Influence of vitamin A on wound healing in rats with femoral fracture

Development of a silk fibroin-based multitask aerosolized nanopowder formula for efficient wound healing

Most of the spray products in the market for wound healing applications are loaded with antibiotics that exert their antibacterial effect within the inflammatory stage of wound healing without demonstrating any effect in the subsequent proliferation stage. This study introduces a new aerosolized nanopowder (ANP) formula that not only exhibits antibacterial effect but also antioxidant and enhanced cell proliferation effects. Within the introduced ANP formula, Avicenna marina (Am) extract and neomycin (NM) antibiotic have been loaded within silk-fibroin nanoparticles (FB NPs). The Am has been extracted via different solvent systems, and investigated for its antioxidant and antibacterial activity as well as its ability to enhance cell proliferation. The physicochemical properties, size, zeta-potential and morphology of the prepared Am/FB NPs, NM/FB NPs and ANP formula were investigated. Besides, the ANP formula exhibited good antibacterial activities against Staphylococcus aureus, Methicillin resistant S. aureus, Pseudomonas aeruginosa and Resistant P. aeruginosa. Scratch wound healing assay on human fibroblast monolayers demonstrated 100% wound closure after 24 h upon using the ANP formula as compared to 70% wound closure for positive control (NM). The wound healing ability of the ANP formula has been further confirmed by histopathological evaluation of the wound site and depicted a marked increase in fibroblast proliferation and reduction of inflammatory cells after 15 days with a complete wound closure as compared to controls. The obtained results prove the beneficial effects of the Am extract on wound healing and introduce the developed multitask nanopowder formula as a potential wound healing spray.

Vitamin A and Wound Healing

Vitamin A is a general term for retinoids. Vitamin A deficiency leads to a variety of cutaneous manifestations. It also functions as a hormone through retinoic acid receptors altering the activity of multiple cell lines. Pancreatic vitamin A levels are critical for retinoid signaling and normal pancreatic control of glucose. Vitamin A deficiency is more common during infection, and supplementation reduces severe morbidity and mortality from infectious diseases. Vitamin A modulates activities at the cellular level and, via its interrelationship with hormones such as thyroid, insulin, and corticosteroids, has diffuse metabolic effects on the body. It plays an important role in all stages of wound healing. Vitamin A is known for its ability to stimulate epithelial growth, fibroblasts, granulation tissue, angiogenesis, collagen synthesis, epithelialization, and fibroplasia. Local (topical) and systemic supplementation with vitamin A has been proven to increase dermal collagen deposition. There are numerous animal studies and limited human studies regarding physiologic effect of vitamin A on acute or chronic wounds via systemic or topical administration. The most common use of vitamin A supplementation is to offset steroids' effect. When considering supplementation, the potential benefits must be weighed against the risk of harm. Vitamin A toxicity can be critical and even result in death. The evidence for supplementation with vitamin A is currently limited to expert opinion and is not backed up by rigorous trials. There is an acute need for therapeutic trials with vitamin A supplementations.

Advances and Promises of Nutritional Influences on Natural Bone Repair

Impaired fracture healing continues to be a significant public health issue. This is more frequently observed in aging populations and patients with co-morbidities that can directly influence bone repair. Tremendous progress has been made in the development of biologics to enhance and accelerate the healing process; however, side-effects persist that can cause significant discomfort and tissue damage. This has been the impetus for the development of safe and natural strategies to hasten natural bone healing. Of the many possible approaches, nutrition represents a safe, affordable, and non-invasive strategy to positively influence each phase of fracture repair. However, our understanding of how healing can be hindered by malnutrition or enhanced with nutritional supplementation has lagged behind the advancements in both surgical management and the knowledge of molecular and cellular drivers of skeletal fracture repair. This review serves to bridge this knowledge gap as well as define the importance of nutrition during fracture healing. The extant literature clearly indicates that pre-existing nutritional deficiencies should be corrected, and nutritional status should be carefully monitored to prevent the development of malnutrition for the best possible healing outcome. It remains unclear, however, whether the provision of nutrients beyond sufficiency has any benefit on fracture repair and patient outcomes. The combined body of pre-clinical studies using a variety of animal models suggests a promising role of nutrition as an adjuvant therapy to facilitate fracture repair, but extensive research is needed, specifically at the clinical level, to clarify the utility of nutritional interventions in orthopedics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:695-707, 2020.

The Role of Vitamin A in Wound Healing

Vitamin A is an essential micronutrient that comes in multiple forms, including retinols, retinals, and retinoic acids. Dietary vitamin A is absorbed as retinol from preformed retinoids or as pro-vitamin A carotenoids that are converted into retinol in the enterocyte. These are then delivered to the liver for storage via chylomicrons and later released into the circulation and to its biologically active tissues bound to retinol-binding protein. Vitamin A is a crucial component of many important and diverse biological functions, including reproduction, embryological development, cellular differentiation, growth, immunity, and vision. Vitamin A functions mostly through nuclear retinoic acid receptors, retinoid X receptors, and peroxisome proliferator-activated receptors. Retinoids regulate the growth and differentiation of many cell types within skin, and its deficiency leads to abnormal epithelial keratinization. In wounded tissue, vitamin A stimulates epidermal turnover, increases the rate of re-epithelialization, and restores epithelial structure. Retinoids have the unique ability to reverse the inhibitory effects of anti-inflammatory steroids on wound healing. In addition to its role in the inflammatory phase of wound healing, retinoic acid has been demonstrated to enhance production of extracellular matrix components such as collagen type I and fibronectin, increase proliferation of keratinocytes and fibroblasts, and decrease levels of degrading matrix metalloproteinases.

Evaluation of the antioxidant activity and the healing action of the ethanol extract of Calotropis procera bark against surgical wounds

The objective of the present study was to evaluate the antioxidant potential and the wound healing effect of the ethanolic extract of the bark of Calotropis procera. The antioxidant study was evaluated in vitro, using 2,2-diphenylpicrylhydrazyl (DPPH) and deoxyribose degradation assays. Wound healing was studied using excision and incision wound on normal and dexamethasone-suppressed wound healing rodent models. Alkaloids, flavonoids, proteins and phenols were screened in the extract used whereas saponins and true tannins were absent. The extract contains only 12.5 gallic acid equivalent and 399.54 rutin equivalent. It was found to inhibit DPPH and deoxyribose oxidation (IC₅₀ = 24.24 and 5.40 respectively). In vivo study demonstrated a significant reduction in the epithelialization time (P < 0.001) to 17-18 days in normal and dexamethasone treated rats following the ethanolic extract of the bark of C. procera application. The same extract also significantly increased the breaking strength in dexamethasone treated rats. Histological examination of incision wounds of treated group showed matured extracellular matrix, numerous fibroblasts. This study illustrated an excellent potential of the bark of C. procera therapy on dermal wound healing, with a tentative mechanism of action related to improved collagen deposition and reduced inflammatory reaction.

Vitamins and cutaneous wound healing

BACKGROUND

Vitamins have long been thought to modulate the various stages of wound healing through a variety of proposed mechanisms. Our goal was to investigate relevant studies examining the role of different vitamins in wound healing.

METHODS

MEDLINE, Cochrane Database of Systematic Reviews, and Google Scholar were searched for basic science and clinical studies examining the role of vitamins as adjuncts in wound healing.

RESULTS

Mechanisms of action for each of the vitamins are reviewed. It was suggested by many of the studies that the major vitamins A, C, E, D, K, and B have demonstrated utility as adjuncts in wound care in basic science and clinical trials.

CONCLUSION

There is a vast amount of literature on the effect of vitamins on wound healing at the basic science level. Further understanding and controlled trials will help better understand how to utilize vitamins in wound care.

DECLARATION OF INTEREST

None.

Retinoids and Wound Healing

BACKGROUND

Retinoids are widely used in dermatology and may play a role in wound healing. The exact role of retinoids in wounds is confusing and controversial, however. Systemic retinoids are presumed to be detrimental to wound healing; however, this standard is based on isolated reports.

OBJECTIVE

The objective was to provide a critical review of the available literature regarding the role of both topical and systemic retinoids in various aspects of wound healing.

CONCLUSIONS

Pretreatment with retinoids likely promotes wound healing after facial resurfacing procedures and full- or partial-thickness wounds. While the evidence is mixed regarding the effects of retinoids applied to fresh and healing wounds, the majority of the evidence available shows favorable wound-healing properties in this setting. The medical-legal standard regarding the avoidance of facial resurfacing and surgical procedures in patients on or recently completing a course of systemic retinoids was likely prematurely established.

Review of Evidenced-Based Practice for the Prevention of Pressure Sores in Burn Patients

Pressure ulcers represent a complex clinical problem, with a reported incidence of 2.7% to 29.5% in hospitalized patients and an etiology that is multifactorial. The prevention of pressure sores in the burn patient population is clearly an area of practice in need of guidelines for care. A multidisciplinary group of advanced burn care professionals have compiled, critiqued, and summarized herein the current evidence of practice in nursing, nutrition, and rehabilitation as it pertains to the prevention of pressure sores after burn injuries. A broad overview of risk factors and assessment scales is described, and current intervention practices and recommendations for care are provided based, whenever possible, on research findings. In addition, research questions are generated in an attempt to move the specialty of burns toward the formal investigation of pressure sores with the ultimate goal being the development of evidence-based practice guidelines.

Investigation of the growth and metastasis of malignant melanoma in a murine model: the role of supplemental vitamin A

Vitamin A possesses both wound-healing and antitumor actions. Vitamin A-induced fibroplasia results in subsequent increased collagen production and deposition. This effect of vitamin A has been shown to result in the production of collagenous capsules around several murine breast and lung tumor systems. This tumor encapsulation process can potentially convert a systemic disease to a local one that can be easily treated by tumor excision. The goal of the present study was to determine whether supplemental vitamin A could promote the encapsulation of a murine melanoma. Sixty DBA/2J male mice were inoculated intracutaneously with 1 x 106 Cloudman S91 melanoma cells using a 30-gauge needle. The mice were divided into three groups: a control group, a pre-vitamin A group, and a post-vitamin A group. The control mice were fed a commercial chow containing 15,000 IU of vitamin A and 6.4 mg of beta-carotene per kilogram diet, considerably more than the National Research Council's recommended daily allowance of vitamin A for normal mice. The control diet was, therefore, not vitamin A-deficient. The pre-vitamin A mice were fed the basal chow supplemented with 150,000 IU of vitamin A per kilogram diet for 10 days before inoculation and for the remainder of the study. The post-vitamin A mice were fed the vitamin A-supplemented diet beginning on the day of inoculation and continuing for the remainder of the study. Sixty days after inoculation, tumor growth was assessed and the five mice remaining in each group were euthanized. Ventral skin at the site of inoculation was harvested for histologic assessment of local tumor growth and invasiveness. The liver and lungs of each of these mice were also harvested for histologic assessment of tumor metastasis. Sixty days after tumor inoculation, a 60 percent survival rate was observed in the control group as opposed to the vitamin A-supplemented animals, which demonstrated a 100 percent survival rate in both groups (n = 5 in each group). Decreased mean tumor size and gross tumor in most vitamin A-supplemented animals were statistically significant when compared with the control animals. The control animals had a mean tumor size of 26.1 mm, whereas the post-vitamin A group had a mean tumor size of 5.7 mm. One hundred percent of the control group exhibited tumor; one animal had distant metastases. The pre-vitamin A group did not exhibit any tumor growth, and the post-vitamin A group exhibited tumor growth in 40 percent of animals. Neither vitamin A-supplemented group showed any evidence of distant metastases. The animals supplemented with vitamin A demonstrated decreased tumor growth and metastasis. This in vivo model may indicate a potential prophylactic and therapeutic role for supplemental vitamin A in the treatment of malignant melanoma.

The effects of corticosteroids and vitamin A on the healing of tracheal anastomoses

OBJECTIVE

This study investigates the deleterious effects of corticosteroids on tracheal anastomotic healing and the ability of vitamin A to reverse these effects in a rat model.

METHODS

Forty-two adult Wistar rats were randomly divided into five groups. The animals underwent tracheal transection and primary anastomoses. The groups were assigned as follows: Group I, sham (N=6); Group II, control (N=6); Group III, dexamethasone, 0.1 mg/kg/day intramuscularly (N=10); Group IV, dexamethasone 0.1 mg/kg/day intramuscularly+vitamin A 10000 IU/kg/day by gavages (N=10); and Group V, vitamin A 10000 IU/kg/day by gavages for a week (N=10). After 7 days, anastomotic healing was assessed by measurement of bursting pressure, hydroxyproline content and subsequent histological grading using the modified Ehrlich/Hunt scale.

RESULTS

Bursting pressures and hydroxyproline contents were as follows: Group I: 977+/-8 mmHg and 11.80+/-0.3 microg/mg (mean+/-standard error of the mean); Group II: 890+/-55 mmHg and 9.93+/-0.6 microg/mg; Group III: 555+/-26 mmHg and 11.90+/-1.3 microg/mg; Group IV: 873+/-73 mmHg and 10.24+/-2.2 microg/mg; Group V: 905+/-45 mmHg and 7.51+/-0.8 microg/mg, respectively. Bursting pressure of Group III was found to be significantly lower when compared to other groups (P<0.0001). However, statistical significance was not found among the study groups for the hydroxyproline content. Except for inflammatory cell infiltration, histological parameters including epithelial regeneration, fibroblast proliferation, collagen content, and angiogenesis demonstrated significant differences among the groups.

CONCLUSION

The present study demonstrates that dexamethasone significantly impairs the healing of tracheal anastomoses in rats and postoperative administration of vitamin A appreciably reverses this inhibitory effect. Patients receiving corticosteroids may benefit from vitamin A when undergoing prolonged intubation and laryngotracheal reconstruction.

Local instillation of Staphylococcus aureus peptidoglycan at operation prevents wound healing impairment after trauma

BACKGROUND

Considerable experimental evidence and limited clinical evidence indicate that wound healing is impaired after trauma. Because Staphylococcus aureus peptidoglycan (SaPG) accelerates healing in normal rats and prevents wound healing impairment induced by glucocorticoids, cyclophosphamide, and streptozotocin-diabetes, we hypothesized that SaPG would prevent the impaired wound healing after trauma.

METHODS

In each of two experiments, 18 Sprague-Dawley male rats were divided into two groups, nine rats each, paired by weight; one group received unilateral comminuted femoral fracture and wounding (two dorsal skin incisions and six subcutaneous polyvinyl alcohol [PVA] sponges), and the other group was only wounded. The incision and PVA sponges on one side were inoculated at operation with saline (200 microL/incision, 50 microL/sponge) and on the other side with SaPG in saline (860 microg of SaPG per centimeter of incision, 0.5 mg of SaPG per sponge). Rats ate chow and drank tap water ad libitum and were killed 7 days postoperatively.

RESULTS

In both experiments, the wound breaking strength (WBS) of saline-inoculated incisions was significantly lower in rats with femoral fracture; histologically, reparative granulation tissue was looser and less prominent. WBS of SaPG-inoculated incisions in rats with and without femoral fracture was significantly higher than that of saline-inoculated incisions and, histologically, reparative tissue was more prevalent, more closely packed, and more mature. WBS of SaPG-inoculated incisions in rats with femoral fracture was similar to that of saline-inoculated incisions in rats without femoral fracture. Reparative tissue hydroxyproline and histologic findings of saline-inoculated PVA sponge reparative tissue were similar in all rats, as were the increases induced by SaPG inoculation.

CONCLUSION

Wound breaking strength and histologic findings of skin incisions (impaired in rats with unilateral femoral fracture) are more sensitive to the adverse effects of trauma than accumulation of PVA sponge reparative tissue. A single inoculation of SaPG at operation increased wound incision healing in rats both without and with femoral fracture and notably prevented the impaired healing in rats with femoral fracture.

Nutritional supplements and surgical patients

Surgical team members should be aware of which nutritional supplements may be harmful or helpful to surgical patients. Informed education of patients may prevent bleeding problems, wound-healing problems, prolonged hematomas, and dangerous immune system depletion.

Surgically significant nutritional supplements

This is not an exhaustive study of all nutritional supplements that patients may be taking. The most frequently used and those potentially most detrimental or most beneficial for surgical patients have been chosen for review of pertinent effects. It is essential to ask patients specifically about supplements or unusual dietary habits that may affect their surgical outcome prior to their invasive procedure and to keep in mind the supplements that may improve their outcome.

Nutrition and wound healing

A role for nutrition therapy in the regulation of wound healing has been predicated on two concepts. The first is that malnutrition increases the risk of wound-related complications. The second is that dietary intervention, either in the form of complete nutrition support or as single nutrient supplementation, can improve or accelerate the wound-healing response. Although frequently stated and extensively discussed, these two concepts are not supported by objective data.

Diabetic foot ulcers

Neuropathic and vascular changes in patients with diabetes mellitus put them at risk for developing chronic foot wounds after minor trauma or after pressure has caused a breakdown in the integrity of the skin. Accurate diagnosis of the underlying cause is the first step toward a successful treatment plan, and in patients with severe ischemia, vascular reconstruction may be needed. Neuropathic ulcers respond well to less-invasive procedures, particularly when combined with reducing the pressure that caused the ulcer. When pressure is relieved by means of total contact casting, necrotic materials are removed, and protection is secured with a hydrocolloid dressing, these wounds have been found to heal, on an outpatient basis, after approximately 6 weeks. All diabetic foot ulcers are contaminated with a variety of organisms, but antibiotic treatments are usually unnecessary. When signs of a clinical infection are present and/or bone is exposed, osteomyelitis should be suspected. In these patients, aggressive surgical debridement, systemic antibiotics, and meticulous wound care regimens to restore the body's own bacterial barrier will often prevent amputation, the most serious complication of these wounds.

Effects of chronic corticosteroids and vitamin A on the healing of intestinal anastomoses

The ability of vitamin A to reverse the inhibitory effects of chronic corticosteroids on cutaneous and fascial wound healing is well established. To investigate this in the unique low-collagen environment of the intestinal anastomosis, 35 rabbits received twice-daily injections of either saline (control), dexamethasone (0.1 mg/kg/day), dexamethasone plus low-dose vitamin A (1,000 IU/kg/day), or dexamethasone plus high-dose vitamin A (10,000 IU/kg/day) for a 2-week period. Animals then underwent creation of single-layer, inverting small and large intestine anastomoses. All injections were continued postoperatively. A fifth group received only dexamethasone preoperatively and dexamethasone plus high-dose vitamin A postoperatively. On postoperative day 7, animals underwent in situ assessment of anastomotic bursting pressure and subsequent histologic examination using a modified Ehrlich/Hunt scale. Corticosteroids significantly impaired the healing of small and large intestine anastomoses, with decreased bursting pressures and histologic parameters at 1 week. Only high-dose vitamin A significantly reversed this inhibitory effect, whether given preoperatively or only postoperatively.

Zone II flexor tendon repair: effects of vitamins A, E, beta-carotene

Ninety-six adult Leghorn chickens each had the flexor profundus tendon in each middle toe sharply divided in Zone II with immediate repair (pentobarbital, ketamine anesthesia). Animals were then randomly assigned to receive unsupplemented standard chick chow or the chow supplemented with vitamin A (150,000 IU/kg chow), Vitamin E (1000 IU/kg chow), or beta-carotene (90 mg/kg chow). Eight animals from each of the four groups were examined at 7, 30, or 45 days post repair. After sacrifice, in situ composite wound breaking strength was measured in the amputated toe by constant speed tensiometry. Vitamin A-supplemented animals demonstrated breaking strength more than double that of control at each postoperative test day, while those animals receiving supplemental Vitamin E had breaking strength less than half that of control at Day 7 and Day 45. These results are statistically significant. Tensiometry curves differed markedly at all time points among the groups: Vitamin A curves being broader, higher, and having more spikes. These differences in the tensiometry curves, both qualitative and quantitative, may be due to differences in intrinsic tendon healing or to differences in adhesion formation or a combination of both. beta-Carotene supplementation had modest effect. We conclude that supplemental dietary vitamin A increases the breaking strength of composite tendon wounds and that supplemental dietary vitamin E decreases it.

Experimental studies on the healing of colonic anastomoses

The leakage of colonic anastomoses is a potentially devastating surgical complication. Several factors, such as bowel preparation prior to surgery, surgical technique, nutritional status, and intervening pathological conditions, have been identified as significantly influencing the healing of colonic anastomoses. Due to the multifactorial nature, it is difficult to investigate the mechanisms of occurrence and prevention of colonic dehiscence in the clinical setting. For this reason, many experimental models have been used to study colonic healing and the pathogenesis of anastomotic failure. This report reviews the use of animal models for the study of colonic anastomotic healing. Special emphasis is devoted to the rationale for selecting animal models, parameters of healing, factors influencing anastomotic healing as well as the clinical potential of dietary and pharmacologic manipulations proposed to improve colonic healing.

Supplemental vitamin A prevents the tumor-induced defect in wound healing

To test our hypothesis that supplemental vitamin A would mitigate the impaired healing that occurs in tumor-bearing animals, six groups of C3H mice, eight per group, eating a standard commercial mouse chow ad libitum that supports normal growth, reproduction, and longevity were innoculated with 200,000 C3HBA cells. When tumors measured approximately 6 mm in diameter, the mice were anesthesized and wounded (dorsal skin incisions and subcutaneous polyvinyl alcohol sponges). Twenty-four hours later, two groups (one continued on the chow and the other started on the chow supplemented with 150,000 IU vitamin A/kg chow) underwent local tumor irradiation; two groups, one ingesting the chow, the other the vitamin A supplemented chow, were started on cyclophosphamide therapy; two groups, one ingesting the chow, the other the vitamin A supplemented chow, received neither local tumor irradiation nor cyclophosphamide therapy. An additional two groups ingesting the chow, one group neither innoculated with tumor nor wounded, the other wounded by not innoculated, served as controls. Wound breaking strength and sponge reparative collagen accumulation (assessed by hydroxyproline proline measurement) were used as indicators of wound healing. The mice were killed 12 days after wounding. Tumor presence decreased wound breaking strength and sponge hydroxyproline content; these effects were largely negated by supplemental vitamin A. Local tumor irradiation diminished the adverse effect of tumor on sponge reparative collagen content but to a lesser extent than the supplemental vitamin A. Supplemental vitamin A added to the irradiation effect on healing but irradiation did not add to the vitamin A effect. Cyclophosphamide, a systemic radiomimetic anti-tumor agent, did not alter the impaired wound healing of the tumor-bearing mice. Supplemental vitamin A mitigated the impaired wound healing in the cyclophosphamide-treated tumor-bearing mice. Supplemental vitamin A also moderated the effects of wounding, tumor, and tumor therapies (local irradiation and cyclophosphamide) on the increase in adrenal size, leukopenia, thrombocytopenia, and thymic involution (except the last was not moderated in the cyclophosphamide-treated tumor-bearing rats). The splenic enlargement in the untreated tumor-bearing wounded rats and in those treated with cyclophosphamide was lessened by supplemental vitamin A. We hypothesize that these anti-stress effects of vitamin A underlie, in part, its action in mitigating the impaired wound healing of tumor-bearing mice, including those treated by local irradiation or cyclophosphamide. These findings have implications for the care of patients with malignant tumors.

Effects of polyprenoic acid on thermal injury

This study was designed to determine the effect of polyprenoic acid on wound healing in rats after thermal injury and to compare the effect with healing in vitamin A deficient controls and in retinol-fed vitamin A deficient rats. Both polyprenoic acid and retinol visibly accelerated wound healing after thermal injury. Both enhanced the induction of platelets in the peripheral blood but neutrophils were not affected by polyprenoic acid. Histologically, in the hypo-vitamin A rat, polyprenoic acid administration increased both capillary formation and also the production of fibroblasts and collagen deposition in the wound by comparison with control vitamin A deficient animals; similar effects were produced by retinol feeding. These results indicate that both polyprenoic acid and retinol can facilitate wound healing. 3H-thymidine incorporation into dermal tissues showed that in polyprenoid-fed rats capillaries multiplied 1.3 times, epithelial cells 2.1 times, and fibroblasts 2.0 times faster than those in vitamin A-deficient animals; 3H-thymidine incorporation was greater after polyprenoid feeding than after retinol feeding. Polyprenoid thus stimulates both collagen deposition and neo-vascularization within burns, and so accelerates healing.

Growth factors and determinants of wound repair

The application of contemporary biochemical, analytical, and production technology have, in part, clarified the physiologic processes and identified many new factors active in wound repair. A restructuring of the sequence of the reparative events for the wound environment followed the identification of an array of hormonal polypeptides and growth factors. Deterrents of the early phases of repair include neoplasms and therapeutic doses of steroidal and cytotoxic agents. The physiological effects of these agents are rapidly reversed following their removal with a resultant enhancement of wound tear strength and wound energy. The use of synthetic growth hormone and recombinant DNA-produced polypeptide may reverse the deleterious wound healing events initiated in the injured and tumor-bearing host.

Effect of supplemental vitamin A on colon anastomotic healing in rats given preoperative irradiation

We studied the effect of dietary supplementation with vitamin A on the healing of colon anastomoses in irradiated bowel. Rats were divided into two groups. Those in the first group were fed a standard chow diet and those in the second group were fed the same diet supplemented with 150 IU vitamin A/g of chow. The rats were maintained on their respective diets throughout the experiment. After 7 days, half the rats in each group underwent abdominal irradiation (200 rads). Seven days later, all of the rats underwent distal colon division and anastomosis under pentobarbital anesthesia. All rats were killed 7 days postoperatively, the colons excised, and bursting strength and hydroxyproline determinations performed on both the anastomotic segment and a normal proximal segment of adjacent colon. There was a significant decrease in the bursting strength at the colon anastomosis (p less than 0.02) and in the collagen content (p less than 0.02) after preoperative irradiation. This effect was mitigated by dietary vitamin A supplementation.

Effect of dietary supplementation with vitamin A on arterial healing in rats

The effect of dietary supplementation with vitamin A on the healing of rat aortas was studied. Rats were divided into two groups: rats fed a standard chow and rats fed the chow supplemented with 150 IU vitamin A palmitate/g diet. Seven rats from each group were fed with the above diets for 7 days, killed with ether, and the abdominal aorta excised and assayed for hydroxyproline content and collagenase activity. Ten rats from each group were fed for 7 days on the above diets and then underwent a longitudinal aortotomy which was sutured with prolene sutures under pentobarbital anesthesia. The rats were maintained on their respective diets for 7 days and then killed with ether, their abdominal aorta was excised and both the segment with the arteriotomy and the adjacent distal normal segment were analyzed for hydroxyproline content and collagenase activity. Seven rats from each group were fed with the above diets and then underwent transverse division of the abdominal aorta and reanastomosis using nylon sutures under pentobarbital anesthesia. Rats were maintained on their respective diets throughout the postoperative period. Seven days later, all rats were killed with ether and the bursting strength of the aortic anastomoses was measured. The results showed that vitamin A supplementation in non-operated animals had no significant effect on aortic hydroxyproline content or collagenase activity. In rats undergoing longitudinal aortotomy and suture, there was a significant increase in hydroxyproline content both at the healing arteriotomy and at the adjacent non-wounded aorta in the vitamin A-supplemented group. There was also a significant increase in bursting strength of the healing aortic anastomosis in the vitamin A-supplemented rats.(ABSTRACT TRUNCATED AT 250 WORDS)

The reversal of an Adriamycin induced healing impairment with chemoattractants and growth factors

Rats treated with 8 mg/kg Adriamycin intravenously 4 days prior to chamber implantation develop impaired wound healing in a wound chamber model. In this study, the effects on healing of supplemental platelet derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), epidermal growth factor (EGF), and insulin were evaluated in chambers extracted from Adriamycin-treated rats 10 and 20 days after implantation. The effects of individual factors, combinations of factors, and different concentrations of TGF-beta were evaluated. The parameters evaluated included collagen content, protein content, cellular proliferation rate, chamber histology, and collagen types. Supplemental TGF-beta alone reversed much of the healing deficit noted. A minimum concentration of 100 ng/ml TGF-beta was required to significantly reverse this deficit. PDGF and EGF alone had no effect. Addition of PDGF and TGF-beta in combination stimulated a significantly higher level of collagen deposit than TGF-beta alone. Addition of EGF in combination with PDGF and TGF-beta restored collagen deposition to 86% of normal. No synergism was seen between TGF-beta and EGF unless PDGF was also present. These data suggest that growth factors contained in platelets may play key roles in initiating the wound healing response and may have clinical utility in healing deficit states.

Supplemental vitamin A prevents the acute radiation-induced defect in wound healing

Acute radiation injury leads to thymic involution, adrenal enlargement, leukopenia, thrombocytopenia, gastrointestinal ulceration, and impaired wound healing. The authors hypothesized that supplemental vitamin A would mitigate these adverse effects in rats exposed to acute whole-body radiation. This hypothesis was based on previous experiments in their laboratory that showed that supplemental vitamin A is thymotropic for normal rodents and lessens the thymic involution, lymphopenia, and adrenal enlargement that follows stress, trauma, and neoplasia, largely obviates the impaired wound healing induced by the radiomimetic drugs streptozotocin and cyclophosphamide, lessens the systemic response (thymic involution, adrenal enlargement, leukopenia, lymphocytopenia) to local radiation, and shifts the median lethal dose (LD50/30) following whole-body radiation to the right. To test their hypothesis, dorsal skin incisions and subcutaneous implantation of polyvinyl alcohol sponges were performed in anesthetized Sprague-Dawley rats at varying times following sham radiation or varying doses of whole-body radiation (175-850 rad). In each experiment, the control diet [which contains about 18,000 IU vit. A/kg chow (3 X the NRC RDA for normal rats)] was supplemented with 150,000 IU vit. A/kg diet beginning at, before, or after sham radiation and wounding or radiation and wounding. The supplemental vitamin A prevented the impaired wound healing and lessened the weight loss, leukopenia, thrombocytopenia, thymic involution, adrenal enlargement, decrease in splenic weight, and gastric ulceration of the radiated (750-850 rad) wounded rats. This was true whether the supplemental vitamin A was begun before (2 or 4 days) or after (1-2 hours to 4 days) radiation and wounding; the supplemental vitamin A was more effective when started before or up to 2 days after radiation and wounding. The authors believe that prevention of the impaired wound healing following radiation by supplemental vitamin A is due to its enhancing the early inflammatory reaction to wounding, including increasing the number of monocytes and macrophages at the wound site; possible effect on modulating collagenase activity; effect on epithelial cell (and possible mesenchymal cell) differentiation; stimulation of immune responsiveness; and lessening of the adverse effects of radiation.

Biology of wound healing

A clear understanding of wound healing is vital to a rational surgical approach. This article describes the major biologic processes of tissue repair and the factors influencing the healing processes, and it discusses specific wound-healing problems and recommends management regimens.

Effect of supplemental vitamin A on the healing of colon anastomosis

The effect of dietary supplementation with vitamin A on the healing of colon anastomoses was studied. Fifty adult male Sprague-Dawley rats were divided into two groups: (1) rats fed a standard chow which contains the equivalent of about 15 IU vitamin A/g diet; (2) rats fed the chow supplemented with an additional 150 IU vitamin A/g diet. Rats were prefed for 5 days; on Day 6 under ether anesthesia the colon was divided 1-in. distal to the ileocecal junction and then reanastomosed. The rats were maintained on the above diets for 5 days and killed on the sixth postoperative day with ether and the segment of colon containing the anastomosis was resected. In 15 rats of each group, the breaking strength of the anastomosis was measured. In the remaining 10 rats of each group, the bursting strength of the anastomotic site and a segment of normal distal colon was measured. Samples of colon from the anastomotic site and the normal segment were analyzed for hydroxyproline. There was a significant decrease in hydroxyproline content at the anastomotic site when compared to the normal distal colon segment in each group of rats (P less than 0.01). The hydroxyproline content of both normal colon and the anastomotic site was significantly higher in the vitamin A-supplemented rats than in the control diet rats (P less than 0.01). There was also a significant increase in bursting strength in the vitamin A-supplemented rats both of the anastomotic site (P less than 0.01) and of the normal colon segment (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Wound healing: a review. IV. Systemic medications affecting wound healing

Physicians performing dermatologic surgery should include a thorough drug history in their preoperative assessments of patients. Such information may allow for the discontinuation, if desired, of drugs that negatively influence the wound-healing process. In some instances, the surgeon may find it useful, during the perioperative period, to substitute a drug known to impede wound healing with another possessing no untoward effects. In other situations, as in the treatment of keloids, physicians may wish to introduce drugs known to reduce scar formation into the biologic environment in which wound healing ensues.

Impaired wound healing in streptozotocin diabetes. Prevention by supplemental vitamin A

Goodson and Hunt showed that wound healing is impaired in streptozotocin (Sz) diabetic rats; we speculated that this impairment results from defective early inflammatory responses to wounding. Because we had shown that supplemental vitamin A stimulates the early inflammatory response to wounding in nondiabetic rats, we studied the effect of supplemental vitamin A on wound healing in rats with Sz-induced diabetes. Male Sprague-Dawley rats were fed a commercial rat chow containing twice the amount of vitamin A recommended by the NRC for healthy rats. The rats ate and drank (tap water) ad libitum. Two-thirds of the rats were injected (intravenously) with Sz 60 mg/kg body weight. All of these rats became diabetic (hyperglycemia greater than 350 mg/dl, hyperphagic, polydipsic, polyuric, glycosuric greater than 2%). Seven days later, half of the Sz-injected rats were continued on the chow (Group 2) while the other half (Group 3) were switched to the chow supplemented with 150,000 units of vitamin A/kg chow. The next day, all were wounded (7 cm skin incisions and s.c. polyvinyl alcohol sponge implants). Similarly wounded saline injected nondiabetic rats ingesting the unsupplemented chow served as controls (Group 1). The wounds of Group 2 rats healed poorly compared to Group 1 (breaking strength of skin incisions, 308 +/- 19 g vs 584 +/- 23 g, p less than 0.001; hydroxyproline of the sponge reparative tissue, 0.87 mg vs 2.40 mg/100 mg sponge p less than 0.001). Supplemental vitamin A (Group 3) did not affect the hyperglycemia, hyperphagia, polydipsia or glycosuria, but increased the breaking strengths of the incisions of the diabetic rats (468 +/- 40 g, p less than 0.001), and the sponge hydroxyproline (2.38 mg/100 mg sponge, p less than 0.001). In another experiment, in which the wounding and start of supplemental vitamin A were delayed until 28 days after streptozotocin administration (50 mg/kg body weight), similar results were obtained. Streptozotocin diabetes also caused a decrease in the cross-linking of reparative collagen as judged by the ratio of breaking strengths of skin incisions before and after formalin fixation. Supplemental vitamin A did not influence this defect. Sz also caused peripheral lymphocytopenia, adrenal hypertrophy and thymic involution which responded to the supplemental vitamin A. Based upon experimental data and theoretical considerations we conclude Sz diabetes causes two defects in wound healing: a) quantitatively (reduction in reparative collagen accumulation) and b) qualitative reduction in the degree of cross-linking of reparative wound collagen. The action of supplemental vitamin A in correcting the impaired wound healing, adrenal enlargement, thymic involution and lymphocytopenia of Sz-diabetic rats is independent of an effect on their disturbed carbohydrate metabolism.

Modulation of glycosaminoglycan biosynthesis by retinoids

In conclusion, retinoids modulate phenotypic changes such as morphology, adhesion, and growth rate. These changes also result in specific alterations of glycosaminoglycans. We have observed increases in the degree of sulfation in fibroblast matrix heparan sulfate and, a change in the ratio of sulfamido to ester sulfate in matrix heparan sulfate in 407 cell surface. Matrix glycosaminoglycans have been functionally implicated in cellular interactions, and have a specific role in adhesion and growth rates. Our results are consistent with the proposed role for heparan sulfate. It is possible that some of the modulation in cellular behavior resulting from retinoid treatment may be mediated by cell surface and cellular changes in heparan sulfate and other glycosaminoglycans.

Wound healing: a review. III. Nutritional factors affecting wound healing

Wound healing proceeds more efficiently and quickly in well-nourished individuals who are in good general health at the time that they have to undergo surgery. Per contra, individuals who are malnourished and chronically ill heal less well and are in general at greater risk of complications during and after surgery. For the latter, elective surgery may be deferred until nutritional improvement is attained, but for emergency or urgent operations, institution of measures promoting good nutrition has to be concurrent with necessitous surgery and continued postoperatively. In this paper, the importance to wound healing of proteins, carbohydrates, fats, vitamins, and trace elements and minerals is reviewed.