Heparin and low-molecular-weight heparin (enoxaparin) significantly ameliorate experimental colitis in rats

Effects of Apixaban, Rivaroxaban, Dabigatran and Enoxaparin on Histopathology and Laboratory Parameters in Achilles Tendon Injury: An in vivo Study

Objectives

To compare the effects of apixaban, rivaroxaban, dabigatran and enoxaparin on histopathology and blood parameters in rats with Achilles tendon injury.

Materials and Methods

Thirty adult, male Wistar albino rats weighting 220-240 g were randomly divided into five (one control and four treatment) groups and placed in a controlled environment. The Achilles tendon was incised and re-sutured in each rat, after which each group was provided the following treatment for 28 days: a) 2 ml saline to the control group, b) apixaban in 1 ml of saline (10 mg/kg/day) +1 ml of saline, c) rivaroxaban in 1 ml of saline (2 mg/kg/day) +1 ml saline, d) dabigatran in 1 ml of saline (30 mg/kg/day) +1 ml of saline, e) enoxaparin (80 μg/kg/day) + 2 ml of saline.

Results

Hemogram, biochemical and coagulation parameters differed significantly between the control and treatment groups (P < 0.05). Compared with the control group, in the apixaban group, type I and type III collagen immunoreactivity were severe and moderate, respectively. In the rivaroxaban and dabigatran groups, both type I and type III collagen immunoreactivity were medium and severe, respectively. In the enoxaparin group, type I and type III collagen immunoreactivity were mild and severe, respectively.

Conclusion

The higher concentration of type I collagen in the apixaban and dabigatran indicates faster tendon healing in these groups, and the higher concentration of the type III collagen in the enoxaparin group indicates slower healing in this group.

Enoxaparin pretreatment effect on local and systemic inflammation biomarkers in the animal burn model

Low-molecular weight heparins (LMWH) are anticoagulants that have shown anti-inflammatory activity in several experimental models. Hot water burn inflammatory model accurately simulates human clinical situations allowing its use for nociception test and evaluation of anti-inflammatory drugs. The present study aims to evaluate the enoxaparin pretreatment on local and systemic inflammation biomarkers in the animal burn model. Inflammation was induced by submersing the rat left hind paw in water at 60^o C for 60 s. C-reactive protein (CRP) and thrombin-antithrombin complex (TAT) were estimated by immunosorbent assay, fibrinogen (Fg) by the gravimetric method and paw oedema by orthogonal digital photography. Highest values of paw oedema, CRP and TAT were observed at 4 h post-burn while Fg peak occurs at 12 h post-burn; enoxaparin pretreatment decreased oedema (- 32.1%), and concentration of TAT (- 66.7%), PCR (- 37.9%) and Fg (- 8%). This study shows that enoxaparin has local and systemic anti-inflammatory effects and should be considered as a potential adjuvant drug for the treatment of burns.

Nanoparticle-based delivery enhances anti-inflammatory effect of low molecular weight heparin in experimental ulcerative colitis

Epithelial administration of low molecular weight heparin (LMWH) has proven its therapeutic efficiency in ulcerative colitis (UC) but still lacks of a sufficiently selective drug delivery system. Polymeric nanoparticles were used here not only to protect LMWH from intestinal degradation but also to provide targeted delivery to inflamed tissue in experimental colitis mice. LMWH was associated with polymethacrylate nanoparticles (NP) type A (PEMT-A) or type B (PEMT-B) of a size: 150 nm resulting in a maximum drug loading: 0.1 mg/mg. In a lipopolysaccharide-stimulated macrophages both, free LMWH and LMWH-NP have significantly reduced the cytokines secretion independently from cellular uptake. The in-vivo therapeutic efficiency was dose dependent as at low doses (100 IU/kg) only minor differences between free LMWH and LMWH-NP were found and the superiority of LMWH-NP became prominent with dose increase (500 IU/kg). Administration of LMWH-NP at 500 IU/kg has markedly improved the clinical activity as compared to LMWH while similarly pathophysiological indicators revealed increased therapeutic outcome in presence of NP compared to LMWH alone: Myeloperoxidase (Colitis control: 10 480 ± 5335, LMWH-PEMT-A NP: 1507 ± 2165, LMWH-PEMT-B NP: 382 ± 143, LMWH: 8549 ± 5021 units/g) and tumor necrosis factor: (Colitis control: 1636 ± 544, LMWH-PEMT-A NP: 511 ± 506, LMWH-PEMT-B NP: 435 ± 473, LMWH: 1110 ± 309 pg/g). Associating LMWH with NP is improving the anti-inflammatory efficiency of LMWH in-vivo by its protection against degradation in luminal environment and selective drug delivery. Such a combination holds promise for a highly specific therapy by its double selectivity towards the inflamed intestinal tissue. LMWH-PEMT NP have significantly improved the clinical activity in-vivo in comparison to free LMWH.

Non-anticoagulant effects of low molecular weight heparins in inflammatory disorders: A review

Low molecular weight heparins (LMWHs) are produced by chemical or enzymatic depolymerization of unfractionated heparin (UFH). Besides their well-known anticoagulant effects, LMWHs have also been reported to exhibit numerous anti-inflammatory properties. Previous studies have, however, shown that different production processes result in unique structural characteristics of LMWHs. The structural variations may help explain the different therapeutic spectrums in disease treatment for non-anticoagulant effects. In the present review, we summarize major advances in understanding and exploiting the anti-inflammatory disorder activities of LMWHs, based on mechanistic studies, preclinical experiments and clinical trials. We highlight differences in these activities of commercially available LMWHs produced using different manufacturing processes. We stress the importance of structure-activity relationship (SAR) studies on the non-anticoagulant effects of LMWHs and discuss strategies for exploring new clinical indications.

Heparins in ulcerative colitis: proposed mechanisms of action and potential reasons for inconsistent clinical outcomes

Current drug therapies for ulcerative colitis (UC) are not completely effective in managing moderate-to-severe UC and approximately 20% of patients with severe UC require surgical interventions. Heparins, polydisperse mixtures of non-anticoagulant and anticoagulant oligosaccharides, are widely used as anticoagulants. However, heparins are also reported to have anti-inflammatory properties. Unfractionated heparin was initially used in patients with UC for the treatment of rectal microthrombi. Surprisingly, it was found to be effective in reducing UC-associated symptoms. Since then, several pre-clinical and clinical studies have reported promising outcomes of heparins in UC. In contrast, some controlled clinical trials demonstrated no or only limited benefits, thus the potential of heparins for the treatment of UC remains uncertain. This review discusses potential mechanisms of action of heparins, as well as proposed reasons for their contradictory clinical effectiveness in the treatment of UC.

Orally Administered Enoxaparin Ameliorates Acute Colitis by Reducing Macrophage-Associated Inflammatory Responses

Inflammatory bowel diseases, such as ulcerative colitis, cause significant morbidity and decreased quality of life. The currently available treatments are not effective in all patients, can be expensive and have potential to cause severe side effects. This prompts the need for new treatment modalities. Enoxaparin, a widely used antithrombotic agent, is reported to possess anti-inflammatory properties and therefore we evaluated its therapeutic potential in a mouse model of colitis. Acute colitis was induced in male C57BL/6 mice by administration of dextran sulfate sodium (DSS). Mice were treated once daily with enoxaparin via oral or intraperitoneal administration and monitored for colitis activities. On termination (day 8), colons were collected for macroscopic evaluation and cytokine measurement, and processed for histology and immunohistochemistry. Oral but not intraperitoneal administration of enoxaparin significantly ameliorated DSS-induced colitis. Oral enoxaparin-treated mice retained their body weight and displayed less diarrhea and fecal blood loss compared to the untreated colitis group. Colon weight in enoxaparin-treated mice was significantly lower, indicating reduced inflammation and edema. Histological examination of untreated colitis mice showed a massive loss of crypt architecture and goblet cells, infiltration of immune cells and the presence of edema, while all aspects of this pathology were alleviated by oral enoxaparin. Reduced number of macrophages in the colon of oral enoxaparin-treated mice was accompanied by decreased levels of pro-inflammatory cytokines. Oral enoxaparin significantly reduces the inflammatory pathology associated with DSS-induced colitis in mice and could therefore represent a novel therapeutic option for the management of ulcerative colitis.

Nadroparin sodium activates Nrf2/HO-1 pathway in acetic acid-induced colitis in rats

Effects of nadroparin sodium, a low molecular weight heparin, in colitis was investigated by analyzing proteins implicated in nuclear factor E2-related factor-2/heme oxygenase-1 (Nrf2/HO-1) and nuclear factor kappa B (NF-κB) pathways. Twenty-eight rats were used. Colitis was induced by acetic acid (AA). Nadroparin sodium was given to prevention and treatment groups in addition to AA. Colitis was assessed histologically and levels of proteins were analyzed with Western blot. Nadroparin not only prevented and ameliorated the AA-induced colitis histopathologically but also decreased expression of colon NF-κB, activator protein-1, cyclooxygenase-2, tumor necrosis factor-alpha, and IL-6, which were significantly increased in group AA compared to control. The accumulation of Nrf2 in nuclear fraction and HO-1 found low in group AA was increased with nadroparin (p < 0.05). The mean malondialdehyde level increased with AA and was decreased significantly with nadroparin prevention and treatment (p < 0.001). Nadroparin sodium has both protective and therapeutic effects against colonic inflammation via exerting anti-oxidative and anti-inflammatory effects by modulating Nrf2/HO-1 and NF-κB pathways.

Efficacy of intracolonic administration of low-molecular-weight heparin CB-01-05, compared to other low-molecular-weight heparins and unfractionated heparin, in experimentally induced colitis in rat

PURPOSE

Parenteral administration of low-molecular-weight heparins (LMWHs) and unfractionated heparin (UFH) resulted effective in improving the symptoms of experimental colitis in rat. Today, there is little information about their activity by intracolonic instillation. The scope of this study was to evaluate the ability of CB-01-05 (a LMWH with a mean molecular weight of about 5,700), compared to a series of other LMWHs and to UFH, directly instilled into the distal colon of the rat, to ameliorate dinitrobenzene (DNB)-induced experimental colitis.

METHOD

Adult male Wistar rats underwent colitis induction by intracolonic instillation of DNB. Starting 24 h after colitis induction, CB-01-05 (0.005-0.9 mg), other LMWHs (0.3-0.6 mg), and UFH (0.6 mg) were instilled, by rectal route, into the distal colon once a day for three consecutive days. On the day following the last administration, the animals were sacrificed and the distal colon was isolated, weighed, macroscopically examined, and processed for histology. Additional experiments in rat splenocytes, performed in order to elucidate the anti-inflammatory mechanisms of CB-01-05, were performed.

RESULTS

Among the tested items, only CB-01-05 at doses ranging from 0.2 to 0.9 mg was significantly effective in reducing colon weight increase and in improving both the mucosal damaged area and the histological score. The other LMWHs resulted far less effective, showing decreasing activity closely related with the decrease of their molecular weight, thus demonstrating their biological nonequivalence. CB-01-05 resulted also more active than UFH. CB-01-05 was shown to interfere with cytokines production by rat splenocytes, mainly inhibiting interferon (IFN)-gamma expression.

CONCLUSIONS

CB-01-05 instilled into the colon is well tolerated, has strong anti-inflammatory effect on DNB-induced colitis in rat, and is the most effective agent among other LMWHs and UFH. These results suggest that the anti-inflammatory activity of CB-01-05, together with its topical administration, could represent a new approach in the management of ulcerative colitis.

An endogenously deposited fibrin scaffold determines construct size in the surgically created arteriovenous loop chamber model of tissue engineering

BACKGROUND

An arteriovenous loop (AVL) enclosed in a polycarbonate chamber in vivo, produces a fibrin exudate which acts as a provisional matrix for the development of a tissue engineered microcirculatory network.

OBJECTIVES

By administering enoxaparin sodium - an inhibitor of fibrin polymerization, the significance of fibrin scaffold formation on AVL construct size (including the AVL, fibrin scaffold, and new tissue growth into the fibrin), growth, and vascularization were assessed and compared to controls.

METHODS

In Sprague Dawley rats, an AVL was created on femoral vessels and inserted into a polycarbonate chamber in the groin in 3 control groups (Series I) and 3 experimental groups (Series II). Two hours before surgery and 6 hours post-surgery, saline (Series I) or enoxaparin sodium (0.6 mg/kg, Series II) was administered intra-peritoneally. Thereafter, the rats were injected daily with saline (Series I) or enoxaparin sodium (1.5 mg/kg, Series II) until construct retrieval at 3, 10, or 21 days. The retrieved constructs underwent weight and volume measurements, and morphologic/morphometric analysis of new tissue components.

RESULTS

Enoxaparin sodium treatment resulted in the development of smaller AVL constructs at 3, 10, and 21 days. Construct weight and volume were significantly reduced at 10 days (control weight 0.337 +/- 0.016 g [Mean +/- SEM] vs treated 0.228 +/- 0.048, [P < .001]: control volume 0.317 +/- 0.015 mL vs treated 0.184 +/- 0.039 mL [P < .01]) and 21 days (control weight 0.306 +/- 0.053 g vs treated 0.198 +/- 0.043 g [P < .01]: control volume 0.285 +/- 0.047 mL vs treated 0.148 +/- 0.041 mL, [P < .01]). Angiogenesis was delayed in the enoxaparin sodium-treated constructs with the absolute vascular volume significantly decreased at 10 days (control vascular volume 0.029 +/- 0.03 mL vs treated 0.012 +/- 0.002 mL [P < .05]).

CONCLUSION

In this in vivo tissue engineering model, endogenous, extra-vascularly deposited fibrin volume determines construct size and vascular growth in the first 3 weeks and is, therefore, critical to full construct development.

The microvascular thrombi of colonic tissue in ulcerative colitis

Mucosal microvascular thrombi in rectal biopsies were observed in some ulcerative colitis (UC). Heparin may be effective in steroid resistant UC in some studies, however, the new results of meta-analysis demonstrated a non-significant effect of heparin in controlled clinical trials, differing markedly from observational studies. The objective of this study was to identify colonic microvascular thrombi in larger cases with UC, and analyse its possible risk factors: age, gender, histologic score, extent of lesions and operation or biopsy specimens, and assess the significance of microvascular thrombosis in patients with UC. The microvascular thrombi were identified by immunohistochemical staining with anti-CD61 monoclonal antibody and Martius scarlet blue (MSB) staining in 40 colonic tissue samples of UC (31 biopsy specimens and nine operated cases) and 12 cases of normal colon tissue from operated colonic carcinoma. Logistic regression analysis was used to assess the relationship of age, gender, degree of histology, origin of the specimens, extent of lesions and microvascular thrombi examined. Microvascular thrombi were positive in 14 of 40 UC cases, and none in the controls. The presence of microvascular thrombi was related to operation specimens with odds ratio 11.667, P=0.0179, it might be also related to histologic score (OR=1.350) and extent of lesions (OR=1.619). These results suggest that microvascular thrombosis may be one of the important pathogenesis in some UC, and that the effect of anticoagulant treatment still needs to be assessed.

Low molecular weight heparin loaded pH-sensitive microparticles

Low molecular weight heparins (LMWH) have shown efficacy in the treatment of inflammatory bowel disease after parenteral administration however risking severe hemorrhagic adverse effects. Therefore, an oral colonic targeted heparin dosage form allowing the release of LMWH directly in the inflamed tissue would be of major interest. Enoxaparin was entrapped into pH-sensitive microspheres using Eudragit P4135F that dissolves at pH>7.2. Particle preparation was based on a double emulsion technique with either solvent extraction or evaporation. In order to increase the entrapment efficacy several preparation parameters were optimized, such as inner phase volume, polymer concentration, stabilization of the internal interface by surfactants. Solvent evaporation led to higher entrapment rates (evaporation: 70.1+/-9.9%; extraction: 46.5+/-6.4%). When increasing the volume of the inner aqueous heparin phase, lower encapsulation rates and larger microspheres ( approximately 100-400 microm) were obtained. Sorbitan monostearate (1.75-28% of the total particle mass) had a stabilizing effect on the primary water/oil emulsion. Indeed, higher encapsulation rates (7%: 78.2+/-3.5%; 14%: 76.4+/-10.1%) and smaller particles ( approximately 120-160 microm) were obtained whereas hexadecyltrimethylammonium bromide destabilized the primary emulsion. Interfacial tension studies at a simulated internal water/oil interface confirmed these results. As expected, in vitro drug release was found to be strongly pH-dependent; LMWH was retained in microspheres at pH<6 (<20% release within 4h) whereas a fast drug release was obtained at pH 7.4. The developed microspheres exhibited a particle size adapted to the needs of inflammatory bowel disease therapy, an efficient LMWH encapsulation, and a pH-controlled drug release. These microspheres represent a promising tool for the selective oral delivery of heparin to the colon, especially interesting in the treatment of inflammatory bowel disease.

Epithelial Heparin Delivery via Microspheres Mitigates Experimental Colitis in Mice

Low-molecular-weight heparins (LMWH) have been shown to be efficient in the treatment of inflammatory bowel disease (IBD). Parenteral heparin therapy, however, may cause hemorrhagic adverse effects. To reduce this risk, epithelial LMWH delivery in combination with a system ensuring selective drug release to the inflamed tissue was tested here. Enoxaparin loaded microspheres (MS) were administered orally to male BALB mice suffering from a pre-existing experimental colitis, whereas control groups received subcutaneous or rectal LMWH solution. Colon weight/length index and alkaline phosphatase and myeloperoxidase activities were assessed to determine the inflammation. Tissue penetration experiments elucidated the processes involved in the proposed new therapeutic approach. Oral LMWH-MS proved to be equally efficient in mitigating experimental colitis as rectally administered LMWH solution when quantified by myeloperoxidase activity (MS, 10.2+/-1.5 U/mg tissue; rectal, 9.2+/-1.6 U/mg) and to be superior to subcutaneous LMWH (s.c., 21.6+/-5.6 U/mg; untreated colitis control, 30.0+/-3.8 U/mg). Pharmacokinetic studies found a notably low systemic availability of oral LMWH delivered from MS (<5%) indicating a low potential for adverse effects. The tissue permeability was selectively enhanced in the inflamed regions where a 9-fold higher LMWH penetration was found compared with healthy tissue. Epithelial LMWH delivery has been found a promising anti-inflammatory therapeutic approach. The use of LMWH-MS in this context offers a promising tool for IBD therapy by enhancing specifically drug availability at inflamed tissue sites while reducing the risk for systemic adverse effects to a negligibly low level.

Dose response of enoxaparin at the cremaster muscle flap microcirculation

The effects of different dosages of enoxaparin (Lovenox), a low molecular-weight heparin, on microcirculation were investigated. The cremaster muscle model for intravital microscopy was used. Four groups were studied: in group I (n = 6), the controls no agent was given; in group II (n = 6), enoxaparin (2 mg/kg s.c.), in group III, (n = 6), enoxaparin (4 mg/kg s.c.); and in group IV, (n = 6), exoxaparin (8 mg/kg s.c.). These agents were injected before muscle dissection. All animals were observed under intravital microscopy, and measurements of capillary density and red blood cell velocity were taken at 2, 3, 5, and 7 h following subcutaneous enoxaparin injection. Statistical analysis revealed that the capillary density significantly increased in group II and group III, respectively, (by 33% (P < 0.0001) and 25% (P < 0.01) when compared to group I at the fifth hour. Group IV was not significantly different from group I in capillary density. There was no significant difference in red blood cell velocity in any of the groups. Propensity for bleeding was not observed in any of the groups during the dissections and observation periods except in group IV. In conclusion subcutaneous administration of 2 mg/kg enoxaparin improves (by 33%) capillary density without any bleeding complications at the cremaster muscle flap microcirculation at the fifth hour following injection (P < 0.0001). (c) 2005 Wiley-Liss, Inc. Microsurgery 25:147-151, 2005.

Effects of low molecular weight heparin on platelet surface P-selectin expression and serum interleukin-8 production in rats with trinitrobenzene sulphonic acid-induced colitis

AIM: To observe the effects of low molecular weight heparin (LMWH) on platelet surface P-selectin expression and serum interleukin-8 production in rats with trinitrobenzene sulphonic acid (TNBS) induced colitis.

METHODS: Colitis was induced in female Sprauge-Dawley rats by colonic administration of 2, 4, 6-TNBS. LMWH, a dalteparin (150 U/kg, 300 U/kg) was subcutaneously administrated one hour before induction of colitis and went on once a day for 6 days. Then a half dose was given for the next 7 days. Control animals received the same volume of normal saline once a day for 14 days after treated by TNBS. Animals were sacrificed at 24 h, days 7 and 14 after induction of colitis. The colon was excised for the evaluation of macroscopic and histological findings and TNF-α immunohistochemical assay. Platelet surface P-selectin expression was determined by radioimmunoassay and serum IL-8 production was assayed by ELISA method.

RESULTS: LMWH treatment in a dose of 300 U/kg for 14 days significantly improved colonic inflammation by histological examination. Serum IL-8 production in the 300 U/kg treatment group was more significantly decreased at day 14 than that at 24 h (P < 0.05). However, platelet surface P-selectin expression and TNF-α staining in colonic tissue were not significantly different among the three groups.

CONCLUSION: LMWH has an anti-inflammatory effect on TNBS induced colitis in rats. The effect is possibly related to inhibition of proinflammatory cytokine IL-8, but not involved platelet surface P-selectin expression.

Curative effects of sodium fusidate on the development of dinitrobenzenesulfonic acid-induced colitis in rats

Fusidic acid and sodium fusidate (fusidin) are antibiotics with low toxicity and powerful immunomodulatory activities in vitro and in vivo. In this study we have evaluated the effect of fusidin on the development of dinitrobenzenesulfonic acid (DNB)-induced colitis in rats that serves as a preclinical model of human inflammatory bowel disease (IBD). The data show that when administered orally at the dose of 80 (but not 40) mg/kg body wt under a "therapeutic" regimen soon after DNB application, fusidin significantly ameliorates clinical, histological, and seroimmunological signs of disease. These entailed a significant reduction in body weight loss, smaller increase in colon weights, milder macroscopic damage, and lower histological scores. In addition, when sacrificed at the end of the study, fusidin-treated rats had significantly lower blood levels of tumor necrosis factor alpha and interferon-gamma compared with untreated controls. The present findings concur with the beneficial actions of fusidin in a pilot study conducted in patients with Crohn's disease and warrant controlled studies in humans with IBD.

Effect of heparin on tissue binding activity of fibroblast growth factor and heparin-binding epidermal growth factor in experimental colitis in rats

There have been several reports implying a benefit for heparin therapy in patients with refractory ulcerative colitis. Although this effect has been attributed to the anti-inflammatory properties of heparin, other mechanisms have not been excluded. Heparin is a potent modulator of receptor binding of growth factors such as fibroblast growth factor (FGF), vascular endothelial growth factor, and heparin-binding epidermal growth factor (HB-EGF), that play a role in wound repair. We examined the effect of heparin on the functional levels of FGF and HB-EGF in a model of experimental colitis. Fifty-six Wistar rats were divided into four groups: group 1 was the control group, group 2 received s.c. heparin 50 units/kg/d, group 3 underwent induction of 3% iodoacetamide colitis, and group 4 underwent induction of colitis and heparin treatment. Rats were killed and evaluated for severity of colitis by macroscopic and microscopic colitis scores, area of inflammation, and myeloperoxidase levels. FGF and HB-EGF levels were functionally assessed in colonic tissue in each group. Heparin therapy resulted in significant improvement in macroscopic and microscopic features of colitis (p < 0.05), accompanied by a partial reduction in myeloperoxidase levels. FGF receptor binding activity was identical in groups 1 and 2 but increased more than 3-fold after colitis induction in group 3 (p < 0.05). Treatment with heparin caused a significant decrease in FGF concentration. Levels of HB-EGF binding activity were similar in groups 1 and 2 and decreased in group 3 (p < 0.01). Heparin caused a significant increase in HB-EGF content in group 4 (p < 0.05). Levels of growth factors are altered differently in experimental colitis. Colonic FGF binding activity increases with colitis, whereas HB-EGF binding decreases with colitis. These trends were reversed by heparin, concomitant with a clinical and pathologic improvement in colitis. We suggest that one mechanism of heparin-mediated improvement in colitis may involve tissue healing associated with changes in functional levels of colonic growth factors.