Wound Healing In Pigs Research Articles

Artificial Dermal Scaffold Loaded with Platelet-Rich Plasma Promotes Wound Healing in Pigs by Favoring Angiogenesis.

BackgroundThe development of artificial dermis provides a new therapeutic method for full-thickness skin defects. However, the slow regeneration of blood vessels in the wound site still cannot be solved perfectly. In our study, we combined platelet-rich plasma (PRP) with Lando® artificial dermal scaffold to promote vascular regeneration and wound healing in pigs.Material/MethodsFirst, PRP was compounded with the artificial dermal scaffold. Then, this material was co-cultured with human vascular endothelial cells (HUVECs) and the growth and proliferation of HUVECs were assessed. Bama miniature pigs wound models were fabricated, the materials were transplanted into the skin defect, and wound healing and blood vessel regeneration were assessed by HE staining and CD31 immunohistochemistry.ResultsScanning electron microscopy (SEM) showed that PRP formed round particles on the surface of the artificial dermis material. Cell co-culture experiments showed that the PRP composite artificial dermal scaffold can promote the growth and proliferation of HUVECs. CCK8 experiments demonstrated that the number of cells in the PRP composites group on days 2, 3, 4, and 5 was higher than that in the material alone group (P<0.01). The results of animal experiments showed that PRP composite artificial dermal material can promote wound healing. Histological staining and immunohistochemical staining indicated that the PRP composites group promoted epithelial tissue thickening and blood vessel regeneration in wounds (P<0.001).ConclusionsOur experimental results showed that the artificial dermal scaffold loaded with platelet-rich plasma can promote the revascularization of wounds and accelerated wound healing.

Effect of topical ozonetherapy on gingival wound healing in pigs: histological and immuno-histochemical analysis.

In this study, the effects of ozonetherapy on secondary wound healing were evaluated histologically and immuno-histochemically. Material and Methods: 8 healthy pigs were used in this study. Six wounds with 10 mm in diameter were created through the punch technique on the palatinal gingiva of each pig. Ozone gas was applied on only 3 wounds (test group) and the remaining 3 were left to natural healing (control group). Biopsy samples were taken from one of the wounds in each group on the third day, from another wound of each group on the seventh day, and from another one on the tenth day. Routine histological analysis and immuno-histochemical staining were performed to investigate transforming growth factor-beta (TGF-β) and (VEGF) expressions. Results: No statistical difference was found between the test and control groups in terms of collagen fibers, epithelial formation and inflammation scores. A VEGF expression found in the test group was statistically higher than control group samples taken on the 3rd and 7th day. There was no statistical difference between the test and control groups in terms of TGF-β expression on any of the sampling days. Conclusion: The topical application of ozone gas could be effective in the early stages of wound healing by increasing the amount of VEGF expression. Clinical Relevance: Topical application of ozone gas may be effective in the early stages of oral wound healing.

Transplanted mesenchymal stem cells are effective for skin regeneration in acute cutaneous wounds of pigs.

IntroductionWe investigated the effects of mesenchymal stem cells (MSCs) on cutaneous wound healing in pigs in order to develop new therapies to enhance wound healing in humans.MethodsWe cultured bone marrow cells from the femurs of male pigs, and the multipotency of these cells were then confirmed. The characteristics of the cultured cells were determined by flow cytometric analyses. The MSCs were injected intradermally into the skin of pigs as auto-transplantation, and linear full-thickness incisional wounds were made through the injected area immediately afterward.ResultsThe MSCs were found to be positive for SWC3a, CD44, SLA class I, CD29, CD44H, and CD90. At 28 days post-surgery, wounds treated with MSCs had healed well, with only very fine scars visible macroscopically. Histologically, collagen architecture was thick and elastic fibers appeared in the wounds. Histomorphologic scale analysis demonstrated that the wounds treated with MSCs scored better than the controls. Significantly larger fibroblasts were observed in the wounds treated with MSCs than controls.ConclusionThese results indicate that transplantation of MSCs causes wounds to heal almost completely, possible indicating regeneration to normal skin. We hypothesize that the transplantation protocol described in this study may also be applicable to human wound healing.

Dual therapeutic functions of F-5 fragment in burn wounds: preventing wound progression and promoting wound healing in pigs

Burn injuries are a leading cause of morbidity including prolonged hospitalization, disfigurement, and disability. Currently there is no Food and Drug Administration-approved burn therapeutics. A clinical distinction of burn injuries from other acute wounds is the event of the so-called secondary burn wound progression within the first week of the injury, in which a burn expands horizontally and vertically from its initial boundary to a larger area. Therefore, an effective therapeutics for burns should show dual abilities to prevent the burn wound progression and thereafter promote burn wound healing. Herein we report that topically applied F-5 fragment of heat shock protein-90α is a dual functional agent to promote burn wound healing in pigs. First, F-5 prevents burn wound progression by protecting the surrounding cells from undergoing heat-induced caspase 3 activation and apoptosis with increased Akt activation. Accordingly, F-5–treated burn and excision wounds show a marked decline in inflammation. Thereafter, F-5 accelerates burn wound healing by stimulating the keratinocyte migration-led reepithelialization, leading to wound closure. This study addresses a topical agent that is capable of preventing burn wound progression and accelerating burn wound healing.

Bulbine Natalensis and Bulbine Frutescens promote cutaneous wound healing

Ethnopharmacological relevanceThe gel from the leaves of Bulbine natalensis (BN) and Bulbine frutescens (BF) is commonly used as a traditional medicine in South Africa for the treatment of skin wounds and burns. Treatment with both leaf gel extracts has previously been demonstrated to increase tensile strength and protein and DNA content in pig dermal wounds. This study examined the effect of the leaf gel extracts in vivo on histology of wound healing in pigs to elucidate the mechanism of increased tensile strength. Materials and methodsMirror imaged wounds on the dorsum of 12 post weaning female pigs were treated with either BN or BF, biopsied at days 2, 4, 7, 10 and 16 post-wounding and fixed. Sections of wound tissue were then stained with haematoxylin and eosin and Mallory's stain to analyse the general morphology and collagen arrangement; and smooth muscle actin, vascular endothelial growth factor (VEGF) and transforming growth factor β (TGFβ) receptors were immunolocalised. ResultsHistological analysis of the wound tissue in the study indicated earlier wound contraction and collagen deposition in both treatment groups with re-organisation of the collagen (indicating collagen maturation) evident as early as at day 10. ConclusionThe results of this study suggests that the leaf extracts increase tensile strength by increasing fibroplasia, differentiation of fibroblasts into myofibroblasts, and increased collagen deposition and maturation. This study further validates the use of the Bulbine leaf gels for the treatment of skin wounds.

Enhanced cryoprecipitate for skin graft and donor site wound healing in pigs

Due to similarities in skin characteristics, the authors hypothesise that a pig model would most accurately show the ability of autologous, enhanced cryoprecipitate (eCryo) to improve the wound healing of split-thickness skin grafts (STSGs) and corresponding donor sites. Fifty-two STSGs (5 × 5 cm) were fashioned and treated according to a randomised protocol with an autologous eCryo-treated and a control group. Macroscopic assessment, histological evaluation and cellular composition were completed at days 7, 14, 21 and 28. Thirty-two donor sites were also created and assessed in a similar manner. Histologic analysis showed enhancement of healing over all time points for eCryo-treated donor sites. All other results showed no statistically significant improvement with the use of eCryo. Autologous cryoprecipitate appears to be a safe, inexpensive and easy-to-use alternative to fibrin glue, which carries risks and is, in many cases, prohibitively expensive. Further studies are necessary to evaluate the full potential of eCryo. Interestingly, eCryo application may improve donor site aesthetic appearance. We believe that a pig model most reliably simulates eCryo's behaviour in humans to accurately reflect its future clinical applicability.

Developing a Porcine Model for Study of Vocal Fold Scar

The porcine larynx is very similar in size and structure to that of humans, and wound healing in pigs is very similar to that of humans. However, the pig is not often used in vocal fold scar research because it is difficult to view the vocal folds endoscopically. To further assess the pig as a model for studying vocal scar, we compared the plane of surgical dissection in the mucosa of four porcine vocal folds with that in eight human cadaver larynges. The plane of dissection was quite similar in porcine and human larynges, occurring within the loose layer of the superficial lamina propria. We also compared healing of porcine vocal folds after elevation and replacement of an epithelial flap versus excision of epithelium, leaving an open wound. After 6 weeks, larynges were harvested for histologic examination. There was no significant difference between the mucosa of the normal vocal fold and that of the healed microflap. However, after healing of epithelial excision, there was a depressed scar, with average lamina propria thickness of 302 μm versus 864 μm for the normal fold (P<0.05). Finally, to document that the mucosal wave can be evaluated in the porcine larynx, we developed a preparation that removes the false vocal folds, to allow ex vivo phonation. Experimentally created scar in the porcine larynx is a favorable model for the study of vocal fold healing and for assessment of treatments for vocal fold scar.

Accelerated Porcine Wound Healing after Treatment with α-Gal Nanoparticles

The α-gal epitope is a carbohydrate antigen that interacts specifically with the natural anti-Gal antibody--the most abundant antibody in humans. Anti-Gal/α-gal epitope interaction activates complement to generate chemotactic factors that induce rapid recruitment of macrophages. The authors hypothesized that α-gal epitopes on nanoparticles can accelerate wound healing by inducing rapid recruitment and activation of macrophages in wounds. α-Gal nanoparticles were generated from phospholipids, cholesterol, and α-gal glycolipids. α-Gal nanoparticle treatment of wounds was studied in 12 α1,3galactosyltrasferase knockout pigs. Like humans, these pigs lack α-gal epitopes and produce the natural anti-Gal antibody. Full-thickness wounds (20 × 20 mm) with tattooed borders were created on the back of pigs. α-Gal nanoparticles (10 or 100 mg) were topically applied onto the wounds. Saline-treated wounds served as control. Wound open surface area was measured every 3 to 4 days during dressing changes. Wounds from euthanized pigs were subjected to histological evaluation. Treated wounds displayed many more macrophages and increased angiogenesis than control wounds in the same pig. On day 10, wounds treated with 10 mg and 100 mg displayed 35 and 60 percent decreased open surface area compared with control wounds, respectively, and 80 and 90 percent less than control wounds on day 13 (p < 0.05). No keloid formation or no increase in scar formation was observed on day 60. α-Gal nanoparticle treatment of wounds accelerates macrophage recruitment, angiogenesis, and wound healing in pigs producing the anti-Gal antibody. As humans produce high titers of anti-Gal antibodies, this treatment may exhibit a similar beneficial effect in the clinical setting.

The effect of a combination of 0.1% octenidine dihydrochloride and 2% 2‐phenoxyethanol (octenisept®) on wound healing in pigs in vivo and its in vitro percutaneous permeation through intact and barrier disrupted porcine skin

A combination of 0.1% octenidine dihydrochloride and 2% 2-phenoxyethanol (octenisept) is a commonly used disinfectant in human medicine. As porcine skin represents an adequate model for human skin, the effect of octenidine dihydrochloride and phenoxyethanol on wound healing is studied in pigs. Furthermore, the in vitro percutaneous permeation of the test substances is studied. The impact of the test formulations on wound healing is examined (A) under non occlusive conditions and (B) in comparison to another disinfectant based on povidone-iodine under occlusive conditions, while wounds are treated daily with the test substances. The percutaneous permeation of octenidine dihydrochloride and phenoxyethanol is studied in Franz-type diffusion cells with intact skin as well as barrier disrupted after tape stripping. Compared with povidone-iodine or vehicle treatment as well as untreated control wounds the treatment of wounds with the test formulation has no influence on the healing rate in pigs and does not induce retardation of wound healing. The in vitro diffusion experiment reveals that octenidine dihydrochloride is only detectable in the acceptor chamber of three-barrier disrupted skin samples. Phenoxyethanol permeates through intact porcine skin in amounts of 11.3% and through barrier disrupted skin in amounts of 43.9%

Effects of platelet-rich plasma on intestinal wound healing in pigs

Anastomotic dehiscence and leakage remain a major problem in gastrointestinal surgery. Recently, attention has been focused on cellular acceleration of the wound healing process using platelet-rich plasma (PRP) and this study reports the effects of PRP on intestinal wound healing in pigs. Autologous PRP was obtained from 35 pigs that were then subjected to two intestinal anastomosis procedures. Activated PRP was applied at one of the anastomosis sites, while the other site served as control. After 24, 48, 72 and 96 h and then at 7 days, histology was performed and wound breaking strength was measured at 72 h and 7 days. PRP application appeared to increase granulation tissue and fibrosis, but did not influence anastomotic breaking strength.

Effects of attention and rewarded activity on immune parameters and wound healing in pigs

Challenging animals with a demanding situation they are able to cope with and where they are rewarded may be a source of positive emotions and possibly of increased welfare. In order to test if this results in changes of immunological parameters and wound healing, 56 pigs (7–20 weeks of age), housed in groups of 8 animals each, were successfully trained to recognize and localize an individual acoustic summons and to receive a small portion of feed as a reward. Immune reactions and the development of a standardized biopsy wound were compared to values of conventionally fed control groups of equal size and animal-to-feeding-place ratio (2:1). In the experimental animals a significantly higher concentration of IgG as well as an increased in vitro T-cell proliferation to ConA but a reduced LPS-induced proliferation of B-cells was found, while basal salivary cortisol concentrations were similar. Wound development was better in the experimental animals as measured by the area of the inflammatory corona. It decreased more rapidly in the experimental animals since the 5th day after biopsy and was significantly smaller than in the control groups. We conclude that environmental enrichment by equipment provoking attention and cognitive activity which is rewarded by feed may play a beneficial role for physical welfare of intensively housed pigs.

Dermal excisional wound healing in pigs following treatment with topically applied pure oxygen

Hypoxia, caused by disrupted vasculature and peripheral vasculopathies, is a key factor that limits dermal wound healing. Factors that can increase oxygen delivery to the regional tissue, such as supplemental oxygen, warmth, and sympathetic blockade, can accelerate healing. Clinical experience with adjunctive hyperbaric oxygen therapy (HBOT) in the treatment of chronic wounds have shown that wound hyperoxia may increase granulation tissue formation and accelerate wound contraction and secondary closure. However, HBOT is not applicable to all wound patients and may pose the risk of oxygen toxicity. Thus, the efficacy of topical oxygen treatment in an experimental setting using the pre-clinical model involving excisional dermal wound in pigs was assessed. Exposure of open dermal wounds to topical oxygen treatment increased tissue pO 2 of superficial wound tissue. Repeated treatment accelerated wound closure. Histological studies revealed that the wounds benefited from the treatment. The oxygen treated wounds showed signs of improved angiogenesis and tissue oxygenation. Topically applied pure oxygen has the potential of benefiting some wound types. Further studies testing the potential of topical oxygen in pre-clinical and clinical settings are warranted.

Enhanced adenoviral-vector mediated gene transfer using human albumin solder.

Laser tissue welding with human albumin solder (HAS) has been used as an alternative method of wound closure. Adenoviral vectors have been used to introduce various cytokine genes into wounds to accelerate wound closure. In the present study, we were interested in the effect of HAS on adenoviral vector transfer of the beta-galactosidase (beta-gal) gene in vitro and in vivo. 3T3 fibroblasts were used to study the effect of HAS on beta-gal gene transfer in vitro. The presence of beta-gal was determined by Western blot, and its activity by a colorimetric assay. A punch biopsy model of wound healing in pigs was used for in vivo experiments. HAS increased the efficiency of adenoviral-mediated beta-gal transduction and stabilized the adenovirus at room temperature. HAS protected adenovirus from inactivation by laser, both in vitro and in vivo. HAS may stabilize adenoviral vectors to deliver cytokine genes in future wound healing experiments.

Detection of Basement Membrane Zone Antigens During Epidermal Wound Healing in Pigs

Bullous pemphigoid (BP) antigen, laminin, and type IV collagen, 3 distinct antigens of basement membrane, were studied by indirect immunofluorescence in the epidermal-dermal junction of re-epithelializing wounds. Partial thickness wounds were made with a dermatome in the skin of white Yorkshire pigs. After 2 or 3 days, the wound site and the surrounding normal skin were excised and cryostat sections were studied using BP sera as well as whole antisera and affinity purified antibodies to laminin and type IV collagen. Laminin and type IV collagen were detected in the basement membrane zone of normal epidermis and at the re-epithelializing epidermal-dermal junction for a variable distance into the healing wound but both were absent from the more distal migrating epidermis. In contrast, BP antigen extended from the basement membrane zone of normal skin throughout the entire epidermal-dermal junction of dermis. These results suggest that in the re-epithelization of superficial wounds laminin and type IV collagen are not present in the initial epidermal-dermal interaction of the migrating epithelium but that BP antigen may be important in this early interaction.