The effect of short, high intensity magnetic field pulses on the healing of skin wounds in rats

The object of this study was to examine the effect of high intensity, short duration pulsed electromagnetic fields (PEMF) on the healing of full thickness skin wounds in rats. Full thickness skin wounds were surgically created in two groups of Sprague-Dawley male rats. The rats were randomly divided into two groups, each containing 20 rats. Animals in the treatment group received treatments with the PEMF device on day 0, 3, 7, 9, 12, 14, 17, and 22, while the rats in the control group were subjected to the same procedure, but with the PEMF device not activated. Photographs of the surgically created wounds were obtained on day 0, 3, 7, 9, 12, 14, 17, and 22. Wound contraction (WC), wound epithelialization (WE), non-healed wound, and contraction-epithelialization (CE) ratio were calculated for each wound. No significant difference was found between the two groups for the parameters of WC, WE, non-healed wound, and CE ratio. A significant group x time interaction was found for WE and CE ratio. This type of PEMF did not have a significantly beneficial effect on wound healing. Wounds in the PEMF treated group were relatively less contracted and showed a compensatory increase in epithelialization in the early stages of wound repair.     

Pulsed electromagnetic fields accelerate wound healing in the skin of diabetic rats

Delayed wound healing is a common complication in diabetes mellitus. From this point of view, the main purpose of the present study is to investigate the effect of extremely low frequency pulsed electromagnetic fields (ELF PEMFs) on skin wound healing in diabetic rats. In this study, diabetes was induced in male Wistar rats via a single subcutaneous injection of 65 mg/kg streptozocin (freshly dissolved in sterile saline, 0.9%). One month after the induction of diabetes, a full‐thickness dermal incision (35 mm length) was made on the right side of the paravertebral region. The wound was exposed to ELF PEMF (20 Hz, 4 ms, 8 mT) for 1 h per day. Wound healing was evaluated by measuring surface area, percentage of healing, duration of healing, and wound tensile strength. Obtained results showed that the duration of wound healing in diabetic rats in comparison with the control group was significantly increased. In contrast, the rate of healing in diabetic rats receiving PEMF was significantly greater than in the diabetic control group. The wound tensile strength also was significantly greater than the control animals. In addition, the duration of wound healing in the control group receiving PEMF was less than the sham group. Based on the above‐mentioned results we concluded that this study provides some evidence to support the use of ELF PEMFs to accelerate diabetic wound healing. Further research is needed to determine the PEMF mechanisms in acceleration of wound healing in diabetic rats. Bioelectromagnetics 31:318–323, 2010. © 2010 Wiley‐Liss, Inc.     

Curcumin treatment enhances the repair and regeneration of wounds in mice exposed to hemibody gamma-irradiation

Hemibody irradiation in multiple fractionated doses is frequently used for the treatment of various neoplastic disorders. It produces both acute and late effects on the skin and subcutaneous tissues that have profound implications in the healing of surgical wounds. Because of the crucial practical importance of hemibody radiation exposure associated with skin wounds, it is imperative to investigate the efficacy of cost-effective herbal products in the reconstruction of irradiated wounds. Therefore, the effect of pretreatment of curcumin was studied on the healing of excision wound in mice exposed to 2, 4, 6, or 8 Gy of hemibody gamma-radiation. A full-thickness skin wound was created by removing the skin flap of the dorsum of 8- to 10-week-old Swiss albino mice partially (lower half, below the rib cage) exposed to 2, 4, 6, or 8 Gy of gamma-radiation. The progression of wound contraction was monitored periodically by capturing video images of the wound, where the first image of each wound from different groups was obtained 1 day after wounding and that day was considered as day 0. Eight animals were used in each group at each exposure dose for wound contraction studies. Furthermore, the effect of curcumin on mean healing time after exposure of mice to 2, 4, 6, or 8Gy of hemibody gamma-radiation was also evaluated, where eight animals were used in each group at each exposure dose. Collagen, hexosamine, DNA, nitric oxide, and histologic profiles were also evaluated during the course of healing of excision wounds at days 4, 8, and 12 after irradiation treated or not with curcumin before exposure to 0 or 6 Gy of gamma-radiation. Six animals were used in each group at each interval for each biochemical parameter studied, except for histologic evaluations, where four animals were used in each group at each interval. Exposure of mice to different doses of gamma-radiation resulted in a dose-dependent delay in contraction and wound-healing time of excision wound, whereas curcumin pretreatment caused a significant elevation in the rate of wound contraction and a decrease in the mean wound-healing time. Treatment with curcumin before irradiation enhanced the synthesis of collagen, hexosamine, DNA, nitrite, and nitrate, and histologic assessment of wound biopsy specimens revealed improved collagen deposition and an increase in fibroblast and vascular densities. The authors' study demonstrates that curcumin pretreatment has a conducive effect on the irradiated wound and could be a substantial therapeutic strategy for ameliorating radiation-induced delay in wound repair in cases of radiation-induced skin injuries.     

EGF and TGF-alpha in wound healing and repair

Wound healing is a localized process which involves inflammation, wound cell migration and mitosis, neovascularization, and regeneration of the extracellular matrix. Recent data suggest the actions of wound cells may be regulated by local production of peptide growth factors which influence wound cells through autocrine and paracrine mechanisms. Two peptide growth factors which may play important roles in normal wound healing in tissues such as skin, cornea, and gastrointestinal tract are the structurally related peptides epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). EGF/TGF-alpha receptors are expressed by many types of cells including skin keratinocytes, fibroblasts, vascular endothelial cells, and epithelial cells of the GI tract. In addition, EGF or TGF-alpha are synthesized by several cells involved in wound healing including platelets, keratinocytes, and activated macrophages. Healing of a variety of wounds in animals and patients was enhanced by treatment with EGF or TGF-alpha. Epidermal regeneration of partial thickness burns on pigs or dermatome wounds on patients was accelerated with topical application of EGF or TGF-alpha, and EGF treatment accelerated healing of gastroduodenal ulcers. EGF also increased tensile strength of skin incisions in rats and corneal incisions in rabbits, cats, and primates. Additional research is needed to better define the roles of EGF, TGF-alpha and their receptor in normal wound healing, to determine if alterations have occurred in the EGF/TGF-alpha system in chronic wounds, and optimize vehicles for effective delivery of peptide growth factors to wounds.     

The Effect of Mesenchymal Stem Cells and Chitosan Gel on Full Thickness Skin Wound Healing in Albino Rats: Histological,Immunohistochemical and Fluorescent Study

Background

Wound healing involves the integration of complex biological processes. Several studies examined numerous approaches to enhance wound healing and to minimize its related morbidity. Both chitosan and mesenchymal stem cells (MSCs) were used in treating skin wounds. The aim of the current work was to compare MSCs versus chitosan in wound healing, evaluate the most efficient route of administration of MSCs, either intradermal or systemic injection, and elicit the mechanisms inducing epidermal and dermal cell regeneration using histological, immunohistochemical and fluorescent techniques.

Material and Methods

Forty adult male Sprague Dawley albino rats were divided into four equal groups (ten rats in each group): control group (Group I); full thickness surgical skin wound model, Group II: Wound and chitosan gel. Group III: Wound treated with systemic injection of MSCs and Group IV: Wound treated with intradermal injection of MSCs. The healing ulcer was examined on day 3, 5, 10 and 15 for gross morphological evaluation and on day 10 and 15 for histological, immunohistochemical and fluorescent studies.

Results

Chitosan was proved to promote wound healing more than the control group but none of their wound reached complete closure. Better and faster healing of wounds in MSCs treated groups were manifested more than the control or chitosan treated groups. It was found that the intradermal route of administration of stem cells enhanced the rate of healing of skin wounds better than the systemic administration to the extent that, by the end of the fifteenth day of the experiment, the wounds were completely healed in all rats of this group. Histologically, the wound areas of group IV were hardly demarcated from the adjacent normal skin and showed complete regeneration of the epidermis, dermis, hypodermis and underlying muscle fibers. Collagen fibers were arranged in many directions, with significant increase in their area percent, surrounding fully regenerated hair follicles and sebaceous glands in the dermis of the healed areas more than in other groups.

Conclusion

MSCs enhanced the healing process of wound closure more than chitosan gel treatment. Furthermore, MSCs injected intradermally, were more efficient in accelerating wound healing than any other mode of treatment.     

创面生物活性玻璃修复材料促进家猪创面愈合的实验研究

目的:观察创面生物活性玻璃修复材料对家猪皮肤创面的促愈合作用。方法:选择14头家猪,随机分成7组,每组2头,在每头猪的脊柱两旁制造3个4×4cm的全层皮肤缺损的创面模型,每头猪6个创面又分成实验组和空白对照组,于试验后每天观察创面愈合情况,第1、3、7、14、21、28、35天图像分析计算创面愈合率,并同时取创面组织行组织学染色,观察各组材料对家猪皮肤全层缺损创面愈合的影响。结果:在涂材料的实验组和空白对照组创面愈合时间分别是23.19±1.27d、29.52±1.54d两组组间比较,具有统计学意义(P<0.05);实验组的创面愈合率在各时间段均高于空白对照组,差异有统计学意义(P<0.05);组织学观察实验组的上皮化程度、表皮生长、成纤维细胞、毛细血管数量均好于空白对照组。结论:创面生物活性玻璃修复材料对家猪皮肤创面愈合具有促进作用,可作为一种新型的促愈合覆盖材料进一步研究。     

VAC 技术治疗兔耳缺血性创面的实验研究

目的:观察间歇和持续负压下缺血创面不同处理与愈合的关系。方法:实验前1天,用脱毛剂(Nair,美国)对兔耳背脱毛。动物用1%戊巴比妥钠耳缘静脉注射麻醉(30 mg/kg体重),固定于手术台。75%乙醇消毒双侧耳背皮肤。距耳根3-3.5cm处分离、结扎兔耳中央神经血管束。在耳背中部形成直径2.5cm全层皮肤缺损创面(保留软骨膜)[1]。止血后置动物于特制木盒内。42只大白兔共84个创面,随机分为-50mmHg-75mmHg和-100mmHg 3大组,分别施以间歇负压(运行2分钟,停1分钟)和持续负压组。实验分别运用-50mmHg,-75mmHg,-100mmHg三个不同负压值进行连续、间歇治疗兔耳缺血性创面,观察伤后1,3,7,10,14,20d创面愈合情况,取伤后7d组织标本进行Western blot、HE染色,观察VEGF(vascular endothelial growth factor)的表达及创面上皮的再生和肉芽组织生长情况[1]。以及各时间点细胞凋亡的检测。结果:-50mmHg(纱布+海绵)间歇负压引流技术治疗兔耳缺血性创面的愈合最快,-75mmHg治疗组次之,-100mmHg治疗组创面愈合最慢。在同一时间点上,-50mmHg治疗组与-75mmHg,-100mmHg治疗组和空白对照组之间相比,能够更快地促进创面VEGF的表达和肉芽组织的再生,毛细血管增多。封闭负压治疗能够降低创面组织细胞的凋亡的发生。结论:(1)封闭负压治疗能够促进缺血创面的肉芽组织再生及VEGF的表达,减少创面组织细胞的凋亡的发生;(2)-50mmHg间歇封闭负压治疗效果最好。     

创面生物活性玻璃修复材料促进家猪创面愈合的实验研究

目的：观察创面生物活性玻璃修复材料对家猪皮肤创面的促愈合作用。方法：选择14头家猪,随机分成7组,每组2头,在每头猪的脊柱两旁制造3个4×4cm的全层皮肤缺损的创面模型,每头猪6个创面又分成实验组和空白对照组,于试验后每天观察创面愈合情况,第1、3、7、14、21、28、35天图像分析计算创面愈合率,并同时取创面组织行组织学染色,观察各组材料对家猪皮肤全层缺损创面愈合的影响。结果：在涂材料的实验组和空白对照组创面愈合时间分别是23.19±1.27d、29.52±1.54d两组组间比较,具有统计学意义（P〈0.05）;实验组的创面愈合率在各时间段均高于空白对照组,差异有统计学意义（P〈0.05）;组织学观察实验组的上皮化程度、表皮生长、成纤维细胞、毛细血管数量均好于空白对照组。结论：创面生物活性玻璃修复材料对家猪皮肤创面愈合具有促进作用,可作为一种新型的促愈合覆盖材料进一步研究。     

Atropa belladonna L. water extract: modulator of extracellular matrix formation in vitro and in vivo

Previously, we found that treatment of cutaneous wounds with Atropa belladonna L. (AB) revealed shortened process of acute inflammation as well as increased tensile strength and collagen deposition in healing skin wounds (Gál et al. 2009). To better understand AB effect on skin wound healing male Sprague-Dawley rats were submitted to one round full thickness skin wound on the back. In two experimental groups two different concentrations of AB extract were daily applied whereas the control group remained untreated. For histological evaluation samples were removed on day 21 after surgery and stained for wide spectrum cytokeratin, collagen III, fibronectin, galectin-1, and vimentin. In addition, in the in vitro study different concentration of AB extract were used to evaluate differences in HaCaT keratinocytes proliferation and differentiation by detection of Ki67 and keratin-19 expressions. Furthermore, to assess ECM formation of human dermal fibroblasts on the in vitro level fibronectin and galectin-1 were visualized. Our study showed that AB induces fibronectin and galectin-1 rich ECM formation in vitro and in vivo. In addition, the proliferation of keratinocytes was also increased. In conclusion, AB is an effective modulator of skin wound healing. Nevertheless, further research is needed to find optimal therapeutic concentration and exact underlying mechanism of action.     

Accelerated healing of full-thickness skin wounds in a wet environment

Full-thickness skin wounds are preferably allowed to heal under controlled hydration dressings such as hydrocolloids. It was hypothesized that a wet (liquid) environment rather than a dry or moist one would accelerate the wound healing process. We compared skin repair by secondary intention in full-thickness skin wounds in wet (saline), moist (hydrocolloid), and dry (gauze) conditions in an established porcine wound healing model. The study included three animals with a total of 70 wounds layered in a standardized fashion on the back of young Yorkshire pigs. Twelve days after wounding, 0 percent of dry, 20 percent of moist, and 86 percent of saline-treated wounds were completely reepithelialized (p values = 0.0046 and 0.027 for saline wounds compared with dry and moist wounds, respectively). The accelerated healing was caused at least in part by faster contraction in wet wounds (p value < 0.005 compared with that of other groups 9 and 12 days after wounding). Development of granulation tissue was faster in moist conditions than it was for dry and wet wounds. The thickness and number of cell layers of the newly formed epidermis were greater in dry and wet wounds than in moist ones. It was concluded that these full-thickness porcine skin wounds healed faster in a wet environment than in a moist one. Dry wounds healed more slowly than moist wounds. The basic mechanisms of skin wound repair were influenced by the treatment modality as demonstrated by the observed differences in granulation tissue formation, reepithelialization, and rate of wound contraction.     

The possible effect of the mechanical factor on the completeness of the regeneration of the spinal skin in mice

In mouse tissues, regenerates forming in the place of full-thickness skin wounds on the back, were exposed to dosed mechanical injuries. As a result the structure of final regenerates in some animals differed from the scar, that is usually formed after healing of this type of wound.     

Mice that lack matrix metalloproteinase-9 display delayed wound healing associated with delayed reepithelization and disordered collagen fibrillogenesis

Matrix metalloproteinase- (MMP-9) is involved in processes that occur during cutaneous wound healing such as inflammation, matrix remodeling, and epithelialization, To investigate its role in healing, full thickness skin wounds were made in the dorsal region of MMP-9-null and control mice and harvested up to 14 days post wounding. Gross examination and histological and immunohistochemical analysis indicated delayed healing in MMP-9-null mice. Specifically, MMP-9-null wounds displayed compromised reepithelialization and reduced clearance of fibrin clots. In addition, they exhibited abnormal matrix deposition, as evidenced by the irregular alignment of immature collagen fibers. Despite the presence of matrix abnormalities, MMP-9-null wounds displayed normal tensile strength. Ultrastructural analysis of wounds revealed the presence of large collagen fibrils, some with irregular shape. Keratinocyte proliferation, inflammation, and angiogenesis were found to be normal in MMP-9-null wounds. In addition, VEGF levels were similar in control and MMP-9-null wound extracts. To investigate the importance of MMP-9 in wound reepithelialization we tested human and murine keratinocytes in a wound migration assay and found that antibody-based blockade of MMP-9 function or MMP-9 deficiency retarded migration. Collectively, our observations reveal defective healing in MMP-9-null mice and suggest that MMP-9 is required for normal progression of wound closure.     

Extracellular vesicle‐enclosed miR‐486‐5p mediates wound healing with adipose‐derived stem cells by promoting angiogenesis

Adipose‐derived stem cells (ASC) are said to have a pivotal role in wound healing. Specifically, ASC‐secreted extracellular vesicles (EV) carry diverse cargos such as microRNAs (miRNAs) to participate in the ASC‐based therapies. Considering its effects, we aimed to investigate the role of ASC‐EVs in the cutaneous wound healing accompanied with the study on the specific cargo‐medicated effects on wound healing. Two full‐thickness excisional skin wounds were created on mouse dorsum, and wound healing was recorded at the indicated time points followed by histological analysis and immunofluorescence staining for CD31 and α‐SMA. Human skin fibroblasts (HSFs) and human microvascular endothelial cells (HMECs) were co‐cultured with EVs isolated from ASC (ASC‐EVs), respectively, followed by the evaluation of their viability and mobility using CCK‐8, scratch test and transwell migration assays. Matrigel‐based angiogenesis assays were performed to evaluate vessel‐like tube formation by HMECs in vitro. ASC‐EVs accelerated the healing of full‐thickness skin wounds, increased re‐epithelialization and reduced scar thickness whilst enhanced collagen synthesis and angiogenesis in murine models. However, miR‐486‐5p antagomir abrogated the ASC‐EVs‐induced effects. Intriguingly, miR‐486‐5p was found to be highly enriched in ASC‐EVs, exhibiting an increase in viability and mobility of HSFs and HMECs and enhanced the angiogenic activities of HMECs. Notably, we also demonstrated that ASC‐EVs‐secreted miR‐486‐5p achieved the aforesaid effects through its target gene Sp5. Hence, our results suggest that miR‐486‐5p released by ASC‐EVs could be a critical mediator to develop an ASC‐based therapeutic strategy for wound healing.     

Effect of helium-neon laser on wound healing

To estimate the biostimulatory effects of low intensity laser radiation on healing of skin wounds, two linear skin wounds were produced on either side of dorsal midline in rats and immediately sutured. Wounds on the left side were irradiated daily with helium neon laser at 4 Joules/sq.cm for 5 min., while those on right side were not exposed and served as controls. The mean time required for complete closure in control group was 7 days while irradiated test wounds took only 5 days to heal (P < 0.01). The mean breaking strength, as measured by the ability of the wound to resist rupture against force, was found to be significantly increased in the test group. Early epithelization, increased fibroblastic reaction, leucocytic infiltration and neovascularization were seen in the laser irradiated wounds. The results establish the biostimulatory effects of low intensity laser radiation on healing of skin wounds.     

Promotive effects of far-infrared ray on full-thickness skin wound healing in rats

The biological effects of far-infrared ray (FIR) on whole organisms remain poorly understood. The aim of our study was to investigate not only the hyperthermic effect of the FIR irradiation, but also the biological effects of FIR on wound healing. To evaluate the effect of FIR on a skin wound site, the speed of full-thickness skin wound healing was compared among groups with and without FIR using a rat model. We measured the skin wound area, skin blood flow, and skin temperature before and during FIR irradiation, and we performed histological inspection. Wound healing was significantly more rapid with than without FIR. Skin blood flow and skin temperature did not change significantly before or during FIR irradiation. Histological findings revealed greater collagen regeneration and infiltration of fibroblasts that expressed transforming growth factor-beta1 (TGF-beta1) in wounds in the FIR group than in the group without FIR. Stimulation of the secretion of TGF-beta1 or the activation of fibroblasts may be considered as a possible mechanisms for the promotive effect of FIR on wound healing independent of skin blood flow and skin temperature.     

Circulating fibrocyte mobilization in negative pressure wound therapy

Non‐healing diabetic wounds are difficult to treat. They also create heavy financial burdens for both patients and society. Negative pressure wound therapy (NPWT) has been adopted to treat intractable wounds and has proved to be effective. However, the mechanisms that underlie the effects of this treatment are not entirely understood. Circulating fibrocytes are unique haematopoietic‐derived stem cells that have been reported to play a pivotal role in wound healing. Here, we have investigated the effect of NPWT on fibrocyte mobilization and the role of fibrocyte mobilization in the healing of diabetic wounds during NPWT. We show that the NPWT group exhibited 2.6‐fold to 12.1‐fold greater numbers of tail vein‐injected PKH‐26‐labelled fibrocytes in the diabetic wound sites compared with the control group. We also demonstrate that the full‐thickness skin wounds treated with NPWT exhibit significantly reduced mRNA and protein expression, blood vessel density and proliferating cells when exogenous fibrocyte mobilization is inhibited. We speculate that systemic mobilization of fibrocytes during NPWT may be a mechanism for healing intractable wounds in a diabetic rat model experiment and that enhancement of cell mobilization may represent a potential treatment idea for intractable wound healing across all fields of surgery.     

An investigation on skin wound healing in mice with a taurine-chitosan gel formulation

Summary. The process of wound healing begins immediately following surface lesions or just after exposure to radiation, chemical agents or extreme temperatures. Taurine (2-aminoethane sulfonic acid), an amino acid containing sulfur, is found in almost all tissues in mammals, playing various important physio-logical roles in each organ. Taurine exhibits an antioxidant effect and is also known to have effects on cell proliferation, inflammation and collagenogenesis. Many antioxidants have been used to eliminate the negative effects of oxygen free radicals on wound healing. The objective of the present study was to examine the wound healing effect in mice of taurine-chitosan gel, which releases taurine slowly over a long time period. Fifty mM of taurine in 1.5% chitosan polymer (TAU-GEL) and 1.5% chitosan polymer (CHI-GEL) were applied to full thickness skin wounds of mice once a day for seven days. After seven days of treatment, lipid peroxide formation-malondialdehyde (MDA) and hydroxyproline (HPX) levels and the tensile strength of wound tissues were measured. All results were compared with those of the untreated control group (CONT). The structural alterations in the skin layers were also histologically investigated. It was found that locally administered TAU-GEL form significantly increased wound tensile strength by decreasing the MDA and increasing HPX levels. These results were supported by histological findings. All observations suggest that taurine gel may be effective in wound healing. Received January 15, 2001 Accepted June 4, 2001     

Effects of CD100 promote wound healing in diabetic mice

Diabetes is a condition that causes delayed wound healing and results in chronic wounds. CD100 has been reported to promote and induce potent and obvious angiogenesis both in vivo and in vitro studies, the absence of which are a main cause of the diabetic chronic wound. In the present study, we investigated the effects of application of soluble CD100 on wound healing in diabetic mice. Four 5-mm full-thickness dermal wounds were made on each male db/db mouse. 12 mice from CD100 group were subcutaneously injected with 250 ng of CD100 (50 µl) per wound, in addition, 12 mice were injected with the same volume phosphate-balanced solution as the control. The animals were treated every other day until the wounds healed completely. Images were obtained to calculate the area ratio of the original area. HE and Masson’s trichrome staining were used for histological examination. Collagen remodeling, angiogenesis and wound bed inflammation were evaluated by immunohistochemical staining and western blot. We demonstrated that CD100 had distinct functions during the wound healing process. Histological and western blotting analysis showed a more organized epithelium and dermis, more collagen fibers, higher angiogenesis and lower inflammation in the CD100 group than in the PBS group. These findings suggest that CD100 may accelerate wound healing in diabetic mice by promoting angiogenesis in the wound and by reducing the inflammatory response.     

The effects of topical treatment with curcumin on burn wound healing in rats

The present study was designed to determine the role of topical treatment with curcumin (Cur) on burn wound healing in rats. The Wistar-albino rats were randomly allotted into one of three experimental groups: 4th, 8th and 12th day (post burn) and all groups include subgroups which Burn and Burn + Cur. Each group contains 12 animals. Burn wounds were made on the back of rat and Cur was administered topically. At the end of the study, all animals were sacrificed and the wound tissues removed for analyse to biochemical and histopathological changes. There was a significant increase in the hydroxyproline levels in the skin of the Cur groups. Cur treated wounds were found to heal much faster as indicated by improved rates of inflammatory cells, collagen deposition, angiogenesis, granulation tissue formation and epithelialization which were also confirmed by histopathological and biochemical examinations. Our data also indicate that there is a rise in the expression of proliferating cell nuclear antigen in skin tissues of Cur-treated rats in the Burn group. The results clearly substantiate the beneficial effects of the topical application of Cur in the acceleration of wound healing.     

A comparison of the effects of immobilization and continuous passive motion on surgical wound healing in mature rabbits

The purpose of this investigation was to compare the effects of continuous passive motion (CPM) and cast immobilization on postoperative wound healing. Medical parapatellar skin incisions and arthrotomies were performed on both knees of 10 mature New Zealand rabbits. After closure of the incisions, one knee was immobilized in a cast while the other was treated by continuous passive motion for 3 weeks. Six standardized skin specimens (2 mm wide) from each wound were tested to failure and one specimen was examined histologically. With respect to the breaking force, tensile strength, strain at failure, stiffness, and toughness, the wounds in the continuous-passive-motion group were significantly stronger, stiffer, and tougher than those in the cast group. Histologically, the structural organization of the collagen fibers was also superior in the scars treated with continuous passive motion. The results of the present investigation indicate that compared to immobilization, continuous passive motion enhances postoperative wound healing in rabbits.