Effect of novel carboxymethyl cellulose-based dressings on acute wound healing dynamics.

The clinical implications and efficacy of newly developed modified cellulose materials were evaluated in an acute wound animal model. In the current study, sixty male rats were divided into four groups. A full-thickness circular excision wound was created in the suprascapular area. Newly developed matrices (acidic partially carboxymethylated cellulose; acidic partially carboxymethylated cellulose impregnated with a povidone-iodine solution) were applied in two test groups, while fifteen animals were used as a control group without any primary dressing. Aquacel Ag, a clinically used dressing, was selected as the reference material. To compare the efficacy in vivo, the wound size and production of selected cytokines and growth factors (TNF-α, TGF-ß1, and VEGF), which play a key role in the healing process, were measured at two, seven, and fourteen days after surgery. The activity of matrix metalloproteinases 2 and 9, which actively participate in cell signalling and are essential for tissue remodelling, was determined in wound tissue by gelatin zymography. A positive effect of the newly developed dressing materials on the healing process, tissue granulation, and wound re-epithelialisation was demonstrated.

Fibrin-Modified Cellulose as a Promising Dressing for Accelerated Wound Healing.

Dermal injuries and chronic wounds usually regenerate with scar formation. Successful treatment without scarring might be achieved by pre-seeding a wound dressing with cells. We aimed to prepare a wound dressing fabricated from sodium carboxymethylcellulose (Hcel® NaT), combined with fibrin and seeded with dermal fibroblasts in vitro. We fabricated the Hcel® NaT in a porous and homogeneous form (P form and H form, respectively) differing in structural morphology and in the degree of substitution of hydroxyl groups. Each form of Hcel® NaT was functionalized with two morphologically different fibrin structures to improve cell adhesion and proliferation, estimated by an MTS assay. Fibrin functionalization of the Hcel® NaT strongly enhanced colonization of the material with human dermal fibroblasts. Moreover, the type of fibrin structures influenced the ability of the cells to adhere to the material and proliferate on it. The fibrin mesh filling the void spaces between cellulose fibers better supported cell attachment and subsequent proliferation than the fibrin coating, which only enwrapped individual cellulose fibers. On the fibrin mesh, the cell proliferation activity on day 3 was higher on the H form than on the P form of Hcel® NaT, while on the fibrin coating, the cell proliferation on day 7 was higher on the P form. The Hcel® NaT wound dressing functionalized with fibrin, especially when in the form of a mesh, can accelerate wound healing by supporting fibroblast adhesion and proliferation.

[Influence of the degree of substitution on the absorptivity of acidic carboxymethyl cellulose in the form of nonwoven fabric]. / Vliv stupne substituce na nasákavost kyselé formy karboxymethylcelulosy v podobe netkané textilie.

Modern wound treatment is based on the creation of moist wound environment which accelerates healing. For these purposes some devices and materials may be used, including carboxymethyl cellulose (CMC). Wound dressings currently available on the market contain CMC in the form of sodium salt. CMC in the acidic form has not been used in wound healing therapy yet. Likewise, there are only a few papers describing the acidic CMC preparation and properties, which are inter alia dependent on the degree of substitution (DS). Therefore, the aim of the study was to evaluate the influence of DS on absorptivity, which is one of the main features of dressings after application on the wound. Samples with DS from 0.1 to 0.45 were examined using five media: purified water, normal saline, buffer solution with pH 7.4, physiological buffer solution with pH 7.2, and solution A. Absorptivity was evaluated using a model wound created by us. It has been found that from the viewpoint of absorptivity the optimal DS of acidic CMC in the form of nonwoven fabric lies in the range from 0.25 to 0.35. Below or above these values the absorptivity is worse.

[Evaluation of the influence of sterilization method on the stability of carboxymethyl cellulose wound dressing]. / Hodnocení vlivu sterilizacní metody na stabilitu karboxymethylcelulosového krytí na rány.

Carboxymethyl cellulose, especially its sodium salt, is a versatile pharmaceutical excipient. From a therapeutic point of view, sodium salt of carboxymethyl cellulose is used in the production of modern wound dressings to allow moist wound healing. Wound dressings must be sterile and stable throughout their shelf life and have to be able to withstand different temperature conditions. At the present time, a number of sterilization methods are available. In the case of polymeric materials, the selected sterilization process must not induce any changes in the polymer structure, such as polymer chains cleavage, changes in cross-linking, etc. This paper evaluates the influence of different sterilization methods (γ-radiation, ß-radiation, ethylene oxide) on the stability of carboxymethyl cellulose and the results of long-term and accelerated stability testing. Evaluation of samples was performed using size-exclusion chromatography. The obtained results showed that ethylene oxide sterilization was the least aggressive variant of the sterilization methods tested. When the γ-radiation sterilization was used, the changes in the size of the carboxymethyl cellulose molecule occurred. In the course of accelerated and long term stability studies, no further degradation changes were observed, and thus sterilized samples are suitable for long term storage.

Local tissue reaction after the application of topical hemostatic agents in a rat partial nephrectomy model.

Various hemostatics are used for renal surgical procedures. We investigated the hemostatic efficacy of cellulose derivatives on the model of partial nephrectomy in rats focusing on the local reaction of renal parenchyma. A total of 50 Wistar rats were divided into five groups of 10 animals each. Partial nephrectomy of the caudal pole without hilar vascular control was performed. Oxidized cellulose (OC), sodium salt of oxycellulose (OCN), carboxymethyl cellulose (CMC), dialdehyde cellulose (DAC), and gelatin-based hemostatic (C) were applied to the bleeding wounds. The time to hemostasis was monitored. Half of the animals were euthanized after 3 days, the second half 30 days from the experiment start date. The left kidney was excised and subjected to histopathological examination. The biochemical data was subjected to statistical analysis. The time to hemostasis in all groups was significantly less than in the C group (in OC p = 0.0057, OCN p = 0.0039, CMC and DAC p = 0.0001). In the C group, massive hemorrhages and necrosis did occur. In the OC and OCN groups, there were regenerative changes, a receding inflammatory reaction and hemorrhage. DAC caused an immune reaction and massive interstitial hemorrhages with biochemical signs of liver damage. Parenchyma in CMC revealed a reduction of necrosis and interstitial hemorrhages with regenerative processes. The most effective hemostatics were CMC and OC, achieving the best results both in the time to hemostasis, and for histopathological evaluation.

Cytotoxicity and effects on inflammatory response of modified types of cellulose in macrophage-like THP-1 cells.

The cytotoxicity and in vitro effects of six variously modified types of cellulose (OC--oxidized cellulose, NaOC--oxidized cellulose sodium salt, DAC--dialdehyde cellulose, CMC--carboxymethyl cellulose, MFC--microfibrilated cellulose, and MCC--microcrystalline cellulose) on the inflammatory response in macrophage-like THP-1 cells were examined, with special focus on their ability to influence gene expression and the production of TNF-α. The study provides evidence that DAC exerts a marked effect on the induction of TNF-α gene expression and its subsequent production in human macrophages. Thus, the use of DAC for anti-hemorrhagic or wound-healing therapy should be considered carefully with regard to its pro-inflammatory activity. On the contrary, MCC showed significant anti-inflammatory effects in the LPS-induced conditions, which might be beneficial for the treatment of non-healing chronic wounds, e.g., diabetic or venous ulcers.