Regulation of proliferation of peritoneal tissue repair cells by peritoneal macrophages

The use of novel hemostatic sealant (Tisseel) in laparoscopic myomectomy: a case-control study

BACKGROUND

This is the first case-control study on the use of a fibrin sealant (Tisseel) on uterine suture during laparoscopic myomectomy (LM), with the primary endpoint to evaluate the intraoperative bleeding and postoperative blood loss. In addition, we evaluated the time required to achieve hemostasis using Tisseel and how much it can influence operative time.

METHODS

From December 2009 to January 2011, consecutive patients older than 18 years with symptomatic isolate intramural myoma with maximal diameter B6 cm and ≥ 4 cm and with a sonographically diagnosed free myometrium margin ≥ 0.5 cm were included in the study. We selected from our institute's database a group of consecutive patients with homogeneous features of the study group, who underwent laparoscopic myomectomy without Tisseel application.

RESULTS

Fifteen women with symptomatic myoma were enrolled in the study (group A). Regarding the control group (group B), we selected a homogenous group of 15 patients with the same preoperative characteristics of the study group. Mean operative time was 47.7 min and 62.1 min, for groups A and B respectively (p < 0.05). Mean time required to achieve complete haemostasis was 195.5 s in group A and 361.8 in control group B (p < 0.0001). Mean estimated blood loss was 111.3 mL and 230 mL in groups A and B, respectively (p < 0.05). Mean hemoglobin decrease was 1.36 g/dL and 2.04 g/dL in groups A and B, respectively (p < 0.05).

CONCLUSIONS

The use of Tisseel during LM may represent a valid alternative solution for obtaining hemostasis, reducing intra- and postoperative bleeding. Furthermore, it may help the surgeon to obtain a rapid healing of the injured surfaces, probably reducing the use of electrocoagulationand traumatisms.

Peritoneal repairing cells: a type of bone marrow derived progenitor cells involved in mesothelial regeneration

The peritoneal mesothelium exhibits a high regenerative ability. Peritoneal regeneration is concomitant with the appearance, in the coelomic cavity, of a free-floating population of cells whose origin and functions are still under discussion. We have isolated and characterized this cell population and we have studied the process of mesothelial regeneration through flow cytometry and confocal microscopy in a murine model lethally irradiated and reconstituted with GFP-expressing bone marrow cells. In unoperated control mice, most free cells positive for mesothelin, a mesothelial marker, are green fluorescent protein (GFP). However, 24 hrs after peritoneal damage, free mesothelin⁺/ GFP⁺ cells appear in peritoneal lavages. Cultured lavage peritoneal cells show colocalization of GFP with mesothelial (mesothelin, cytokeratin) and fibroblastic markers. Immunohistochemical staining of the peritoneal wall also revealed colocalization of GFP with mesothelial markers and with procollagen-1 and smooth muscle α-actin. This was observed in the injured area as well as in the surrounding not-injured peritoneal surfaces. These cells, which we herein call peritoneal repairing cells (PRC), are very abundant 1 week after surgery covering both the damaged peritoneal wall and the surrounding uninjured area. However, they become very scarce 1 month later, when the mesothelium has completely healed. We suggest that PRC constitute a type of monocyte-derived cells, closely related with the tissue-repairing cells known as ‘fibrocytes’ and specifically involved in peritoneal reparation. Thus, our results constitute a synthesis of the different scenarios hitherto proposed about peritoneal regeneration, particularly recruitment of circulating progenitor cells and adhesion of free-floating coelomic cells.

Stimulation of mesothelial cell proliferation by exudate macrophages enhances serosal wound healing in a murine model

Examination of thermally induced serosal lesions in mice displayed collections of inflammatory cells, predominantly macrophages, on and surrounding the wound within 48 hours of injury. Furthermore, by 2 days a large number of uninjured mesothelial cells adjacent to the wound were synthesizing DNA. From these findings, it was hypothesized that macrophages play a major role in serosal repair by stimulating mesothelial cell proliferation. Again, using a murine model of mesothelial regeneration, depletion of circulating monocytes significantly delayed serosal healing whereas addition of peritoneal exudate cells to the wound site 36 hours before injury increased the healing rate. In vivo assessment of mesothelial cell proliferation using tritiated thymidine incorporation and autoradiography demonstrated that peritoneal exudate cells stimulated mesothelial cell proliferation (12.44 +/- 1.63% labeling index, compared with controls in which medium only was used 4.48 +/- 0.71%). The mesothelial proliferation was predominantly because of macrophage-secreted products with molecular weights of 36 to 53 kd or 67 to 100 kd. These data support the hypothesis that macrophages play an important role in serosal healing by stimulating mesothelial cell proliferation.

Glucose and prednisolone alter basic fibroblast growth factor expression in peritoneal mesothelial cells and fibroblasts

The mechanism of peritoneal fibrosis in patients on continuous ambulatory peritoneal dialysis is poorly understood. The production of basic fibroblast growth factor (bFGF) by human peritoneal mesothelial cells cultured in high glucose medium was investigated, and the behavior of peritoneal fibroblasts, as well as the inhibitory effect of prednisolone, was assessed. Reverse transcriptase-PCR and immunocytochemistry showed the expression of glucocorticoid receptors in mesothelial cells. The semiquantitative reverse transcriptase-PCR showed that high glucose medium (4.0%) increased bFGF mRNA by 2.5-fold relative to control medium (0.1% glucose), with 83% suppression of the increase by 1 microM prednisolone. The bFGF protein level in culture supernatant was also increased by 1.5-fold in high glucose medium, with this change showing 45% suppression by 1 microM prednisolone. These effects of prednisolone were prevented by a glucocorticoid receptor antagonist (RU486) in a concentration-dependent manner. The proliferation of peritoneal fibroblasts was increased 1.9-fold by the supernatant of mesothelial cells cultured in high glucose medium, with 85% suppression by 1 microM prednisolone and suppression to 16% below basal proliferation by an anti-bFGF neutralizing antibody (10 microg/ml), whereas proliferation showed a concentration-dependent increase on addition of an anti-transforming growth factor beta-neutralizing antibody. Recombinant bFGF (50 to 1000 pg/ml) likewise caused a concentration-dependent increase of peritoneal fibroblast proliferation and fibronectin release by these cells was also increased (at 50 to 5000 pg/ml). These results suggest the potential importance of bFGF for initiation of peritoneal fibrosis and the possible efficacy of glucocorticoids for preventing such fibrosis in patients receiving peritoneal dialysis.

Changes of cytokine profiles during peritonitis in patients on continuous ambulatory peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) has emerged as an important dialysis treatment modality worldwide. One of the major complications is bacterial peritonitis, which may result in subsequent technique failure because of loss of peritoneal clearance or peritoneal fibrosis. Bacterial peritonitis leads to the release of proinflammatory cytokines from resident and infiltrating cells in the peritoneal cavity. We studied 35 patients undergoing CAPD with acute bacterial peritonitis. All patients treated with antibiotics for 2 weeks after the clinical diagnosis of peritonitis had a good recovery. Peritoneal dialysate effluent (PDE) was collected on days 1, 3, 5, 10, 21, and 42 after the start of treatment. Cell populations were monitored by flow cytometry. PDE levels of interleukin-1beta (IL-1), IL-6, transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (FGF) were measured by enzyme-linked immunosorbent assay. Gene transcription of TGF-beta in macrophages from PDE was measured by quantitative polymerase chain reaction. Bacterial peritonitis was associated with a sharp increase in total cell and neutrophil counts (400-fold) in PDE up to 3 weeks after peritonitis despite clinical remission (P < 0.0001). There was an increased absolute number of macrophages during the first 3 weeks despite the reduced percentage of macrophages among total cells in PDE compared with noninfective PDE. There was a progressive increase in the percentage of mesothelial cells or dead cells in the total cell population in PDE over the entire 6-week period. PDE levels of IL-1, IL-6, TGF-beta, and FGF increased markedly on day 1 before their levels decreased gradually. PDE levels of these cytokines or growth factors were significantly greater than those in noninfective PDE (n = 76) throughout the study period (P < 0.01). Similarly, TGF-beta complementary DNA (cDNA) molecules per macrophage were significantly greater than those of macrophages in noninfective PDE throughout this period (P < 0.01). There was no significant correlation between PDE levels of TGF-beta and TGF-beta cDNA molecules per macrophage, suggesting that peritoneal macrophages are not the only source of TGF-beta in PDE. We conclude there is an active release of proinflammatory cytokines and sclerogenic growth factors through at least 6 weeks despite apparent clinical remission of peritonitis. The peritoneal cytokine networks after peritonitis may potentially affect the physiological properties of the peritoneal membrane.

Fibroblast growth in vitro suppressed by LPS-activated macrophages. Reversal of suppression by hydrocortisone

Activated macrophages are among the major constituents of the periapical granuloma. Their state of activation may persist for long periods after the local irritant is removed and may delay resolution and repair of the lesion. The effect of activated macrophages on fibroblast growth was studied in vitro. Circular fibroblast colonies were formed using a drop containing 7.5 x 10(5) murine dermal fibroblasts and allowed to grow for 7 days. When peritoneal exudate macrophages were added (0.5-3.0 x 10(6) cells/dish) and activated in vitro by LPS (1 microgram/ml), the fibroblast colony's growth was suppressed. LPS alone, at the concentration used, had no effect on the fibroblast growth. Hydrocortisone (> or = 10(-7) M) totally reversed the suppression, when added either simultaneously with or 6, 24, or 48 h after the LPS. The efficacy of late hydrocortisone treatment suggests that its effect was through prevention of the expression of the LPS activation of the macrophages. These findings may provide a possible clue to a pharmacological modulation of the healing processes that occur in the periapical lesion once its infective source had been eliminated.

Evaluation of a carboxymethylcellulose sponge for prevention of postoperative adhesions

BACKGROUND

A novel lyophilized carboxy-methylcellulose (CMC) sponge has been developed for prevention of surgical wound adhesions. One potential mechanism for preventing abdominal adhesion is suppression of the cytokine transforming growth factor beta (TGF-beta) and other macrophage derived fibroblast stimulating factors that partially mediate adhesion formation.

METHODS

To study the efficacy and mechanisms of action of the CMC sponge, we performed standard cecal denudation and abdominal wall apposition on rats. A CMC sponge or a commercially available adhesion preventive barrier (Interceed) was placed on the denuded surface. After 14 days, adhesion severity was graded blindly on a scale ranging from 0 (no adhesion) to 5 (severe adhesion). TGF-beta expression was determined by immunocytochemical staining. To assess the secretion of macrophage derived fibrogenic factors in control and CMC rats, labeled thymidine and proline uptake and hydroxyproline production were measured in NRK rat fibroblasts cultured with conditioned medium of peritoneal macrophages.

RESULTS

The severity of adhesions in the CMC sponge group (0.7 +/- 0.3) was significantly lower than in the Interceed or control groups (2.2 +/- 0.3; 4.6 +/- 0.1). In control animals TGF-beta expression in endothelium and fibroblasts was maximal on day 3. Neither CMC nor Interceed reduced this expression. Conditioned media derived from sponge-exposed postsurgical peritoneal macrophages did not inhibit fibroblast growth or collagen formation.

CONCLUSIONS

In this model the CMC sponge was more effective than Interceed in preventing postoperative adhesions. Its action was not due to inhibition of TGF-beta expression or macrophage derived fibrogenic factors. These data highlight the primary importance of local barrier effect in adhesion prevention.

Inhibition of basal and TGF beta-induced fibroblast collagen synthesis by antineoplastic agents. Implications for wound healing

Antineoplastic drugs, given in the perioperative period, are thought to be a hazard to wound repair. Since fibroblast collagen synthesis is crucial to healing, we examined the effects of bleomycin, cisplatin and 5-fluorouracil on collagen synthesis in confluent cultures of fibroblasts from human colon and skin. The drugs were added in final concentrations between 0.1 and 50 microM. Bleomycin did not affect collagen synthesis in colon fibroblasts but inhibited synthesis in skin fibroblasts. Collagen synthesis in colon fibroblasts was strongly, and specifically, inhibited by cisplatin while synthesis in skin fibroblasts was affected only slightly. 5-Fluorouracil had no effect whatsoever on the collagen synthetic capacity in either colon or skin fibroblasts. If skin fibroblasts were cultured in the presence of transforming growth factor beta (TGF beta), the antineoplastic agents inhibited the TGF beta-stimulated collagen synthesis at far lower concentrations than those needed to suppress non-stimulated synthesis. This effect was not observed in fibroblasts from colon. The possible implications of these observations, as pertain to the use of perioperative chemotherapy, are discussed. Since 5-fluorouracil did not directly affect collagen synthesis in colon fibroblasts under any of the conditions tested it is suggested that the data support the contention that this drug is relatively harmless for intestinal healing.

Modulation of peritoneal re-epithelialization by postsurgical macrophages

The studies reviewed here show that postsurgical macrophages are capable of modulating the proliferation of TRC. That is, macrophages either suppress or enhance the proliferation of TRC depending on the culture time and the medium used as a comparison, i.e., culture medium with only serum or spent medium from cultures of resident peritoneal macrophages. Postsurgical macrophages also modulate the morphology of (spindly or rounded appearance) and the secretion of extracellular matrices by TRC. The responsivity of TRC to control by postsurgical macrophage-spent media or growth factors changes as a function of postsurgical and/or culture time. In addition, cells harvested from the site of peritoneal trauma (TRC) did not respond to growth factors in a fashion entirely the same as fibroblasts. This indicates that cells harvested from the site of peritoneal injury are unique. Lastly, after removal of a suppressive factor from postsurgical macrophage-spent media by dialysis, the factors secreted by postsurgical macrophages are more potent in enhancing TRC proliferation than growth factors individually.