Wounds In Sheep Research Articles

Comparative study of the therapeutic efficacy of autologous platelet-rich plasma and honey in healing skin wounds in sheep.

Background and Aim:This investigation is the continuation of a published preliminary study examining the therapeutic efficacy of platelet-rich plasma (PRP) as a topical treatment for skin wounds in sheep. The study aimed to compare the healing effects of autologous PRP with that of natural honey.Materials and Methods:This study involved nine clinically healthy male sheep. After sterile skin preparation, full-thickness longitudinal incision wounds were created on the backs of each animal. The animals were randomly divided into three groups of three sheep each. In Group I, the wounds were treated with PRP; in Group II, the wounds were treated with honey; and in Group III, the wounds were treated with saline solution. The different treatments were administered topically every 3 days. Healing was assessed by a semi-quantitative histopathological study from biopsies taken on the 3rd, 7th, 14th, 21st, and 28th days of healing. The data obtained were compared using the non-parametric Mann–Whitney U-test, and p<0.05 and 0.01 were used to determine the level of significance of the recorded differences.Results:Semi-quantitative histopathological evaluation showed significant differences in the progression of wound healing between the three study groups. Recorded data showed that PRP may reduce inflammation during the first 3 days after the incision. Moreover, the synthesis and organization of collagen fibers were significantly improved in the group treated with PRP compared with those in the group treated with honey.Conclusion:PRP offers a promising therapeutic option for healing skin wounds in sheep compared with honey.

Ovine model of burn wounds grafted with ovine cadaver skin

Shortage in autograft to cover burn wounds involves a frequent use of cadaver skin (CS) as a temporary cover to prevent infection, dehydration and preparation of wounds for subsequent autografting.We aimed to establish an ovine model of burn wound healing using ovine CS (OCS). Quality and efficacy of fresh and frozen OCS overlaid on to excised 3rd degree flame burn wounds in sheep were evaluated in comparison to autograft.Histologically, autografted wounds maintained normal skin structure at different time points. Wounds overlaid with fresh OCS graft showed signs of rejection starting from day 7. At day 14, the epidermis was mostly rejected. The rejection was completed by day 20 with signs of immunoreaction and presence of many immune cells. Frozen OCS was rejected in the same pattern. Immediately prior to grafting, the thickness was comparable between freshly prepared and frozen OCS for 10 or 40 days. Significant reduction in viability was detected in OCS frozen for 40 days.Both fresh or frozen ovine OCS were rejected within 10 days that mimics CS rejection time in humans (∼8.4 days), suggesting that ovine model of burn wound grafted with OCS can successfully be used in burn wound research mimicking clinical scenario.

Could cold plasma act synergistically with allogeneic mesenchymal stem cells to improve wound skin regeneration in a large size animal model?

Skin wound healing may sometimes lead to open sores that persist for long periods and expensive hospitalization is needed. Among different kinds of therapeutic innovative approaches, mesenchymal stem cells (MSCs) and low-temperature atmospheric pressure cold plasma (ionized gas) have been recently tested to improve this regenerative process. To optimize wound healing the present study intended to combine, for the first time, these two novel approaches in a large size animal wound healing model with the aim of assessing the putative dual beneficial effects. Based on clinical, histopathological, and molecular results a synergistic action in a second intention healing wound in sheep has been observed. Experimental wounds treated with cold plasma and MSCs showed a slower but more effective healing compared to the single treatment, as observed in previous studies. The combined treatment improved the correct development of skin appendages and structural proteins of the dermis showing the potential of the dual combination as a safe and effective tool for skin regeneration in the veterinary clinical field.

Differential efficacies of marigold leaves and turmeric paste on the healing of the incised wound in sheep.

Objective:This study was undertaken to compare the curative efficacy of marigold leaf paste and turmeric paste on healing the incised wound in sheep. The study also determined the antimicrobial effects and histopathological changes in a wound’s healing process treated with these medicinal herbs.Materials and Methods:Surgical wounds (n = 18) were created aseptically in the skin of the flank region of six healthy sheep dividing them into three experimental groups. Follow-up data were taken up to day 21. Different morphological characteristics of the wound and wound contraction (length and width) were recorded weekly. Samples were collected on days 1, 2, and 3 to test the antimicrobial effects and on days 1, 3, and 7 for histopathological studies.Results:Treatment with marigold leaf paste and turmeric paste resulted in a swelled wound area of 11.78 ± 0.38 mm and 11.52 ± 0.27 mm, respectively. The wound areas were comparatively lower than that of the control group (11.44 ± 0.20 mm). Moreover, the least elevation (2.44 ± 0.12 mm) of the sutured line from the skin surface was noted and compared between the marigold leaf paste and normal saline (2.74 ± 0.13 mm). Bacterial colonies in the nutrient agar medium cultured with swabs from the normal saline-treated group’s wound area were found on day 1. On the contrary, bacterial colonies were absent on days 2 and 3 of treatment in the groups treated with both the paste of marigold leaves and turmeric. Less intense tissue reactions and higher keratinization of epithelium were shown in the group treated with marigold leaf paste than turmeric paste and saline-treated groups.Conclusion:Marigold leaf paste showed less tissue reaction and healed the wounds effectively. Thus, this paste could be used for the treatment of superficial wounds in sheep.

A comparison between Platelet-rich plasma and low-level laser therapy for the treatment of second degree burn in sheep

Background and aims: This experiment was conducted in order to compare the effect of Platelet-rich plasma (PRP) and low-level laser (LLL) therapy on healing of second-degree burn wound in sheep. Materials and Methods: Fourteen adult rams were divided into four groups of equal numbers. A second-degree burn was generated on the back of all animals. The burned area in the first and second group was exposed and autologous PRP and LLL (6 J/cm2), respectively were applied on burned area continuously for five days. Fourteen days later, samples were collected from all animals for histopathological examinations. Results: Histopathological evaluations on the second week showed the burn healing to be better in the PRP than LLL and both of them were better with respect to the control group. Conclusion: The application of PRP for five days is effective than LLL application in healing burn-related skin wounds in sheep model.

Prevalence and characterisation of wounds in sheep attributed to attacks by kea (Nestor notabilis) on high country farms in New Zealand

ABSTRACTAims: To characterise and classify wounds in sheep suspected to have been caused by attacks by kea (Nestor notabilis) (kea strike), and to report the prevalence of these wounds on five high country farms in the South Island of New Zealand.Methods: Data were collected from farms between 28 August 2012 and 20 September 2013. Sheep were examined opportunistically immediately after shearing for signs of wounds caused by kea. The age and sex of sheep were also recorded. Wounds were measured and characterised as recent, healing, or healed, and the estimated true prevalence was calculated for each farm.Results: Injuries consistent with kea strike wounds were identified in 70/13,978 (0.5%) sheep examined. The estimated true prevalence varied between farms, from 0 (95% CI = 0–0.16) to 1.25 (95% CI = 0.97–1.61)%. Of the 76 wounds identified, 61 (80%) were located in the lumbar region, and 74 (97%) consisted of full-thickness ulceration of the skin, one showed evidence of injury to muscle and one to bone. The median length of the 63 wounds measured was 6 (min 1, max 23.5) cm, and 10/63 (13%) were categorised as recently healed, 47/63 (62%) as healing, and 17/63 (22%) as recent wounds.Conclusions: The results of this study show that kea strike on sheep was occurring at a low prevalence on the high country farms surveyed. The wounds identified were survivable, but the welfare impact of kea strike on sheep should be considered in balance with the conservation status of kea. There was clear variation in the prevalence of wounds attributed to kea strike between the farms but we were not able to identify the risk factors contributing to these differences. Future studies of kea strike should examine variables such as altitude, local kea density and distribution, and differences in kea strike management and husbandry practices, and should include high country farms without a history of kea strike.

Comparative evaluation of metallic skin staples or polypropylene sutures for primary closure of teat wounds in sheep

ABSTRACTAimsTo compare stainless steel staples and polypropylene suture material for primary closure of wounds after teat amputation in ewes and to assess progress of healing in the presence or absence of intramammary infection (IMI).MethodsChios-cross ewes, aged 3–5 years were randomly allocated to be infected in one teat with 1,200–1,500 cfu of Mannheimia haemolytica 5 days after parturition (groups A and B; n = 8 in each group) or remain uninfected (groups C and D; n = 4 in each group). On the following 4 days one teat from each ewe was amputated 2.5 cm from the teat end and the wound was closed using skin staples (groups A and C) or polypropylene sutures (groups B and D). Clinical evaluation of wound healing was performed between 1–21 days after surgery. On day 21 tissue sections were collected for tensiometric and histological evaluation.ResultsThe mean interval from the start to finish of wound closure was shorter when staples were used than when sutures were used (p < 0.001). Healing scores were lower (improved) for ewes in group A than B between days 1–7 after surgery (p = 0.005), but were similar between days 10–21 (p = 0.43). Healing scores were similar in groups C and D (p = 0.98). The tensile strain at maximum load was higher in tissue from group A than B (p = 0.001) and D (p = 0.004), but all other tensiometric measures were similar between groups. Histologically, collagen density was higher in sections from group A than B (p = 0.05) and D (p = 0.01), and angiogenesis was lower in sections from group A than B (p = 0.03) and D (p = 0.01).Conclusions and clinical relevanceSkin staples and polypropylene sutures can be used effectively for primary closure of teat wounds, even in the presence of IMI. Skin staples had the advantage of a reduction in surgical time.AbbreviationIMI: intramammary infection

Biogenic Silver Nanoparticles as a Post-surgical Treatment for Corynebacterium pseudotuberculosis Infection in Small Ruminants.

Caseous lymphadenitis (CL) is an infectious and zoonotic disease characterized by the development of granulomas in the lymph nodes and internal organs of small ruminants. The etiological agent of this disease is Corynebacterium pseudotuberculosis, a Gram-positive and facultative intracellular bacterium. The conventional treatment for CL consists of drainage and chemical cauterization of the lesions using a 10% iodine solution. However, this type of treatment is not effective, due to iodine’s cytotoxic profile and low antibacterial activity. Currently, silver nanoparticles (AgNPs) can be seen as an alternative treatment for CL due to their antimicrobial activity and wound healing effects. Therefore, the present study aimed to evaluate AgNPs as a post-surgical treatment for CL. Twenty-nine goats and sheep with clinical signs of CL were selected. Surgical intervention was performed to excise the caseous lesions. To treat the lesions, an ointment formulation based on AgNP mixed with natural waxes and oils was used in the experimental group, and the conventional treatment with 10% iodine was used in the control group. Bacteria were isolated from the excised caseous material. The animals were observed for 8 weeks after the surgical treatment, and blood samples were taken weekly. The surgical wounds of sheep treated with AgNP healed faster, and the surgical wound area was smaller during the observation period; the latter effect was also observed in goats. AgNP-treated animals also had less purulent discharge and less moisture in the surgical wounds. The AgNP-treated animals had lower leukocyte counts and lower titers of anti-C. pseudotuberculosis antibodies. There was no statistically significant difference between the groups with regard to the hemogram results. The results of the susceptibility testing of C. pseudotuberculosis strains (T1, 1002, FRC41, and VD57 strains) and clinical isolates to AgNPs showed growth inhibition, even at low concentrations. It can be concluded that post-surgical treatment of CL using the AgNP-based ointment may be a promising tool in the control of CL, through faster healing, decreased wound contamination, and no apparent toxic effects.

Evaluation of Topicure® Plus spray on sheep infested with Myiasis

The present study was designed to evaluate the therapeutic efficacy of polyherbal aerosol spray - Topicure® Plus against maggot infested wounds in sheep. Two sheep presented at Vellore Veterinary Dispensary with a history of maggot infested wound were selected. Based on the severity of wound, antibiotics (Ampicillin - 10 mg/kg body weight) and NSAIDs (Meloxicam - 0.5 mg/kg body weight on 1st day) were administered. The site of wound was clipped off the hair and cleaned with sterile saline solution and wiped with dry sterile cotton on first day of the treatment. Then Topicure® Plus was sprayed in sufficient quantities to cover the entire wound twice daily till complete healing of wound occurs. When Topicure® Plus spray was administered concurrent local treatment with other fly repellents/maggoticidal agents was not followed. Wound was observed for the changes in swelling, discharge, granulation tissue and wound healing process following the treatment till complete recovery. Similarly, fly repellent activity and duration, maggot repellent property, activity level and product satisfaction score were also recorded. The results indicate that Topicure® Plus had ensured faster wound healing (within 8 days) which is evident through reduction in pain, swelling, discharge and granulation tissue score along with superior fly repellent activity and duration, maggot repellent property. Therefore, it appears from the present study that treatment of myiasis wound with Topicure® Plus spray along with antibiotic regime was the most effective in field conditions as it avoids the day to day manual removal of maggots and induces the faster wound healing.Asian J. Med. Biol. Res. June 2017, 3(2): 216-220

Histological and surgical study of the henna on wound healing in animals Field ( Sheep )

Wounding in first group, while in second group it was more than 4 weeks. Within the clinical follow up, no complications occurred in the first group, while the second group showed some complications such as infection and abscess formation. Histopathological examination showed formation of granulation tissue in Henna treated group was faster than control group and the regular collagen fiber noticed at 15 days post treated with Henna.The present study demonstrates that use of Henna is useful for treatment and accelerates healing of full thickness wounds of skin in the current study was conducted to evaluate the efficacy of Henna in the treatment of skin wounds in sheep ( 5) , Awassi rams were used in this study. The animals were randomly 2 groups ( control &amp;treated ) , 5cm injury full-thickness skin wound was created on the right flank region of each animal. The wounds in first group were treated with Henna single daily after operation until complete healing was occurred, while its in second group treated with sterile saline solution as control group.The results revealed the wound healing process in Henna treated group occurred faster than the control group , the healing occurred in 14-15 days after treated .

Therapeutic use of honey for skin wounds healing in Iraqi Awassi sheep

The current study was conducted to evaluate the efficacy of honey in the treatment of skin wounds in sheep. Twelve Awassi rams were used in this study. The animals were randomly divided into two equal groups. A 5cm full-thickness skin wound was created on the right flank region of each animal. The wounds in first group were treated with honey single daily after operation until complete healing was occurred, while its in second group treated with sterile saline solution as control group. The results revealed the wound healing process in honey treated group occurred faster than the control group; the healing occurred in 14-15 days after wounding in first group, while in second group it was more than 4 weeks. Within the clinical follow up, no complications occurred in the first group, while the second group showed some complications such as infection and abscess formation. Histopathological examination showed formation of granulation tissue in honey treated group was faster than control group and the regular collagen fiber noticed at 15 days post treated with honey. The present study demonstrates that use of honey is useful for treatment and accelerates healing of full thickness wounds of skin in sheep.

Anti‐inflammatory Activities of Eleven Centaurea Species Occurring in the Carpathian Basin

Our study aimed at the identification of anti-inflammatory activities of different fractions of C. sadleriana extract after per os administration in rats, the identification of the active compounds of the plant and the investigation of the in vitro anti-inflammatory activities of Centaurea species native to or cultivated in the Carpathian Basin. The aerial parts of Centaurea sadleriana Janka have been used in Hungarian folk medicine to treat the wounds of sheep. Methanol extract of C. sadleriana was fractioned by solvent-solvent partitioning. The n-hexane fraction was further fractionated and the anti-inflammatory activities of certain subfractions were confirmed in vivo in rats. The n-hexane and chloroform fraction of the methanol extract of C. sadleriana exhibited remarkable COX-1 and COX-2 inhibiting effects in vitro. Chromatographic separation of the fractions led to the identification of the active subfractions and 11 compounds (α-linolenic acid, γ-linolenic acid, stigmasterol, β-sitosterol, campesterol, vanillin, pectolinarigenin, salvigenin, hispidulin, chrysoeriol and apigenin). The in vitro screening for anti-inflammatory activities of further Centaurea species occurring in the Carpathian Basin (C. adjarica, C. bracteata, C. cataonica, C. cynaroides, C. dealbata, C. indurata, C. macrocephala, C. melitensis, C. nigrescens, C. ruthenica) revealed considerable COX-1 and COX-2 inhibitory activities. Because C. sadleriana is an endangered species native only to the Carpathian Basin, the investigation of more prevalent species is reasonable.

Six fatal cases of classical rabies virus without biting incidents, Iran 1990–2010

BackgroundRabies is an endemic fatal zoonotic disease, commonly transmitted to humans through contact (bites and scratches) with infected animals. ObjectivesDuring the years 1990–2010, six patients with the clinical symptoms of rabies (fever, tinnitus, buzzing, delirium and hydrophobia), with no history of a bite, were diagnosed by physicians in Iran. To obtain laboratory confirmation of rabies infection, different clinical specimens from each patient were sent to the World Health Organisation (WHO) Collaborating Center for Reference and Research on Rabies, Pasteur Institute of Iran.The first case was a 39-year-old male veterinary technician who entered his uncovered scratched hand into the mouth of a rabid bovine and became infected. Two years later, a herd of sheep being tended by a shepherd and his two sons were attacked by a rabid wolf. All three individuals were infected when they applied burnt thorny wool to the sheep's wounds as a bandage. Their hands were scratched and then infected through contact with the remaining saliva of the rabid wolf on the sheep's wounds. In 1994, two other human cases occurred through corneal transplantation from the same donor who had died with the clinical signs of food poisoning (according to his hospital record), which probably was a misdiagnosis of rabies infection. Study designThis is a case series study that describes human rabies cases without biting incidents. According to the WHO recommendation, human rabies cases are notifiable, therefore, in Iran, a rabies surveillance system has been established to follow these cases. During the last decade, six patients with no ‘history of a bite’ were hospitalised with growing symptoms of rabies. The data were collected from each patient by the physicians and transferred to the Ministry of Health and Medical Education of Iran, and to the WHO Collaborating Center for Reference and Research on Rabies, Pasteur Institute of Iran as the only testing laboratory. Thus, they came to the attention of the surveillance system. Ante-mortem diagnosis was performed on saliva, cerebrospinal fluid and blood samples that were collected from the first patient by the physicians. Fresh brain specimens from all patients were kept in a mixture of 50% glycerol in phosphate-buffered saline and transported on ice to the WHO Collaborating Center for Reference and Research on Rabies. ResultsFor the first patient, rabies virus was investigated in saliva using the rapid tissue cell inoculation test (RTCIT) and the mouse inoculation test (MIT). Anti-rabies antibodies in this patient's serum and cerebrospinal fluid (CSF) were examined using the mouse neutralisation test (MNT). Fresh brain specimens from all patients were examined using the fluorescence antibody test (FAT) as recommended by the WHO laboratory manual in rabies as the post-mortem diagnostic test for rabies. Rabies infection was confirmed in all of the deceased patients. Anti-rabies antibodies were identified only in one patient's serum specimen. Testing also showed that the rabies virus isolated was the classic rabies virus (serotype 1), which is widespread in Iran. ConclusionsPrevention and control of this fatal disease require a sensitive surveillance system to follow ‘suspected’ animal and human rabies cases thoroughly through the improved reporting system, which contains the history of exposure, clinical examinations, symptoms and laboratory results. This study describes some notable human rabies infections and their transmission modes to prevent occupational accidents.

Anti-inflammatory compounds of the traditional Hungarian medicinal plant Centaurea sadleriana

The decoction of the aerial parts of Centaurea sadleriana JANKA (Asteraceae), a plant native to Hungary, is traditionally used to treat the wounds of sheep in the Southern Great Plain region. Phytochemical and pharmacological studies on this plant have not been performed so far. Only we have recently confirmed the wound healing effect of the plant on rats [1]. The objective of the present work was the in vivo and in vitro investigation of the anti-inflammatory effect of C. sadleriana and the isolation and identification of its active compounds. The concentrated methanol extract of aerial parts of C. sadleriana was partitioned using n-hexane and chloroform. These two fractions were further fractionated via VLC and the anti-inflammatory effects of the fractions were studied by in vitro (COX-1, COX-2 and LTB4 formation inhibitory activity) and in vivo (intraperitoneal and oral administration to rats) methods. Some of the fractions gained from the n-hexane extract possessed marked in vitro (70–85% LTB4 formation inhibition, 59–83% COX-1 inhibition, 80–92% COX-2 inhibition at a concentration of 50µg/ml) and in vivo anti-inflammatory effects (25–50% oedema volume reduction). Chromatographic purification (VLC, MPLC, HPLC, preparative TLC, CPC and gel filtration) of the active fractions resulted in the isolation of flavonoids, triterpenoids and lignans. Our present study confirmed the marked anti-inflammatory effect of C. sadleriana which may play role in the ethnomedicinal application of the plant.

Microvascular changes in large flame burn wound in sheep

Advances in local wound management with early excisional therapy have decreased morbidity and mortality of massive third-degree burn patients. Although blood redistribution within burned tissue is of clinical interest, few studies have longitudinally determined the regional blood flow of various layers of the burn wound. We used a conscious ovine model in which animals were subjected to 40% third degree burn. Burned tissue was divided into the four layers (i.e. skin, panniculus carnosus, adipose tissue, and skeletal muscle), and regional blood flow was determined separately, with fluorescent microspheres, while measuring systemic hemodynamics and total burned tissue microvascular fluid flux. The subburn adipose tissue exhibited a remarkable biphasic alteration in regional blood flow, whereas the skin layer showed only decreased blood flow during the whole experimental period. The increase in blood flow to the adipose tissue seems to be related to a sustained fluid filtrate in the postresuscitation period, resulting in edema formation mainly located in the adipose tissue at the endpoint.

Stimulation of oogenesis by proteinaceous adult diets for screwworm,Cochliomyia hominivorax(Diptera: Calliphoridae)

AbstractThe influence of protein in the adult diet on first cycle gonotrophic development was examined in newly colonized screwworm flies,Cochliomyia hominivorax(Coquerel), reared on an artificial larval diet and bred in subsequent generations from females stimulated to oviposit only after all individuals in a colony were expected to have matured their eggs. This latter criterion was established with the goal of reducing selection for early ovarian maturity and increased autogeny. Under these conditions, supplementing the diet with raw meat during the first week after adult emergence hastened egg maturation by two to four days or more, increased the percentage of seven- to ten-day-old females that was gravid by 45%, and boosted the number of eggs per gravid female byc.30%. The serous discharge from screwworm-infested sheep wounds, a casein–salt mixture, or casein in potassium hydroxide was as effective as raw meat. Addition of B vitamins to the casein–salt mixture was without further effect. The measures taken to reduce selection for altered gonotrophic development were not critically evaluated here, but they appeared successful in that age and protein affected ovarian maturation rates similarly in F2and F27. Fecundity measured as eggs matured per gravid female differed between generations, but appeared correlated with size differences that were unrelated to colonization duration.

Myofibroblast persistence in fetal sheep wounds is associated with scar formation.

Myofibroblast persistence in fetal sheep wounds is associated with scar formation.

Relative distribution and crosslinking of collagen distinguish fetal from adult sheep wound repair

Background/Purpose: Collagen deposition in midgestation fetal skin wounds occurs rapidly and in a normal reticular pattern unlike adult scar. Although collagen types I, III, and V are present in both fetal and adult skin wounds, their relative distribution and pattern of crosslinking are unknown. We compared the quantity, distribution, and crosslinking of specific collagen types in fetal and adult sheep wounds. Methods: Nine fetal lambs at 75, 100, and 120 days' gestation (term, 145 days) and their ewes received subcutaneous polyvinylalcohol (PVA) sponge implants. PVA sponges were harvested at 3, 7, or 14 days after implantation, were processed, and then analyzed for collagen content, distribution, and corsslinking by two-dimensional cyanogenbromide (2-D CNBr) peptide mapping. Collagen types were further analyzed in normal skin of fetal sheep at 75, 90, 125, and 140 days' gestation and in their ewes. Results: Between days 3 and 14 after implantation, total collagen deposition within PVA sponges increased 25-fold in fetal lambs but only 10-fold in adult sheep. The type I to III ratios inside 14-day sponges of 75-day gestation fetuses and adult ewes were 6.4 and 1.3, respectively. Thus, by day 14 in both fetal and adult sponges, type I collagen emerged as the major constituent. Although type V comprised less than 2% of normal skin collagen, α 1(V) chains constituted the greatest collagen fraction in 3-day fetal implants, whereas within 3-day adult sponges only α 2(V) collagen was detected. The total collagen content of unwounded fetal sheep skin increased twofold from 75 to 90 days' gestation. However, noncrosslinked forms of collagen type I diminished rapidly after 90 days' gestation, corresponding with the transition to scarring of fetal sheep wounds. Conclusions: Collagen types I, III, and V are deposited rapidly in fetal wounds and display an ontogenic transition in their metabolism from a fetal to an adult phenotype. Crosslinking of type I collagen increases during development and corresponds with the transition to scarring of fetal wounds after midgestation. These observations may help design strategies that induce a more fetallike repair of adult wounds.

Myofibroblast persistence in fetal sheep wounds is associated with scar formation

The scarless repair capabilities of the fetus are influenced by the size of the wound and the gestational age of the fetus. Whereas small wounds heal scarlessly, large wounds in the same fetus heal with scar. Myofibroblasts are specialized fibroblasts that express α-smooth muscle actin (α-SMA), a contractile cytoskeletal protein. The authors hypothesized that small fetal wounds that heal scarlessly will have a relative absence of myofibroblasts, whereas large wounds that heal with scar will have abundant myofibroblasts. In this study, an incisional wound and four punch biopsy wounds of 2, 4, 6, and 10 mm diameter were placed on the backs of 60- to 90-day-gestation fetal sheep (term, 145 days). Fourteen days after wounding, the healed fetal wounds were harvested, the repair morphology was determined (scarless, transitional repair, or scar), and the expression of α-SMA was analyzed by immunohistochemistry. In the second part of this study the authors analyzed the temporal expression of α-SMA in fetal wounds at 1, 2, 3, and 7 days after wounding in 70-day-gestation fetal sheep. In the 14-day wounds, the authors found that α-SMA was not expressed in any incisional or 2-mm wound that healed scarlessly, but it was expressed in all wounds that healed with scar. Overall, α-SMA expression strongly correlated with increasing wound size ( P < .005). Myofibroblasts were seen as early as 24 hours after wounding, and at 3 and 7 days all wounds showed strong expression of α-SMA. These results demonstrate that although myofibroblasts are induced early in fetal wound repair, by 14 days there is a notable lack of myofibroblasts in wounds that heal scarlessly and an abundance of myofibroblasts in those wounds that scar. By determining the factors that regulate the disappearance of the myofibroblast in scarless fetal wounds, the authors hope to gain new insights into the mechanisms of scarless fetal repair.

Fetal fibroblast contraction of collagen matrices in vitro: the effects of epidermal growth factor and transforming growth factor-beta.

Wound contraction is an important component of healing but, in the extreme, may lead to excessive scar formation and pathological wound contracture. Fetal rabbit wounds heal without contraction or scarring, whereas excisional fetal sheep wounds have been shown to contract, but no scarring or pathological wound contracture is noted. We used an in vitro model, the fibroblast-populated collagen lattice, to study the ability of fetal fibroblasts to coordinate contraction of a collagen matrix and the modulating effects of epidermal growth factor and transforming growth factor-beta 1 on this contraction. With increasing gestational age, fibroblasts increased the degree of collagen lattice contraction. Epidermal growth factor inhibited contraction by fetal fibroblasts, whereas transforming growth factor-beta 1 stimulated it. These findings suggest that while intrinsic differences between fetal and adult fibroblasts exist, polypeptide growth factors may operate at the site of tissue repair to alter cell phenotype. Further work is underway to delineate the role of soluble protein factors responsible for the absence of scarring and contracture seen in the fetal wound.