FK 506 and aminoguanidine suppress iNOS induction in orthotopic corneal allografts and prolong graft survival in mice.

The aim of this study was to compare the effectiveness of immunosuppressant FK 506 and the specific inhibitor of inducible nitric oxide synthase (iNOS) aminoguanidine (AG) in prevention of corneal graft rejection and to investigate the iNOS expression in the rejection process. Orthotopic corneal allografting in mice was performed (C57BL/10; H-2(b) to BALB/c; H-2(d)). FK 506 (0.3 mg/kg per day) or AG (100 mg/kg per day) was injected intraperitoneally for 4 weeks. Grafted mice without therapy served as controls. Immunohistological evaluation of iNOS-positive cells and macrophage infiltration in grafts 27th day after grafting was performed. Within 4 weeks FK 506 prevented graft rejection in 71% and AG in 57% of animals compared to 29% of clear grafts in controls. A significant proportion of iNOS-positive cells was detected in the rejected grafts of the control and AG-treated groups. The treatment with FK 506 resulted in the inhibition of iNOS expression to a high degree in the rejected corneas. Non-rejected corneas of all groups and non-transplanted corneas exhibited no iNOS-positive cells. A massive infiltration of macrophages was detected in the rejected grafts, whereas non-rejected grafts exhibited only slight infiltration of macrophages. The presented data suggest that overexpression of iNOS and/or activation of iNOS is one of the several influential factors that contribute to the rejection process and that iNOS suppression delays corneal allograft rejection. FK 506 and AG are effective drugs in preventing corneal allograft rejection. Higher beneficial effect of FK 506 on graft survival could be explained by its well-known selective T-cell immunosuppression.     

Dose-dependent effects of FK506 on neuroregeneration in a rat model

This study explored the effects of different doses of FK506 on peripheral nerve regeneration, to determine whether neuroregeneration could be enhanced without the toxicity of systemic immunosuppression. In the first part of the study, subimmunosuppressive doses of FK506 were determined by examining skin allograft survival in a rat model. Full-thickness skin grafts (2 cm2) from Wistar rats were grafted to recipient Lewis rats. The procedure was performed for six groups (n = 6). The control group received no FK506, and the other five groups received daily doses of FK506 of 0.125, 0.25, 0.5, 1.0, or 2.0 mg/kg. Animals that received 2.0 mg/kg FK506 per day exhibited complete skin graft take, whereas all other groups demonstrated complete rejection. After determination of the immunosuppressive dose of FK506, the neuroregenerative effects of different doses of FK506 were explored by assessing nerve regeneration in 80 rats after tibial nerve transection and repair. The control group received no FK506, whereas the other four groups were given daily doses of FK506 of 0.25, 0.5, 1.0, or 2.0 mg/kg. Rats were euthanized at three time points (25, 30, and 35 days), to fully investigate the effects of different FK506 dosing regimens on neuroregeneration. Histomorphometric analyses performed on postoperative days 30 and 35 demonstrated statistically significant improvements in neuroregeneration with subimmunosuppressive FK506 doses of 0.5 and 1.0 mg/kg per day. Therefore, the study demonstrated that neuroregeneration was enhanced at low doses of FK506 that were not sufficient to prevent skin allograft rejection.     

Effect of FK506 on osteoinduction by recombinant human bone morphogenetic protein-2

FK506 is an immunosuppressant that is used widely in organ transplantation, and it has recently been recognized as effective for promoting the growth of bone grafts [J. Bone Miner. Res. 15 (2000) 1147]. In this study, we evaluated the influence of FK506 on osteoinduction by recombinant human bone morphogenetic protein-2 (rhBMP-2) using atelopeptide type I collagen as a carrier. We administered FK506 (1 mg/kg/day intramuscularly) on days -2 to 0, -2 to 7, and -2 to sacrifice. rhBMP-2 was implanted into the calf muscle of Wistar rats (thirty per group) and the implant was sampled on days 7, 14, and 21. Radiographic evaluation, histological examination, and biochemical analysis were performed. It was found that FK506 promoted the early stage of osteoinduction after short-term administration. However, long-term administration of this agent accelerated both bone formation and bone resorption. In order to use FK506 effectively for promoting bone growth, we must further examine the appropriate dose, method, and period of administration.     

Prevention of antigen-induced bronchial hyperreactivity and airway inflammation in sensitized guinea-pigs by tacrolimus

We examined the effect of the immunosuppressive agent, tacrolimus (FK506), on antigen-induced bronchial hyperreactivity to acetylcholine and leukocyte infiltration into the airways of ovalbumin-challenged guinea-pigs. Subcutaneous injection of 0.5 mg/kg of FK506, 1 h before and 5 h after intra-nasal antigen challenge prevented bronchial hyperreactivity to aerosolized acetylcholine, eosinophilia in bronchoalveolar lavage (BAL) fluid and bronchial tissue and the invasion of the bronchial wall by CD4+ T-lymphocytes. FK506 also suppressed ovalbumin-induced increase in the number of leukocytes adhering to the pulmonary vascular endothelium and expressing alpha4-integrins. Inhibition by FK506 of antigen-induced bronchial hyperreactivity in sensitized guinea-pigs may thus relate to its ability to prevent the emergence of important inflammatory components of airway inflammation, such as eosinophil accumulation, as well as CD4+ T-lymphocyte infiltration into the bronchial tissue.     

PEP-1-FK506BP inhibits alkali burn-induced corneal inflammation on the rat model of corneal alkali injury

FK506 binding protein 12 (FK506BP) is a small peptide with a single FK506BP domain that is involved in suppression of immune response and reactive oxygen species. FK506BP has emerged as a potential drug target for several inflammatory diseases. Here, we examined the protective effects of directly applied cell permeable FK506BP (PEP-1-FK506BP) on corneal alkali burn injury (CAI). In the cornea, there was a significant decrease in the number of cells expressing pro-inflammation, apoptotic, and angiogenic factors such as TNF-α, COX-2, and VEGF. Both corneal opacity and corneal neovascularization (CNV) were significantly decreased in the PEP-1-FK506BP treated group. Our results showed that PEP-1-FK506BP can significantly inhibit alkali burn-induced corneal inflammation in rats, possibly by accelerating corneal wound healing and by reducing the production of angiogenic factors and inflammatory cytokines. These results suggest that PEP-1-FK506BP may be a potential therapeutic agent for CAI. [BMB Reports 2015; 48(11): 618-623]     

FK506 accelerates functional recovery following nerve grafting in a rat model.

The sometimes dramatic and permanent functional deficits that result from severe peripheral nerve injuries provide compelling incentives to identify exogenous agents that may expedite axonal regrowth and avoid prolonged denervation of end organs. The purpose of this study was to identify, whether the regular systemic administration of tacrolimus (FK506) or cyclosporin A (CsA) would influence the speed and efficiency of nerve regeneration through short nerve grafts. A total of 35 Buffalo rats each received a 2-cm posterior tibial nerve graft and were randomized to one of three experimental groups. Group I animals were left untreated, group II received daily CsA (5 mg/kg intraperitoneally), and group III received daily FK506 (1 mg/kg intraperitoneally). Walking tracks were obtained starting 3 weeks after graft placement and continuing biweekly for the next 7 weeks. FK506-treated animals fully recovered hindlimb function 7 days earlier than CsA-treated animals or untreated control animals. Regenerated nerves from one-half of each treatment group were harvested for histomorphometric analysis at 7 weeks, shortly after recovery was complete in the FK506-treatment group but not in the other two groups, and once again at 10.5 weeks when recovery of function had stabilized in all groups. At 7 weeks, FK506-treated animals had significantly greater fiber density and percentage of neural tissue per nerve and a significantly larger population of mature, myelinated fibers in comparison with either CsA-treated or untreated animals. The authors concluded that the daily, systemic administration of low-dose FK506 facilitates peripheral nerve recovery and regeneration after nerve grafting.     

Tacrolimus (FK506) Suppresses TREM-1 Expression at an Early but Not at a Late Stage in a Murine Model of Fungal Keratitis

Purpose

To investigate the efficacy and mechanism of tacrolimus(FK506), which is a novel macrolide immunosuppressant, in inhibiting triggering receptor expressed on myeloid cells-1 (TREM-1) expression in a murine keratitis model induced by Aspergillus fumigatus.

Method

TREM-1 was detected in 11 fungus-infected human corneas by quantitative real-time PCR (qRT-PCR). RAW264.7 macrophages were divided into four groups, which received treatment with zymosan (100 µg/ml), zymosan (100 µg/ml) + mTREM-1/Fc protein (1 µg/ml), or zymosan (100 µg/ml) + FK506 (20 µM) or negative-control treatment. After this treatment, the expression of TREM-1, interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) was assayed using qRT-PCR and ELISA. The mouse model of fungal keratitis was created by intrastromal injection with Aspergillus fumigatus, and the mice were divided into 2 groups: group A received vehicle eye drops 4 times each day, and group B received 4 doses of FK506 eye drops each day. Corneal damage was evaluated by clinical scoring and histologic examination,and myeloperoxidase (MPO) protein levels were also detected by ELISA. The expression of TREM-1, IL-1β and TNFα was then determined at different time points using qRT-PCR and ELISA.

Results

TREM-1 expression dramatically increased in the human corneas with fungal keratitis. In contrast, FK506 reduced the expression of TREM-1, IL-1β and TNFα in RAW264.7 macrophages stimulated with zymosan. In the mouse model, at day 1 post-infection, the corneal score of the FK506-treated group was lower than that of the control, and polymorphonuclear neutrophil (PMN) infiltration was diminished. TREM-1, IL-1β and TNFα expression was significantly reduced at the same time point. However, the statistically significant differences in cytokine expression, clinical scores and infiltration disappeared at 5 days post-infection.

Conclusions

FK506 may inhibit the inflammation induced by fungi and alleviate the severity of corneal damage at an early stage of fungal keratitis by downregulating TREM-1 expression.     

Sustained QT prolongation induced by tacrolimus in guinea pigs.

Recently, clinical cases have been reported of QT prolongation and torsades de pointes associated with the use of tacrolimus (FK506). We examined the relationship between QTc prolongation and the pharmacokinetics of FK506 in guinea pigs in order to evaluate the arrhythmogenicity of FK506 in comparison with quinidine (QND). FK506 (0.1 or 0.01 mg/hr/kg) or QND (30 mg/hr/kg) was intravenously infused to guinea pigs and time profiles of drug concentration in blood and QTc interval were examined during and after infusion. Both FK506 and QND evoked a significant QTc prolongation, and the dose-response relationship showed an anti-clockwise hysteresis, FK506-induced QTc prolongation persisted throughout the duration of the experiment despite a decline in the plasma FK506 concentration, whilst QND-induced QTc prolongation disappeared as plasma concentrations decreased. FK506 induced a sustained QTc prolongation in guinea pigs at drug concentrations in blood that correspond to its therapeutic range in human, suggesting that it might be of clinical significance to monitor the electrocardiogram, especially when patients have congenital or acquired QT-prolonging risk factors.     

Antinociceptive action of FK506 in mice

Immunophilins are abundantly present in the brain as compared to the immune system. Immunophilin-binding agents like FK506 are known to inactivate neuronal nitric oxide synthase (nNOS) by inhibiting calcineurin and decrease the production of nitric oxide. Nitric oxide is involved in the mediation of nociception at the spinal level. In the present study, the effect of FK506 on the tail flick response in mice and the possible involvement of NO-L-arginine pathway in this paradigm was evaluated. FK506 (0.5, 1 and 3 mg/kg, ip) produced a significant antinociception in the tail flick test. Nitric oxide synthase (NOS) inhibitor L-NAME significantly and dose dependently (10-40 mg/kg, ip) potentiated the FK506 (0.5 mg/kg)-induced antinociception. On the other hand, NOS substrate L-arginine (100, 200 and 400 mg/kg) inhibited the FK506-induced antinociception in a dose-dependent manner. Concomitant administration of L-NAME (20 and 40 mg/kg) with L-arginine (200 mg/kg) blocked the inhibition exerted by L-arginine on the FK506-induced antinociception. Thus, it was concluded that NO- L-arginine pathway may be involved in the FK506-induced antinociception in tail flick test.     

Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils.

FK506 and dexamethasone were used to investigate whether or not immunosuppression affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infection, FK506 and dexamethasone or vehicle alone were subcutaneously administered once daily for the following 2 weeks. FK506 or vehicle alone was administered subcutaneously once daily for 5 weeks (1 week before and 4 weeks after infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosions and inflammatory responses (neutrophil infiltration and lymphoid follicle formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such mucosal changes. In these animals, H. pylori viability in the stomach was significantly elevated. FK506 administered for 5 weeks also significantly inhibited the hemorrhagic erosions, edema and neutrophil infiltration in the stomach. H. pylori viability was slightly elevated as compared with the control. It was concluded that the host immune responses might play dual roles both by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage.     

免疫抑制剂FK506对大鼠移植性肝癌肿瘤生长和脾转移的影响

目的观察在大鼠移植性肝癌模型中不同FK506剂量下肿瘤的大小和侵润以及脾脏转移情况,用以评价FK506对肝癌细胞增殖和转移的情况。方法在Wistar大鼠肝左叶种植walker-256细胞株成瘤的癌组织块以构建转移性肝癌模型,54只大鼠随机分为FK506低剂量组（0.5 mg/kg.d）,正常剂量组（1.0 mg/kg.d）和空白对照组,测量肿瘤大小,通过病理组织学观察7、14、21 d脾脏转移发生率和中位数。结果与空白组相比,第14、21天两个剂量组肝癌体积明显增大（P〈0.05）;同时也出现了脾转移,第14天FK506各组转移中位数均不同。根据病理组织学,各组脾转移的发生率没有明显性差异。结论用药早期,脾脏还存在免疫功能,免疫抑制剂不能完全压制抗肿瘤效应。低剂量FK506也许有利于减少癌症脾转移,仍需进一步的探讨FK506低剂量长期使用在肝癌复发和转移的作用。     

Intravenously injected FK506 failed to inhibit hippocampal calcineurin

FK506 (tacrolimus) is known as an inhibitor for calcineurin and is used in numerous research fields. It is not clear whether intravenously injected FK506 inhibits neuronal calcineurin. We measured the calcineurin activities of normal and postischemic rat hippocampi after intravenous injection of FK506 (3 mg/kg). Intravenously injected FK506 had no inhibitory effect on calcineurin activity in the hippocampi of normal and postischemic rats, whereas FK506 inhibited the calcineurin in vitro (purified enzyme, hippocampal homogenate, and hippocampal slice culture homogenate). Thus, it is considered that intravenously injected FK506 does not act on intraneuronal calcineurin and that several effects of FK506 are not due to the inhibition of neuronal calcineurin.     

FK506 Protects Neurons Following Peripheral Nerve Injury Via Immunosuppression

In this study, we have evaluated neuroprotective effect of an immunosuppressant immunophilin ligand, FK506, in the sciatic nerve injury model in rats. FK506 was injected to the sciatic nerve transected 3-month-old female Wistar rats (2 mg/kg/day starting 1 day prior to sciatic nerve injury up to 7 day post operation). Equal number of sciatic nerve transected animals served as injured untreated controls. The contralateral side served as respective control. L4-L5 region of the spinal cord was removed on day 1, 3, 7, 14, 21, and 28, post operation and then processed for cryo-sectioning and paraffin sectioning. The cryocut sections were used for immunohistochemistry for localizing all microglia (using anti-Iba-1) and MHC-II expressing microglia (with OX-6). The physical dissector method was applied on Nissl stained paraffin sections for absolute motor neuron counting in the L4-L5 region of spinal cord. FK506 treated animals presented 88.7% neuronal survival while the injured alone had 79.12%, which is significantly less than the treated animals. FK506 caused early proliferation of microglia at 1 and 3 days post operation. FK506 also significantly restricted transformation of these cells in to phagocytes. Colocalization of activated microglia by anti-Iba-1 and OX-6 antibodies, confirms that the MHC-II expressing cells in injured spinal cord are none other than microglial cells and MHC-II expressing cells are significantly less in treated as compared to untreated injured animals. We propose that immunosuppression is one of the main mechanisms by which FK506 protects the central neurons following peripheral injury.     

Overexpression of calmodulin induces cardiac hypertrophy by a calcineurin-dependent pathway

The possible role of calcineurin in cardiac hypertrophy induced by calmodulin (CaM) overexpression in the heart was investigated. CaM transgenic (CaM-TG) mice developed marked cardiac hypertrophy and exhibited up-regulation of atrial natriuretic factor (ANF) and beta-myosin heavy chain gene expression in the heart during the first 2 weeks after birth. The activity of calcineurin in the heart was also significantly increased in CaM-TG mice compared with wild-type littermates. Treatment of CaM-TG mice with the calcineurin inhibitor FK506 (1mg/kg per day) prevented the increase in the heart-to-body weight ratio as well as that in cardiomyocyte width. FK506 also inhibited the induction of fetal-type cardiac gene expression in CaM-TG mice. Overexpression of CaM in cultured rat cardiomyocytes activated the ANF gene promoter in a manner sensitive to FK506. Activation of a calcineurin-dependent pathway thus contributes to the development of cardiac hypertrophy induced by CaM overexpression in the heart.     

Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils

FK506 and dexamethasone were used to investigate whether or not immunosuppression affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infection, FK506 and dexamethasone or vehicle alone were subcutaneously administered once daily for the following 2 weeks. FK506 or vehicle alone was administered subcutaneously once daily for 5 weeks (1 week before and 4 weeks after infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosions and inflammatory responses (neutrophil infiltration and lymphoid follicle formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such mucosal changes. In these animals, H. pylori viability in the stomach was significantly elevated. FK506 administered for 5 weeks also significantly inhibited the hemorrhagic erosions, edema and neutrophil infiltration in the stomach. H. pylori viability was slightly elevated as compared with the control. It was concluded that the host immune responses might play dual roles both by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage.     

IL-12 gene therapy is an effective therapeutic strategy for hepatocellular carcinoma in immunosuppressed mice

Immunosuppressive therapy for organ transplantation is essential for controlling rejection. When liver transplantation is performed as a therapy for hepatocellular carcinoma (HCC), recurrent HCC is one of the most fatal complications. In this study, we show that intratumoral murine IL-12 (mIL-12) gene therapy has the potential to be an effective treatment for malignancies under immunosuppression. C3H mice (H-2(k)), injected with FK506 (3 mg/kg) i.p., were s.c. implanted with 2.5 x 10(6) MH134 cells (H-2(k)) and we treated the established HCC with electroporation-mediated gene therapy using mIL-12 plasmid DNA. Intratumoral gene transfer of mIL-12 elevated intratumoral mIL-12, IFN-gamma, and IFN-gamma-inducible protein-10, significantly reduced the number of microvessels and inhibited the growth of HCC, compared with HCC-transferred control pCAGGS plasmid. The inhibition of tumor growth in immunosuppressed mice was comparable with that of mIL-12 gene therapy in immunocompetent mice. Intratumoral mIL-12 gene therapy enhanced lymphocytic infiltration into the tumor and elicited the MH134-specific CTL response even under FK506. The dose of FK506 was sufficient to prevent the rejection of distant allogenic skin grafts (BALB/c mice, H-2(d)) and tumors, B7-p815 (H-2(d)) used as transplants, during mIL-12 gene therapy against MH134. Ab-mediated depletion studies suggested that the inhibition of tumor growth, neovascularization, and spontaneous lung metastasis by mIL-12 was dependent almost entirely on NK cells and partially on T cells. These results suggest that intratumoral mIL-12 gene therapy is a potent effective strategy not only to treat recurrences of HCC in liver transplantation, but also to treat solid malignant tumors in immunosuppressed patients with transplanted organ.     

Transduced PEP-1-FK506BP ameliorates corneal injury in Botulinum toxin A-induced dry eye mouse model

FK506 binding protein 12 (FK506BP) belongs to a family of immunophilins, and is involved in multiple biological processes. However, the function of FK506BP in corneal disease remains unclear. In this study, we examined the protective effects on dry eye disease in a Botulinum toxin A (BTX-A) induced mouse model, using a cell-permeable PEP-1-FK506BP protein. PEP-1-FK506BP efficiently transduced into human corneal epithelial cells in a time- and dose-dependent manner, and remained stable in the cells for 48 h. In addition, we demonstrated that topical application of PEP-1-FK506BP was transduced into mouse cornea and conjunctiva by immunohistochemistry. Furthermore, topical application of PEP-1-FK506BP to BTX-A-induced mouse model markedly inhibited expression levels of pro-inflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and macrophage inhibitory factor (MIF) in corneal and conjunctival epithelium. These results suggest PEP-1-FK506BP as a potential therapeutic agent for dry eye diseases. [BMB Reports 2013; 46(2): 124-129]     

FK506 as effective adjunct to L-dopa in reserpine-induced catalepsy in rats

Reserpine-induced catalepsy is a widely accepted animal model of Parkinson's disease. In the present study reserpine (2.5 mg/kg, ip) 20 hr and alpha-mehyl-para-tyrosine (AMPT; 200 mg/kg, ip), one hour before the experiment induced significant catalepsy in rats as assessed by bar test. There was a significant increase in the time spent on the bar in bar test as compared to the control untreated rats. L-dopa (100 mg/kg, ip) and carbidopa (10 mg/kg, ip) combination, a conventional therapy was less effective in reversing reserpine-induced catalepsy. Pretreatment with FK506, a neuroprotectant (0.5-2 mg/kg, po) not only dose dependently reduced the catalepsy in reserpine-treated rats but a lower dose (1 mg/kg) potentiated the motor stimulant actions of sub threshold dose of L-dopa (100 mg/kg, ip) and carbidopa (10 mg/kg, ip) combination. Anticataleptic effect of FK506 was blocked dose dependently by specific D2 receptor blocker sulpiride (25-100 mg/kg, ip). In conclusion, the findings of the present study suggest that FK506 has an indirect modulatory action on the dopamine D2 receptors. FK506 being a neuroprotectant, could be used as an effective adjunct to L-dopa for the treatment of neuroleptic-induced extrapyramidal side effects.     

Characterization of liposomal tacrolimus in lung surfactant-like phospholipids and evaluation of its immunosuppressive activity

Tacrolimus (FK506) is a hydrophobic immunosuppressive agent that rapidly penetrates the plasmatic membrane and inhibits the signal transduction cascade of T lymphocytes. The objective of this study was the characterization of liposomal FK506 with surfactant-like phospholipids to be administered intratracheally after lung transplantation or in inflammatory lung diseases. We evaluated the optimal incorporation of FK506 in dipalmitoylphosphatidylcholine (DPPC) and DPPC/1-palmitoyl-2-oleoylphosphatidylglycerol (POPG) monolayers and bilayers and the effects of FK506 on the physical properties of DPPC and DPPC/POPG (8:2 w/w) vesicles. In addition, we assessed the immunosuppressive effects of surfactant-like phospholipid vesicles containing different amounts of FK506 on T-cell proliferation and interleukin 2 production. From surface pressure measurements of FK506/DPPC and FK506/DPPC/POPG mixed monolayers, we determined that FK506 was embedded into these monolayers up to an FK506 concentration of about 0.4 mol %. Beyond this concentration, FK506 was not quantitatively incorporated into the monolayer, suggesting possible concentration-dependent aggregation of tacrolimus. The incorporation of FK506 into DPPC monolayers, at concentrations 相似文献   

Novel model for end-neuroma formation in the amputated rabbit forelimb

Background

In our previous study, allogeneic-transplanted peripheral nerve segments preserved for one month in a polyphenol solution at 4°C could regenerate nerves in rodents demonstrated the same extent of nerve regeneration as isogeneic fresh nerve grafts. The present study investigated whether the same results could be obtained in a canine model.

Methods

A sciatic nerve was harvested from a male beagle dog, divided into fascicules of < 1.5 mm diameter, and stored in a polyphenol solution (1 mg/ml) for one month at 4°C. The nerve fascicles were transplanted into 10 female beagle dogs to bridge 3-cm right ulnar nerve gaps. In the left ulnar nerve in each dog, a 3-cm nerve segment was harvested, turned in the opposite direction, and sutured in situ. Starting one day before transplantation, the immunosuppressant FK506 was administered subcutaneously at doses of 0.1 mg/kg daily in four dogs (PA0.1 group), 0.05 mg/kg daily in four dogs (PA0.05 group), or 0.05 mg/kg every other day in two dogs (PA0.025 group). Twelve weeks after surgery, electrophysiological and morphological studies were performed to assess the regeneration of the right and left ulnar nerves. The data for the right ulnar nerve were expressed as percentages relative to the left ulnar nerve. Polymerase chain reaction (PCR) was used to identify the sex-determining region of the Y-chromosome (Sry) and β-actin to investigate whether cells of donor origin remained in the allogeneic nerve segments. FK506 concentration was measured in blood samples taken before the animals were killed.

Results

The total myelinated axon numbers and amplitudes of the muscle action potentials correlated significantly with the blood FK506 concentration. Few axons were observed in the allogeneic-transplanted nerve segments in the PA0.025 group. PCR showed clear Sry-specific bands in specimens from the PA0.1 and PA0.05 groups but not from the PA0.025 group.

Conclusions

Successful nerve regeneration was observed in the polyphenol-treated nerve allografts when transplanted in association with a therapeutic dose of FK506. The data indicate that polyphenols can protect nerve tissue from ischemic damage for one month; however, the effects of immune suppression seem insufficient to permit allogeneic transplantation of peripheral nerves in a canine model.