Biocompatibility of wound management products: a study of the effects of various polysaccharides on murine L929 fibroblast proliferation and macrophage respiratory burst

Evaluation of the Effectiveness of Medical-Grade Honey and Hypericum Perforatum Ointment on Second-Intention Healing of Full-Thickness Skin Wounds in Cats

This study aimed to determine the effects of two topical treatments on second-intention wound healing in cats. Eight 2 × 2 cm full-thickness wounds were created, four on each side of the dorsal midline of eight laboratory cats, to receive either medical-grade honey ointment (MGH) and its control (HC), or Hypericum-based ointment (HP) and its control (HPC). MGH or HP ointment was applied to four wounds on the same side, while the remaining four were used as controls, chosen at random. Planimetry, laser Doppler flowmetry, daily physical examinations, and histologic examinations on days 0, 7, 14, and 25 were used to assess the healing of wounds. Tissue perfusion was better in the MGH-treated (2.14 ± 0.18 mm/s) and HP-treated wounds (2.02 ± 0.13 mm/s) than in the untreated controls HC (1.59 ± 0.11 mm/s) and HPC (1.60 ± 0.05 mm/s), respectively (p = 0.001). Histopathology revealed that the median edema score was lower in the MGH-treated (2; range 1-4) compared to the HC-treated wounds (3; range 2-4) on day 7 (p < 0.05). The median angiogenesis score was higher on day 7 in the MGH-treated (2; range 1-3) compared to the HP-treated wounds (2; range 1-2) (p = 0.046). The fibroblast concentration was increased in the MGH-treated wounds (3.5; range 3-4) compared to the HP-treated wounds (3; range 2-4) on day 25 (p = 0.046). MGH and HP increased tissue perfusion compared to the untreated controls. The MGH-treated wounds had histologic parameters superior to the HP-treated wounds regarding angiogenesis and fibroblast concentration in cutaneous wound healing in cats. Topical application of MGH and HP did not accelerate the healing process of feline cutaneous wounds.

Process and applications of alginate oligosaccharides with emphasis on health beneficial perspectives

Alginates are linear polymers comprising 40% of the dry weight of algae possess various applications in food and biomedical industries. Alginate oligosaccharides (AOS), a degradation product of alginate, is now gaining much attention for their beneficial role in food, pharmaceutical and agricultural industries. Hence this review was aimed to compile the information on alginate and AOS (prepared from seaweeds) during 1994-2020. As per our knowledge, this is the first review on the potential use of alginate oligosaccharides in different fields. The alginate derivatives are grouped according to their applications. They are involved in the isolation process and show antimicrobial, antioxidant, anti-inflammatory, antihypertension, anticancer, and immunostimulatory properties. AOS also have significant applications in prebiotics, nutritional supplements, plant growth development and others products.

High Tensile Strength Regenerated α-1,3-Glucan Fiber and Crystal Transition

α-1,3-Glucan is a linear and crystalline polysaccharide which is synthesized by in vitro enzymatic polymerization from sucrose. A previous study reported that regenerated fibers of α-1,3-glucan were prepared using a wet-spinning method. However, the mechanical properties were poorer than cellulose regenerated fibers. Then, in this study, the mechanical properties of the regenerated α-1,3-glucan fiber were improved by the transformation of the crystal structure and stretching. The regenerated fiber stretched in water and dehydrated by heating showed high tensile strength (18 cN/tex) that is comparable with that of viscose rayon. Moreover, the crystal structures of the regenerated fibers were investigated using wide-angle X-ray diffraction (WAXD). To date, four crystal polymorphs of α-1,3-glucan from polymorph I to IV have been reported. This study revealed that the regenerated α-1,3-glucan fibers had two different polymorphs, polymorph II (hydrated form) and polymorph III (anhydrous form), depending on post-treatment methods of stretching and annealing procedures. Furthermore, the obtained distinctive 2D-WAXD patterns suggested that polymorph III is identical to polymorph IV.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Alternative methods for assessing biocompatibility and function of implant materials

Biocompatibility testing is used to evaluate the host response to implantable materials and to assess their ability to perform in applications in which they are intended to interact with biological systems. In compliance with international and/or national standards, such assessment is based mainly on the results of experimental implantation into animal tissues. However, the development of in vitro experimental techniques creates new opportunities to observe and to understand the interaction of biomaterials with host tissue. The state-of-the-art application of alternative methods in biocompatibility testing is presented in this review article. It is discussed with respect to the Three Rs concept (reduction, refinement, replacement) of Russell & Burch. Perspectives on alternative methods in biocompatibility studies are discussed with regard to the possible role of biomaterials in tissue engineering.

The influence of molecular weight of chitosan on the physical and biological properties of collagen/chitosan scaffolds

Biopolymer blends between collagen and chitosan have the potential to produce cell scaffolds with biocompatible properties. However, the relationship between the molecular weight of chitosan and its effect on physical and biological properties of collagen/chitosan scaffolds has not been elucidated yet. Porous scaffolds were fabricated by freeze-drying the solution of collagen and chitosan, followed by cross-linking by dehydrothermal treatment. Various types of scaffolds were prepared using chitosan with various molecular weights and blending ratios. Fourier transform infrared spectroscopy proved that collagen and chitosan scaffolds at all blending ratios contained mainly electrostatic interactions at the molecular level. The compressive modulus decreased with increasing the concentration of chitosan. Equilibrium swelling ratios of approximately 6-8, determined in phosphate-buffered saline at physiological pH (7.4), were found in case of collagen-dominated scaffolds. The lysozyme biodegradation test demonstrated that the presence of chitosan, especially the high-molecular-weight species, could significantly prolong the biodegradation of collagen/chitosan scaffolds. In vitro culture of L929 mouse connective tissue fibroblast evidenced that low-molecular-weight chitosan was more effective to promote and accelerate cell proliferation, particularly for scaffolds containing 30 wt% chitosan. The results elucidated that the blends of collagen with low-molecular-weight chitosan have a high potential to be applied as new materials for skin-tissue engineering.

Alginate graft copolymers and alginate-co-excipient physical mixture in oral drug delivery

OBJECTIVES

Use of alginate graft copolymers in oral drug delivery reduces dosage form manufacture complexity with reference to mixing or coating processes. It is deemed to give constant or approximately steady weight ratio of alginate to covalently attached co-excipient in copolymers, thereby leading to controllable matrix processing and drug release. This review describes various grafting approaches and their outcome on oral drug release behaviour of alginate graft copolymeric matrices. It examines drug release modulation mechanism of alginate graft copolymers against that of co-excipients in non-grafted formulations.

KEY FINDINGS

Drug release from alginate matrices can be modulated through using either co-excipients or graft copolymers via changing their swelling, erosion, hydrophobicity/hydrophilicity, porosity and/or drug adsorption capacity. However, it is not known if the drug delivery performance of formulations prepared using alginate graft copolymers is superior to those incorporating graft-equivalent co-excipient physically in a dosage form without grafting but at the corresponding graft weight, owing to limited studies being available.

CONCLUSIONS

The value of alginate graft copolymers as the potential alternative to alginate-co-excipient physical mixture in oral drug delivery cannot be entirely defined by past and present research. Such an issue is complicated by the lack of green chemistry graft copolymer synthesis approach, high grafting process cost, complications and hazards, and the formed graft copolymers having unknown toxicity. Future research will need to address these matters to achieve a widespread commercialization and industrial application of alginate graft copolymers in oral drug delivery.

Chitosan supports the initial attachment and spreading of osteoblasts preferentially over fibroblasts

The aim of this study was to determine chitosan's effect on osteoblast and fibroblast cell attachment. Mouse MC3T3-E1 osteoblasts and 3T3 fibroblasts were grown in the presence of serum on two commercially available chitosans, Chitosan-H (CH) and Protasan CL212 (PR). Cell attachment and immunofluorescent analysis at various time points were done to analyze initial phenotypic profiles. At 1h, significantly (P<0.05) fewer fibroblasts attached to CH or PR than serum-coated substrates. Osteoblast attachment to the same biopolymers at 1h was significantly greater than those seen with fibroblasts. At 24 h, levels of cell attachment for fibroblasts to both CH and PR significantly increased and were similar to levels seen in osteoblast cultures at both 1 and 24 h. Morphologically, immunofluorescent analysis showed that osteoblasts plated on the biopolymers were attached and beginning to spread at 1h, whereas fibroblasts appeared more rounded. At 24 h, fibroblasts plated on CH or PR revealed a heterogeneous population of round and semi-spread cells. In comparison, osteoblasts displayed phenotypes that were well spread with a developed cytoskeleton. These results suggest that CH and PR support the initial attachment and spreading of osteoblasts preferentially over fibroblasts, and that manipulation of the biopolymer can alter the level of attachment and spreading.

Porous alginate/hydroxyapatite composite scaffolds for bone tissue engineering: Preparation, characterization, andin vitro studies

In this study a series of alginate/hydroxyapatite (HAP) composite scaffolds was prepared by phase separation. HAP was incorporated into the alginate gel solution to improve both the mechanical and cell-attachment properties of the scaffolds. These scaffolds had a well-interconnected porous structure with an average pore size of 150 microm and over 82% porosity. The alginate/HAP scaffold prepared at -40 degrees C with a 50% HAP content showed the best mechanical properties. The morphology of scaffolds could be manipulated by tuning the quenching temperature during the preparation. The dissolution of alginate/HAP composite scaffolds could be slowed by the pretreating them by immersion in 1.0 M CaCl(2) solution. The rat osteosarcoma UMR106 cells, an osteoblastic cell line, seeded in the scaffolds, displayed better cell attachment to the 75/25 and 50/50 alginate/HAP composite scaffolds than to the pure alginate scaffold. The natural polymeric sponges that fabricated in this study may be a promising approach for tissue-engineering applications.

Flexible chitin films as potential wound-dressing materials: wound model studies

Chitin films possessing increased flexibility, softness, transparency, and conformability have been prepared. These attributes enable the potential application of chitin films as occlusive, semipermeable film wound dressings similar to commercial products such as Opsite trade mark. The chitin films are generally nonabsorbent, exhibiting a total weight gain of only up to 120-160% in physiological fluid. Dry chitin films transpire water vapor at a rate of about 600 g/m(2)/24 h, similar to commercial polyurethane-based film dressings, but rises to 2400 g/m(2)/24 h, when wet, which is higher than the water vapor transmission rate of intact skin. The chitin films are nontoxic to human skin fibroblasts, maintaining 70-80% cell viability. Wound studies using a rat model showed no signs of allergenicity or the high inflammatory response associated with biodegradable biomaterials. The chitin films displayed accelerated wound-healing properties. Based on histological examination, wound sites dressed with the chitin films stabilized and healed faster, and appeared stronger than those dressed with Opsite trade mark and gauze dressings after 7 days of healing.

Effect of a chitosan-based hemostatic dressing on blood loss and survival in a model of severe venous hemorrhage and hepatic injury in swine

BACKGROUND

Hemorrhage is a leading cause of death from trauma. An advanced hemostatic dressing could augment available hemostatic methods. We studied the effects of a new chitosan dressing on blood loss, survival, and fluid use after severe hepatic injury in swine.

METHODS

Swine received chitosan dressings or gauze sponges. Standardized, severe liver injuries were induced. After 30 seconds, dressings were applied and resuscitation initiated. Blood loss, hemostasis, resuscitation volume, and 60-minute survival were quantified.

RESULTS

Posttreatment blood loss was reduced ( p< 0.01) in the chitosan group (264 mL; 95% confidence interval [CI], 82-852 mL) compared with the gauze group (2,879 mL; 95% CI, 788-10,513 mL). Fluid use was reduced ( p= 0.03) in the chitosan group (1,793 mL; 95% CI, 749-4,291) compared with the gauze group (6,614 mL; 95% CI, 2,519-17,363 mL). Survival was seven of eight and two of even in the chitosan and gauze groups ( p= 0.04), respectively. Hemostasis was improved in the chitosan group ( p= 0.03).

CONCLUSION

A chitosan dressing reduced hemorrhage and improved survival after severe liver injury in swine. Further studies are warranted.

The effect of chitin and chitosan on the proliferation of human skin fibroblasts and keratinocytes in vitro

The effects of chitin [(1 --> 4)-2-acetamido-2-deoxy-beta-D-glucan] and its partially deacetylated derivatives, chitosans, on the proliferation of human dermal fibroblasts and keratinocytes were examined in vitro. Chitosans with relatively high degrees of deacetylation strongly stimulated fibroblast proliferation while samples with lower levels of deacetylation showed less activity. Fraction, CL313A, a shorter chain length, 89% deacetylated chitosan chloride was further evaluated using cultures of fibroblasts derived from a range of human donors. Some fibroblast cultures produced a positive mitogenic response to CL313A treatment with proliferation rates being increased by approximately 50% over the control level at an initial concentration of 50 microg/ml, whilst others showed no stimulation of proliferation or even a slight inhibition (< 10%). The stimulatory effect on fibroblast proliferation required the presence of serum in the culture medium suggesting that the chitosan may be interacting with growth factors present in the serum and potentiating their effect. In contrast to the stimulatory effects on fibroblasts, fraction CL313A inhibited human keratinocyte mitogenesis with up to 40% inhibition of proliferation being observed at 50 microg/ml. In general highly deacetylated chitosans were more active than those with a lower degree of deacetylation. These data demonstrate that highly deacetylated chitosans can modulate human skin cell mitogenesis in vitro. Analysis of their effects on cells in culture may be useful as a screen for their potential activity in vivo as wound healing agents, although in the case of fibroblasts it is important to select appropriate strains of cells for use in the screen.

Growth modulation of fibroblasts by chitosan-polyvinyl pyrrolidone hydrogel: implications for wound management?

Wounds in adults and fetuses differ in their healing ability with respect to scar formation. In adults, wounds lacking the epidermis exhibit excess collagen production and scar formation. Fibroblasts synthesize and deposit a collagen rich extracellular matrix. The early migration and proliferation of fibroblasts in the wound area is implicated in wound scarring. We have synthesized a hydrogel from chitosan-polyvinyl pyrrolidone (PVP) and examined its effect on fibroblast growth modulation in vitro. The hydrogel was found to be hydrophilic as seen from its octane contact angle (141.2+/-0.37 degrees). The hydrogel was non-toxic and biocompatible with fibroblasts and epithelial cells as confirmed by the 3(4,5-dimethylthiazolyl-2)-2, 5-diphenyl tetrazolium bromide (MTT) as-say. It showed dual properties by supporting growth of epithelial cells (SiHa) and selectively inhibiting fibro-blast (NIH3T3) growth. Growth inhibition of fibroblasts resulted from their inability to attach on to the hydrogel. These findings are supported by image analysis, which revealed a significant difference (P<0.05) between the number of fibroblasts attached to the hydrogel in tissue culture as compared to tissue culture treated polystyrene (TCPS) controls. However, no significant difference was observed (P>0.05) in the number of epithelial (SiHa) cells attached on to the hydrogel as compared to the TCPS control. Although in vivo experiments are awaited, these findings point to the possible use of chitosan-PVP hydrogels in wound-management.

Local hemostatic effects of microcrystalline partially deacetylated chitin hydrochloride

The hemostatic effects of microcrystalline partially deacetylated chitin hydrochloride (DAC-HCl) were compared with those of cotton and collagen hydrochloride (collagen-HCl). The DAC-HCl had excellent physical properties as a hemostatic agent such as its ability to absorb and retain blood. In canine blood it induced the release of substances involved in the process of platelet activation, such as beta-thromboglobulin and platelet factor 4, and it also had excellent hemoagglutinative properties. Moreover, in a hemostatic study on bleeding from cancellous bone in canines it exhibited a hemostatic effect comparable to that exhibited by collagen-HCl. Because it also has an intrinsic promotive effect on wound healing, chitin hydrochloride is considered to be a promising hemostatic material.

Chitosan-polyvinyl pyrrolidone hydrogels as candidate for islet immunoisolation: in vitro biocompatibility evaluation

The success of immunoisolation devices for islet transplantation depends on the nature of semipermeable membranes, which permit the crossover of micronutrients, glucose, and insulin and prevent the entry of immunocytes and other transplant rejection mechanisms. In the present study we examined the properties of chitosan-polyvinyl pyrrolidone (PVP) hydrogels for possible application as an immunoisolation device. Hydrogels with two different proportions of chitosan-PVP (M1 1:1 and M2 2:1, v/v) were synthesized by cross-linking with glutaraldehyde. Hydrogels were characterized for their hydrophilic nature, protein adsorption, diffusion properties, cytotoxicity, and islet compatibility. Hydrogel membranes were found to be hydrophilic as determined by high octane contact angle value (M1: 142.9 +/- 0.46; M2: 143.6 +/- 0.49). Protein adsorption on the hydrogels was found to be low (0.0143 +/- 0.0027 mg for M1 and 0.0136 +/- 0.0049 mg for M2) compared to tissue culture polystyrene (TCPS) (0.0434 +/- 0.001 mg) and pure chitosan (0.0214 +/- 0.0025 mg) control. Hydrogel M1 was tested as a representative for diffusion studies. M1 allowed regulated transport of insulin and did not allow anti-insulin antibodies to pass through. In vitro biocompatibility of M1 and M2 was found to be excellent with no cytotoxic effects on the HeLa cells as determined by MTT and NR assay. Mouse islets cultured on the hydrogel membranes retained their integrity and intact morphology as assessed by image analysis study. Viability of islets cultured on hydrogels was comparable to that of controls (M1: 97%; M2: 90.4%) as assessed by trypan blue dye exclusion test. Islets retained their functionality when cultured on hydrogels, as judged by insulin secretion in response to glucose challenge (16.0 mM). Although in vivo experiments are awaited, the present study provides sufficient documentation to consider chitosan-PVP membranes as potential candidates for immunoisolation of islets.

Further biocompatibility testing of silica-chitosan complex membrane in the production of tissue plasminogen activator by epithelial and fibroblast cells

The effects of the physicochemical characteristics of a silica-chitosan complex membrane (SiCM) on the expression of tissue plasminogen activator (tPA) by contacting cells were investigated with the aim of improving the biocompatibility of the novel implant biomaterial. Expression of tPA is considered to be effective in wound healing by preventing thrombus formation, which causes inflammatory responses and rejection of implant materials. Inducing the epithelial cells surrounding implant materials to secrete tPA, which serves as an early signaling system to proliferate cells underlying connective tissues, would be further effective in accelerating wound healing. An epithelial 293 cell line derived from human embryonic kidney and a fibroblast IMR-90 cell line from human lung possessing the ability to secrete tPA were cultured on SiCMs, whose composition was stepwise controlled by adjusting the mixing ratio between silica and chitosan to give silica contents of 20, 33, 43, and 50wt%. Both strains showed strong adhesion on chitosan (0%-SiCM) and 50%-SiCM. The cell proliferation rates were also accelerated in a manner that was dependent on the increase in the adhesion strength of the cells cultured on the SiCMs. Furthermore, the tPA activity in the culture medium increased in accordance with the cell density, while the cellular specific activity of IMR-90 cells to secrete tPA was synergistically enhanced by strong adhesion and a high cell density on the surface of chitosan and 50%-SiCM. Analysis of the physico-chemical effects of the SiCMs revealed that the cells were dominantly affected by the surface hydrophobicity rather than by the zeta potential, as well as by the mixing ratio between chitosan and silica. The wet contact angles of 50%-SiCM and chitosan, which were 68 degrees and 65 degrees , respectively, were found to be suitable for adhesion and growth of both the epithelial 293 cells and fibroblast IMR-90 cells. A hydrophobic surface at 65 degrees -68 degrees was also effective for the production of tPA by IMR-90 cells, whereas the tPA activity of 293 cells reached its highest level on the SiCM with a wet contact angle of 63 degrees . These results suggest that a suitable adhesion strength is a significant factor in the expression of tPA by cells contacting an implant biomaterial.

Initial anchoring and proliferation of fibroblast L-929 cells on unstable surface of calcium phosphate ceramics

Calcium phosphate ceramics constructed from beta-tricalcium phosphate (TCP) and hydroxyapatite (HAP) have been successfully used as implant materials. However, there is a possibility that these materials are responsible for an unwanted inflammatory response during wound healing. Since TCP is soluble in the body, the instability of this material may contribute to this inflammatory response. Using composite ceramics of TCP and HAP that possessed Ca/P molar ratios of 1.50, 1.55, 1.60, 1.64, and 1.67, the effect of surface instability on fibroblast L-929 cells was investigated. The time-dependent variation of the initial anchoring ratio, cell density, and cell viability were measured. In general, the cells were severely damaged and ruptured on the highly soluble thin surface layer of the TCP-HAP ceramics. The initial anchoring ratio for TCP-HAP ceramics was as high as that for the polystyrene dish (Lux, control). However, viability at 6 h decreased to less than 50% of the initial cell density on ceramics with a Ca/P molar ratio of 1.64 (20% TCP-80% HAP), while 85% of the cells were viable on Lux. The viability on 100% TCP, whose surface is the most highly soluble among the TCP-HAP ceramics used in this study, was reduced to 20%. Morphological observation showed that the anchored cells were ruptured when grown in culture medium on the 100% TCP. Although the high solubility of the thin surface layer on the TCP-HAP ceramics of the carrier was found to be the dominant factor in the decreasing cell viability, the initial viability was enhanced by the stabilization of the surface of the TCP-HAP ceramics by pre-incubating the scaffolds in a culture medium containing 10% fetal bovine serum for 3 d.

In vitro and in vivo models for the reconstruction of intercellular signaling

A critical need in both tissue-engineering applications and basic cell culture studies is the development of synthetic extracellular matrices (ECMs) and experimental systems that reconstitute three-dimensional cell-cell interactions and control tissue formation in vitro and in vivo. We have fabricated synthetic ECMs in the form of fiber-based fabrics, highly porous sponges, and hydrogels from biodegradable polymers (e.g., polyglycolic acid) and tested their ability to regulate tissue formation. Both cell seeding onto these synthetic ECMs and subsequent culture conditions can be varied to control initial cell-cell interactions and subsequent cell growth and tissue development. Three-dimensional tissues composed of cells of interest, matrix produced by these cells, and the synthetic ECM (until it degrades) can be created with these systems. For example, smooth muscle cells can be grown on polyglycolic acid fiber-based synthetic ECMs to produce tissues with cell densities in excess of 10(8) cells/mL. These tissues contain extensive elastin and collagen, and the smooth muscle cells within the tissue express the contractile phenotype (e.g., alpha-actin staining). Similar approaches can be used to grow a number of other tissues (e.g., dental pulp) that resemble the native tissue. These engineered tissues may provide novel experimental systems to study the role of three-dimensional intercellular signaling in tissue development and may also find clinical application as replacements to lost or damaged tissues.

Effects of chitin and chitosan particles on BALB/c mice by oral and parenteral administration

Chitin and chitosan were administered orally and parenterally into mice and their toxicity was investigated. When 5 mg of chitin were injected intraperitoneally every 2 weeks over a 12-week period, the mice were apparently normal, but histologically, many macrophages with hyperplasia were observed in the mesenterium and foreign-body giant-cell-type polykaryocytes were observed in the spleen. The polykaryocytes were also observed in the spleen of the mice injected subcutaneously with 5 mg of chitin, but no other changes were observed. When 5 mg of chitosan were injected intraperitoneally, the body weights of the mice decreased significantly and inactivity was observed in the fifth week. Histologically, many macrophages with hyperplasia were observed in the mesenterium. Subcutaneous injection of 5 mg of chitosan did not evoke the general and cellular abnormalities. Oral administration of 5% chitosan via a casein diet caused mouse body weights to decrease and also decreased the number of Bifidobacterium and Lactobacillus in normal flora of the intestinal tract. These results indicate that special care should be taken in the clinical use of chitin and chitosan over a long time period.

Effects of calcium alginate on cellular wound healing processes modeled in vitro

Although the clinical experience with calcium alginate has been generally good, well-controlled studies examining the effect of such dressings on the processes of wound healing have not been conducted. The healing of cutaneous ulcers requires the development of a vascularized granular tissue bed, filling of large tissue defects by dermal regeneration, and the restoration of a continuous epidermal keratinocyte layer. These processes were modeled in vitro in the present study, utilizing human dermal fibroblast, microvascular endothelial cell (HMEC), and keratinocyte cultures to examine the effect of calcium alginate on the proliferation and motility of these cultures, and the formation of capillarylike structures by HMEC. This study demonstrates that the calcium alginate tested increased the proliferation of fibroblasts but decreased the proliferation of HMEC and keratinocytes. In contrast, the calcium alginate decreased fibroblast motility but had no effect on keratinocyte motility. There was no significant effect of calcium alginate on the formation of capillarylike structures by HMEC. The effects of calcium alginate on cell proliferation and migration may have been mediated by released calcium ions. These results suggest that the calcium alginate tested may improve some cellular aspects of normal wound healing, but not others.

Biocompatibility of potential wound management products: fungal mycelia as a source of chitin/chitosan and their effect on the proliferation of human F1000 fibroblasts in culture

Aspergillus oryzae, Mucor mucedo, and Phycomyces blakesleeanus cultures were examined as sources of chitin/chitosan. The nitrogen content of the alkali-treated mycelia/sporangiophores of A. oryzae, M. mucedo, and P. blakesleeanus was 2.52, 3.61, and 6.27% w/w, which relates to an estimated chitin content of 37, 52, and 91%, respectively. The effect of these fungal materials on the rate of proliferation of human F1000 fibroblasts in culture was examined. At 0.01% w/v, all three materials exhibited significant (P < .05) proproliferant activity over a period of 13 days. However, at 0.05% w/v, P. blakesleeanus further enhanced cell proliferation, whereas A. oryzae and M. mucedo produced a significant (P < .05) antiproliferant effect. Higher concentrations of P. blakesleeanus (0.1 and 0.5%) caused marked inhibition of F1000 cell proliferation when measured on days 3 and 6. Only the proproliferant effect of these fungal materials appears to correlate to their chitin content. Furthermore, the cytomorphology of the fibroblasts indicated that P. blakesleeanus, and to a lesser extent M. mucedo, possessed cell attractant properties, again correlating with chitin content. If developed for use as wound management materials, the sporangiophores of P. blakesleeanus and the mycelium of M. mucedo could possibly promote the growth of fibroblasts and provide a matrix for their anchorage, thus contributing to the granulation phase of the healing cascade.

A study of hydrogen peroxide generation by, and antioxidant activity of, Granuflex (DuoDERM) Hydrocolloid Granules and some other hydrogel/hydrocolloid wound management materials

The effect of Granuflex Hydrocolloid Granules (0.01-0.50% w/v) on the rate of proliferation of murine (L929) fibroblasts was examined. The dose-response curve showed a significant (P < 0.02) pro-proliferant effect at 0.05%, and a significant (P < 0.02) antiproliferant effect at 0.50%, mirroring the dose-response curve produced by hydrogen peroxide in the concentration range 10(-9) - 10(-4) mol/l. The antiproliferant effect at 0.20% w/v was abolished by catalase, suggesting that the biological activity of Granuflex was mediated by the in situ generation of hydrogen peroxide. Formation of hydrogen peroxide by Granuflex was confirmed by performing the scopoletin-horseradish peroxidase assay in the presence and absence of catalase. The total concentration of hydrogen peroxide detected was about 8 x 10(-6) mol/l (using 0.5% w/v Granuflex) after 48 h at 37 degrees C. In contrast, when hydrogen peroxide itself was added to L929 cultures, a similar antiproliferant activity was observed at concentrations between 10(-4) and 10(-5) mol/l. These results suggested that Granuflex was undergoing autoxidation in the culture medium, and hence that it might possess antioxidant activity. In assays for antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), Granuflex, and two other hydrocolloid dressings (Comfeel Powder and Bard Absorption Dressing) showed significant ability to reduce DPPH to DPPH2. These three dressings also displayed superoxide scavenging activity in a nitroblue tetrazolium reduction assay. We conclude that, in addition to providing a moist wound-healing environment, Granuflex and certain other hydrocolloids might contribute to the establishment and maintenance of the reducing environment necessary for energy production and hence cell division.(ABSTRACT TRUNCATED AT 250 WORDS)