical wounds were made and allowed to heal for 21 days. Wounds were excised and wound tensile strength was assessed. Significant decreases (p less than .05) were noted in wound tensile strength of Groups 2, 3, and 4 compared to the controls, with the decrease being directly related to the dose received. Dermal changes were noted in all irradiated groups as early as four weeks after initial UVA/B exposure. Electron microscopy revealed elastosis and disruption of collagen fibers. Prolonged exposure to radiation, predominantly in the UVA range, appears to impede wound healing in a dose-related fashion and elicits elastosis and collagen disruption.

The effects of ultraviolet radiation on wound healing

The effects of prior ultraviolet light exposure on wound tensile strength and skin histology were evaluated in the hairless guinea pig model. Hairless guinea pigs (strain IAF/HA-HO) were irradiated with either UVA (80 J/cm2) or UVB (0.46 J/cm2) every other day for 16 weeks. Following cessation of treatment, a standard dorsal wound was made in each animal, allowed to heal, and mechanically tested to failure at 21 days. Serial 4 mm punch biopsies were obtained prior to the initial exposure and at 2, 4, 8, 12 and 16 weeks. Histological examination with haematoxylin and eosin, trichrome and elastin stains was performed. In comparison to the unexposed control group, wound tensile strength was significantly less in the UVA- and UVB-irradiated animals. Histological examination revealed a marked endothelial swelling and eosinophilic infiltration in the irradiated groups. These results indicate that repeated exposure to even moderate doses of non-ionising radiation alters normal skin structure and adversely affects subsequent wound tensile strength in this model.

Influence of methylprednisolone on the healing of intestinal anastomoses in rats

Although steroids are generally thought to impair intestinal anastomotic healing, this effect has never been proven unequivocally in either clinical or experimental studies. We have investigated the influence of methylprednisolone (2.5 or 10.0 mg kg-1 day-1) given from 2 days before operation onwards, on 3-day-old and 7-day-old ileal and colonic anastomoses in rats. Anastomotic abscesses occurred more frequently in the ileum, but not in the colon, after steroid medication. However, methylprednisolone did not lower anastomotic bursting pressures in either of the bowel segments. Comparison of the hydroxyproline content of the anastomotic segment yielded no significant difference between control and methylprednisolone groups in either small or large bowel. Thus, healing of experimental colonic anastomoses remains unaffected by short-term administration of this corticosteroid.

Wound healing in skin

Wound healing in mammals occurs by a process of regeneration and scar tissue production. In particular, epithelium has marked regenerative capacity. Healing is an active process from the moment the wound is inflicted--a "lag" phase does not exist. In surgery the important factors affecting wound healing are protein deficiency, uremia, corticosteroids, and local tissue injury. Stimulants to wound healing are not available for clinical application.

A rat uterine horn model of genital tract wound healing

A rat uterine horn model of genital tract wound healing is described. Healing was reflected by acquisition of strength and elasticity, measured by burst strength (BS) and extensibility (EX), respectively. A tensiometer (Instron Corp., Canton, MA) was used to assess these characteristics in castrated and estrogen-supplemented or nonsupplemented animals. While the horn weights (HW), BS, and EX of contralateral horns were not significantly different, the intra-animal variation of HW was 7.2%, BS was 17.7% and EX was 38.2%. In a second experiment, one uterine horn was divided and anastomosed, and the animal given estrogen supplementation or a placebo pellet. Estrogen administration was found to increase BS and EX of anastomosed horns prior to 14 days, but had no beneficial effect at 21 or 42 days. The data suggest that estrogen may be required for optimal early healing of genital tract wounds.