Wound Healing In Rat Model Research Articles

Effects of Metoclopramide and Ranitidine on Survival of Flat Template McFarlane Skin Flaps in a Rat Wound Healing Model

Wound healing re-provides the morphological integrity after trauma. We investigated the effects of Metoclopramide and Ranitidine on survival of flat template McFarlane skin flaps in an experimental wound healing model.Rats (n:32) were randomly allocated in following groups: Flap control (Control), Metoclopramide(MET), Ranitidine(RAN) and Metoclopramide+Ranitidine (MET+RAN). After flap elevation, ip 10 mg/kg Ranitidin or 5 mg/kg Metoclopramide or the combination of both drugs were administered for 3 days. Next analgesia was maintained. No additional drugs were used for controls. On 10th day, whole cut skin flaps were excised, fixed in buffered formaldehyde and processed with histological techniques. Paraffine sections were stained with Hematoxylen-Eosin, Mallory-Azan and immunohistochemically with Desmin and Fibronectin and then evaluated with light microscopy.Experimental groups showed differences for epidermal degeneration, edema, hypertrophy of the hair follicles, neutrophil infiltration and areolar degeneration. Metoclopramide or Ranitidine administration positively impacts wound healing.This unique study emphasizes the importance of considering Metoclopramide or Ranitidine for possible adverse effects on flap survival in surgical clinics, therefore the combination of both drugs is not more effective.

Cutaneous wound healing after treatment with plant-derived human recombinant collagen flowable gel.

Chronic wounds, particularly diabetic ulcers, represent a main public health concern with significant costs. Ulcers often harbor an additional obstacle in the form of tunneled or undermined wounds, requiring treatments that can reach the entire wound tunnel, because bioengineered grafts are typically available only in a sheet form. While collagen is considered a suitable biodegradable scaffold material, it is usually extracted from animal and human cadaveric sources, and accompanied by potential allergic and infectious risks. The purpose of this study was to test the performance of a flowable gel made of human recombinant type I collagen (rhCollagen) produced in transgenic tobacco plants, indicated for the treatment of acute, chronic, and tunneled wounds. The performance of the rhCollagen flowable gel was tested in an acute full-thickness cutaneous wound-healing rat model and compared to saline treatment and two commercial flowable gel control products made of bovine collagen and cadaver human skin collagen. When compared to the three control groups, the rhCollagen-based gel accelerated wound closure and triggered a significant jumpstart to the healing process, accompanied by enhanced re-epithelialization. In a cutaneous full-thickness wound pig model, the rhCollagen-based flowable gel induced accelerated wound healing compared to a commercial product made of bovine tendon collagen. By day 21 post-treatment, 95% wound closure was observed with the rhCollagen product compared to 68% closure in wounds treated with the reference product. Moreover, rhCollagen treatment induced an early angiogenic response and induced a significantly lower inflammatory response than in the control group. In summary, rhCollagen flowable gel proved to be efficacious in animal wound models and is expected to be capable of reducing the healing time of human wounds.

A Comparison Study of Growth Factor Expression following Treatment with Transcutaneous Electrical Nerve Stimulation, Saline Solution, Povidone-Iodine, and Lavender Oil in Wounds Healing

This study compared the effects of transcutaneous electrical nerve stimulation (TENS), saline solution (SS), povidone-iodine (PI), and lavender oil (Lavandula angustifolia) through expression of growth factors in a rat model of wound healing. Six experimental groups were established, each containing 8 rats: a healthy group with no incision wounds, an incision-control group, an incision and TENS group, an incision and SS group, an incision and PI group, and an incision and lavender oil group. Experiments continued for 5 days, after which the skin in the excision area was removed. Tissue concentrations of epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)-A were measured using enzyme-linked immunosorbent assay (ELISA). Tissue expressions of EGF, PDGF-A, and fibroblast growth factor (FGF)-2 were determined using immunohistochemistry. Wound closure progressed more rapidly in the TENS and lavender oil groups than in the control and other study groups. In particular, PDGF-A expressions in the dermis and EGF expression in the epidermis were significantly intense in the TENS group (P < 0.05). In addition, ELISA levels of growth factors such as PDGF-A and EGF were significantly higher in TENS group compared to the control group (P < 0.05). These immunohistochemical and ELISA results suggest that TENS may improve wound healing through increasing growth factors in the dermis and epidermis more than other topical applications.

Usefulness of Basic Fibroblast Growth Factor (bFGF) Loaded Dissolving Microneedles for Local Therapy of Skin Wounds

Purpose: The usefulness of dissolving microneedles (DMs) for local skin therapy by basic fibroblast growth factor (bFGF) was studied in rats. Methods: We prepared four kinds of bFGF-loaded DMs, approximately 500 μm length and 300 μm diameter at the bottom. Long-term stability and dissolution studies were performed by HPLC method. Pharmacokinetic and pharmacological evaluations were performed after administration of bFGF loaded DMs to rats. Results: The bFGF contents were 2.15 ± 0.07, 1.07 ± 0.04, 0.56 ± 0.07 and 0.12 ± 0.03 μg. The 100.2 ± 3.4%, 100.2 ± 3.3%, 99.3 ± 1.4% and 100.4 ± 3.0% of bFGF were recovered after 1, 3 and 6 months and 1 year incubation at 40°C. The bFGF was released from DMs within 5 min. In a pharmacokinetic study using 2.0 and 1.0 μg bFGF-loaded DMs, no systemic exposure of bFGF was detected. The initial bFGF concentrations in the rat skin tissue after administration of bFGF-loaded DMs to the hair-removed rat abdominal skin were 510.2 ± 20.1 ng/g wet weight for 2 μg bFGF DMs and 264.2 ± 56.5 ng/g wet weight for 1 μg DMs, declining slowly thereafter to 226.3 ± 33.5 and 105.1 ± 27.4 ng/g wet weight at 6 hr after administration. Good dose-dependency was observed. Pharmacological evaluation of bFGF-loaded DMs of 2.0, 1.0, 0.5, and 0.1 μg, in the wound healing rat model, all used DMs, but 0.1 μg DMs, showed good healing effects. Considered collectively, these results suggest the usefulness of bFGF-loaded DMs for local therapy of skin wound disease.

Red Deer Antler Extract Accelerates Hair Growth by Stimulating Expression of Insulin-like Growth Factor I in Full-thickness Wound Healing Rat Model.

In order to investigate and evaluate the effects of red deer antlers on hair growth in the full-thickness wound healing model, Sprague-Dawley rats were given incision wounds through the full thickness of their dorsal skin and deer antler was applied for 40 days. At specified intervals thereafter (4, 8, 16, 32 and 40 days), the animals were sacrificed and the wound site skins were excised, processed, and sectioned. At post-injury days 16, 32 and 40, longer and more active new hair appeared around the healing wound of antler-treated skin. Histological studies showed that the antler extract markedly increases the depth, size, and number of hair follicles. Expression of IGF-I (insulin-like growth factor) mRNA was detected by RT-PCR and real time RT-PCR. The result showed that the expression of IGF-I (days 16, 32, and 40) was obviously up-regulated in antler-treated skins compared to control skins. Similar results were seen in the ELISA analysis to quantify the IGF-I expression. These results support the notion that wound healing can cause hair growth by enhancing the expression of IGF-I. Deer antler extract appears to have the potential to promote hair growth and could be used in hair growth products.

In vivo evaluation on Malaysian coastal isolates of Gracilaria changii and Stichopus badionotus through heat-burn methicillin-resistant Staphylococcus aureus (MRSA) infection animal model

Staphylococcus aureus commonly causes bacterial infections such as boils, carbuncles, infections wounds, deep abscesses and bloodstream infections (or bacteraemia). Nowadays, it becomes more difficult to treat such infections due to the appearance of resistant strain known as methicillin-resistant Staphylococcus aureus(MRSA). The objective of this study was to screen on methanolic extracts of seaweed (Gracilaria changii) and local sea cucumber (Stichopus badionotus) for their anti-MRSA activities in vitro and in vivo; by a heat-burn, wound-healing model in rats. Both extracts demonstrated in vitro anti-MRSA activity. The sea cucumber extract demonstrated the same extent of wound healing as did vancomycin at P<0.05. The wound-healing activity of the seaweed extract was superior to that of vancomycin as shown by Tukey’s test (P<0.05). It was concluded that both of these crude extracts have a potential to become an alternative resource for anti-MRSA drugs. Key words: Staphylococcus aureus, methicillin-resistant Staphylococcus aureus(MRSA), heat-burn injury, marine’s natural productseaweed, sea cucumber, Malaysia.

Locally Administered Adipose-Derived Stem Cells Accelerate Wound Healing through Differentiation and Vasculogenesis

Despite advances in wound closure techniques and devices, there is still a critical need for new methods of enhancing the healing process to achieve optimal outcomes. Recently, stem cell therapy has emerged as a new approach to accelerate wound healing. Adipose-derived stem cells (ASCs) hold great promise for wound healing, because they are multipotential stem cells capable of differentiation into various cell lineages and secretion of angiogenic growth factors. The aim of this study was to evaluate the benefit of ASCs on wound healing and then investigate the probable mechanisms. ASCs characterized by flow cytometry were successfully isolated and cultured. An excisional wound healing model in rat was used to determine the effects of locally administered ASCs. The gross and histological results showed that ASCs significantly accelerated wound closure in normal and diabetic rat, including increased epithelialization and granulation tissue deposition. Furthermore, we applied GFP-labeled ASCs on wounds to determine whether ASCs could differentiate along multiple lineages of tissue regeneration in the specific microenvironment. Immunofluorescent analysis indicated that GFP-expressing ASCs were costained with pan-cytokeratin and CD31, respectively, indicating spontaneous site-specific differentiation into epithelial and endothelial lineages. These data suggest that ASCs not only contribute to cutaneous regeneration, but also participate in new vessels formation. Moreover, ASCs were found to secret angiogenic cytokines in vitro and in vivo, including VEGF, HGF, and FGF2, which increase neovascularization and enhance wound healing in injured tissues. In conclusion, our results demonstrate that ASC therapy could accelerate wound healing through differentiation and vasculogenesis and might represent a novel therapeutic approach in cutaneous wounds.

Acceleration of diabetic wound healing by collagen-binding vascular endothelial growth factor in diabetic rat model

Aims Vascular endothelial growth factor (VEGF) is an important active protein for the induction of angiogenesis and plays an important role in the tissue regeneration of diabetic wounds. In this study, we used collagen-binding VEGF in a diabetic rat model to investigate the effects of this new method. Methods We produced a fusion protein (CBD-VEGF) consisting of VEGF and a collagen-binding domain (CBD), which allowed VEGF to bind to collagen. The diabetic rat models were made by injected streptozocin (STZ) peritoneally and removed full thickness skin on the back. All the rats were randomly divided into 3 groups: PBS group ( n = 24), NAT-VEGF group ( n = 24), and CBD-VEGF group ( n = 24). After model establishment, the dissolved drugs were evenly given on the wounds using syringe. The healing rates were calculated and compared among the groups and the tissues of the wound were taken and evaluated for histological analysis. Results The CBD-VEGF group showed better result in wound healing rate, better vascularization and higher amount of VEGF in the wound granulation tissue compared with NAT-VEGF group and control. Conclusions Topical application of CBD-VEGF can promote diabetic wound healing in rat model, which could potentially provide a better therapeutic option for diabetic wounds.

Involvement of the endocannabinoid system in periodontal healing

Endocannabinoids including anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are important lipid mediators for immunosuppressive effects and for appropriate homeostasis via their G-protein-coupled cannabinoid (CB) receptors in mammalian organs and tissues, and may be involved in wound healing in some organs. The physiological roles of endocannabinoids in periodontal healing remain unknown. We observed upregulation of the expression of CB1/CB2 receptors localized on fibroblasts and macrophage-like cells in granulation tissue during wound healing in a wound-healing model in rats, as well as an increase in AEA levels in gingival crevicular fluid after periodontal surgery in human patients with periodontitis. In-vitro, the proliferation of human gingival fibroblasts (HGFs) by AEA was significantly attenuated by AM251 and AM630, which are selective antagonists of CB1 and CB2, respectively. CP55940 (CB1/CB2 agonist) induced phosphorylation of the extracellular-regulated kinases (ERK) 1/2, p38 mitogen-activated protein kinase (p38MAPK), and Akt in HGFs. Wound closure by CP55940 in an in-vitro scratch assay was significantly suppressed by inhibitors of MAP kinase kinase (MEK), p38MAPK, and phosphoinositol 3-kinase (PI3-K). These findings suggest that endocannabinoid system may have an important role in periodontal healing.

Correlation of near infrared absorption and diffuse reflectance spectroscopy scattering with tissue neovascularization and collagen concentration in a diabetic rat wound healing model

The objective of this paper was to correlate optical changes of tissue during wound healing measured by near infrared (NIR) and diffuse reflectance spectroscopy (DRS) with histologic changes in an animal model. Amplitude and phase of scattered light were obtained in a diabetic rat and control model and biopsies were taken for blood vessel ingrowth and collagen concentration. NIR absorption coefficient correlated with blood vessel ingrowth over time, in both the control and diabetic animals. DRS data correlated with collagen concentration. Previous publications by this group documented only the NIR changes during the wound healing process but this is the first reported correlation with histology data. The ability to correlate DRS scattering with collagen concentration during healing is another important and novel finding. This technology may play an important role clinically in assessing the efficacy of wound healing agents in diabetics.

Effect of a Low Molecular Weight Heparin Molecule, Dalteparin, on Cellular Apoptosis and Inflammatory Process in an Incisional Wound-Healing Model

In this study we aimed to test the effect of a low molecular weight heparin molecule, namely dalteparin, on the inflammation and cellular apoptosis in an incisional wound-healing model in rats. Eighteen male Sprague-Dawley rats were randomly assigned to three groups (n = 6 for each group). Two full-thickness skin incisions were made over cervical and lumbar regions of all rats. Group 1 (sham group) received no treatment, group 2 (control group) received 0.01 ml/g saline subcutaneously 12 h two times daily from 0 to 10th postoperative day, and group 3 (dalteparin group): received 1 IU/g dalteparin subcutaneously two times daily from 0 to 10th postoperative day. A histological evaluation was done by light microscopy. Apoptosis was detected immunohistochemically by anti-poly (ADP-ribose) polymerase p85 fragment pAb. The early inflammatory response and related tissue edema were depressed on day 3 in the dalteparin group when compared with those in the other groups (P < 0.05). Fibroblast proliferation was also depressed on day 10 in the dalteparin group compared to the others (P < 0.05). Furthermore, increased apoptosis was detected in the dalteparin group both on day 3 and day 10. Our results showed that dalteparin may adversely affect the incisional wound healing by suppressing the early inflammatory process and increasing cellular apoptosis; however, further studies are warranted to confirm the results.

Purification of antibacterial agents from Tragia involucrata–A popular tribal medicine for wound healing

Tragia involucrata has been widely used in traditional systems of medicine for a variety of diseases. In the present study, in vitro antibacterial properties of nine different compounds including vinyl hexylether, shellsol, 2,4-dimethyl hexane, 2-methylnonane and 2,6-dimethyl heptane were isolated from the leaf of Tragia involucrata studied against Escherichia coli, Proteus vulgaris and Staphylococcus aureus using the disc-diffusion method at 50 μg/ml concentrations. The compound vinyl hexylether showed a broad spectrum of activity. The highest activity was found in shellsol (50 μg/ml) against Proteus vulgaris and Staphylococcus aureus. Minimum inhibitory concentrations were determined for the effective compounds (MICs 2.5–40 μg/ml), shellsol and vinyl hexylether showed inhibitory action at the lowest dilution (10 μg/ml) than 2-methylnanone. Shellsol inhibited the growth of Staphylococcus aureus very effectively than the other compounds. These compounds showed bactericidal effects against all the tested bacteria (MBC, 12.25 μg/ml). However, the compound shellsol showed effective killing of wound causing bacteria ( Staphylococcus aureus). So, the study was focused on the constituent to evaluate wound healing in rat model. Rats that received 50 μg/kg, b.w. of shellsol showed complete healing after 24 days. Histological examination revealed an increase in the fibroblast, neovascularization, granulation and thickness of scar tissue after the treatment of shellsol as compared to control. The topical application of shellsol did not cause any toxic response on rat skin. Thus, the antibacterial properties of the constituents give some scientific basis to its usage in traditional medicine.

Electroporation improves transfection efficiency in rat wound healing model

Abstract Introduction: We are investigating the use of electroporation in vivo to enhance transfection efficiency and improve wound healing with DNA plasmid expression vectors for growth factors. Methods: For electroporation (EP) transfection efficiency and wound healing we used luciferase and keratinocyte growth factor (KGF) DNA plasmid expression vectors respectively (gWIZ-Lux vector controlled by CMV promoter, Invitrogen, Carlsbad, CA). Animals were electroporated at the site of injection within two minutes of plasmid administration, using a square wave electroporator (ECM 830, BTX Genetronics, San Diego, CA). For luciferase, photon emission was quantified using the IVIS Imaging System (Xenogen Corporation, Alameda, CA). For the KGF experiment, healing 4 cutaneous 8mm punch biopsies was assessed using image analysis software based on NIH image (Scion Image, Frederick, MD). A Sprague Dawley rat sepsis model of wound healing with partial cecal ligation was utilized. We found in previous experiments that wound healing was delayed in septic animals. Results: Single EP enhanced average luciferase expression three-fold compared to plasmid without EP (p 5 ± SEM (photons/sec). Values were recorded as total photon flux from each wound, with 4 wounds per rat. Wound size values represent average ± SEM (pixels). Conclusions: These results encourage us to explore further the possible benefit of electroporation-facilitated transfection of growth factors to improve wound healing.

Effects of Epicatechin Gallate on Wound Healing and Scar Formation in a Full Thickness Incisional Wound Healing Model in Rats

Catechins are naturally occurring polyphenolic compounds with putative anti-inflammatory, antioxidant and free radical scavenging effects in vitro. However, their potential effects in vivo have not been established. Therefore we have investigated the effects of the catechin epicatechin gallate (ECG), on scar formation in a full thickness incisional model of wound healing in rats. ECG showed a significant improvement in the quality of scar formation both in terms of maturity and orientation of the collagen fibers. An increase in inducible nitric oxide synthase and cyclooxygenase-2 and a decrease in arginase-I activity and protein levels were observed at earlier time points. In addition, an increase in the number of new blood vessels was observed in the ECG-treated group. This correlated with the protein levels of vascular endothelial growth factor, the most potent angiogenic protein known. This study has therefore demonstrated, for the first time, that catechins, namely ECG, can significantly improve the quality of wound healing and scar formation. These effects may in part be due to an acceleration of the angiogenic response and an up-regulation of the enzymes nitric oxide synthase and cyclooxygenase.

Connective Tissue Growth Factor and Its Correlation to Other Growth Factors in Experimental Granulation Tissue

Connective tissue growth factor (CTGF) is upregulated in a variety of fibrotic disorders, probably secondary to the activation and production of transforming growth factor-beta (TGF- g ). We have studied the expression of CTGF in a rat wound-healing model using Northern blot, in situ hybridization, and immunohistochemistry. The expression of CTGF mRNA in Northern blot and immunohistochemistry were correlated to the expression of TGF- g 1 and platelet-derived growth factor (PDGF). Northern hybridization showed the maximum expression of CTGF mRNA on day 14, whereas TGF- g 1 expression was maximal on days 7 and 14 and the time-related changes were smaller than for CTGF. PDGF A and PDGF B mRNA expressions were at maximum on day 14 and on day 21, respectively. In situ hybridization showed that fibroblast-like cells expressed CTGF most intensively, expression declining rapidly after day 14. CTGF mRNA and protein were found in blood vessel cells during the first week. In immunohistochemistry, all growth factors were expressed by fibroblast-like cells, macrophage-like cells, and blood vessels but CTGF-positive cells were fewer and were more restricted on days 5 and 7. These results demonstrate that CTGF expression together with TGF- g and PDGF are upregulated in wound healing, and CTGF expression in blood vessels suggests that CTGF is involved in angiogenesis.

Skin Blood Flow Response in the Rat Model of Wound Healing: Expression of Vasoactive Factors

Background. Although the microvascular blood flow response to wounding is predominantly vasodilation at skin sites with nutritive capillary perfusion (NUTR), there is a significant vasoconstrictive response at sites with high arteriovenous perfusion (AV). There may be a difference between NUTR and AV sites in the vasoactive factors which mediate the blood flow response to wounding. We measured the levels of mRNA expression of several potential mediators of the blood flow response to assess this possible difference. Materials and methods. We measured skin blood flow at wounds placed at the back, a NUTR site, and at the paw, an AV site, in 12 Wistar Kyoto rats. Measurements were performed at baseline and then at 7 days post wounding. There was a significant increase in blood flow at back wound sites, with a rise from 4.1 ± 0.3 ml/min/100 g to 9.8 ± 1.9 ml/min/100 g. At the undisturbed wound perimeter, outside the zone of granulation tissue, flow rose to 7.3 ± 1.1 ml/min/100 g. At the paw wound site, Day 0 flow was 8.8 ± 0.8 ml/min/100 g. At 7 days, there was a significant decrease in flow at wound center to 5.5 ± 0.5 ml/min/100 g. We measured the levels of inducible nitric oxide synthetase (iNOS), endothelin, endothelin receptor, vascular endothelial growth factor (VEGF), and keratinocyte growth factor (KGF) gene mRNAs using reverse transcriptase PCR. Results. There was a 10-fold increase in NOS mRNA in granulation tissue of both wounds on Day 7. There was a lesser but still substantial increase in the wound perimeter tissue. Levels of endothelin mRNA in the wound and wound perimeter were significantly lower at the paw than at the back. At baseline, the level of endothelin receptor B (ETrB) mRNA was greater at the back than at the paw. Wounding resulted in a substantial increase in EtrB mRNA levels in granulation tissue, reaching the same level at the back and paw wounds. There was also a substantial rise in EtrB mRNA levels at the paw wound perimeter, so that there was a reversal of the baseline condition, with paw levels actually surpassing the levels at the back perimeter. Conclusions. Thus, we have found significant changes in mediators both of vasoconstriction and vasodilation affecting the healing wound. These changes affect NUTR and AV sites in different ways. These results demonstrate the complexity of the regulatory processes controlling microvascular blood flow in wound healing.

Skin Blood Flow Response in the Rat Model of Wound Healing: Expression of Vasoactive Factors

Background. Although the microvascular blood flow response to wounding is predominantly vasodilation at skin sites with nutritive capillary perfusion (NUTR), there is a significant vasoconstrictive response at sites with high arteriovenous perfusion (AV). There may be a difference between NUTR and AV sites in the vasoactive factors which mediate the blood flow response to wounding. We measured the levels of mRNA expression of several potential mediators of the blood flow response to assess this possible difference. Materials and methods. We measured skin blood flow at wounds placed at the back, a NUTR site, and at the paw, an AV site, in 12 Wistar Kyoto rats. Measurements were performed at baseline and then at 7 days post wounding. There was a significant increase in blood flow at back wound sites, with a rise from 4.1 ± 0.3 ml/min/100 g to 9.8 ± 1.9 ml/min/100 g. At the undisturbed wound perimeter, outside the zone of granulation tissue, flow rose to 7.3 ± 1.1 ml/min/100 g. At the paw wound site, Day 0 flow was 8.8 ± 0.8 ml/min/100 g. At 7 days, there was a significant decrease in flow at wound center to 5.5 ± 0.5 ml/min/100 g. We measured the levels of inducible nitric oxide synthetase (iNOS), endothelin, endothelin receptor, vascular endothelial growth factor (VEGF), and keratinocyte growth factor (KGF) gene mRNAs using reverse transcriptase PCR. Results. There was a 10-fold increase in NOS mRNA in granulation tissue of both wounds on Day 7. There was a lesser but still substantial increase in the wound perimeter tissue. Levels of endothelin mRNA in the wound and wound perimeter were significantly lower at the paw than at the back. At baseline, the level of endothelin receptor B (ETrB) mRNA was greater at the back than at the paw. Wounding resulted in a substantial increase in EtrB mRNA levels in granulation tissue, reaching the same level at the back and paw wounds. There was also a substantial rise in EtrB mRNA levels at the paw wound perimeter, so that there was a reversal of the baseline condition, with paw levels actually surpassing the levels at the back perimeter. Conclusions. Thus, we have found significant changes in mediators both of vasoconstriction and vasodilation affecting the healing wound. These changes affect NUTR and AV sites in different ways. These results demonstrate the complexity of the regulatory processes controlling microvascular blood flow in wound healing.

Effects of transforming growth factor beta on corneal epithelial and stromal cell function in a rat wound healing model after excimer laser keratectomy.

Transforming growth factor beta (TGF-beta) regulates extracellular matrix deposition, cell proliferation, and migration, and is expressed in cornea. TGF-beta is thought to be involved in the corneal wound healing process. The central corneal area (3 mm in diameter) of Lewis rats was ablated using PTK mode excimer laser and the wound healing process was observed at 12 and 24 h and 2, 5, 10, and 30 days after treatment. The expression of TGF-beta 1, -beta 2 and -beta 3, TGF-beta type I and type II receptors, alpha 3, alpha 5, beta 4 integrin subunits, laminin and fibronectin was studied immunohistochemically. Antibody neutralizing TGF-beta 1, -beta 2 and -beta 3 was administered intraperitoneally, 50 micrograms daily, for 5 days after the laser treatment to investigate the effects of TGF-beta function blockade. At the leading edge of the regenerating epithelium, no TGF-beta type I and type II receptors and beta 4 integrin subunits were expressed after 24 h. Regenerating epithelium covered the ablated area after 2 days. An abnormal fibrotic layer was formed in the subepithelial area. This layer contained round-shaped cells in the stroma in the early stage (2-5 days after laser ablation) and spindle-shaped fibroblast-like keratocytes after 10 days. Laminin and fibronectin expression increased in the fibrotic layer. The increased stromal cells expressed TGF-beta isoforms and TGF-beta receptors. Neutralizing TGF-beta inhibited the stromal cell increase in the laser ablated area after 5 days. TGF-beta may be involved in epithelial cell migration and stromal cell reaction during the corneal wound healing process after excimer laser ablation in rat models.

Cyclosporine a impairs wound healing in rats

Cellular immune responses may play an important role in the early inflammatory and cellular phases of wound healing. Cyclosporine A (CSA), a new immunosuppressive agent, impairs cellular immunity and T-cell-dependent humoral immunity. Therefore, the effect of CSA-induced immunosuppression in a rat wound-healing model was studied. Sprague-Dawley rats underwent a standardized skin incision and subcutaneous implantation of sterile polyvinyl alcohol sponges. CSA was dissolved in olive oil and given by gavage to one group of animals at a total dose of 125 mg/kg/10 days. The control group received an equivalent volume of olive oil. Ten-day-old wounds were weaker in CSA-treated animals, both in the fresh state (282 ± 19 g vs 380 ± 27 g, P < 0.01), and after formalin fixation (1111 ± 74 g vs 1419 ± 57 g, P < 0.01). In addition, CSA-treated rats accumulated significantly less hydroxyproline in the wound sponge granuloma, an index of reparative collagen deposition. The impairment in wound healing occurred without differences in body weight gain or organ weights. There was a profound immunosuppression in the animals receiving CSA as determined by thymic lymphocyte blastogenesis in response to Con A and PHA. These findings suggest that immunosuppression in otherwise healthy animals impairs wound healing.