Serum TGF-beta in thermally injured rats.

A severe thermal injury is commonly associated with immune suppression and increased susceptibility to sepsis, frequently leading to multiple organ failure. Transforming growth factor-beta (TGF-beta) is a potent immunosuppressive cytokine involved in complications associated with major trauma. Interleukin- 4 (IL-4) is thought to synergize the immunosuppressive activity of TGF-beta by promoting naive lymphocytes to differentiate and generate TGF-beta secreting cells. This study examines the alterations in serum levels of TGF-beta and IL-4 after a thermal injury. Male Sprague-Dawley rats (300-400 g) were anesthetized and received a 50% total body surface area full-thickness scald burn followed by fluid resuscitation and analgesia. Control rats were given the same treatment, but were immersed in water at room temperature. Rats were sacrificed from 1 h to 8 days after injury. Blood samples were collected aseptically from the inferior caval vein. Serum levels of TGF-beta and IL-4 were measured by enzyme linked immunosorbent assay. Rats in the control and thermal injury groups showed similar increases in serum TGF-beta 1 h after injury. A progressive increase in serum TGF-beta was observed in burned animals compared to control animals starting on day 3 and continued through day 8 (P < 0.01). Serum IL-4 levels in control and thermally injured animals remained undetectable (< 15.6 pg/mL) throughout the experiment. Thermal injury induces a significant increase in serum TGF-beta, which may contribute to post-burn immunosuppression with an increased susceptibility to sepsis.     

Skeletal muscle glutamine production in thermally injured rats

1. The effect of thermal injury (33-35% of body surface area) on the regulation of glutamine metabolism was studied in skeletal muscles of rats 7 days after injury. 2. Injury increased the rates of glutamine production in muscle, skin and adipose tissue preparations, with muscle production accounting for over 90% of total glutamine produced by the hindlimb. 3. Injury produced decreases in the concentrations of skeletal muscle glutamine (36%, P less than 0.001), glutamate (39%, P less than 0.001), alanine (24%, P less than 0.001), pyruvate (35%, P less than 0.001), 2-oxoglutarate (51%, P less than 0.001) and adenosine 5'-triphosphate (38%, P less than 0.001). The concentrations of ammonia (42%, P less than 0.001) and inosine 5'-phosphate (430%, P less than 0.001) were increased. 4. The maximal activity of glutamine synthetase was increased (22-40%, P less than 0.001) in muscles of injured rats, whereas that of glutaminase was unchanged. 5. Hindlimb blood flow decreased by approximately 15% in injured rats, which was accompanied by an enhanced net release of glutamine (80%, P less than 0.001) and alanine (44%, P less than 0.001). 6. It is concluded that there is an enhanced rate of release of both glutamine and alanine from skeletal muscle of thermally injured rats. This may be due to changes in efflux and/or increased intracellular formation of glutamine and alanine.     

IGF-I gene transfer in thermally injured rats.

Exogenous insulin-like growth factor-I (IGF-I) is known to improve the pathophysiology of a thermal injury, however, deleterious side-effects have limited its utility. Cholesterol-containing cationic liposomes that encapsulate complementary DNA (cDNA) are nonviral carriers used for in vivo gene transfection. We propose that liposome IGF-I gene transfer will accelerate wound healing in burned rats and attenuate deleterious side-effects associated with high levels of IGF-I. To test this hypothesis IGF-I gene constructs, encapsulated in liposomes, were studied for their efficacy in modulating the thermal injury response. Thirty adult male Sprague-Dawley rats were given a 60% TBSA scald burn and randomly divided into three groups to receive weekly subcutaneous injections of liposomes plus the lacZ gene coding for beta-galactosidase, liposomes plus cDNA for IGF-I and beta-galactosidase or liposomes plus the rhIGF-I protein. Body weights and wound healing were measured. Muscle and liver dry/wet weights and IGF-I concentrations in serum, skin and liver were measured by radioimmunoassay. Transfection was confirmed by histochemical staining for beta-galactosidase. Rats receiving the IGF-I cDNA constructs exhibited the most rapid wound re-epithelialization and greatest increase in body weight and gastrocnemius muscle protein content (P < 0.05). Local IGF-I protein concentrations in the skin were higher when compared to liposomes containing only the lacZ gene (P < 0.05) Transfection was apparent in the cytoplasm of myofibroblasts, endothelial cells and macrophages of the granulation tissue. Liposomes containing the IGF-I gene constructs proved effective in preventing muscle protein wasting and preserving total body weight after a severe thermal injury.     

Hepatocyte growth factor leads to recovery from alcohol-induced fatty liver in rats

A fatty liver is characterized by the hyperaccumulation of lipids within hepatocytes and is often caused by excessive alcohol intake. Rats fed ethanol-containing diets for 37 days showed remarkable increase in hepatic lipids and lipid droplet accumulation in the hepatocytes, indicating the onset of alcoholic fatty liver. Administration of hepatocyte growth factor (HGF) for the last seven days of ethanol treatment markedly decreased hepatic lipids to a level lower than that seen before HGF treatment. In contrast, serum levels of lipids and lipoproteins increased with HGF administration. Primary cultured hepatocytes prepared from the fatty liver retained lipid droplets during a 48-hour culture. However, when cultured in the presence of HGF, intracellular lipid concentrations decreased and lipid secretion was enhanced. Consistent with these events, HGF stimulated the rate of protein synthesis of apolipoprotein B (apoB) and enhanced subsequent mobilization of lipids into the medium. These results indicate that HGF administration induced recovery from the fatty liver, at least in part, by enhancing apoB synthesis and the subsequent mobilization of lipids from hepatocytes with fatty change. The possibility that HGF can be therapeutic for subjects with an alcohol-related fatty liver warrants further attention.     

Hepatocyte growth factor facilitates colonic mucosal repair in experimental ulcerative colitis in rats

Hepatocyte growth factor (HGF) modulates intestinal epithelial cell proliferation and migration, serving as a critical regulator of intestinal wound healing. In this study, we examined the effect of administration of recombinant human HGF on colonic mucosal damage in vivo. Acute colitis was induced in rats by feeding with 5% dextran sulfate sodium (DSS) for 7 days, and colitis was subsequently maintained by feeding with 1% DSS. On the 5th day of DSS administration, osmotic pumps releasing recombinant human HGF (200 microg/day) were implanted into the peritoneum of the rats. Continuous intraperitoneal delivery of HGF led to both increased serum human HGF levels and c-Met tyrosine phosphorylation within the colonic mucosa. Compared with mock-treated rats, those administered human HGF showed a reduction in colitis-associated weight loss, large intestinal shortening, and improved colonic erosions. Enhanced epithelial regeneration and cellular proliferation were observed in rats treated with recombinant human HGF. The weights of the liver, kidneys, and spleen were not affected by HGF administration. These results indicate that HGF administration accelerates colonic mucosal repair in rats with DSS-induced colitis and suggest that recombinant human HGF may be a useful therapeutic tool to facilitate intestinal wound healing in patients with ulcerative colitis.     

诱导人骨髓间充质干细胞向肝系细胞分化过程中肝细胞生长因子和碱性成纤维细胞生长因子的作用

背景:骨髓间充质干细胞是一种存在于骨髓内的非造血干细胞,因其具有自我更新能力及多向分化潜能,且分离培养方法成熟,在组织器官修复及再生方面显示出良好的应用前景,将为终末期肝病的治疗如生物人工肝及肝细胞移植提供新的细胞来源,但目前人骨髓间充质干细胞向肝系细胞诱导分化培养体系尚不成熟。目的:观察肝细胞生长因子和碱性成纤维细胞生长因子联合应用诱导人骨髓间充质干细胞在体外向肝系细胞分化的可能性。设计:开放性实验。单位:南昌大学第一附属医院传染科与泌尿外科研究所。材料:实验于2004-07/2005-03在南昌大学第一附属医院泌尿外科研究所完成。所用骨髓由成年健康志愿者提供(均对本实验知情同意)。DMEM/F12培养基(Gibco公司);表皮细胞生长因子,肝细胞生长因子,胰岛素,转铁蛋白,鼠抗人甲胎蛋白单克隆抗体,FITC-兔抗鼠IgG(Sig-ma公司);碱性成纤维细胞生长因子(Invitrogen公司);鼠抗人角蛋白18,19单克隆抗体(Chemicon公司);胎牛血清(杭州四季青)。方法:以骨髓腔穿刺方式抽取成年健康志愿者髂后上棘处骨髓10mL,采用密度梯度离心法分离和反复贴壁法纯化骨髓间充质干细胞。取培养至4～8代细胞,消化后以107L-1接种到放置20mm×20mm爬片的预先铺被有0.1%明胶的24孔板中,次日换液,改用无血清DMEM/F12培养基(含20μg/L的表皮细胞生长因子和10μg/L的碱性成纤维细胞生长因子)培养2d后,换成无血清DMEM/F12培养基(含20μg/L的肝细胞生长因子,10μg/L的碱性成纤维细胞生长因子,5mg/L的胰岛素,5mg/L的转铁蛋白)进行诱导分化,每3d换液1次,以未加入肝细胞生长因子和碱性成纤维细胞生长因子的骨髓间充质干细胞作为对照组。骨髓间充质干细胞诱导培养过程中,放射免疫荧光法测甲胎蛋白浓度。诱导当天及第7,14,21,28天,取诱导细胞爬片,细胞免疫荧光法检测肝细胞表面标志物甲胎蛋白、角蛋白18和角蛋白19的表达,并进行糖原染色检测诱导细胞的糖原合成情况。主要观察指标:①细胞形态学观察。②培养上清液中甲胎蛋白表达量的测定。③肝细胞表面标志检测结果。④诱导细胞的糖原合成情况。结果:①诱导第14天可观察到细胞变成短梭形和多角形,随培养时间的延长多角形细胞增多,并可形成肝细胞样的细胞集落。②诱导第14天培养上清液内可检测到甲胎蛋白的分泌,每孔浓度为0.1μg/L;第17天达高峰0.4μg/L;第21天下降至0.3μg/L。③诱导第14天甲胎蛋白、角蛋白18表达呈阳性,第28天角蛋白19表达呈阳性。④诱导第21天糖原染色呈阳性反应。结论:肝细胞生长因子和碱性成纤维细胞生长因子能够诱导人骨髓间充质干细胞在体外向肝细胞分化,表达肝细胞特异性表面标志,并具有合成糖原、分泌甲胎蛋白的功能。     

Hepatocyte growth factor as potential cardiovascular therapy

Hepatocyte growth factor is a mesenchyme-derived pleiotropic factor that regulates the growth, motility and morphogenesis of various types of cells, and is also a member of the angiogenic growth factors. Hepatocyte growth factor is secreted by vascular endothelial cells and smooth muscle cells, and the hepatocyte growth factor receptor, c-met, was also observed in these vascular cells. Treatment of human aortic endothelial cells with recombinant hepatocyte growth factor resulted in a significant increase in cell proliferation, accompanied by mitogen-activated protein kinase and Akt/protein kinase B phosphorylation. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As preclinical study of gene therapy using hepatocyte growth factor to treat peripheral arterial disease, naked hepatocyte growth factor plasmid was intramuscularly injected into the ischemic hind limb of rabbits in order to evaluate its angiogenic activity. Intramuscular injection of hepatocyte growth factor plasmid once on day 10 following surgery, produced significant augmentation of collateral vessel development in the ischemic limb on day 30. In the clinical setting, the authors further investigated the safety and efficacy of hepatocyte growth factor plasmid DNA in patients with critical limb ischemia, in a prospective open-labeled trial. Intramuscular injection of naked plasmid DNA was performed in the ischemic limbs of six patients with critical limb ischemia with arteriosclerosis obliterans (n = 3) or Buerger disease (n = 3) graded as Fontaine III or IV. In the efficacy evaluation, a reduction of pain scale of more than 1 cm on a visual analog pain scale was observed in five out of six patients. An increase in ankle pressure index of more than 0.1 was observed in five out of five patients. The long diameter of eight out of 11 ischemic ulcers in four patients was reduced by more than 25%. Intramuscular injection of naked hepatocyte growth factor plasmid is safe, feasible and can achieve successful improvement of ischemic limbs. Although the present data were obtained to demonstrate safety in a Phase I/early Phase II trial, the initial clinical outcome with hepatocyte growth factor gene transfer seems to indicate its usefulness as sole therapy for critical limb ischemia. Randomized placebo-controlled clinical trials of alternative dosing regimens of gene therapy will be required to define the efficiency of this therapy.     

Hepatocyte growth factor as potential cardiovascular therapy

Hepatocyte growth factor is a mesenchyme-derived pleiotropic factor that regulates the growth, motility and morphogenesis of various types of cells, and is also a member of the angiogenic growth factors. Hepatocyte growth factor is secreted by vascular endothelial cells and smooth muscle cells, and the hepatocyte growth factor receptor, c-met, was also observed in these vascular cells. Treatment of human aortic endothelial cells with recombinant hepatocyte growth factor resulted in a significant increase in cell proliferation, accompanied by mitogen-activated protein kinase and Akt/protein kinase B phosphorylation. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As preclinical study of gene therapy using hepatocyte growth factor to treat peripheral arterial disease, naked hepatocyte growth factor plasmid was intramuscularly injected into the ischemic hind limb of rabbits in order to evaluate its angiogenic activity. Intramuscular injection of hepatocyte growth factor plasmid once on day 10 following surgery, produced significant augmentation of collateral vessel development in the ischemic limb on day 30. In the clinical setting, the authors further investigated the safety and efficacy of hepatocyte growth factor plasmid DNA in patients with critical limb ischemia, in a prospective open-labeled trial. Intramuscular injection of naked plasmid DNA was performed in the ischemic limbs of six patients with critical limb ischemia with arteriosclerosis obliterans (n = 3) or Buerger disease (n = 3) graded as Fontaine III or IV. In the efficacy evaluation, a reduction of pain scale of more than 1 cm on a visual analog pain scale was observed in five out of six patients. An increase in ankle pressure index of more than 0.1 was observed in five out of five patients. The long diameter of eight out of 11 ischemic ulcers in four patients was reduced by more than 25%. Intramuscular injection of naked hepatocyte growth factor plasmid is safe, feasible and can achieve successful improvement of ischemic limbs. Although the present data were obtained to demonstrate safety in a Phase I/early Phase II trial, the initial clinical outcome with hepatocyte growth factor gene transfer seems to indicate its usefulness as sole therapy for critical limb ischemia. Randomized placebo-controlled clinical trials of alternative dosing regimens of gene therapy will be required to define the efficiency of this therapy.     

Cachectin/tumor necrosis factor regulates hepatic acute-phase gene expression.

The monokine, cachectin/tumor necrosis factor (TNF) differs from interleukin 1 (IL-1) in primary structure and in recognition by a distinct cellular receptor. It does, however, encode effector functions that are similar to those of IL-1 and characteristic of the host response to inflammation or tissue injury. Accordingly, we examined the possibility that recombinant-generated human TNF regulates hepatic acute-phase gene expression. In picomolar concentrations, TNF mediated reversible, dose- and time-dependent increases in biosynthesis of complement proteins factor B and C3, alpha 1 antichymotrypsin, and decreases in biosynthesis of albumin and transferrin in human hepatoma cell lines (Hep G2, Hep 3B). Biosynthesis of complement proteins C2 and C4, and alpha 1 proteinase inhibitor were not affected by TNF. TNF also increased factor B gene expression, but had no effect on C2 gene expression, in murine fibroblasts transfected with cosmid DNA bearing the human C2 and factor B genes. The effect of TNF on acute-phase protein expression (C3, factor B, albumin) was pre-translational as shown by changes in specific messenger RNA content.     

神经生长因子对大鼠脑缺血再灌注损伤的保护作用

目的：探讨神经生长因子（NGF）对大鼠脑缺血再灌注损伤的保护作用及其机制。方法：采用大脑中动脉内栓线阻断法（MCAO）造成大鼠局灶性损伤模型，同时给予NGF治疗。观测神经评分改变，计算脑组织梗死灶，测定脑组织含水量以及一氧化氮合酶（NOS）活动的变化。结果：NGF治疗组神经评分明显降低（P〈0.05）；与脑缺血再灌注组比较，NGF治疗组脑缺血梗死区缩小，脑组织含水量和NOS活性明显降低（P〈0．05）。结论：NGF具有保护脑缺血再灌注损伤的作用，可能与抑制NOS的活性有关。     

碱性成纤维细胞生长因子对大鼠骨骼肌拉伤修复的影响

目的探讨外源性碱性成纤维细胞生长因子(bFGF)对大鼠骨骼肌拉伤后肌肉再生修复的影响.方法雄性Sprague-Dawley大鼠,体质量约250 g,随机区组法分为3组,每组6只肌肉拉伤后给bFGF组、拉伤后给生理盐水对照组以及假拉伤组.用万能材料测试仪对大鼠腓肠肌造成拉伤后,于损伤肌肉皮下肌膜外注射bFGF(200AU/d×6)或生理盐水,免疫组织化学染色观察再生肌纤维中结蛋白的表达(用其积分光密度integra optical density,IOD表示).结果生理盐水对照组结蛋白IOD值(25.79±10.44)×103显著高于假拉伤组(9.28±4.83)×103(t=13.85,P＜0.01),bFGF治疗组肌肉结蛋白IOD值(34.48±10.62)×103高于生理盐水对照组(25.79±10.44)×103组,差异具有显著性(t=24.08,P＜0.01).结论外源性碱性成纤维生长因子可以促进肌肉拉伤后的结蛋白表达,提高肌肉再生能力,从而改善肌肉损伤后的结构修复.     

Hepatocyte growth factor modulates H2O2-induced mesangial cell apoptosis through induction of heme oxygenase-1

Oxidative stress plays an important role in the induction of mesangial cell (MC) injury. In the present study, we evaluated the molecular mechanism involved in hydrogen peroxide (H2O2)-induced MC apoptosis. In addition, we examined the role of heme oxygenase-1 (HO-1) in hepatocyte growth factor (HGF)-modulated, H2O2-induced MC injury. H2O2 promoted (p < 0.001) mouse MC (MMC) apoptosis. This effect of H2O2 was associated with translocation of cytochrome c from the mitochondrial to the cytosolic compartment. In addition, a caspase-9 inhibitor partially attenuated this effect of H2O2. These findings suggest that H2O2-induced MMC apoptosis is mediated through the mitochondrial pathway. HGF not only prevented H2O2-induced MMC apoptosis, but also inhibited H2O2-induced translocation of cytochrome c from the mitochondrial to the cytosolic compartment. HGF also promoted the expression of HO-1 by MMCs; interestingly, hemin inhibited (p < 0.001) H2O2-induced MMC apoptosis. On the other hand, zinc protoporphyrin inhibited the protective influence of HGF on H2O2-induced MMC apoptosis. These findings suggest that H2O2-induced apoptosis occurs through the mitochondrial pathway. HGF provides protection against H2O2-induced MMC apoptosis through induction of HO-1.     

Hepatocyte growth factor gene therapy for islet transplantation

Recent clinical studies have documented that human islet transplantation has the potential to replace pancreatic endocrine function in patients with type 1 diabetes. These studies have also highlighted an enormous shortage of human islets that impedes the use of islet transplantation in clinical practice on a larger scale. To address this problem, one potential approach is to use islet growth factors to increase beta cell replication, to improve beta cell function and to enhance beta cell survival. In that context, transgenic mice overexpressing hepatocyte growth factor (HGF) in the pancreatic beta cell display increased beta cell proliferation, function and survival. More importantly, HGF-overexpressing transgenic mouse islets markedly improve transplant performance in severe combined immunodeficiency (SCID) mice and reduce the number of islets required for successful islet transplantation. Recently, adenoviral-mediated gene transfer of HGF into normal rodent islets has confirmed the beneficial effects of HGF in improving islet transplant outcomes in two marginal mass islet transplant models in rodents: islet transplant under the kidney capsule in SCID mice; and portal islet allograft transplantation in rats treated with the Edmonton immunosuppressive regimen. These studies suggest that ex vivo HGF gene therapy has the potential to reduce the number of human islets required for successful islet transplantation.     

Implementing nutritional therapy in the thermally injured patient

Providing adequate nutritional support is an important adjuvant therapy in the management of thermal injuries. Technological advances in both enteral and parenteral nutrition have enabled clinicians to administer large amounts of essential nutrients to critically ill patients who frequently cannot or will not take these nutrients orally. The use of any method of nutritional support requires careful administration and scheduled monitoring to ensure its safety and efficacy. Critical care nurses have an integral role in assuring that appropriate nursing care and monitoring measures are performed.     

Metabolism and nutrition in the thermally injured patient

Following severe thermal injury, the metabolic rate increases to a level often exceeding twice that of the uninjured individual. This hypermetabolic response necessitates a corresponding increase in nutritional support, which must be maintained until the wound has closed and fully matured. Nutrient composition and administration techniques are determined by the patient's ongoing physiologic response to injury.