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A method for studying wound healing in humans is described. The technique is based on the production of a standard subcutaneous injury during implantation of a retrievable sponge. The injury is produced by introducing a small device (PVA implant) which consists of a 5.7-cm piece of perforated silicone tubing containing two pieces of polyvinyl alcohol sponge. The sponge provides a site for attracting inflammatory cells with subsequent fibroblast infiltration. The sterile PVA implant is inserted subcutaneously in the upper arm by means of a 12-gauge needle and remains there for 14 days. Upon removal, one sponge has hydroxyproline deposition quantitated using a high-performance liquid chromatography technique. The other sponge may be processed for light and electron microscopy or specialty staining. Other collagen determinations such as percentage neutral salt-soluble collagen are also possible. Using the PVA implant has made it possible to follow the kinetics of collagen deposition in the rat. There was a marked increase in collagen accumulation from Day 2 (0.89 nmole/mg sponge) to Day 14 (18 nmole/mg sponge) in the rat. Collagen deposition was also measured in human control subjects (5.07 nmole/mg sponge, n = 12) and compared to trauma patients (2.04 nmole/mg sponge, n = 5). Histologic staining showing fibroblast infiltration and collagen deposition correlated well with the biochemical findings. This implant, coupled with recent HPLC technology, provides a safe, acceptable technique to study human wound healing parameters and overcomes many of the limitations of previous methods.

Growth kinetics and collagen production were determined in smooth muscle cells isolated from human jejunum and maintained in cell culture. Collagen synthesis increased during the first 15 days in culture at a time when the rate of cell proliferation was maximal. When confluent, these cells produced significantly more collagen than human dermal fibroblasts cultured under identical conditions. The smooth muscle cells required daily replenishment of ascorbate for maximal collagen synthesis. The types of collagen produced by human intestinal smooth muscle cells in culture were the same as those collagens extracted from strictured human bowel (types I, III, and V). These findings suggest that collagen production by human intestinal smooth muscle cells has a role in the repair as well as the fibrosis of the gastrointestinal tract.

Immunohistochemical techniques were used to confirm biochemical evidence that parenchymal cells isolated from adult rat liver and maintained in nonreplicating monolayer culture for 2 days synthesized type IV basement membrane collagen. On continued incubation in serum-free medium, the hepatocytes also synthesized the interstitial collagens, types I and III. Consistent with these results in culture, type IV collagen was localized to the hepatocytes in slices of pathologic rat liver. Hence collagen formation is a previously unrecognized function of the hepatocyte that may be important in the pathogenesis of liver fibrosis or cirrhosis.

A highly reactive biomaterial (clay) and a relatively nonreactive substance (silicone) were implanted separately in primarily closed incisions on the backs of rats. Collagen synthesis was determined in biopsies from each test site after 8 days. The biochemical measurements of collagen synthesis showed a significant correlation with the gross pathologic and histologic findings.

The adult cellular response to tissue injury is characterized by acute inflammation followed eventually by fibroblast proliferation and collagen synthesis. Fetal tissue responses to injury differ markedly from those of the adult; an early acute inflammatory response is absent, few fibroblasts participate, and no collagen is deposited. The object of the present study was to analyze the effects of transforming growth factor beta (TGF-beta), an important regulatory molecule in adult healing events, on the fetal tissue response following wounding. Fetal cellular and extracellular matrix responses to injury were evaluated by placing subcutaneous wound implants containing TGF-beta (0.01 to 10 ng) in fetal rabbits at 24 days gestation (term = 31 days). Histologic responses one to seven days later were compared with fetal and adult control implants without TGF-beta. The histology of the adult implant was characterized by an early acute inflammatory response: by day 7 fibroblasts and collagen were predominant. In contrast, control implants removed from fetal rabbits had no histologic evidence of acute inflammation or fibroblast penetration and no collagen was deposited. When implants containing 1.0 ng TGF-beta were removed from fetal rabbits at seven days, a grossly fibrotic reaction was observed: histology confirmed marked fibroblast penetration with collagen deposition. Fetal implants containing 0.01 ng or 10 ng TGF-beta showed few fibroblasts but had increased numbers of inflammatory cells compared with controls. These observations demonstrate that the fetal response becomes adultlike with fibroblast proliferation and collagen accumulation when TGF-beta is added, thus documenting the responsiveness of the fetal system to adult repair signals.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular sieve column chromatography was used to determine the amount of type I and III collagen synthesized by normal dermis and keloid biopsies and fibroblasts derived from these tissues. After incubation with radioactive proline, the collagen was extracted and separated into types I and III and then quantitated. There was no significant difference in the percent type III collagen synthesized by fresh keloid biopsies compared to normal dermis. Likewise, there was no significant difference in the percent type III collagen synthesized by keloid fibroblasts compared to normal dermal fibroblasts. However, fibroblasts from both keloid and normal dermis synthesized a lower percentage of type III collagen in cell culture compared to the original biopsies. These findings demonstrate that keloid collagen has the same type distribution as normal dermis and suggest that increased collagen synthesis in these lesions is not related to altered collagen types.

Fetal, neonatal, and adult tissue response to a standardized injury was studied using subcutaneous wound implants, linear incisions, and punch wounds in New Zealand white rabbits. In the fetus, sutured incisions healed by primary intention without antecedent inflammation. However, neither contraction nor healing by secondary intention was seen in punch or unsutured wounds. Healing both by primary and secondary intention following inflammatory infiltration was observed uniformly in neonatal and adult rabbits. Wound implants were extensively infiltrated with collagen in the adults studied; however, no collagen was seen in fetal implants and collagen hydroxyproline content could not even be detected by high performance liquid chromatography techniques; rather, a matrix rich in hyaluronic acid was found. The fetal tissue response to injury differs from the adult, proceeding in the absence of a classical inflammatory stimulus and lacking contractile capabilities. The deposition of extracellular matrix rich in hyaluronic acid but devoid of collagen suggests that the fetal response to injury may be a process more closely resembling regeneration or growth rather than repair by scar deposition.

Every somatic cell within vertebrate species contains genetic information and therefore the potential to synthesize collagen. Normally, when there is a requirement for new connective tissue following injury, cells of mesodermal origin are activated to meet that demand and supply sufficient amounts of collagen to return structure and function to the damaged tissue or organ. Under these conditions, nonconnective tissue cells either do not synthesize collagen or may produce only minute quantities which are barely detectable by our most sensitive techniques. However, when these nonmesodermal cells are exposed to an abnormal or toxic environment, collagen expression may become greatly enhanced. For example, when hepatocytes are removed from their normal in vivo environment and placed in cell culture, they demonstrate a dramatic increase in their potential to produce collagen. Hepatocytes may also express this ability to produce significant quantities of collagen when they are exposed to toxins or injury in vivo. The list of cells shown to produce collagen or contain enzymes related to collagen biosynthesis has expanded in recent years and now includes such diverse and specialized cells as glomerular mesangial, adipocytes, aortic endothelial, smooth muscle, Schwann cells, and lymphocytes. Therefore, the loss of structure and function in a tissue or organ due to fibrosis may result from excessive deposition of collagen from nonmesodermal sources as well as from connective tissue cells.

Contraction and epithelization are two phenomena of "wound healing" retarded by corticosteroids. It is unclear how these agents affect collagen synthesis and wound remodeling. The methods used by several authors to conclude that steroids inhibit collagen synthesis are questioned. Therefore, collagen synthesis was measured in cultured steroid-treated chick embryo calvaria, 5 day open wounds in treated rats, and intralesionally injected human keloids. Collagen synthesis was suppressed only by long-term administration of massive systemic doses of a sustained release form of methylprednisolone (Depo-Medrol). Large, intermittent doses of corticosteroids (triamcinolone and Solu-Medrol) did not alter collagen synthesis. Because human keloids become softer and smaller following intralesional administration of triamcinolone without lowering the normally high rate of collagen synthesis, we hypothesize that corticosteroids enhance collagen degradation.

The collagen content and the relative amount of collagen types were quantitated in control intestine as well as in both inflamed and strictured intestine resected from patients with Crohn's disease. The major collagen type in control intestine was type I (68%), followed by types III (20%) and V (12%). In strictured intestine both collagen content and the relative amount of type V collagen were significantly increased compared with control intestine. Histologic studies demonstrated that in strictured specimens there was a striking proliferation of smooth muscle cells of the muscularis mucosae associated with an accumulation of collagen in the submucosa. The thickness of the muscularis propria was also increased. Immunohistochemical studies demonstrated small amounts of type V collagen in the submucosa of control bowel. In contrast, large amounts of type V collagen were seen in the fibrotic, expanded submucosa of strictured bowel, particularly in the areas where smooth muscle cells of the muscularis mucosae had proliferated. Intestinal strictures in Crohn's disease are therefore characterized by an accumulation of collagen, a proliferation of smooth muscle cells, and an increase in type V collagen, a collagen type produced in relatively large amounts by smooth muscle cells. These changes appear to result in both a loss of the normal compliance of the intestine and a thickening of the intestine wall, resulting ultimately in the intestinal obstruction so frequently seen in patients with Crohn's disease.

A chicken tendon explant model system has been developed to investigate the effects of extremely-low-frequency (ELF), low-amplitude, unipolar, square wave pulsed electric fields on fibroplasia in vitro. An electric field parameter set consisting of 1-Hz, 1-ms duration pulses, with a time-averaged current density of 7 mA/m2 (peak current density 7 A/m2) induced maximal (32%) increase in fibroblast proliferation in tendon explants exposed for 4 days. Exposure to the same field at an average current density of 1.8 mA/m2 had no effect on fibroblast proliferation, whereas exposure to current densities on greater than 10 mA/m2 inhibited proliferation and relative collagen synthesis, without affecting noncollagen protein synthesis. Fibroplasia was significantly increased in explants oriented parallel to applied electric fields having current densities of 3.5 or 7 mA/m2, but there was no detectable effect on explants oriented perpendicular to the same electric field. Fibroblast proliferation and relative collagen synthesis were inversely proportional to donor age for chickens in the 3- to 16-week age group used in this study. For these dependent variables (proliferation and relative collagen synthesis), there was no interaction between donor age and ELF electric field exposure.

Collagen synthesis is increased over three-fold in capsules surrounding dimethylbenzanthracene-induced rat breast tumors compared to the tumor parenchyma and over six-fold compared to normal breast connective tissue. Increased collagen synthesis is independent of the rate of tumor growth and final tumor size. Pretreatment of animals with beta-aminopropionitrile to inhibit collagen cross-linking caused an 82% decrease in tumor formation and a significant reduction in tumor volume (approximately 0.4 cu cm) compared to controls (approximately 10 cu cm). The four small tumors that did develop in the lathyritic animals had increased collagen synthesis in the interior tumor stroma and reduced collagen synthesis in the tumor capsule. These findings suggest that the collagenous capsule surrounding dimethylbenzanthracene tumors functions as a physical barrier to protect the tumor from the immune system of the host. The apparent antitumor effects of beta-aminopropionitrile may be due to immunopotentiation and/or cytotoxic actions of the drug.

Previous studies have shown that isolation and primary culture of rat hepatocytes in a standard, chemically defined medium is associated with selective changes in microsomal function. These changes were found to be selectively sensitive to addition of hormones to the culture medium. The concentration of cytochrome P-450 declined dramatically during the first 24 hours of incubation. However, cytochrome P(1)-450, a form of the hemoprotein induced by polycyclic aromatic hydrocarbons, was resistant to this change. Cytochrome P(1)-450 levels selectively rose during the first ten hours in culture and, thereafter, declined at a less rapid rate than did the cytochrome P-450 in normal hepatocytes or in cells prepared from phenobarbital pretreated animals. Addition of dexamethasone to the medium at the time of cell plating partially prevented the fall of cytochrome P-450 and of (14)C-heme in microsomes prepared from hepatocytes derived from rats given 5(14)[C]-δ-aminolevulinic acid. This suggests that the steroid decreases degradation of the hemoprotein. As compared to the loss of cytochrome P-450 in cultures of normal hepatocytes, the hemoprotein fell to lower levels in hepatocytes prepared from regenerated liver four days after partial hepatectomy. This result may be related to the accelerated formation of the monolayer in the cultures of regenerated hepatocytes. Both sn-glycerol-3-phosphate acyltransferase activity and glycerol kinase activity declined in the first 24 hours of culture. The fall in the latter enzyme was partially prevented by addition of estradiol. Collagen prolyl hydroxylase, a newly discovered microsomal constituent of the hepatocyte, rose slightly during the first 24 hours in culture. This change was augmented threefold by addition of insulin to the medium. We conclude that the present hepatocyte culture system with its attendant changes in functional phenotype may be useful in better defining the role of hormones in modulating metabolic processes in the liver.

An implantable chamber consisting of a small reservoir and a perforated segment of silicone tubing has been developed for the collection of leukocytes, fibroblasts, and collagen to analyze inflammatory components and fibroplasia during tissue repair. Using aseptic techniques, these sterile chambers were placed into subcutaneous pockets on the backs of Sprague-Dawley rats with cells obtained in daily aspirates for 14 d. Differential cell counts were made by using aliquots from the wound fluid. The aspirated cells represented the characteristic, sequential influx of neutrophils, inflammatory macrophages, lymphocytes, activated macrophages, and fibroblasts documented in other models of tissue repair. On d 14, the connective tissue within the lumen of the silicone tube was removed and analyzed for collagen synthesis by measuring 3H-proline incorporation into collagenase-sensitive protein. This new device for studying wound healing provides a convenient means to harvest cells, fluid, and tissue for cellular, humoral, and biochemical analyses of tissue repair.

The effect of heparin on human intestinal smooth muscle cell proliferation, collagen and noncollagen protein synthesis, and collagen lattice contraction was studied in vitro. Proliferation of serum-stimulated cells was inhibited in a concentration-related fashion by continuous exposure to heparin. The inhibition of proliferation was reversible when heparin was removed from the culture medium. Collagen synthesis was inhibited by 24-h exposure to heparin, but only during that phase of culture (8-12 days) when collagen synthesis was maximal. Noncollagen protein synthesis was down-regulated by 24-h exposure to heparin at all phases of culture tested (5-21 days). Heparin also abolished the contraction of collagen lattices populated by human intestinal smooth muscle cells. These studies demonstrate that heparin plays a significant role in the modulation of human intestinal smooth muscle cell behavior in vitro and suggest that a similar role is played by heparinlike components of the extracellular matrix in vivo.

Fetal response to injury has been characterized by the deposition of a matrix that is not primarily collagen. This study was designed to identify this matrix, in order to better understand the fetal mechanism of tissue repair. Silastic/polyvinyl alcohol sponge (PVA) wound implants were placed paravertebrally in 24-day gestation (31 days = term) fetal (n = 65) and adult (n = 43) rabbits and then harvested from one hour to 6 days post-wounding. Histologic analysis of the fetal wound matrix deposited in the PVA implants suggested the presence of glycosaminoglycans (GAG) rather than the collagen found in adult wound implants. To further analyze the fetal wound matrix, the GAG content was quantitated using an Alcian Blue dye-binding assay. Results showed significantly increased (p less than 0.05) GAG deposition on days 2-6 in the fetal wound compared to the adult wound. Fetal GAG levels were approximately three times those of the adult during this period. Separation of individual GAG species by cellulose acetate electrophoresis demonstrated that the GAG matrix of the fetal wound was composed predominantly of hyaluronic acid. This finding was confirmed by selective enzymatic digestion of separated GAG species using highly specific polysaccharidases. These observations of hyaluronic acid deposition in the fetal wound may be ascribed an important physiologic role by providing a more fluid and malleable matrix rather than a restrictive matrix composed of collagen. This new evidence coupled with earlier findings of the lack of an acute inflammatory response in the fetus further supports the hypothesis that the fetal response to injury is significantly different from the adult response.

The increased collagen synthesis and deposition, which is characteristic of keloids, may be related to an immune response initiated by wounding. Therefore, we examined various systemic and localized immune parameters in keloid patients to establish if such factors are related to keloid pathogenesis. To determine if there is a systemic immune response, we compared the serum levels of IgG and IgM in keloid patients to those in a closely matched population. In addition, we measured complement levels (Clq, C3, and C4) and receptors for sheep (E), mouse erythrocytes (MRBC), and complement (EAC) on blood lymphocytes. All of these were in the normal range in the keloid patients. However, the extractable IgG from keloid tissue was significantly increased (compared to normal skin and normal scar controls), suggesting a localized immune response. To determine whether keloid formation is associated with a specific histocompatibility locus, human lymphocyte antigen (HLA) profiles of 45 keloid patients were analyzed; no significant differences in the incidence of HLA-A and B antigens were found (compared to 200 controls). These studies suggest that there is a localized immune response involved in keloid pathogenesis, one which is not related to either the HLA-A or B histocompatibility loci.

The events of wound healing are defined as collagen metabolism, epithelialization, and contraction. Recent findings that further our understanding of these pheneomena are presented and correlated with the important clinical problems confronting plastic surgeons. The future direction of wound healing investigation and its application to practical surgical care are predicted.

There has been considerable controversy concerning the capacity of tendons to heal intrinsically without adhesion formation. To help clarify this issue, a tissue culture model was developed to study the potential of tendon fibroblasts to proliferate and migrate. Avian flexor tendons, isolated free of sheath and all synovial components, were maintained in sterile culture plates with Dulbecco's Modified Eagle Medium. After 5 days in culture, the 2 mm tendon biopsies were analyzed for DNA synthesis [( 125I])iododeoxyuridine incorporation) and migration of fibroblasts out of the explant (planimeter analysis). DNA synthesis was maximal on day 5 in culture, and tendon fibroblasts were observed migrating from the biopsy within 48 h. Addition of cells from plasma resulted in a significant increase in fibroblast migration, and the presence of fibrin in the plasma clot was an absolute requirement for the migratory process. These findings further support the hypothesis that injured tendons can heal by an intrinsic healing process in addition to healing by adhesion formation.

Previous studies of fibroblast proliferation, migration, and collagen synthesis have been limited in their ability to define the interrelationship among these events in response to various inflammatory mediators. We have now defined an in vitro tissue culture model for the synchronous quantification of these parameters of fibroplasia. Biopsies (2 mm) of chicken flexor tendons are embedded in a fibrin matrix and exposed to various factors for 5 days in tissue culture. The availability of the fibrin matrix surrounding the tendon biopsy satisfies the need for a solid support medium for fibroblast migration. Multiple measurements of tendon fibroblast proliferation, migration into the fibrin matrix, and relative collagen synthesis are then made on these preparations. Fetal calf serum stimulated tendon fibroblast proliferation and migration in a dose responsive fashion, whereas the selective expression of collagen synthesis was decreased. Platelet lysate stimulated fibroblast proliferation at low concentration, but migration only at high concentration and was without effect on relative collagen synthesis. This model now provides a means of more clearly defining the influence of various inflammatory factors on the events of fibroplasia.

The effect of cyclic nucleotides on collagen production by human intestinal smooth muscle cells was examined in vitro. Cholera toxin and isobutylmethylxanthine, agents that elevate cyclic adenosine monophosphate, caused selective inhibition of collagen production when cells were exposed to these agents for 24-72 h. Exposure for 6 h inhibited noncollagen protein synthesis without effects on collagen production. Forskolin similarly inhibited collagen production, decreasing relative collagen synthesis 40% at 10 microM and 60% at 100 microM. After 48 h of exposure to cholera toxin and isobutylmethylxanthine, levels of cyclic adenosine monophosphate had increased in a concentration-dependent manner. The effect of cyclic nucleotide analogues was also examined. Dibutyryl cyclic adenosine monophosphate inhibited collagen production, whereas dibutyryl cyclic guanosine monophosphate increased collagen production by 65%. This effect was maximal at a concentration of 10 microM. These observations suggest that cyclic adenosine monophosphate has a significant effect on collagen production by human intestinal smooth muscle cells in vitro and may play a role in the modulation of collagen production by these cells in vivo.

Human intestinal smooth muscle cells have recently been identified as the major cell type responsible for stricture formation in Crohn's disease. Heparin, a sulfated glycosaminoglycan, has been shown to be a key modulator of vascular smooth muscle cell growth both in vivo and in vitro and to affect the release of proteins from these cells. Heparin has also been shown to affect the growth of human intestinal smooth muscle cells. In this report we demonstrate that heparin, in addition to its effects on proliferation, also has very specific effects on proteins released by these cells in vitro. Examination of the culture medium proteins of heparin-treated human intestinal cells revealed an increase in three proteins of molecular weight between 150-250 kd, an increase in a 37 kd protein and a decrease in synthesis of lower molecular weight (less than 20 kd) proteins. In substrate-attached material a transient effect on a 48 kd protein was observed. No effects on intracellular labeled proteins could be demonstrated. The 35S-methionine labeled protein profile of human intestinal smooth muscle cells exposed to heparin is similar to that observed in rat vascular smooth muscle cells yet distinct differences do exist. Extracellular processing does not account for the released proteins nor is de novo protein synthesis required suggesting that altered intracellular protein processing is the mechanism for the heparin-induced protein pattern. The release of specific proteins following exposure to heparin may reflect a significant influence of this glycosaminoglycan on the metabolism of smooth muscle cells in general and particularly in the human intestine.

Based on the finding that prolyl hydroxylase, a key enzyme in collagen biosynthesis, is a constituent of the hepatic parenchymal cell, we have suggested that the hepatocyte may synthesize collagen (Exp. Cell Res. 123: 269-279, 1979). We now report that, consistent with this idea, collagen formation has been detected in primary nonproliferating cultures of isolated rat hepatocytes prepared from either normal liver or regenerated liver four days after partial hepatectomy. The characteristics of the radiolabeled collagen formed in two-day old cultures incubated for 24 hours in the presence of either [3H]-proline or [35S]-cystine were its resistance to pepsin and its susceptibility to degradation by highly purified, protease-free bacterial collagenase. The presence of fibroblasts in the hepatocyte cultures was excluded as an explanation for these results because we detected no type I collagen, a universal product of the cultured fibroblast. The initial low rates of synthesis of collagen relative to total cellular protein (0.1-0.4 percent) increased dramatically upon continued incubation of the cells reaching 0.31 and 0.81 percent in nine-day old cultures of normal or regenerated hepatocytes, respectively. This change was accompanied by the synthesis of an additional 100,000 molecular weight from of collagen, possibly type I or A, B. Morphologically, the hepatocytes progressively flattened and overlapped adjacent cells with time in culture. However, their identify as hepatocytes was confirmed by the fact that synthesis of fibrinogen, a liver-specific function, was maintained above initial levels throughout the experiment. We conclude that synthesis of collagen is a constitutive function of the hepatocyte. This function is linked to hepatocyte replication, is subject to phenotypic change in culture, and may be important in the pathogenesis of hepatic fibrosis or cirrhosis.

Colchicine has been reported to disrupt microtubules and thereby inhibit collagen secretion. Because of this "anti-collagen" activity, colchicine has been suggested for use in the treatment of hepatic fibrosis. Using biochemical and immunohistochemical techniques, our laboratory has identified the hepatocyte as one possible source of collagen in the liver. The present study examined the direct effect of colchicine on collagen secretion by hepatocytes in culture. Parenchymal cells were isolated from the livers of adult rats four days following a two-thirds hepatectomy. Total collagen and the fraction secreted into the medium were quantitated as incorporation of [3H]-proline into bacterial collagenase-sensitive protein. Treatment of the hepatocytes with 100 microM colchicine (2-3 hours) resulted in a substantial inhibition of collagen secretion. However, upon longer exposure of the hepatocytes to the drug (24 hours and 8 days), the inhibitory effect on collagen secretion was abolished. The anti-protein secretion activity of the colchicine in the conditioned medium removed from the hepatocytes was still present as verified by a 2.5 hour fibroblast-collagen secretion bioassay. The secretion of the plasma proteins albumin, fibrinogen and the third component of complement was not altered by the presence of colchicine. We conclude that the hepatocyte is a highly efficient secretory cell, and is not entirely dependent upon microtubules as organelles for protein secretion. Therefore, to the extent that hepatocytes may contribute to the hepatic fibrosis, the therapeutic use of colchicine to block collagen secretion might be expected to have only limited effectiveness.

Collagen synthesis in chick-embryo frontal bone and 3T3 fibroblasts from mice was measured by incorporation in vitro of [(14)C]proline into collagenase-digestible material. About 15-25% of the collagen synthesized by the frontal bone in 60 min, and 60% of that synthesized by the fibroblasts in 2 hr, was found to be soluble in the culture medium. The microtubular disruptive drugs colchicine and vinblastine, at 10 muM, inhibited collagen secretion in both systems almost completely. Formation of collagen hydroxyproline from proline was not inhibited by these drugs. Cytochalasin B, which impairs microfilament function, had no effect on collagen secretion. Our results support the theory that collagen is transported in vesicles to the cell membrane, where it is secreted. This conclusion is based on the similarity of the collagen-secreting system to other systems in which the movement of secretory vesicles or storage granules is inhibited by microtubule disruption.