RESUMO
Traumatically injured spinal cord (SC) displays structural damage that includes discontinuity of long tracts and cavitations. Axonal regrowth beyond the lesion is necessary to achieve functional recovery following SC injury. We report here the development of an artificial collagen-filament (CF) scaffold to replace the SC in 8-week-old female Fisher rats. Axonal sprouting and regrowth was very rapid following grafting of the CF. One week after implantation, the scaffold was filled with cells of host origin and with regenerated axons. Histological examination of SC adjacent to the scaffold showed little cavity formation or fibrous scarring. Eight weeks after implantation, myelinated nerve fibers were found in the scaffold and 10-25 % of rubrospinal tracts were repaired. Four to six weeks after transplantation, motor evoked potentials were recorded in CF-grafted rats but were not detectable in non-grafted rats. Electrophysiological and histological examinations revealed the grafted CF was likely to function as a nerve tract. In addition, these results suggest that collagen fibers may provide a permissive microenvironment for the elongation of SC axons and to support the process of spinal cord regeneration.
Assuntos
Axônios/fisiologia , Colágeno/uso terapêutico , Traumatismos da Medula Espinal/terapia , Regeneração da Medula Espinal , Alicerces Teciduais , Animais , Modelos Animais de Doenças , Fenômenos Eletrofisiológicos , Potencial Evocado Motor , Feminino , Modelos Animais , Ratos , Ratos Endogâmicos F344 , Recuperação de Função FisiológicaRESUMO
Na(x), a sodium concentration-sensitive sodium channel, is expressed in non-myelinating Schwann cells of the adult peripheral nervous system, but the pathophysiological role remains unclear. We found that functional recovery of the hind paw responses from the sciatic nerve transection was delayed in Na(x) knockout (Na(x)â»/â») mice. Histological analyses showed a decrease in the number of regenerated myelinated axons in (Na(x)â»/â») sciatic nerves. The delay in the recovery in Na(x)â»/â» mice was improved by lactate and inhibited by a monocarboxylate transporter inhibitor. In vitro experiments using cultured Schwann cells showed that lactate release was enhanced by endothelin (ET)-1 and blocked by an ET receptor type B antagonist. Here, it is conceivable that Na(x) was activated by ET-1. The amount of lactate release by ET-1 was lower in Na(x)â»/â» mice than in wild-type mice. These results indicated that Na(x) is functionally coupled to ET for lactate release via ET receptor type B and is involved in peripheral nerve regeneration.
Assuntos
Ácido Láctico/metabolismo , Regeneração Nervosa/fisiologia , Transdução de Sinais/fisiologia , Canais de Sódio/metabolismo , Animais , Axotomia , Células Cultivadas , Endotelinas/metabolismo , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Nervos Periféricos/metabolismo , Receptores de Endotelina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Nervo Isquiático/fisiologiaRESUMO
A recent study of a rat model treated with grafted collagen filament (CF) after spinal cord transection showed dramatic recovery of motor function but did not report on the acute-stage phenomenon. In the present study, we describe molecular and histological aspects of the axonal regeneration process during the acute stage following spinal cord transection. The spinal cord of 8-week-old rats was completely transected, and a scaffold of almost the same size as the resected portion was implanted in the gap. Changes in the mRNA expression of four neurotrophic factors [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT-3, and glial cell-derived neurotrophic factor (GDNF)] were analyzed after 72 h. The expression of BDNF and NT-3 mRNA increased significantly in the CF-grafted group compared to the nongrafted group. Immunostaining for BDNF and NT-3 revealed that cells positive for these neurotrophic factors extended along the collagen filaments in the CF-grafted group. Similarly, astrocytes extended into the collagen filament scaffold together with the neurotrophic factors and partly across a border line. These findings indicate that collagen filament helps to reduce scar tissue, supports the expression of neurotrophic factors, and serves as a scaffold for the outgrowth of regenerating axons.
Assuntos
Regeneração Tecidual Guiada/métodos , Regeneração Nervosa/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Animais , Astrócitos/metabolismo , Colágeno/metabolismo , Feminino , Implantes Experimentais , Fatores de Crescimento Neural/genética , Fatores de Crescimento Neural/metabolismo , Ratos , Ratos Endogâmicos F344RESUMO
The aim of the present study was to investigate the factors contributing to pulse wave velocity (PWV) in patients with type 2 diabetes mellitus. We focused on tumor necrosis factor (TNF) including soluble TNF receptors (sTNF-R1, sTNF-R2) in this study because TNF seems to be associated with the progression of atherosclerosis and because the relationships between PWV and TNF were not yet examined in type 2 diabetic patients. Univariate regression analyses showed that PWV was positively correlated with age (r=0.492, P<.001), diabetes duration (r=0.251, P=.021), systolic (r=.595, P<.001) and diastolic (r=0.248, P=.022) blood pressure, antihypertensive medication (r=0.268, P=.013), and the concentrations of sTNF-R1 (r=0.354, P=.001) and sTNF-R2 (r=0.415, P<.001). Although there was a positive correlation between TNF-alpha and sTNF-R1 (r=0.382, P<.001) or sTNF-R2 (r=0.394, P<.001), TNF-alpha was not associated with PWV. Other variables including gender were not associated with PWV. Multiple regression analyses showed that PWV was independently predicted by the level of age (F=15.1), systolic blood pressure (F=31.6), and sTNF-R2 (F=5.2), which explained 49.2% of the variability of PWV. From these results, it can be concluded that serum soluble TNF receptor is an important independent factor associated with aortic PWV in type 2 diabetic patients.
Assuntos
Diabetes Mellitus Tipo 2/fisiopatologia , Receptores do Fator de Necrose Tumoral/sangue , Glicemia/análise , Pressão Sanguínea , Diabetes Mellitus Tipo 2/sangue , Humanos , Resistência à Insulina , Japão , Pessoa de Meia-IdadeRESUMO
The aim of the present study was to investigate the relationships between interleukin 6 (IL-6) and insulin resistance, serum leptin, serum adiponectin, or serum lipids including triglycerides in 98 nonobese Japanese type 2 diabetic patients. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Serum IL-6 concentration was negatively correlated to high-density lipoprotein cholesterol (r = -0.295, P = .004), but was not associated with HOMA-IR (r = 0.016, P = .871), body mass index (BMI) (r = 0.090, P = .375), systolic (r = 0.169, P = .116) and diastolic (r = -0.061, P = .570) blood pressures, leptin (r = 0.062, P = .544), and adiponectin (r = -0.020, P = .841) in these patients. In contrast, serum leptin level was positively correlated to HOMA-IR (r = 0.291, P = .004), BMI (r = 0.338, P < .001), and systolic blood pressure (r = 0.241, P = .025). Serum adiponectin level was negatively correlated to HOMA-IR (r = -0.288, P = .005), BMI (r = -0.308, P = .002), diastolic blood pressure (r = -0.269, P = .012), and triglycerides (r = -0.338, P < .001), and positively correlated to high-density lipoprotein cholesterol (r = 0.300, P = .003) in our patients. From these results, it can be suggested that fasting serum IL-6 is not a major factor responsible for the evolution of insulin resistance in nonobese Japanese type 2 diabetic patients.
Assuntos
Adiponectina/sangue , Diabetes Mellitus Tipo 2/sangue , Resistência à Insulina/fisiologia , Interleucina-6/sangue , Leptina/sangue , Glicemia/metabolismo , Pressão Sanguínea/fisiologia , Colesterol/sangue , Feminino , Humanos , Insulina/sangue , Japão , Masculino , Pessoa de Meia-Idade , Estatísticas não Paramétricas , Triglicerídeos/sangueRESUMO
The aim of the present study was to investigate the relationships between insulin resistance and soluble E-selectin, body mass index (BMI), leptin, and serum lipid profile including triglycerides in nonobese Japanese type 2 diabetic patients. A total of 97 nonobese Japanese type 2 diabetic patients aged 43 to 84 years were examined. The duration of diabetes was 11.2 +/- 0.8 years. In conjunction with BMI and fasting concentrations of plasma glucose, serum lipids (triglycerides, total cholesterol, and high-density lipoprotein cholesterol) and serum insulin, soluble E-selectin, and leptin were also measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula. Insulin resistance was estimated by the homeostasis model assessment. The subjects were divided into 2 groups according to the value of insulin resistance estimated by the homeostasis model assessment. Values greater than 2.5 were indicative of the insulin-resistant state, and values less than 2.5 were indicative of the insulin-sensitive state. The insulin-resistant group had significantly higher levels of E-selectin, leptin, triglycerides, total and LDL cholesterol, and diastolic blood pressure as compared with the insulin-sensitive group. There was, however, no significant difference in age, sex, diabetes duration, BMI, systolic blood pressure, HbA1c, and high-density lipoprotein cholesterol between the 2 groups. Univariate regression analysis showed that insulin resistance was positively correlated to E-selectin (r = 0.305, P = .003), BMI (r = 0.283, P = .006), leptin (r = 0.296, P = .004), HbA1c (r = 0.241, P = .018), serum triglycerides (r = 0.385, P < .001), serum total (r = 0.240, P = .019) and LDL cholesterol (r = 0.254, P = .013) levels, and systolic (r = 0.247, P = .024) and diastolic (r = 0.305, P = .006) blood pressure. Multiple regression analyses showed that insulin resistance was independently predicted by serum E-selectin (F = 18.4), serum leptin (F = 14.0) and serum triglycerides (F = 20.0) levels, which explained 45.0% of the variability of insulin resistance. From these results, it can be concluded that in conjunction with serum triglycerides and serum leptin, serum E-selectin is another important independent factor associated with insulin resistance in nonobese Japanese type 2 diabetic patients.
Assuntos
Diabetes Mellitus Tipo 2/sangue , Selectina E/sangue , Resistência à Insulina , Leptina/sangue , Triglicerídeos/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea , Índice de Massa Corporal , Colesterol/sangue , LDL-Colesterol/sangue , Hemoglobinas Glicadas/análise , Homeostase , Humanos , Japão , Pessoa de Meia-Idade , Análise de RegressãoRESUMO
The aim of the present study was to investigate the relationship between insulin resistance and tumor necrosis factor alpha (TNF-alpha) as well as soluble TNF receptors (sTNF-R), body mass index (BMI), leptin, adiponectin, and serum lipid profile including triglycerides in nonobese Japanese patients with type 2 diabetes. A total of 88 nonobese Japanese type 2 diabetic patients were studied. The duration of diabetes was 11.0 +/- 0.8 years. In conjunction with BMI, glycosylated hemoglobin (HbA1c), fasting concentrations of plasma glucose, serum lipids (triglycerides, high-density lipoprotein cholesterol, and total cholesterol), serum leptin, serum adiponectin, serum TNF-alpha, and soluble TNF receptors (sTNF-R1 and sTNF-R2) were also measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment. Insulin resistance was positively correlated with BMI, triglycerides, leptin, and total cholesterol and negatively correlated with adiponectin and high-density lipoprotein cholesterol. In contrast, insulin resistance was not associated with TNF-alpha, nor sTNF-R (sTNF-R1 and sTNF-R2) in our diabetic patients. There was no significant relationship between the 3 measures of TNF-alpha system (TNF-alpha, sTNF-R1, and sTNF-R2) and BMI, serum triglycerides, leptin, or adiponectin in these patients. From these results, it can be concluded that peripheral levels of TNF-alpha system activity are not a major factor responsible for insulin resistance in nonobese Japanese type 2 diabetic patients.
Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Resistência à Insulina , Receptores Tipo II do Fator de Necrose Tumoral/sangue , Receptores Tipo I de Fatores de Necrose Tumoral/sangue , Fator de Necrose Tumoral alfa/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Leptina/sangue , Masculino , Pessoa de Meia-IdadeRESUMO
The aim of this study was to investigate the relationships between insulin resistance and regional abdominal fat area, body mass index (BMI), and serum lipid profile in nonobese Japanese type 2 diabetic patients. A total of 63 nonobese Japanese type 2 diabetic patients aged 45 to 83 years were examined. The duration of diabetes was 8.4 +/- 0.8 years. BMI, glycosylated hemoglobin (HbA(1c)) levels, and fasting concentrations of plasma glucose, serum lipids (total cholesterol, high-density lipoprotein [HDL] cholesterol, and triglycerides), and serum insulin were measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula (LDL cholesterol = total cholesterol - HDL cholesterol - 1/5 triglycerides). Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). Computed tomography (CT) was used to measure cross-sectional abdominal subcutaneous and visceral fat areas in all the patients. Adipose tissue areas were determined at the umbilical level. Subcutaneous and visceral abdominal fat areas were 136.5 +/- 6.0 and 86.0 +/- 4.1 cm(2), respectively. Univariate regression analysis showed that insulin resistance was positively correlated with subcutaneous (r =.544, P <.001) and visceral (r =.408, P =.001) fat areas, BMI (r =.324, P =.009), HbA(1c) (r =.254, P =.001), serum triglycerides (r =.419, P <.001), and serum LDL cholesterol (r =.290, P =.019) levels and was negatively correlated with serum HDL cholesterol level (r =.254, P =.041). Multiple regression analyses showed that insulin resistance was independently predicted by the areas of subcutaneous (F = 6.76, P <.001) and visceral (F = 4.61, P <.001) abdominal fat and serum triglycerides (F = 8.88, P <.001) level, which explained 36.9% of the variability of insulin resistance. Moreover, the present study demonstrated that whereas BMI was positively correlated with visceral (r =.510, P <.001) and subcutaneous (r =.553, P <.001) fat areas, serum triglyceride level was positively associated with visceral (r =.302, P =.015), but not with subcutaneous (r =.222, P =.074) fat area. From these results, it can be suggested that (1) both subcutaneous and visceral abdominal fat areas are independently associated with insulin resistance and (2) visceral fat area, but not the subcutaneous one, is associated with serum triglyceride levels in our nonobese Japanese type 2 diabetic patients.
Assuntos
Tecido Adiposo , Composição Corporal , Diabetes Mellitus Tipo 2/fisiopatologia , Resistência à Insulina , Triglicerídeos/sangue , Idoso , Idoso de 80 Anos ou mais , Glicemia/análise , Índice de Massa Corporal , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Hemoglobinas Glicadas/análise , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Análise de RegressãoRESUMO
The aim of the present study was to investigate the relationship between C-reactive protein (CRP) and insulin resistance in non-obese Japanese type 2 diabetic patients. A total of 135 non-obese Japanese type 2 diabetic patients (96 men and 39 women, aged 36 to 83 years, with a body mass index [BMI] of 16.2 to 26.8 kg/m2) were studied. BMI, glycosylated hemoglobin (HbA(1c)), fasting concentrations of plasma glucose, serum lipids (triglycerides, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, and total cholesterol), CRP, and fibrinogen were measured. LDL cholesterol was calculated using the Friedewald formula. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Univariate regression analysis showed that CRP value was positively correlated to age (r = 0.218, P =.012), BMI (r = 0.239, P =.006), HOMA-IR (r = 0.397, P <.0001), triglycerides (r= 0.310, P <.005), LDL cholesterol (r= 0.179, P =.038), and fibrinogen (r = 0.371, P <.0001) levels and inversely correlated to HDL cholesterol (r = 0.174, P =.044) level in our diabetic patients. Multiple regression analysis showed that CRP was independently predicted by HOMA-IR (P<.0001, F = 11.6) and fibrinogen (P<.0001, F = 34.2), which explained 23.5% of the variability of CRP in our non-obese Japanese type 2 diabetic patients. These results indicate that insulin resistance and fibrinogen level are independent predictors of CRP in non-obese Japanese type 2 diabetic patients.
Assuntos
Povo Asiático , Diabetes Mellitus Tipo 2/etnologia , Diabetes Mellitus Tipo 2/fisiopatologia , Proteína C-Reativa , Diabetes Mellitus Tipo 2/metabolismo , Feminino , Fibrinogênio/análise , Homeostase , Humanos , Resistência à Insulina , Japão , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , MagrezaRESUMO
The aim of the present study was to investigate the relationship between platelet count and insulin resistance in non-obese Japanese type 2 diabetic patients. A total of 163 non-obese Japanese type 2 diabetic patients (112 men and 51 women, aged 36 to 84 years, body mass index [BMI] 16.2 to 26.9 kg/m(2)) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA(1c)), fasting concentrations of plasma glucose and serum lipids (triglycerides, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, and total cholesterol), and hematological parameters (platelets, white blood cell count, red blood cell count, hematocrit, hemoglobin) were measured. LDL cholesterol was calculated using the Friedewald formula. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Univariate regression analysis showed that HOMA-IR was positively correlated to BMI (r = 0.465, P <.0001), HbA(1c) (r = 0.423, P <.0001), platelet count (r = 0.310, P <.0001), triglycerides (r = 0.277, P <.0005), white blood cell count (r =.222, P =.005), red blood cell count (r = 0.210, P =.008), hematocrit (r = 0.156, P =.047), total cholesterol (r = 0.178, P =.023), and systolic (r = 0.216, P =.011) and diastolic (r = 0.263, P =.002) blood pressure, and inversely correlated to HDL cholesterol (r = -0.312, P <.0001) level in our diabetic patients. Multiple regression analysis showed that HOMA-IR was independently predicted by BMI (P <.0001, F = 22.45), HbA(1c) (P <.0001, F = 16.15), platelet count (P <.0001, F = 10.75), and serum triglycerides (P <.0001, F = 10.47) levels, which explained 34% of the variability of HOMA-IR in non-obese Japanese type 2 diabetic patients. These results indicate that not only BMI, HbA(1c), and triglycerides levels but also platelet counts are independent predictor of insulin resistance in non-obese Japanese type 2 diabetic patients.
Assuntos
Povo Asiático , Plaquetas , Diabetes Mellitus Tipo 2/sangue , Resistência à Insulina , Adulto , Idoso , Análise de Variância , Glicemia/metabolismo , Índice de Massa Corporal , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Diabetes Mellitus Tipo 2/metabolismo , Contagem de Eritrócitos , Feminino , Hematócrito , Hemoglobinas/metabolismo , Humanos , Japão/etnologia , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Obesidade/metabolismo , Contagem de PlaquetasRESUMO
The aim of the present study was to investigate whether non-obese Japanese type 2 diabetic patients with porphyromonas gingivalis infection have atherosclerotic vascular diseases. A total of 134 non-obese Japanese type 2 diabetic patients (96 men and 38 women, aged 36 to 84 years, body mass index [BMI] 20.1 to 26.9 kg/m(2)) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA(1c)), fasting glucose, and serum lipids (triglycerides, total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol) were measured. LDL cholesterol was calculated using the Friedewald formula. Using high-resolution B-mode ultrasound scan, we measured intimal medial thickness (IMT) in plaque-free segments of bilateral common carotid arteries, and the mean of IMT in 2 vessels was used for the analysis. Furthermore, we calculated the degree of stenosis in plaque segments of bilateral common carotid arteries. The degree of carotid atherosclerosis was expressed as a percentage ratio between the area of plaque and that of the lumen using the formula (Lumen Area Residual - Lumen Area)/Lumem Area x 100. Both the areas were automatically measured by the system on a frozen transverse scanning plane at the site of maximal narrowing. When 2 or more plaques were present in the vessel, only that causing the greatest degree of stenosis was considered for analysis. Values represent mean+/-SEM unless otherwise stated. Immunoglobulin G (IgG) titer against porphyromonas gingivalis was 245 +/- 65 (mean +/- 2 SD) in nondiabetic healthy subjects. In contrast, there was a wide variation in IgG titer against porphyromonas gingivalis in type 2 diabetic patients studied (range, 16 to 26,800). Thus, we classified our type 2 diabetic patients into 2 subpopulations according to the value of mean +/- 2 SD (= 310) of nondiabetic healthy subjects: one with high IgG titer against porphyromonas gingivalis (>310) (1,422 +/- 408) and the other with normal IgG titer against porphyromonas gingivalis (<310) (152 +/- 10, P =.002). The populations did not differ with respect to age, sex, BMI, fasting glucose, HbA(1c), serum triglycerides, total, HDL, and LDL cholesterol levels. Although the mean IMT in plaque-free segments was not different between the 2 groups (0.73 +/-0.03 v 0.68 +/- 0.02 mm, P =.098), the degree of stenosis in plaque segments was significantly higher in the high IgG titer group (12.0% +/- 2.2%) than in normal one (5.5% +/- 1.4%, P =.009). From these results, it can be concluded that porphyromonas gingivalis infection, although still a subclinical infection, is associated with atherosclerotic vascular disease in non-obese Japanese type 2 diabetic patients.
Assuntos
Povo Asiático , Infecções por Bacteroidaceae/complicações , Peso Corporal , Doenças das Artérias Carótidas/microbiologia , Diabetes Mellitus Tipo 2/microbiologia , Porphyromonas gingivalis , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças das Artérias Carótidas/etnologia , Diabetes Mellitus Tipo 2/etnologia , Diabetes Mellitus Tipo 2/patologia , Feminino , Humanos , Japão/etnologia , Masculino , Pessoa de Meia-IdadeRESUMO
This paper describes 30 mm regeneration of peripheral nerve axons along collagen filaments; 31-mm-long collagen filaments or collagen tube were grafted to bridge a 30-mm defect of rat sciatic nerve. The mean number and the diameter of regenerated myelinated axons were 330+/-227 and 2.7+/-0.9 microm at the distal end of the collagen-filaments 12 weeks postoperatively; while at the distal end of the tube no axon was found.
Assuntos
Colágeno , Regeneração Nervosa , Nervo Isquiático/fisiologia , Animais , Colágeno/uso terapêutico , Masculino , Ratos , Ratos Wistar , Nervo Isquiático/crescimento & desenvolvimento , Nervo Isquiático/lesõesRESUMO
This article describes a 30-mm regeneration of severed peripheral nerve axons along collagen filaments. Two thousand or 4000 31-mm-long collagen filaments were grafted to bridge a 30-mm defect of the rat sciatic nerve. A collagen tube was grafted as a control. The mean number and mean fiber diameter of regenerated myelinated axons were 330 +/- 227 and 2.7 +/- 0.9 microm in the distal end of the 2000 collagen-filaments nerve guide, and 564 +/- 275 and 2.5 +/- 1.1 microm in the distal end of the 4000 collagen-filaments nerve guide at 12 weeks postoperatively, whereas in the distal end of the collagen tube, no regenerated axon was found. These results suggest that the collagen filaments guide axons of the rat's sciatic nerve to regenerate for 30 mm and act as a scaffold for axonal regeneration. Thirty-millimeter nerve regeneration of a 1-mm-diameter rat sciatic nerve by an artificial nerve guarantees a clinical application of the implant which should be very important for patients and surgeons.
Assuntos
Axônios/fisiologia , Colágeno/fisiologia , Regeneração Nervosa/fisiologia , Nervo Isquiático/lesões , Animais , Bovinos , Colágeno/ultraestrutura , Masculino , Microscopia Eletrônica , Ratos , Nervo Isquiático/fisiologiaRESUMO
The restoration of function of transected adult mammalian spinal cord without living tissue has not been reported previously. We report the first success of functional restoration of transected spinal cord without living tissue. We grafted collagen filaments parallel or transverse to the axis of the spinal cord to bridge 5-mm defects of 47 adult rat spinal cords. Twenty-five rats were used as a control. Of the 72 rats, 42 rats survived the experimental period. At 4 weeks postoperatively, regenerated axons crossed the proximal and distal spinal cord-implant interfaces in all 5 rats of the parallel-grafted group. At 12 weeks postoperatively, the rats in the parallel-grafted group (8 rats) could walk, run, and climb with hind-forelimb coordination. The somatosensory-evoked potentials were seen. Results suggest that the collagen filaments support the axonal regeneration of the transected spinal cord and the restoration of function when grafted parallel to the axis of the spinal cord. The functional restoration appeared to be permanent, raising the possibility of therapeutic application in humans.
Assuntos
Implantes Absorvíveis , Colágeno/uso terapêutico , Traumatismos da Medula Espinal/tratamento farmacológico , Traumatismos da Medula Espinal/fisiopatologia , Cicatrização/efeitos dos fármacos , Animais , Bovinos , Colágeno/farmacologia , Eletrofisiologia , Masculino , Ratos , Ratos Wistar , Nervo Isquiático/fisiologia , Traumatismos da Medula Espinal/patologiaRESUMO
This article describes the regeneration of severed peripheral nerve axons along collagen filaments in the absence of the distal nerve stump. 22-mm long nerve guides made of collagen filaments were sutured to the proximal ends of severed rat sciatic nerves. The distal ends of the guides were sutured to the distal stumps of the nerves in a group and not sutured in the other. Nerve autografts and collagen tubes were used as controls. At 8 weeks postoperatively, the mean number and the mean diameter of myelinated axons were 5491 +/- 617 (mean +/- SD) and 2.3 +/- 1.3 microns at the distal ends of the collagen filaments nerve guides those the distal ends were sutured to the distal stumps of the nerves, while in the nerve autografts these were 4837 +/- 604 and 3.3 +/- 1.4 microns. These were 1992 +/- 770 and 2.7 +/- 1.2 microns at the distal ends of the collagen-filaments guides those the distal ends were not sutured to the distal stumps of the nerves, while in the nerve autografts these were 3041 +/- 847 and 2.3 +/- 1.1 microns. No axon was found at the distal ends of the collagen tubes. The results suggested that the contact guidance and the chemotaxis guided regenerating axons along the collagen filaments.
Assuntos
Materiais Biocompatíveis , Colágeno/fisiologia , Regeneração Nervosa/fisiologia , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia , Animais , Materiais Biocompatíveis/farmacologia , Materiais Biocompatíveis/uso terapêutico , Bovinos , Quimiotaxia/efeitos dos fármacos , Quimiotaxia/fisiologia , Colágeno/farmacologia , Colágeno/uso terapêutico , Implantes Experimentais , Masculino , Fibras Nervosas Mielinizadas/efeitos dos fármacos , Fibras Nervosas Mielinizadas/fisiologia , Ratos , Ratos Wistar , Nervo Isquiático/efeitos dos fármacosRESUMO
We evaluated sciatic nerve regeneration in thy1-YFP transgenic mice selectively expressing a fluorescent protein in their axons. Using in vivo imaging, we observed the dorsal cutaneous renervation of the hind paw for 8 weeks. Three to four weeks after the operation, the length of the regenerated nerve treated with NGF tended to be longer than that of the regenerated nerve treated with saline. Functional recovery was evaluated by a withdrawal response of the hind paw to mechanical stimuli. In NGF and GDNF groups, mice started to resume a mechanical response 4 weeks after the operation, earlier than in the saline control group. Histological and ultrastructural analyses showed that the density of unmyelinated axons in the regenerated nerve of the NGF group was larger than that of those in the saline group. These results indicate that NGF accelerated the regeneration of the sciatic nerve and thus that the monitoring of cutaneous nerve regeneration in the dorsal foot is useful to evaluate the regeneration of the sciatic nerve in vivo.
Assuntos
Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Fator de Crescimento Neural/metabolismo , Regeneração Nervosa/fisiologia , Análise de Variância , Animais , Axônios/fisiologia , Axônios/ultraestrutura , Membro Posterior/inervação , Imuno-Histoquímica , Proteínas Luminescentes/genética , Camundongos , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Medição da Dor , Estimulação Física , Recuperação de Função Fisiológica , Nervo Isquiático/lesões , Nervo Isquiático/ultraestrutura , Pele/inervação , Antígenos Thy-1/genéticaRESUMO
STUDY DESIGN: A rat model of spinal cord defect was designed to evaluate the effect of collagen filament implant on nerve regeneration in the spinal cord defect. OBJECTIVES: To bridge a spinal cord defect and restore the function in adult mammals. SUMMARY OF BACKGROUND DATA: Resection of the spinal cord in mammals is always followed by motor paralysis and loss of voluntary function below the lesion. Partial success in bridging the ends of the spinal cord after complete resection was reported. However, restoration of function has not been reported in adult mammalian. MATERIALS AND METHODS: Four thousand collagen filaments 5-mm-long were grafted to bridge a 5-mm defect of rat spinal cord. Controls had their spinal cord defect left ungrafted after resection. At 1-week intervals, animals were evaluated functionally. After 4 and 12 weeks, animals were evaluated histologically. After 12 weeks, animals were evaluated electrophysiologically. RESULTS: The severed spinal cord axons regenerated along the collagen filament implant crossing the proximal and distal spinal cord implant interfaces at 4 weeks after surgery. The rats with collagen filament grafts could walk, run, and climb with hind forelimb coordination at 12 weeks after surgery. Sensory-evoked potential waveform was found in the rats with collagen filament at 12 weeks after surgery. CONCLUSIONS: The collagen filaments support the axonal regeneration of the transected spinal cord and the restoration of function.