transforming-growth-factor-alpha and Ischemia

Hepatic ischemia/reperfusion (I/R) describes the paradox of additional tissue injury caused by reperfusion. The aim of this survey was to investigate the mRNA expression of genes exerting their inflammatory and regenerative reaction in a porcine model of I/R and extended hepatectomy.. Twelve pigs were used, weighing 30-35 kg in average, which were allocated in two groups: the I/R group with eight pigs and the sham-operated (control) one with four pigs. The I/R group underwent portacaval anastomosis and Pringle maneuver followed by extended hepatectomy. The hepatoduodenal ligament was occluded for 150 min and the liver remnant was reperfused for 24 hours. Blood samples were steadily received throughout the surgical procedure, where hepatic biopsies were taken for pathological evaluation. Animals were sacrificed in 24 hours after the onset of reperfusion.. Between the two groups, statistically significant differences were noticed in serum values of AST, ALT, ALP, and total bilirubin in the early and late phase of reperfusion. The mRNA expression of iNOS, IL-1b, and TGF-a did not increase significantly in the I/R group. Conversely, the mRNA modification of IL-6, STAT-3, and E-selectin demonstrated significantly increased expression in I/R animals.. In the present survey, a new I/R swine model was proposed and specific parameters were analyzed, revealing differences between the study groups.

Topics: Alanine Transaminase; Alkaline Phosphatase; Animals; Aspartate Aminotransferases; Bilirubin; Biopsy; Disease Models, Animal; E-Selectin; Female; Hepatectomy; Inflammation; Interleukin-1beta; Interleukin-6; Ischemia; Liver; Liver Diseases; Liver Regeneration; Nitric Oxide Synthase Type II; Reperfusion Injury; RNA, Messenger; STAT3 Transcription Factor; Swine; Transforming Growth Factor alpha

Tissue necrosis resulting from critical limb ischemia (CLI) leads to amputation in a significant number of patients. Autologous cell therapy using angiogenic cells such as endothelial progenitor cells (EPCs) holds promise as a treatment for CLI but a limitation of this treatment is that the underlying disease etiology that resulted in CLI may also contribute to dysfunction of the therapeutic EPCs. This study aimed to elucidate the mechanism of EPC dysfunction using diabetes mellitus as a model and to determine whether correction of this defect in dysfunctional EPCs ex vivo would improve the outcome after cell transplantation in the murine hind limb ischemia model. EPC dysfunction was confirmed in a homogenous population of patients with type 1 diabetes mellitus and a microarray study was preformed to identify dysregulated genes. Notably, the secreted proangiogenic protein osteopontin (OPN) was significantly downregulated in diabetic EPCs. Furthermore, OPN-deficient mice showed impaired recovery following hind limb ischemia, suggesting a critical role for OPN in postnatal neovascularization. EPCs isolated from OPN KO mice showed decreased ability to adhere to endothelial cells as well as impaired angiogenic potential. However, this dysfunction was reversed upon exposure to recombinant OPN, suggesting that OPN may act in an autocrine manner on EPCs. Indeed, exposure of OPN knockout (KO) EPCs to OPN was sufficient to induce the secretion of angiogenic proteins (IL-6, TGF-α, and FGF-α). We also demonstrated that vascular regeneration following hind limb ischemia in OPN KO mice was significantly improved upon injection of EPCs preexposed to OPN. We concluded that OPN acts in an autocrine manner on EPCs to induce the secretion of angiogenic proteins, thereby playing a critical role in EPC-mediated neovascularization. Modification of cells by exposure to OPN may improve the efficacy of autologous EPC transplantation via the enhanced secretion of angiogenic proteins.

Topics: Adult; Animals; Cell- and Tissue-Based Therapy; Cells, Cultured; Diabetes Mellitus, Type 1; Endothelial Cells; Female; Fibroblast Growth Factors; Hindlimb; Human Umbilical Vein Endothelial Cells; Humans; Interleukin-6; Ischemia; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neovascularization, Physiologic; Osteopontin; Peripheral Vascular Diseases; Rabbits; Recombinant Proteins; Regeneration; Stem Cell Transplantation; Stem Cells; Transforming Growth Factor alpha; Young Adult

We studied control of the epidermal growth factor (EGF) receptor and its ligands during kidney injury, since they may be importantly involved in repair.. The folic acid model of renal injury was used in these studies. Messenger RNA (mRNA) was evaluated by solution hybridization. Immunohistochemistry of transforming growth factor alpha (TGF-alpha) was also performed.. Twenty-four hours after folic acid induced acute renal injury, creatinine increased from 0.3 +/- 0.03 mg/dl in controls to 2.0 +/- 0.8 mg/dl in folic acid injured kidneys (n = 4, p < 0.03). mRNA for the EGF receptor was increased nearly sevenfold by 24 h, and mRNA for the receptor was increased as early as 1 h following folic acid treatment. EGF receptor ligand caused a profound downregulation of the receptors in proximal tubule basolateral membranes, but receptors returned rapidly to the membrane surface in injured kidneys. The mRNA levels for heparin-binding EGF and TGF-alpha, two EGF receptor ligands, increased within 1 h of injury. TGF-alpha mRNA increased from 1.0 +/- 0.09 (relative densitometry units) in control animals to 2.9 +/- 0.13 in folic acid treated rats at 24 h (n = 4, p < 0.01), and immunohistochemical staining for TGF-alpha increased in injured kidneys at distal nephron sites.. These studies indicate that upregulation of the EGF receptor is related to an increase in mRNA. The rapid return of receptors to the membrane surface following ligand stimulation may be useful in maintaining a mitogenic stimulus. Multiple EGF-like ligands may be important in activating the upregulated EGF receptor during repair from renal injury.

Topics: Acute Disease; Animals; Creatinine; Epidermal Growth Factor; ErbB Receptors; Folic Acid; Gene Expression; Heparin-binding EGF-like Growth Factor; Intercellular Signaling Peptides and Proteins; Ischemia; Kidney Diseases; Ligands; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transforming Growth Factor alpha

Portal vein branch embolization is often performed before hepatectomy to prevent postoperative liver failure. It is, however, still not clear how the embolized lobe shrinks and the non-embolized lobe proliferates in counterbalance. We investigated the expression of positive and negative regulators of hepatocyte growth to clarify the mechanisms of liver growth and atrophy in a rat portal vein ligation (PVL) model compared with partial hepatectomy (PH). A significant increase in DNA synthesis within the non-ligated lobe reached a peak at 36 h, a delay of 12 h as compared with PH, while no increase occurred in the ligated lobe. Expression of hepatocyte growth factor mRNA remarkably increased in the non-ligated growing lobe between 6 and 24 h, but was only slightly elevated in the ligated shrinking lobe. Contrarily, negative regulators of hepatocyte proliferation, such as TGF-beta1 and IL-1beta, were strongly expressed in the ligated shrinking lobe. Thus, the changes of portal venous flow and/or pressure caused by PVL may contribute to induction of different kinds of growth factors between the ischemic and non-ischemic lobes; these factors possibly regulate liver regeneration and atrophy after PVL.

Topics: Animals; Blotting, Northern; Hepatectomy; Hepatocyte Growth Factor; Interleukin-1; Interleukin-6; Ischemia; Ligation; Liver; Male; Organ Size; Portal Vein; Rats; Rats, Wistar; RNA, Messenger; Transforming Growth Factor alpha; Transforming Growth Factor beta

Recovery of the ability to digest and absorb lipids is essential to the maintenance of normal nutrition in infants with bowel damage. Two intrinsic microsomal enzymes, monoacylglycerol acyltransferase (MGAT) and diacylglycerol acyltransferase (DGAT), catalyze the major pathway for intestinal triacylglycerol biosynthesis. This study describes the effects of intestinal ischemia on epithelial DGAT and MGAT activities and their recovery in response to two luminal treatments: L-glutamine (Gln), the primary intestinal fuel, and transforming growth factor-alpha (TGF-alpha), a mitogenic hormone similar to epidermal growth factor present in breast milk. Ischemic damage and recovery were analyzed in mucosa from Thiry-Vella loops in the mid-ileum of 7-wk-old pigs. Loops were subjected to 2-h occlusion of local mesenteric arteries, followed by 6 or 72 h of recovery in the presence of luminal glucose (control), Gln, or TGF-alpha. Ischemic tissue followed by 6-h recovery exhibited an approximate 50% decrease in both MGAT and DGAT activities compared with nonischemic loop tissue. At 72 h, MGAT and DGAT recovery in Gln plus TGF-alpha-treated loops was significantly greater than their corresponding 6-h peak damage levels (p < 0.05). From 6 to 72 h, MGAT increased 4-fold and DGAT increased 3.6-fold after Gln plus TGF-alpha treatment. With other treatments, MGAT and DGAT activities increased <2.5-fold from 6 to 72 h. This study shows that intestinal MGAT and DGAT activities decrease after ischemic damage, yet recover rapidly in bowel exposed to Gln and/or TGF-alpha. By stimulating the rate of recovery of the villi and lipid synthesizing enzymes, these treatments could improve the efficacy of enteral feeding in infants recovering from bowel damage.

Topics: Acyltransferases; Animals; Diacylglycerol O-Acyltransferase; Duodenum; Glutamine; Ileum; Intestinal Mucosa; Ischemia; Jejunum; Male; Swine; Transforming Growth Factor alpha

Keratinocyte growth factor acts specifically on epithelial cells and is presumed to play an important role in tissue repair.. To examine the wound-healing effects of keratinocyte growth factor under hypoxic conditions in vivo and in vitro.. Dermal ulcers were created in the ischemic ears of 40 anesthetized young female rabbits. Either recombinant keratinocyte growth factor (rKGF) or buffer was applied to each wound. Wounds were bisected and analyzed histologically at days 7 and 10 after wounds were created. For the in vitro study, normal keratinocytes were treated with rKGF (20 ng/mL) and cultured under hypoxic (3.5% oxygen) conditions. The conditioned media were collected at 48 and 72 hours.. The amount of epithelial growth and deposition of granulation tissue were measured in all wounds. The amount of transforming growth factor alpha in keratinocyte-conditioned media was measured by using a sensitive radioimmunoassay. A proliferation assay of dermal fibroblasts, treated with conditioned media, was also performed under 3.5% oxygen culture conditions.. The rKGF (range, 5-40 micrograms per wound) that was applied significantly increased new epithelium by greater than 70% (P = .03) at days 7 and 10 after wounds were created. A significant increase in new granulation tissue formation (170%) was also observed in rKGF-treated wounds at day 10, at a dose of 40 micrograms per wound (P < .002). The amount of transforming growth factor alpha protein in the conditioned media that were treated with rKGF (20 ng/mL) increased by 26.8% and 171% at 48 and 72 hours, respectively, over that of controls. The conditioned media from rKGF-treated keratinocytes, grown for 72 hours, resulted in a 51% increase in the proliferation of primary rabbit dermal fibroblasts.. Keratinocyte growth factor enhances the wound-healing process of ischemic ulcers, indicating that epithelial-mesenchymal cell interactions are critical for the healing of wounds under ischemic conditions and possibly under normal conditions as well.

Topics: Animals; Cell Division; Cells, Cultured; Culture Media; Epithelial Cells; Female; Fibroblast Growth Factor 10; Fibroblast Growth Factor 7; Fibroblast Growth Factors; Fibroblasts; Granulation Tissue; Growth Substances; Ischemia; Keratinocytes; Mesoderm; Rabbits; Radioimmunoassay; Skin Ulcer; Transforming Growth Factor alpha; Wound Healing

A problem in lung transplantation is tracheal or bronchial dehiscence from ischemia. To determine if an angiogenic factor applied to the airway would improve capillary regrowth, a three-ring segment of trachea was completely severed and sutured in rats. In one group of animals the ischemic segment was wrapped with Gelfoam soaked in an angiogenic factor, transforming growth factor-alpha. In a second group the ischemic area was wrapped with Gelfoam soaked with only the vehicle. In a third group the devascularized area received no additional treatment. One animal from each group was killed daily for 7 days after operation. The tracheal vasculature was cast and viewed by light and scanning electron microscopy. None of the four animals that died early were in the transforming growth factor-alpha group. All animals lost weight between the day of operation and death, but this was least in the transforming growth factor-alpha group (p = 0.05). The light microscopy showed ischemic changes and the development of granulation tissue. The scanning electron microscopy of the vascular casts showed extensive loss of the vessels in the cut area. On day 1 the vessels of all animals dilated and their walls became rough. By day 3 a few corkscrew vessels penetrated the ischemic zone. By day 4 the animal that received transforming growth factor-alpha had more capillaries than the others. By day 6 revascularization in the transforming growth factor-alpha animal was abundant. Besides budding, new capillaries appeared to develop by lateral growth. After the fifth day vessels about 30 to 50 microns in diameter bulged focally. On the bulges, ridges the size, shape, and pattern of capillaries formed. Capillary formation in this manner has not been reported previously. Revascularization emerged sooner and more extensively with transforming growth factor-alpha. No adverse effect of transforming growth factor-alpha was found.

Topics: Animals; Capillaries; Ischemia; Male; Microscopy, Electron, Scanning; Neovascularization, Pathologic; Rats; Rats, Sprague-Dawley; Trachea; Transforming Growth Factor alpha; Weight Loss