Localization of interleukin-1 in human cholesteatoma.

Recent studies by other investigators have shown that interleukin-1 (IL-1) promotes bone resorption by stimulating various cells. Interleukin-1 not only stimulates collagenase production by fibroblasts and macrophages, but also acts as an osteoclast-activating factor. In this study, IL-1 was localized in human cholesteatoma tissues using both immunoperoxidase and immunofluorescent-staining methods with specific monoclonal antibodies. Highly concentrated IL-1 was found in the epithelial layer and granulation tissue. More specifically, intense staining was seen in basal and spinous cells of the epithelial layer, and in fibroblasts and macrophages of the granulation layer. We also located IL-1 in the normal external ear canal skin; however, the intensity of the staining in the cholesteatoma epithelium was found to be stronger. The presence of IL-1 in the epithelial layer and granulation tissue of the cholesteatoma suggests that IL-1 from the stimulated keratinocytes of the cholesteatoma could be one factor responsible for the markedly increased bone resorption observed in cholesteatoma patients.

Purification of rabbit bone morphogenetic protein derived from bone, dentin, and wound tissue after tooth extraction.

Bone morphogenetic protein (BMP) was extracted from bone matrix, dentin matrix, and wound tissue after tooth extraction in rabbits, and purified. These purified fractions were shown to be homogeneous by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis (SDS-PAGE), and induced new bone in situ in 3 weeks when implanted into the calf muscles of Wistar rats. The dentin matrix-derived BMP was different from the other two types in molecular weight and the properties revealed in the process of purification. However, each tissue-derived BMP was shown to induce new bone growth in a bioassay of xenogenic implantation. For this reason, BMP is thought to have subunits with certain commonalities in different tissue.

Comparative growth dynamics and actin concentration between cultured human myofibroblasts from granulating wounds and dermal fibroblasts from normal skin.

The normal contraction of open wounds and many forms of pathologic contracture are related by the presence of a contractile fibroblast known as a myofibroblast. The function of this cell has been postulated as a result of previous pharmacological, immunological, and biochemical testing on strips of contracted connective tissue. The purpose of this study was to develop a specific assay that could measure the concentration of one contractile element (actin) within cultured myofibroblasts isolated from a contracting wound and in normal fibroblasts from uninjured dermis. Rates of growth and actin concentration through 15 days of culture were compared among populations of paired control fibroblasts from normal dermis and granulating wound myofibroblasts from three patients. Growth curves showed that myofibroblasts always grew slower than fibroblasts. An enzyme-linked immunosorbent assay showed that actin concentration was generally greater in mass cultures of granulating wound myofibroblasts than in fibroblasts from uninjured dermis. During exponential growth (1-6 days) the average actin concentration among myofibroblast lines ranged from 24 to 62 pg/cell. Average actin levels among control fibroblasts ranged from 3 to 47 pg/cell during the same interval. After 15 days of culture, actin concentration peaked twice. The first actin peak occurred within the period of exponential growth. At confluency, cellular actin levels dropped. Superconfluent cultures exhibited a second actin peak that displayed an irregular pattern of actin concentration. The latter observation suggested an artifact that might be the result of three-dimensional matrix of cells that altered points of cell adhesion and produced an irregular pattern of actin concentration. These data show that the phenotype of increased actin in cultured myofibroblasts was carried over by myofibroblasts from contracted skin wounds to culture. Because of a higher concentration of actin in myofibroblasts than in undifferentiated fibroblasts, these data suggest that the differentiation process of myofibroblasts may be associated with an increased availability of monomeric actin for filament synthesis. This study demonstrates that the use of tissue culture and our enzyme-linked immunosorbent assay will be a useful method to study factors affecting myofibroblast phenotypic modulation. Future studies should be directed toward developing procedures for isolation of pure populations of myofibroblasts as well as extracellular matrices that would maintain the morphology of both differentiated myofibroblasts and normal undifferentiated fibroblasts.

Biocompatibility of the central electroauditory prosthesis and the human cochlear nuclei.

Previous studies from the House Ear Institute have reported the possibility of sound sensation from the central electroauditory prosthesis (CEP) implanted in patients during removal of bilateral acoustic neuromas. This study describes histologic features of tissues formed around a CEP that was removed due to infection in the area of the electrical plug on the external surface of the skull. We found a layer of compact collagen tissue around the CEP. The tissue penetrated spaces of the Dacron mesh matrix, preventing our determination of the precise place of the electrode-tissue interface. We also found a layer of connective tissue on the Silastic covering on the CEP leads. Histopathologic analysis showed no unusual pathologic changes around the CEP except for degeneration of the abdominal fat used for placement and stabilization of the CEP on the surface of the cochlear nuclei.

Alpha-smooth muscle actin, a differentiation marker of smooth muscle cells, is present in microfilamentous bundles of pericytes.

alpha-Smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle cells (SMC) and present in high amounts in vascular SMC, was demonstrated in the cytoplasm of pericytes of various rat and human organs by means of immunocytochemistry at the electron microscopic level. In SMC and pericytes, alpha-sm actin was localized in microfilament bundles, strengthening the assumption that it is the functional isoform in these cell types and supporting the assumption that pericytes exert contractile functions.

Distinction between two molecular species of type V collagen from human post-burn granulation tissues.

Human type V collagen was purified from post-burn granulation tissues, and was demonstrated to exist in two different molecular assemblies consisting of [alpha 1(V)]2 alpha 2(V) and alpha 1(V)alpha 2(V)alpha 3(V) heterotrimers which are designated as type V(112) and V(123) collagens, respectively, in this paper. The two molecular species were separated by salt fractionation at neutral pH under non-denaturing conditions. When crude type V collagen was dialyzed against phosphate-buffered saline at 4 degrees C, mainly collagen V(112) precipitated, leaving collagen V(123) in the solution. Type V(112) collagen, but not type V(123), precipitated at 0.15 M NaCl in 50 mM Tris-HCl buffer (pH 7.5), whereas the type V(123) molecule precipitated at 4.5 M NaCl in the same buffer. When the crude type V collagen was electrophoresed under non-denaturing conditions, two bands were observed; and it was confirmed that the fast-migrating band was composed of [alpha 1(V)]2 alpha 2(V) and the slow-migrating band was alpha 1(V)alpha 2(V)alpha 3(V). Both alpha 1 and alpha 2 chains of V(112) showed biochemical properties that were very similar, if not identical, to those of the corresponding alpha chains of V(123) judging from amino acid compositions, peptide mapping patterns obtained following treatment with cyanogen bromide and lysyl endopeptidase, and periodic acid Schiff and concanavalin A stainings. Alpha 3 chain, in contrast, was distinct from both alpha 1 and alpha 2 chains. The amino acid composition and peptide maps of alpha 3 chain were similar to some extent, but not identical, to those of the alpha 1 chain. The intensity of carbohydrate stainings of the alpha 3 chain was clearly different from that of the alpha 1 chain. The negatively stained segment-long-spacing crystallites of the two molecular species exhibited an identical banding pattern. The crystallite derived from collagen V(112) was usually in a dimeric form exhibiting the C-C terminal junction, but that of collagen V(123) was mostly in a monomeric form. Differences between the two molecular species is ascribed to the presence of the alpha 3 chain in collagen V(123).

Time-dependent changes of collagen crosslinks in the socket after tooth extraction in rabbits.

Time-dependent changes of the reducible collagen crosslinks in the healing tissue of rabbit tooth extraction wounds were analyzed chromatographically. The ratio of dihydroxylysinonorleucine to hydroxylysinonorleucine in the collagen from normal alveolar bone was 4.4. This value increased about four times, on the 10th day after tooth extraction, coinciding with the phase of active woven bone formation, and then decreased rapidly toward a normal value on the 14th day after tooth extraction. The data suggest that active biosynthesis and fibrillogenesis of bone collagen precede the morphological completion of lamellar bone formation.

Calcitonin and granulation tissue formation in the rat. An experimental study.

The effects of systemically administered calcitonin (CT) on granulation tissue development were compared using viscose cellulose sponges as wound model in the rat. The ingrowth of new granulation tissue was analyzed for the contents of various connective tissue components (total nitrogen, hydroxyproline, DNA, and RNA) and for the differential counts of the cells infiltrating the sponges. The results indicate that up to 4 weeks postoperatively (p.o.) CT did not affect the net amount of collagen, measured as hydroxyproline, total nitrogen, aminosugars nor the dynamics of differentiation and viability of the invading cells. The present observation that CT has negligible effects, if any, on the early stages of connective tissue formation and on the cell population indicates that surgical procedures could be carried out safely during systemic CT therapy without an increased risk of wound complications.

The effect of epidermal growth factor on granulation tissue formation in the rat.

Subcutaneously implanted cylindrical hollow viscose cellulose sponges were used to investigate the effects of locally applied EGF on developing granulation tissue. The test implants were treated with a single or daily injections of a solution containing 0.2, 1 or 5 micrograms of EGF in 0.1-0.5% albumin while the control implants were treated correspondingly with the carrier solution only. Analyses of wound fluid and granulation tissue in the sponge cylinders were carried out 7 or 10 days after implantation. After daily application of EGF a stimulatory effect on granulation tissue formation was observed: cellularity increased as demonstrated by the elevated amounts of nucleic acids, and the accumulation of collagen and glycosaminoglycans was enhanced. The effect was dose-dependent. After a single application of EGF no essential differences were detected in wound fluid prostaglandin E2 levels or measured components of granulation tissue between the groups. Thus daily application of EGF was necessary to obtain an augmenting effect on granulation tissue formation. EGF seemed to be a potent mitogen for fibroblastic cells released from experimental granulation tissue in a dose-dependent manner. EGF treatment inhibited the production of radioactive hydroxyproline. The decreased rate of collagen synthesis was also indicated by decreased amounts of procollagen mRNAs. In the EGF-treated rats granulation tissue blood flow was significantly higher than that in the control rats 7 days after implantation. In both groups blood flow values of the incision scar region were significantly higher than those of the lumbar skin, but no intergroup differences were detected. In implants injected with EGF the albumin extravasation clearly exceeded that of the control implants. Albumin extravasation in the incision scar region was higher than that in the lumbar skin in both groups. EGF treatment increased procollagen mRNA, particularly at day 4. To study the influence of EGF on methylprednisolone-induced inhibition of granulation tissue formation, the sponge cylinder was injected immediately after implantation with a single dose of 2 mg (approximately equal to 1.7 x 10(-3) M) of depot methylprednisolone. This methylprednisolone injection resulted in a significant fall in the accumulation of nucleic acids, collagen and glycosaminoglycans. After daily injections of EGF these parameters returned to levels close to the control values. In the presence of methylprednisolone EGF could not increase collagen synthesis of fibroblastic cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Thrombospondin in early human wound tissue.

We examined partial thickness incised human wounds of 2, 3, 5, 7, and 14 days of age for the presence of thrombospondin by immunostaining and light microscopy. At 2, 3, 5, and 7 days after wounding, thrombospondin is present primarily at the cut edges of the lateral and deep margins of the wound. It appears to be cleared from these extracellular matrix sites, and is no longer detectable in those sites in most 14-day-old wounds. Thrombospondin staining is present, however, in increased amounts around the vascular channels within and adjacent to the 7- and 14-day wounds in increased amounts relative to vascular channels distant from the wound. Our observations are consistent with known in vitro data regarding the binding of thrombospondin to fibrin and components of the extracellular matrix, as well as with data showing that proliferating endothelial cells secrete more thrombospondin than quiescent endothelial cells. These data support the hypothesis that thrombospondin plays a role in the early organization of the extracellular matrix of wounds.

Hyaluronidase activity of rabbit skin wound granulation tissue fibroblasts.

The objective of this work was to identify and compare hyaluronidase activities of normal dermal and dermal wound granulation tissue fibroblasts. Direct evidence of the fibroblast as a source of tissue hyaluronidase was obtained. Fourth passage rabbit dermal fibroblasts were harvested on culture days 4, 8, 14, 18, and 22. Hyaluronidase activity and [35S]-sulfate- or [3H]-glucosamine-labeled glycosaminoglycans (GAGs) were monitored. Hyaluronidase assays were performed on medium and cellular fractions at the designated intervals. Enzyme activity of cellular fractions for both normal dermal and 14-day post-wound granulation tissue fibroblasts increased progressively through culture day 8. Thereafter (days 14-22), an eight-fold drop in cellular activity was coupled with cell death and emergence of hyaluronidase activity in medium fractions. Marked increases in degradation of secreted matrix components were concurrent with lysis-induced release of hyaluronidase. In this culture system, hyaluronidase activity was confined exclusively to cellular fractions and was released into the medium only under non-physiological conditions conducive to cellular death and lysis. Accordingly, this work suggests that previously reported skin wound hyaluronidases may be of fibroblastic origin and that susceptible GAGs are not degraded extracellularly, but, rather, must be internalized as a prerequisite to depolymerization.

Superoxide dismutase does not cause scar thinning after myocardial infarction.

Previous studies demonstrated that treatment with superoxide dismutase, a scavenger of superoxide anions, limits the extent of myocardial injury in a canine preparation of regional myocardial ischemia and reperfusion. Little is known, however, about the effects of superoxide dismutase on the healing of a myocardial infarct. Therefore, this study was performed to determine whether treatment with superoxide dismutase during myocardial ischemia impairs formation of scar tissue after infarction. Dogs received 2 hour infusions of superoxide dismutase or albumin (controls) by way of the left atrium beginning 15 minutes before and ending 15 minutes after a 90 minute occlusion of the left circumflex coronary artery. Six weeks later the animals were killed. Two-dimensional echocardiography was performed before surgery and before induced death. Wall thickening in the central ischemic zone was decreased at 6 weeks compared with baseline studies (p less than 0.05), but the decrease was similar for both groups. The hydroxyproline concentrations (microgram/mg dry weight) of the scar tissue in the superoxide dismutase and control groups, respectively, were 35.3 +/- 3.8 and 28.7 +/- 5.0 (p less than 0.05). The ratios of the scar thickness to normal wall thickness were superoxide dismutase 0.91 +/- 0.03 and control 0.89 +/- 0.03 (p greater than 0.05). Thus, superoxide dismutase had no adverse effect on wall thickening or scar formation assessed 6 weeks after myocardial infarction, and may be useful to limit oxygen radical-mediated damage during reperfusion of the ischemic myocardium.

Accelerated tissue repair induced by micrococcus varians.

The present investigation was undertaken to study the effect of inoculated Micrococcus varians organisms on developing granulation tissue in rats. Subcutaneously implanted hollow cylindrical cellulose sponges were used as an inductive matrix for the growth of granulation tissue. The control implants were injected immediately after implantation with 1 milliliter of physiologic saline solution while the experimental implants were injected with a corresponding volume of saline solution containing live micrococci 10(7) microorganisms per milliliter. Cytologic and bacteriologic analyses of wound fluid aspirated from the central dead space of the implants were carried out three, seven and 14 days after implantation. Local blood flow and albumin extravasation were measured on day seven and granulation tissue grown into the implants was analyzed chemically on days seven and 14. No macroscopic infection with pus formation occurred, while Micrococcus varians was cultured from each inoculated implant. In the inoculated implants, the number of wound fluid neutrophils, granulation tissue blood flow and albumin extravasation increased significantly above the control level. Correspondingly, the amounts of granulation tissue deoxyribonucleic acid, nitrogen, collagen hydroxyproline, hexosamines and uronic acids in the inoculated implants exceeded significantly the control value on both days seven and 14. To conclude, inoculation of experimental wounds with nonpathogenic Micrococcus varians organisms enhanced local inflammatory reaction and blood flow, and promoted granulation tissue formation.

Diabetes-induced increases in vascular permeability and changes in granulation tissue levels of sorbitol, myo-inositol, chiro-inositol, and scyllo-inositol are prevented by sorbinil.

In a recently developed animal model, we investigated the pathogenesis of diabetic vascular disease and demonstrated that 125I-albumin permeation is markedly increased in new "granulation tissue" vessels formed in subcutaneous tissue after the onset of diabetes. The studies described in this report were undertaken to examine the effects of an aldose reductase inhibitor on diabetes-induced increases in vascular permeability in this animal model. 125I-albumin permeation was assessed 3 weeks after the subcutaneous implantation of sterile preweighed polyester fabric (to stimulate angiogenesis) in diabetic male Sprague-Dawley rats, in controls, and in diabetic rats given sorbinil approximately 12 or approximately 25 mg/kg/d mixed in ground rat chow. Sorbinil administration prevented the diabetes-induced increase in vascular permeability by approximately 60% at the lower dose and by approximately 80% at the higher dose without affecting body weight or plasma glucose levels. Diabetes-induced changes in tissue levels of sorbitol, myo-inositol, scyllo-inositol, and chiro-inositol were also prevented by the high dose of sorbinil (data were not obtained for the lower dose). These observations are consistent with evidence linking diabetic cataracts and neuropathy to imbalances in sorbitol/inositol metabolism and support the hypothesis that diabetic vascular disease as well as neuropathy and cataracts are mediated by excess metabolism of glucose through the polyol pathway. Furthermore, these observations suggest that increased vascular permeability associated with diabetic microangiopathy in humans may be prevented by inhibitors of aldose reductase without the need to normalize blood glucose levels.

Type I collagen messenger RNA levels in experimental granulation tissue and silicosis in rats.

A complementary DNA (cDNA) clone was constructed for chick pro alpha 2(I) collagen mRNA. This and previously constructed cDNA clones for chick and human pro alpha 1(I) collagen mRNAs were used to measure levels of type I procollagen messenger RNAs in two experimental models: viscose cellulose sponge-induced experimental granulation tissue and silica-induced experimental lung fibrosis in rats. Both Northern RNA blot and RNA dot hybridizations were used to quantitate procollagen mRNAs during formation of granulation tissue. The period of rapid collagen synthesis was characterized by high levels of procollagen mRNAs, which were reduced when collagen production returned to a low basal level. The rate of collagen synthesis and the levels of procollagen mRNAs during the period of rapid reduction in collagen production did not, however, parallel with each other. This suggests that translational control mechanisms are important during this time in preventing overproduction of collagen. In silicotic lungs, the early stages of fibroblast activation follow a similar path but appear faster. At a later stage, however, the RNA levels increase again and permit collagen synthesis to continue at a high rate, resulting in massive collagen accumulation.

cAMP levels in reactive tissues around dimethylpolysiloxane solid implants.

By the aid of radioimmunologic assay, the authors measured the cAMP content of the reactive capsules around solid dimethylpolysiloxane implants in mice at different times; they also measured the same substance in some human connective tissues (granulation tissue and normal dermis) and compared together all the values they obtained. Different concentrations of cAMP in different tissues seem to reflect correspondent histologic findings, since they vary according to them. These values also seem to indicate a close correspondence between the development of the process of wound healing and of the foreign-body reaction following the implantation of alloplastic materials. On the basis of these data, the authors suggest an experimental therapeutic trial to enhance peripheral cAMP synthesis in order to control the process of reactive capsule constitution.

The contractile properties of wound granulation tissue.

A systematic examination of the contractile properties of wound granulation tissue is presented. Shortening of and tension generated by granulation tissue in the presence of 30 mM diphenhydramine HCl have been measured. Analysis of the stress (load per unit area)/strain (extent of shortening) results from isotonic shortening studies showed that over the range of 0 to 2.5% shortening there was an approximately linear relationship between stress and strain with a high modulus of elasticity. At lower stresses, wide variations in the amount of shortening occurred with little change in stress. Our interpretation of these findings is that diphenhydramine HCl caused an active shortening of the granulation tissue by 2.5% of its length and contractions greater than this were the result of secondary effects such as coiling and bending of the strips. It is shown that the granulation tissue would have to shorten by 2% once every 3 days to account for observed in vivo rates of contraction for large human wounds and once every 13 hr for rapidly contracting experimental rabbit wounds. The time course of the development of isometric tension by the granulation tissue is shown to be consistent with the proposal that each contractile cell contributes equally to the overall tension developed and that each cell is individually activated by a critical concentration of diphenhydramine HCl which is transported through the tissue by diffusion.

Immunohistochemical localization of collagens in the ear.

The aim of this work was to prepare specific antibodies to various types of collagen in order to study on immunohistological localization of collagen under normal and pathologic conditions. Human type I and III collagens were extracted from human dura mater and placenta using limited pepsin digestion followed by differential salt precipitation and chromatographic purification. The purity of collagens was assessed by SDS polyacrylamide gel electrophoresis. Antibodies to type I and III were prepared in rabbits, and showed a high reaction with the corresponding human collagens, and these antibodies were tested to determine activity using ELISA. However, antibody to type I also showed some cross-reaction with type III, and antibody to type III, with type I. Using these antibodies, tissue distribution of collagen was examined in the middle ear by peroxidase anti-peroxidase method. In granulation tissue, it was revealed that types I and III co-existed.