Fetal tissue repair and wound healing

The fibrosis and scar formation that characterize adult wound healing are also the cause of clinical problems; scar contracture, hypertrophic scar, and pulmonary and hepatic fibrosis are only a few examples. Studies of fetal wound healing can provide an insight into the initiation and regulation of a scarless repair process akin to regeneration. Studies of fetal repair have already suggested mechanisms that might favorably alter adult healing. Topical application of hyaluronic acid to wounds in adult diabetic rats leads to enhanced epithelial migration. It has been recognized that the addition of TGF-beta to fetal wounds causes an adultlike healing response with fibrosis and inflammation. A subsequent study using neutralizing antibody to TGF-beta in adult wounds showed enhanced healing with a more normal dermal architecture with fewer macrophages, fewer blood vessels, and less collagen. As our understanding of regenerative tissue repair increases, the opportunities to modulate adult fibrotic conditions should expand.     

Tendon injury repair in a war wound

During 18 months of the 1991-1992 war against Croatia, 4425 injured were treated at the Department of Surgery, Osijek University Hospital. Among them 46 had tendon injuries, 20 with tendon laceration and 26 with total rupture. In 12 wounded primary repair was performed, 4 of an extensor tendon, 7 of a flexor tendon and 1 of both flexor and extensor. Four patients with primary flexor tendon repair had a good functional result. In other 34 no primary repair was done. Good function was achieved in 18 cases.     

Confocal microscopic characterization of wound repair after photorefractive keratectomy

PURPOSE: Development of postoperative corneal haze and regression of refractive effect are unfavorable clinical complications of excimer laser photorefractive keratectomy (PRK). Although exact mechanisms remain to be elucidated, these outcomes have been attributed to post-PRK corneal wound healing. The purpose of this study was to evaluate corneal wound repair quantitatively after PRK in a rabbit model using a newly developed in vivo technique, termed confocal microscopy through focusing (CMTF). METHODS: Twelve rabbit corneas received a monocular, 6-mm diameter, 9.0-diopter PRK myopic correction. Animals were evaluated sequentially up to 6 months after surgery by in vivo CMTF, which uses an image-intensity depth profile to measure epithelial and stromal thickness and uses corneal light reflectivity as an objective estimate of corneal haze. At differing temporal intervals, in vivo morphology was correlated with ex vivo histology using fluorescence microscopy. RESULTS: One week after PRK, an acellular layer of 86 +/- 24 microns was found anteriorly in the remaining stroma, which demonstrated surgically induced keratocyte death. Underlying keratocytes became activated and migrated toward the wound bed; repopulation was completed within 3 weeks. One week after PRK, there was a significant increase (P < 0.001) in light reflections detected from the photoablated stromal surface (1745 +/- 262 U) and from the underlying activated fibroblasts (713 +/- 607 U). Corneal reflectivity peaked at 3 weeks (4648 +/- 1263 U) and decreased linearly to 889 +/- 700 U by 6 months after the PRK; this corresponded to a reflectivity six times greater than the level seen in unoperated corneas. Two weeks after PRK, initial corneal edema had resolved, revealing an actual ablation depth (maximal stromal thinning) of 118 +/- 8 microns. Starting at 2 weeks after surgery, the stroma underwent gradual rethickening that reached 98% of the preoperative thickness at 6 months after PRK; at that time, only 6% of the initial photoablation depth persisted. By contrast, the central corneal epithelium showed no significant postoperative hyperplasia. CONCLUSIONS: Rabbit corneas treated by PRK showed a remarkable stromal wound-healing response that ultimately led to the restoration of the original stromal thickness by 6 months after surgery, demonstrating complete regression of the initial photoablative effect. Additionally, corneal wound healing was associated with increased light reflections from both the photoablated stromal surface and the activated wound-healing keratocytes underlying this area. Based on these findings, the authors hypothesize that the development of clinically observed corneal haze in PRK patients may be related, in part, to activation of corneal keratocytes and to putative changes in the extracellular matrix.     

Lasers in the military for cutaneous disease and wound healing

The clinical laser experience of military dermatologists mirrors that of their civilian counterparts; however, there are applications for lasers in dermatology in which there is special military relevance. These range from treatment of common diseases such as pseudofolliculitis barbae to noninvasive identification of shrapnel injuries on the battlefield using novel laser-based diagnostic techniques. Although some applications in this report are experimental, emerging technologies should allow for their clinical or field implementation in the near future.     

A microscopical study of wound repair in the human placenta

In order to fulfill its many functions as the selective interface between maternal and fetal circulations it is imperative that the human placenta remains intact and in good operational order. That damage of some sort occurs during its short but extremely active life seems inevitable given the dynamic environment in which the placenta exists, and evidence has accumulated that disruption is indeed a regular event. The implications of such damage, one could speculate, may impact on functions such as transport and hormone secretion as well as mutual protection against attack by maternal and fetal immune systems. Consequently, it would seem a theoretical necessity for discontinuities in the placenta surface to be repaired as soon as possible. We have used a combination of ex vivo observation, in vitro modelling, immunohistochemistry and correlative microscopy to provide evidence for a wound response in the placenta and to begin dissecting the detail of how this may operate. Evidence for small lesions caused by fusion and subsequent tearing of the syncytiotrophoblast in vivo, as well as plugging of such wounds by underlying cells is shown. We also identify a putative role for migratory cytotrophoblasts in the healing of larger scale injuries and demonstrate that certain molecules, common to wound repair in other tissues, appear to be involved in placenta repair also. Taken together these results clearly show that the human placenta is capable of a degree of self-maintenance by activating what appears to be an endogenous wound healing mechanism.     

Therapeutic touch, nursing practice and contemporary cutaneous wound healing research

The nursing profession is and always has been at the cutting edge of research and development into innovative and effective methods to treat, manage and enhance wound regeneration. One such method which was developed specifically for nursing science is a non-invasive, easily administered technique known as therapeutic touch (TT). Although there have been numerous anecdotal reports over the last two decades attesting to the efficacy of TT for cutaneous wounds, there have been only five experimental studies to date which have examined the phenomena in a scientifically rigorous manner. These five studies utilized randomized, double-blind, placebo controlled protocols to analyse the effect of an experimental derivative of TT-non-contact therapeutic touch (NCTT)-on the healing rate of surgically administered full thickness human dermal wounds. The experiments introduced many original concepts and approaches to healing research and nursing practice. The data from the five studies indicated a statistically significant accelerated rate of wound healing for the treatment group in the initial two experiments, and non-significant and reverse significant effects for the remaining three studies. Although, experimentally, these results are far from impressive, clinically, the significant results of the first two experiments should be enough to encourage the nurse clinician to explore and utilize a similar non-invasive TT treatment method for patients with dermal lacerations. While the results of the studies were inconsistent overall, the series of experiments nonetheless significantly expanded the theoretical boundaries and understanding of the TT process and, due to the rigorous, double-blind methodological protocols used, have established the critical groundwork and guidelines for future nursing science research in the area.     

Basics of constipation

In this article, the author defines and describes the causes of constipation. Physiology of the colon is reviewed, and the nurse's role in helping patients and families with constipation is also described.     

Basics of surveillance--an overview

Surveillance of nosocomial infections is the foundation of an infection control program. This article describes components of a surveillance system, methods for surveillance, methods for case-finding, and data sources. We encourage the epidemiology team to use this background information as they design surveillance systems that meet the goals of their individual institution's infection control program.     

The in vivo effect of hyaluronan associated protein-collagen complex on wound repair

Fetal skin wounds heal without scarring, however the underlying mechanisms remain unknown. Immunohistochemical staining and biochemical studies indicate the deposition of a collagen repair matrix that is highly organized. We have previously described a unique hyaluronan associated protein-collagen complex (HA-PC) profile present during the period of scarless healing in the sheep fetus. In this study, we examined the biologic activity of this HA-PC in an in vivo model of adult rat wound repair. A total of 84 incisional and 84 excisional wounds were examined by histology, TGF-beta immunocytochemistry and computer planimetry (excisional wounds only). Planimetry of the excisional wounds demonstrated the mean wound area remaining at day 1 was 88.7% for the control and 63.6% for the treated (p<0.01). At day 2, mean wound area was 81.5% for the control and 63.6% for the treated (p<0.01). At day 4, mean wound area was 56.6% for the control and 41.9% for the treated (p<0.01). At day 7, mean wound area was 26.9% for the control and 16.8% for the treated (p<0.01). At day 14, mean wound area was 7.9% for the control and 3.4% for the treated (p<0.05). Collagen organization was judged to be greater in the treated compared to control wounds, with a mean organization score of 2.3 vs. 1.9 (p=0.0596; Wilcoxon Signed Rank Sum Test). There were significantly more neutrophils at the wound margin of the treated compared to control wounds, 4.0 vs. 2.7 (p=0.038; Paired Two Tailed Student's t-Test). There was no difference in the number of microphages at the wound margin of the treated compared to control wounds, 6.15 vs. 6.0 (p>0.05). TGFbeta1 and beta2 staining was decreased whereas TGFbeta3 staining was increased in the HA-PC treated wounds. These results suggest that compared to control wounds HA-PC treated wounds heal more quickly, with more organized collagen, more neutrophils at the wound margin and increased TGFbeta3 expression. Furthermore, these data suggest that the manipulation of scarring in adult wounds is possible by the addition of proteins present in fetal skin.     

MIP-1alpha as a critical macrophage chemoattractant in murine wound repair

At sites of injury, macrophages secrete growth factors and proteins that promote tissue repair. While this central role of the macrophage has been well studied, the specific stimuli that recruit macrophages into sites of injury are not well understood. This study examines the role of macrophage inflammatory protein 1alpha (MIP-1alpha), a C-C chemokine with monocyte chemoattractant capability, in excisional wound repair. Both MIP-1alpha mRNA and protein were detectable in murine wounds from 12 h through 5 d after injury. MIP-1alpha protein levels peaked 3 d after injury, coinciding with maximum macrophage infiltration. The contribution of MIP-1alpha to monocyte recruitment into wounds was assessed by treating mice with neutralizing anti-MIP-1alpha antiserum before injury. Wounds of mice treated with anti-MIP-1alpha antiserum had significantly fewer macrophages than control (41% decrease, P < 0. 01). This decrease in wound macrophages was paralleled by decreased angiogenic activity and collagen synthesis. When tested in the corneal micropocket assay, wound homogenates from mice treated with anti-MIP-1alpha contained significantly less angiogenic activity than control wound homogenates (27% positive for angiogenic activity versus 91% positive in the control group, P < 0.01). Collagen production was also significantly reduced in the wounds from anti-MIP-1alpha treated animals (29% decrease, P < 0.05). The results demonstrate that MIP-1alpha plays a critical role in macrophage recruitment into wounds, and suggest that appropriate tissue repair is dependent upon this recruitment.     

Active transforming growth factor-beta in wound repair: determination using a new assay

The increase in serum FSH that accompanies female reproductive aging occurs before changes in estradiol (E2). A decrease in negative feedback from inhibin A (a product of the dominant follicle and corpus luteum) and/or inhibin B (secreted by developing follicles) may explain the rise in FSH with age. To test the hypothesis that decreases in inhibin A or inhibin B occur at an age at which the first increase in follicular phase FSH is evident, daily blood samples were obtained across the menstrual cycle from younger (<35 yr; n = 23) and older (35-46 yr; n = 21) cycling women. These cross-sectional studies were complemented by longitudinal data in 3 women studied at a 10-yr interval. In the early follicular phase, mean inhibin B was lower in older cycling women (88 +/- 7 vs. 112 +/- 10 pg/mL; P < 0.05) and FSH was higher (13.0 +/- 0.5 vs. 11.2 +/- 0.7 IU/L in older vs. younger, respectively; P < 0.04). In the mid- and late follicular phases, inhibin B was also lower in the older women (117 +/- 9 vs. 146 +/- 10 and 85 +/- 8 vs. 117 +/- 11 pg/mL; P < 0.04), whereas E2 was higher (105 +/- 14 vs. 68 +/- 5 and 240 +/- 27 vs. 163 +/- 9 pg/mL; P < 0.02), and no differences in FSH were observed in the two groups at these times. In women studied longitudinally, FSH and inhibin B varied inversely in the follicular phase. In the early luteal phase, mean inhibin B was lower in the older group (64 +/- 6 vs. 94 +/- 12 pg/mL; P < 0.03), and FSH was higher (12.5 +/- 1.0 vs. 9.7 +/- 0.6 IU/L; P < 0.03). In the mid- and late luteal phases, inhibin B was also lower in older subjects (21 +/- 2 vs. 33 +/- 5 and 22 +/- 2 vs. 36 +/- 6 pg/mL; P < 0.02). No difference in inhibin A, E2, or progesterone was observed across the luteal phase, between the two groups. However, in all subjects studied longitudinally, increased age was associated with a decrease in inhibin A, inhibin B, and progesterone in the absence of changes in E2. Our conclusions were: 1) reproductive aging is accompanied by decreases in both inhibin B and inhibin A; 2) the decrease in inhibin B precedes the decrease in inhibin A and occurs in concert with an increase in E2, suggesting that inhibin B negative feedback is the most important factor controlling the earliest increase in FSH with aging; 3) these studies suggest that the decrease in inhibin B is the earliest marker of the decline in follicle number across reproductive aging.     

In vitro wound repair by human gastric fibroblasts: implications for ulcer healing

Fibroblasts modulate epithelial biological activities and play a key role in the ulcer healing process. There is no information regarding the biological response of human gastric fibroblasts to regulatory compounds. The aim of this study was to assess the effects of growth factors and prostaglandins on an in vitro model of human gastric fibroblast wound repair. Subconfluent fibroblast cultures were used to study proliferative responses, determined by [3H]thymidine incorporation into DNA. In vitro wound repair was determined in confluent fibroblast monolayers after mechanical denudation. The presence of putative growth factors secreted by fibroblasts was studied in conditioned medium by heparin-affinity chromatography and immunodetection with specific antibodies. Serum and platelet-derived growth factor (PDGF) -BB induced a dramatic increase in both gastric fibroblast proliferation and closure of wounded cell monolayers, whereas these activities were inhibited by both transforming growth factor (TGF) -beta1 and prostaglandin E1. Basal activities in unstimulated gastric fibroblasts were lower than those obtained in skin fibroblasts. Conditioned medium stimulated fibroblast proliferation and wound repair activity, which was inhibited by the addition of suramin, and was partially dependent on the presence of PDGF-like factor. PDGF is a major, autocrine promotor of human gastric fibroblast-dependent wound repair activities, which are inhibited by prostaglandins and TGF-beta. These findings might be important for future therapeutic ulcer healing approaches.     

Enhanced cell proliferation and biosynthesis mediate improved wound repair in refed, caloric-restricted mice

Aged mice that have undergone long-term caloric-restriction (CR) have improved health and enhanced longevity in comparison to aged mice that are ad libitum-fed (AL). However, caloric-restriction does not benefit the impaired wound healing of aged mice. To test the hypothesis that CR mice have the capacity for enhanced wound repair, but require a short-term period of additional nutrient intake to show this advantage, we assessed wound healing in CR mice that had been refed (RF) an ad libitum diet for 4 weeks prior to wounding. Two strains of AL young (Y AL) (4-6 months), AL middle-aged (M AL) (15-17 months), and three different, matched cohorts of old mice (O) (30-33 months): O AL, O CR, and O RF were studied. Two full-thickness 4 mm diameter punch biopsy skin wounds were created on the dorsum of each mouse. Animals were sacrificed and wounds were harvested at 1,2,3,5, and 7 days post-wounding. Repair of wounds was slower in O AL and O CR mice compared to Y AL and M AL animals. In contrast, the O RF mice healed similarly to that of the Y AL and M AL mice, as assessed by measures of wound area and histologic criteria. O RF mice demonstrated enhanced synthesis of type I collagen mRNA in comparison to O AL and O CR mice. A greater number of endothelial cells and fibroblasts at the wound edge of the O RF mice exhibited replication in vivo as measured by uptake of BrdU. O RF mice had higher levels of insulin-like binding protein 3 (IGFBP-3). Furthermore, fibroblasts derived from the explant of the punch biopsy of O CR mouse skin revealed enhanced proliferation and contraction in vitro, in comparison to fibroblasts from the O AL mice. In conclusion, O RF mice demonstrate an enhanced capacity to undergo wound repair in comparison to O AL mice. This effect appears to be mediated, in part, by enhanced cell proliferation, contraction, and collagen biosynthesis. In addition, short-term refeeding induced an increase in the serum level of IGFBP-3, the major binding protein for IGF-1. These data confirm that cells from O CR animals have a preserved proliferative, biosynthetic, and contractile capacity, but that an adequate source of nutrients is necessary to demonstrate this advantage in wound healing.     

Strong induction of activin expression after injury suggests an important role of activin in wound repair

Activins are members of the transforming growth factor beta (TGF beta) superfamily, which comprises a growing group of dimeric proteins. TGF beta and several other members of this superfamily are known to play an important role in wound healing. However, expression of activin during wound healing has not been demonstrated so far. In this study we have analyzed the expression pattern of activin and activin receptors in normal and wounded skin. We found a large induction of activin A and a minor induction of activin B mRNA expression 1 day after skin injury and high expression levels of activin A and B were found within the first 7 days after wounding. At 13 days after injury, expression of activin A mRNA had returned to the basal level, whereas high levels of activin B persisted. In situ hybridization studies revealed expression of activin A in the granulation tissue below the wound and activin B in the hyperproliferative epithelium at the wound edge and in the migrating epithelial tongue. All known types of activin receptors as well as the activin binding protein follistatin were expressed in normal and wounded skin. However, no significant induction of receptor gene expression was seen during the repair process. The distribution of activins and activin receptors in the wound suggests multiple autocrine and paracrine activities of the ligands during wound healing. Our data provide evidence for a novel function of activin and indicate that--besides TGF beta s themselves--other members of this superfamily might also play an important role in tissue repair.     

Enhanced biosynthesis of extracellular matrix proteins and TGF-beta 1 by polyinosinic-polycytidylic acid during cutaneous wound healing in vivo

OBJECTIVES: We sought to determine the utility of left ventricular expansion velocities in differentiating constrictive pericarditis from restrictive cardiomyopathy. BACKGROUND: Several studies have shown that left ventricular diastolic expansion is influenced by the elastic recoil forces of the myocardium. These forces are affected by intrinsic myocardial disease but should be preserved when diastole is impaired as a result of extrinsic causes. METHODS: Using Doppler tissue imaging, we measured peak early velocity of longitudinal axis expansion (Ea) in 8 patients with constrictive pericarditis, 7 patients with restriction and 15 normal volunteers. Transmitral early (E) and late (A) Doppler flow velocities, left ventricular systolic and diastolic volumes, ejection fraction and mitral annular M-mode displacement were also compared between the groups. RESULTS: The Ea value was significantly higher in normal subjects (14.5 +/- 4.7 cm/s [mean +/- SD]) and in patients with constriction (14.8 +/- 4.8 cm/s) than in those with restriction (5.1 +/- 1.4 cm/s, p < 0.001 constriction vs. restriction). There was weak correlation between Ea and the extent of annular displacement (r = 0.55, p = 0.004) and the E/A ratio (r = 0.44, p = 0.03). There was no correlation between Ea and E (r = 0.33, p = 0.07) or ejection fraction (r = 0.21, p = 0.26). By multivariate analysis, Ea was the best variable for differentiating constriction from restriction. CONCLUSIONS: Our study indicates that longitudinal axis expansion velocities are markedly reduced in patients with restrictive cardiomyopathy. The poor correlation found with transvalvular flow velocities suggests that Ea may be relatively preload independent. The measurement of longitudinal axis expansion velocities provides a clinically useful distinction between constrictive pericarditis and restrictive cardiomyopathy and may prove to be valuable in the study of diastolic function.     

Skin flap closure by dermal laser soldering: a wound healing model for sutureless hypospadias repair

OBJECTIVES: Laser tissue soldering (LTS) with the diode laser and human albumin-hyaluronate-indocyanine green solder is a safe and effective method of providing an immediate leak-free closure during hypospadias repair. In this report, we compare the physiology, histology, and immunohistochemistry of wound healing following LTS and suturing in a rat skin flap model. METHODS: A 4 x 5-cm skin flap was raised and bisected (4 cm) on the dorsum of 48 Sprague-Dawley rats. The central wound was either closed from a dermal approach by suturing or LTS or left open, and studied at 0, 3, 5, 7, 10, 14, and 21 days postoperatively. An intraoperative comparison was made between suturing and LTS with respect to operative time. Postoperatively, flaps were excised for tensiometric analysis, and sections were stained with hematoxylin-eosin to define wound architecture. Resting skin temperature, laser exposed temperature without solder, and maximum temperature with solder (one drop) were measured at the level of the deep dermis, superficial striated muscle layer, and within the solder. Mean peak temperatures were recorded during a 1-minute laser activation time. RESULTS: Mean continuous suturing time (4.9 +/- 1.1 minutes) was significantly (P < 0.001) faster than either LTS (7.7 +/- 0.77 minutes) or discontinuous suturing (8.2 +/- 0.62 minutes). Two seromas (sutured) and two instances of partial wound dehiscence (1 sutured, 1 LTS) were noted. Tensile strength was increased significantly (P < 0.001) for up to 5 days in the LTS group, but was equal to suturing at 7 and 10 days. Immediate tensile strength after LTS was equivalent to a 7-day healed wound. At 14 days, wounds initially left open and those closed by LTS were stronger than sutured wounds (P < 0.05). There was no evidence of thermal injury or foreign body reaction in the LTS group. Solder was incorporated within the dermis in all wounds at 21 days. Laser activation of solder resulted in significant increases in temperature at all three tissue levels: 65.0 +/- 5.2 and 69.9 +/- 6.8 degrees C in the deep and superficial skin (no significant difference between the two), and 101 +/- 15.6 degrees C within the solder (P < 0.001 versus superficial and deep skin). CONCLUSIONS: Our results indicate that sutureless dermal LTS of skin flaps provides increased tensile strength for up to 7 days, with relatively greater tensile strength provided within the first 3 days. Our laser technique does not appear to alter the normal wound healing process. Rather, solder-tissue interaction initially, and extracellular matrix infiltration of solder later, provide the basis for improved wound strength. For hypospadias repair using skin flaps, these wound attributes may permit sutureless surgery.     

Bacterial toxins block endothelial wound repair. Evidence that Rho GTPases control cytoskeletal rearrangements in migrating endothelial cells

Pharmacological experiments were conducted to determine the neuronal mechanisms involved in the suppressive effects of the thyrotropin-releasing hormone analog TA-0910 on alcohol intake in alcohol-preferring (P) rats. We previously reported that single intraperitoneal injections of TA-0910 dose-dependently reduced alcohol intake in P rats without altering fluid or total calorie intake; however, after several consecutive, once-daily injections, P rats developed tolerance to the suppressive effects of TA-0910 on alcohol intake and cross-tolerance to like effects of the dopamine D2 agonist bromocriptine, but not to like effects of the serotonin uptake inhibitor fluoxetine. In the present study, rats were injected with vehicle or different doses of the D2 antagonist s(-)-eticlopride (0.01 to 0.05 mg/kg) or the D1 antagonist R(+)-SCH23390 (0.1 to 0.5 mg/kg) and 20 min later with TA-0910 (0.75 mg/kg). Alcohol and water intakes were measured at 2, 4, 6, and 24 hr, and food was measured every 24 hr. Both s(-)-eticlopride and R(+)-SCH23390 produced modest reductions in alcohol intake alone; however, only s(-)-eticlopride antagonized the suppressive effect of TA-0910 on alcohol intake. In related experiments, it was confirmed that the dopamine D3 agonist 7-hydroxy-N,N-di-n-propyl-2-aminotetralin reduced alcohol intake in P rats, and it was found that tolerance to this effect did not develop during or after seven consecutive once-daily injections. Furthermore, this effect of 7-hydroxy-N,N-di-n-propyl-2-aminotetralin was not diminished in rats made tolerant to the effect of TA-0910 on alcohol intake. These data, those of previous studies, and recent preliminary findings support involvement of dopamine D2, but not D1 or D3 receptors in mediating the suppressive effect of TA-0910 on alcohol intake of P rats.