Immediate tracheal reconstruction with forearm flap and bone graft.

BACKGROUND: "Window" resection of the trachea is sometimes performed to remove tumors invading the trachea. Here, we present a novel reconstructive procedure to this end. METHODS: Eleven patients (mean age, 64 years; range, 46-80 years) were included. Primary diagnoses included thyroid cancer and adenoid cystic carcinoma of the trachea. All defects were partial and located in the neck (mean width and length, 3/5 circle and 7.5 rings; range, 1/2-2/3 circle and 5-9 rings). Immediate 2-stage reconstruction was performed using a forearm flap and free bone graft. The bone graft was utilized as a supportive skeleton. A tracheostoma was left open for several months following the initial surgery, and then closed. RESULTS: The mean flap size was 6.1 × 9.7 cm (range, 6-7 × 7-16 cm). Mean number of grafted bone strips and length were 1.6 (range, 1-3) and 6.1 cm (range, 4.5-7 cm). All flaps survived. Five patients developed complications in the neck, including surgical site infections (SSIs), recurrent nerve palsy, and lymphorrhea. Four patients developed donor site complications, including clavicular fracture and SSIs. Mean postoperative follow-up lasted 85 months (range, 11-149 months). Normal speech was restored in 9 patients. Stoma closure was abandoned in 2 patients, because 1 patient showed vocal cord fixation with advanced age and the other showed bone graft loss following SSI. CONCLUSIONS: Creating a tracheostoma during the first operation prevents postoperative airway compromise. Our bone graft placement easily achieves tracheal rigidity. This procedure is simple and safe for tracheal window defect repair.

Free jejunal flap transfer containing multiple vascular pedicles for pharyngoesophageal reconstruction in conjunction with anterior mediastinal tracheostomy.

BACKGROUND: When pharyngoesophagectomy is performed in conjunction with anterior mediastinal tracheostomy, reconstructing both the trachea and alimentary tract is extremely difficult. We developed a novel 1-stage reconstructive procedure using a single free jejunal flap containing multiple vascular pedicles to decrease postoperative morbidity and mortality. Free jejunal flap transfer with multiple vascular pedicles could offer a viable option for reducing associated life-threatening complications. METHODS: We performed a retrospective review of 34 patients who underwent free jejunal flap transfer with multiple vascular pedicles in anterior mediastinal tracheostomy and pharyngoesophagectomy due to lesions involving both the airway and esophagus. In all cases, 1-stage reconstruction of the digestive tract and trachea was performed. Technical details and outcomes were analyzed. RESULTS: All 34 jejunal flaps (100%) survived. Major morbidity classified as Clavien-Dindo grades III and IV occurred in 10 (29.4%) and 0 (0%) patients, respectively during hospitalization. With regard to common complications, anastomotic leakage from transferred jejunal flaps and surgical site infections occurred in 0 (0%) and 7 (20.6%) patients, respectively. Five (14.7%) patients experienced tracheal stoma dehiscence. Donor site morbidity was observed in 2 (5.9%) patients. The overall in-hospital mortality rate was 2.9%. CONCLUSIONS: Our 1-stage reconstruction procedure achieved low morbidity and low mortality rates following anterior mediastinal tracheostomy and pharyngoesophagectomy. Only 1 jejunal flap transfer is needed to simultaneously reconstruct the trachea and alimentary tract in a safe and reliable manner with this procedure.

Endothelial cell-derived endothelin-1 is involved in abnormal scar formation by dermal fibroblasts through RhoA/Rho-kinase pathway.

Hypertrophic scars and keloids are characterized by excessive dermal deposition of extracellular matrix due to fibroblast-to-myofibroblast differentiation. Endothelin-1 (ET-1) is primarily produced by vascular endothelial cells and plays multiple roles in the wound-healing response and organ fibrogenesis. In this study, we investigated the pathophysiological significance of ET-1 and involvement of RhoA, a member of the Rho GTPases, in hypertrophic scar/keloid formation. We found that ET-1 expression on dermal microvascular endothelial cells (ECs) in hypertrophic scars and keloids was higher than that in normal skin and mature scars. We also confirmed that ET-1 induced myofibroblast differentiation and collagen synthesis in cultured human dermal fibroblasts through the RhoA/Rho-kinase pathway. Finally, since hypertrophic scar/keloid formation was most prominent in areas exposed to mechanical stretch, we examined how mechanical stretch affected ET-1 secretion in human dermal microvascular ECs, and found that mechanical stretch increased ET-1 gene expression and secretion from ECs. Taken together, these results suggest that dermal microvascular ECs release ET-1 in response to mechanical stretch, and thereby contribute to the formation of hypertrophic scars and keloids through the RhoA/Rho-kinase pathway.

A two-tiered structure device based on stereolithography for residual mandible repositioning in mandibular reconstruction with fibular flap.

OBJECTIVE: We invented a two-tiered structure device based on stereolithography for residual mandible repositioning in mandibular reconstruction with fibular flap, and examined its usefulness. PATIENTS AND METHODS: A total of eight patients (six carcinomas and two osteomyelitis) who had undergone mandibular reconstruction with fibular flap were included. Mandibular defects according to Jewer's classification were L for five, LC for two, and H for one patient (range of bone defect size, 7.7-13.3 cm). Based on a stereolithographic mandibular model, a two-tiered structure device was made preoperatively with resin, and was applied during surgery to define the accurate position of residual mandible following segmental mandibulectomy. Postoperative aesthetic and functional outcomes, including dental status, diet, and speech were evaluated. RESULTS: The device was applied without any problems during surgery. Follow-up period ranged from eight to twenty-two months. Good postoperative alignment of the grafts and occlusion were also achieved in all eight patients. Five patients were able to return to eating meals as they had pre-surgery, and two patients required dental rehabilitation with dentures. As for speech, four patients scored ten points, three patients scored eight points, and one patient scored four points in Hirose's scoring system, which means that seven patients was rated as excellent, and one patient was rated as poor. Aesthetic outcomes were excellent in three patients, good in three patients, and fair in two patients. CONCLUSION: Our device was easy to prepare, successfully maintained the precise position of the residual mandible, and facilitated bone graft cutting and insetting during reconstruction. © 2016 Wiley Periodicals, Inc. Microsurgery 37:509-515, 2017.

Behavior of anastomozed vessels and transferred flaps after anastomosed site infection in head and neck microsurgical reconstruction.

OBJECTIVE: This report evaluates the behavior of anastomosed vessels and transferred flaps after anastomosed site infection in head and neck reconstruction. PATIENTS AND METHODS: Eleven free-flap cases after infection at the vascular pedicle site were included, the patency of which was observed macroscopically after re-exploration and pus drainage. Location was in the tongue (5 cases), oropharynx (3 cases), mouth floor (1 case), mandible (1 case), and hypopharynx (1 case). Transferred flaps originated from rectus abdominis (3 cases), anterolateral thigh (3 cases), radial forearm (3 cases), jejunum (1 case), and latissimus dorsi (1 case). Days for infection found were ranged 3-14 days postoperatively. Causes of infection were the salivary fistula formation in 5 cases, and precise etiology was not defined in the other 6 cases. RESULTS: Disruption of the vascular pedicles occurred with high frequency after infection. Disruption of vein occurred most frequently (5 cases), followed by both artery and vein (2 cases) and artery only (1 case). Of the eight flaps, two flaps failed, but the other six flaps survived despite pedicle disruption, indicating overall survival of nine flaps after pedicle site infection. Five of the nine survived cases were healed with simple washing and ointment application. However, the other four patients, whose cause of infection was a salivary fistula, needed second flap transfer to treat those fistulas. CONCLUSION: Disruption of anastomosed vessels can occur with high frequency after infection, causing subsequent flap loss. Therefore, surgeons need to deal with pedicle site infection to save the flap. © 2015 Wiley Periodicals, Inc. Microsurgery 36:658-663, 2016.

Covering implantable left ventricular assist device (DuraHeart) with free flap.

Severe donor shortage in Japan makes the waiting period for heart transplantation extremely long and the left ventricular assist devices (LVADs) are often used for bridge-to-transplant. We present three cases of infected and exposed DuraHeart LVAD system treated with free flaps. Four free flaps (two latissimus flaps and two anterolateral thigh flaps) were transferred using the right internal thoracic vessels or left deep inferior epigastric vessels as recipients. The potential significance of the continuous low pressure blood flow generated by the LVAD system on microvascular patency has not been previously reported. All flaps survived and worked efficiently to control the infection and cover the devices. Heart transplantation was conducted in the two of three patients. Free flap transfer is an efficient treatment for the patients with infected and exposed implantable LVAD.

Adipose-derived stem cells protect against endoneurial cell death: Cell therapy for nerve autografts.

BACKGROUND: One of the major problems with nerve grafts is that the survival of a graft segment, including endoneurial Schwann cells (SCs), is uncertain. We investigated whether the survival of nerve grafts is improved when adipose-derived stem cells (ASCs) are incorporated into the grafts. METHODS: To examine the cell-protective effects of ASCs on SCs in vitro, we used an indirect coculture system. In vivo effects of the incorporation of ASCs into grafts were examined using a graft model in the rat common peroneal nerve. Grafts were entubulated to isolate them from the surrounding tissues, mimicking the clinical conditions of a poorly vascularized recipient bed. Thirty-six Lewis rats were divided into three groups, i.e., nerve graft only, entubulated nerve graft, and entubulated nerve graft + ASC transplantation. In each group, four rats and eight rats were used for short-term (10 days) and long-term (12 weeks) follow-up study, respectively. RESULTS: After 24 hours of serum deprivation, the numbers of 7-aminoactinomycin D, and TUNEL-positive SCs significantly decreased when indirectly cocultured with ASCs (P < 0.01). When ASCs were transplanted to the epineurial layer of the grafts, the number of endoneurial TUNEL-positive cells decreased significantly, as compared with grafts without ASCs, at 10 days postoperatively (P < 0.05). Postoperative walking track analysis showed that the ASC-transplanted grafts showed significantly faster function recovery, as compared with grafts without ASCs (P < 0.05). CONCLUSION: These results suggest that nerve autografts + ASC therapy could offer a new approach to obtaining optimal outcomes after peripheral nerve injury.

Cyp26b1 within the growth plate regulates bone growth in juvenile mice.

Retinoic acid (RA) is an active metabolite of vitamin A and plays important roles in embryonic development. CYP26 enzymes degrade RA and have specific expression patterns that produce a RA gradient, which regulates the patterning of various structures in the embryo. However, it has not been addressed whether a RA gradient also exists and functions in organs after birth. We found localized RA activities in the diaphyseal portion of the growth plate cartilage were associated with the specific expression of Cyp26b1 in the epiphyseal portion in juvenile mice. To disturb the distribution of RA, we generated mice lacking Cyp26b1 specifically in chondrocytes (Cyp26b1(Δchon) cKO). These mice showed reduced skeletal growth in the juvenile stage. Additionally, their growth plate cartilage showed decreased proliferation rates of proliferative chondrocytes, which was associated with a reduced height in the zone of proliferative chondrocytes, and closed focally by four weeks of age, while wild-type mouse growth plates never closed. Feeding the Cyp26b1 cKO mice a vitamin A-deficient diet partially reversed these abnormalities of the growth plate cartilage. These results collectively suggest that Cyp26b1 in the growth plate regulates the proliferation rates of chondrocytes and is responsible for the normal function of the growth plate and growing bones in juvenile mice, probably by limiting the RA distribution in the growth plate proliferating zone.

(+)-Catechin protects dermal fibroblasts against oxidative stress-induced apoptosis.

BACKGROUND: Oxidative stress has been suggested as a mechanism underlying skin aging, as it triggers apoptosis in various cell types, including fibroblasts, which play important roles in the preservation of healthy, youthful skin. Catechins, which are antioxidants contained in green tea, exert various actions such as anti-inflammatory, anti-bacterial, and anti-cancer actions. In this study, we investigated the effect of (+)-catechin on apoptosis induced by oxidative stress in fibroblasts. METHODS: Fibroblasts (NIH3T3) under oxidative stress induced by hydrogen peroxide (0.1 mM) were treated with either vehicle or (+)-catechin (0-100 µM). The effect of (+)-catechin on cell viability, apoptosis, phosphorylation of c-Jun terminal kinases (JNK) and p38, and activation of caspase-3 in fibroblasts under oxidative stress were evaluated. RESULTS: Hydrogen peroxide induced apoptotic cell death in fibroblasts, accompanied by induction of phosphorylation of JNK and p38 and activation of caspase-3. Pretreatment of the fibroblasts with (+)-catechin inhibited hydrogen peroxide-induced apoptosis and reduced phosphorylation of JNK and p38 and activation of caspase-3. CONCLUSION: (+)-Catechin protects against oxidative stress-induced cell death in fibroblasts, possibly by inhibiting phosphorylation of p38 and JNK. These results suggest that (+)-catechin has potential as a therapeutic agent for the prevention of skin aging.

Direct contact of fibroblasts with neuronal processes promotes differentiation to myofibroblasts and induces contraction of collagen matrix in vitro.

Wound healing is often delayed in the patients whose sensory and autonomic innervation is impaired. We hypothesized that existence of neurites in the skin may promote wound healing by inducing differentiation of fibroblasts into myofibroblasts with consequent wound contraction. In the current study, we examined the effect of neurons on differentiation of fibroblasts and contraction of collagen matrix in vitro using a new co-culture model. Neuronal cell line, PC12 cells, of which the neurite outgrowth can be controlled by adding nerve growth factor, was used. Rat dermal fibroblasts were co-cultured with PC12 cells extending neurites or with PC12 cells lacking neurites. Then, differentiation of fibroblasts into myofibroblasts and contraction of the collagen matrix was evaluated. Finally, we examined whether direct or indirect contact with neurites of PC12 cells promoted the differentiation of fibroblasts. Our results showed that fibroblasts co-cultured with PC12 extending neurites differentiated into myofibroblasts more effectively and contracted the collagen matrix stronger than those with PC12 lacking neurites. Direct contact of fibroblasts with neurites promoted more differentiation than indirect contact. In conclusion, direct contact of fibroblasts with neuronal processes is important for differentiation into myofibroblasts and induction of collagen gel contraction, leading to promotion of wound healing.

Identification and characterization of cartilage oligomeric matrix protein as a novel pathogenic factor in keloids.

To elucidate pathogenic molecules in keloids, microarray analysis was performed using RNAs extracted from keloid-derived fibroblasts and normal skin-derived fibroblasts from the same patient with a typical keloid. Among 11 up-regulated extracellular matrix genes, cartilage oligomeric matrix protein (COMP) was most prominently increased. Up-regulation of COMP mRNA and protein was confirmed in the keloid tissue by quantitative RT-PCR and Western blot. Using immunohistochemistry, we compared 15 keloids and 6 control normal tissues using a COMP-specific antibody and found that COMP stained positively in 10 keloids (66.7%), whereas no staining was observed in normal tissues, demonstrating the ectopic expression of COMP in keloids. Comparing keloids smaller or larger than 10 cm(2), the larger keloids were significantly more intensely stained with the COMP-specific antibody. Because COMP reportedly accelerates collagen type I fibril assembly, we examined whether extracellular type I collagen deposition is altered by silencing COMP mRNA by small interfering RNA (siRNA). Immunocytochemistry showed at 96 hours after transfection with COMP siRNA that the extracellular deposition of type I collagen was decreased compared to that observed with control siRNA. Further, COMP knockdown decreased amount collagens type I to V in the medium and on the cell surfaces. Our data suggest that COMP facilitates keloid formation by accelerating collagen deposition, thus providing a new therapeutic target.

Green light emitting diodes accelerate wound healing: characterization of the effect and its molecular basis in vitro and in vivo.

Because light-emitting diodes (LEDs) are low-coherent, quasimonochromatic, and nonthermal, they are an alternative for low level laser therapy, and have photobiostimulative effects on tissue repair. However, the molecular mechanism(s) are unclear, and potential effects of blue and/or green LEDs on wound healing are still unknown. Here, we investigated the effects of red (638 nm), blue (456 nm), and green (518 nm) LEDs on wound healing. In an in vivo study, wound sizes in the skin of ob/ob mice were significantly decreased on day 7 following exposure to green LEDs, and complete reepithelialization was accelerated by red and green LEDs compared with the control mice. To better understand the molecular mechanism(s) involved, we investigated the effects of LEDs on human fibroblasts in vitro by measuring mRNA and protein levels of cytokines secreted by fibroblasts during the process of wound healing and on the migration of HaCat keratinocytes. The results suggest that some cytokines are significantly increased by exposure to LEDs, especially leptin, IL-8, and VEGF, but only by green LEDs. The migration of HaCat keratinocytes was significantly promoted by red or green LEDs. In conclusion, we demonstrate that green LEDs promote wound healing by inducing migratory and proliferative mediators, which suggests that not only red LEDs but also green LEDs can be a new powerful therapeutic strategy for wound healing.

Clinicopathological assessment of locally recurrent rectal cancer and relation to local re-recurrence.

BACKGROUND: Local re-recurrence after R0 resection of local recurrence of rectal cancer (LRRC) is not rare. The purpose of this study was to examine the pathological features of LRRC and determine the prognostic factors. METHODS: Twenty-one patients underwent R0 resection of LRRC without preoperative therapy from 2000 to 2008. Tumor progression patterns were classified into three types: A, expanding type; B, infiltrating type; and C, intermediate type. Distant isolated cancer cells (DICCs) were defined as cancer cells present in isolation and at a distance (>1 mm) from the tumor edge. RESULTS: Venous invasion was identified in all but one patient (95%). DICCs were observed in 11 of 21 cases. Type A patients had a significantly lower local re-recurrence rate (0/5) compared with type B and/or C patients (11/16, P = 0.012) and a significantly lower incidence of distant metastasis compared with type B and C patients (0/5 vs. 13/16, respectively; P = 0.0028). Multivariate regression analysis identified venous invasion of the primary lesion (P = 0.027) and tumor progression patterns (P = 0.039) as independent predictors of local re-recurrence. CONCLUSIONS: The main features of LRRC were infiltrating growth, venous invasion, and DICCs. Tumor progression patterns correlated with local re-recurrence and distant metastasis. Preoperative adjuvant therapy to terminate peri-tumor cancer cells may be required for better tumor control.

The animal model of spinal cord injury as an experimental pain model.

Pain, which remains largely unsolved, is one of the most crucial problems for spinal cord injury patients. Due to sensory problems, as well as motor dysfunctions, spinal cord injury research has proven to be complex and difficult. Furthermore, many types of pain are associated with spinal cord injury, such as neuropathic, visceral, and musculoskeletal pain. Many animal models of spinal cord injury exist to emulate clinical situations, which could help to determine common mechanisms of pathology. However, results can be easily misunderstood and falsely interpreted. Therefore, it is important to fully understand the symptoms of human spinal cord injury, as well as the various spinal cord injury models and the possible pathologies. The present paper summarizes results from animal models of spinal cord injury, as well as the most effective use of these models.

Recovery of sensation in immediate breast reconstruction with latissimus dorsi myocutaneous flaps after breast-conservative surgery and skin-sparing mastectomy.

In breast reconstruction, sensation in the reconstructed breasts affects the patients' quality of life along with its aesthetic outcome. Fortunately, less invasive procedures such as breast-conservative surgery (BCS) and skin-sparing mastectomy (SSM) have greatly contributed to the improved aesthetic outcome in immediate breast reconstruction. However, there are few reports on the recovery of breast sensation after BCS and SSM. We retrospectively reviewed 104 consecutive patients who underwent immediate breast reconstruction with the latissimus dorsi myocutaneous flap between 2001 and 2006 at our institution. The sensations of pain, temperature, touch, and vibration were examined at the nipple and skin envelope during the follow-up period (range: 12-61 months, mean: 31 months), and a stratified analysis was performed to determine the critical factors affecting the sensation recovery after BCS and SSM. We found that large breast size significantly impaired the recovery of sensation in the nipple and skin envelope after BCS as well as SSM. Older age and high body mass index value were the factors which negatively affected the sensation in the skin envelope after SSM. While all our BCS patients underwent postoperative radiation therapy, it did not negatively affect the recovery of sensation in SSM patients. On the basis of these findings, we could further improve the sensation of the reconstructed breasts after BCS and SSM. Especially after SSM, the use of innervated flaps is recommended in the patients with large breast, increased age, or obesity when the nipple-areola complex is resected.

Visualized sclerotherapy of varicose veins.

BACKGROUND: The spread and movement of sclerosant after injection during sclerotherapy is difficult to monitor. OBJECTIVE: To develop a new visualization method that allows monitoring of sclerosant dosage and flow during sclerotherapy. METHODS: We used a photodynamic eye (PDE) to perform indocyanine green (ICG) imaging. ICG produces strong fluorescence detectable using PDE and allows monitoring of sclerosant spread through blood vessels in real time. We performed visualized sclerotherapy on 50 limbs, comprising high ligation and sclerotherapy (35 limbs), stripping and sclerotherapy (10 limbs), and sclerotherapy alone (5 limbs). RESULTS: In all cases, fluorescence imaging of the injected sclerosant was possible. No complications resulted from combining ICG and polidocanol in any of the patients, all of whom received follow-up evaluations at 1 week, 1 month, and 3 months after treatment. CONCLUSIONS: Our new method not only avoids the risk of radiation exposure, but also allows for simple observation of sclerosant range of access, determination of the dosage for each lesion, and accurate administration of therapy to target lesions. This method will contribute to further advances in sclerotherapy, given that it allows administration of sclerosant and visual confirmation of optimal injection dosage, speed, and movement of sclerosant after injection. The authors have indicated no significant interest with commercial supporters.

Near-infrared fluorescence venography: a navigation system for varicose surgery.

BACKGROUND: Successful varicose vein surgery depends on accurate assessment and identification of veins. We report clinical experiences with a simple, rapid method of detecting varicose veins using indocyanine green (ICG) fluorescence video venography. PATIENTS AND METHOD: ICG percutaneously injected into the great saphenous vein at the ankle or into the ligated end of veins in 20 patients with varicose veins was used as the optical tracer agent. Intraoperative ICG imaging was performed using a laser-fluorescence imaging device. RESULTS: ICG fluorescence venography was performed without any adverse effects. The imaging device provides unparalleled visualization of varicose veins during vein ligation, phlebectomy, and stripping. CONCLUSION: This method enabled easy, safe, and accurate diagnoses, simplified the search for veins during the operation, and minimized surgical invasiveness in varicose vein surgery. The system has great potential as a navigational technique for phlebologic diagnosis and treatment of varicose veins. Further research and development to improve its utility are suggested.

Reconstruction of adult auricular defect with thin titanium mesh and prelaminated free radial forearm flap.

We used a thin titanium mesh combined with a prelaminated free radial forearm flap to construct a framework to reconstruct a traumatic defect in an adult ear. The prelaminated forearm flap covered both the anterior and posterior aspects of the titanium framework. A raised ear could therefore be created.

Periostin is induced by IL-4/IL-13 in dermal fibroblasts and promotes RhoA/ROCK pathway-mediated TGF-ß1 secretion in abnormal scar formation.

Excess scar formation can occur after skin injurふy and lead to abnormal scar formation, such as keloids and hypertrophic scars, which are characterised by substantial deposition of extracellular matrix in the dermis. Periostin, an extracellular matrix protein that plays a crucial role in skin development and maintaining homeostasis, is also involved in skin disorders such as systemic/limited scleroderma, wound closure, and abnormal scar formation. However, the mechanism of periostin involvement in abnormal scar formation is not yet fully understood. In this study, we investigated the mechanism by which periostin is involved in abnormal scar formation. Treatment of human dermal fibroblasts (HDFs) with IL-4 and IL-13, which are cytokines of Th2 type immune responses that are up-regulated in abnormal scars, dramatically elevated the levels of periostin mRNA and protein, and also promoted the secretion of periostin by HDFs. Transforming growth factor-ß1 (TGF-ß1) had the same effect on HDFs as IL-4 and IL-13. Stimulation of HDFs with periostin promoted RhoA/ROCK pathway-mediated TGF-ß1 secretion from HDFs. Our results suggest that IL-4 and IL-13 induce periostin expression and secretion, and in turn, secreted periostin induces RhoA/ROCK pathway-mediated TGF-ß1 secretion. Secreted TGF-ß1 then induces further periostin production and secretion, thereby promoting abnormal scar formation.

mRNA expression changes of slit proteins following peripheral nerve injury in the rat model.

Slit family of proteins is one of the repulsive axonal guidance cues, and it also plays an important role in neuronal migration and branching through the interaction with roundabout receptors. The function and role of Slit family proteins during peripheral nerve regeneration are still unknown. We examined the expressions of Slits 1-3 mRNAs in the facial nerve nuclei after facial nerve transection by in situ hybridization, using Sprague-Dawley rats. Slit 1 mRNA was weakly expressed in the facial motoneurons, and its expression increased from day 5 to day 28 after transection, with the peak on day 14 after axotomy. Slits 2 and 3 mRNAs were expressed in the motoneurons of the facial nerve before injury, but the expression of Slit 2 mRNA was down-regulated from day 1 to day 7 after axotomy, with the peak on the first day after injury. Slit 3 mRNA expression in the axotomized side remained unchanged throughout the examination period. Slits 1 and 2 mRNA expression returned to the normal level on day 56 postoperatively. The difference in expression pattern of Slit family mRNA in the neurons during peripheral nerve regeneration suggests that it plays a different role in axonal regeneration after axotomy of peripheral nerves.