Hyaluronic Acid Carrier Research Articles

Nursing Effect of Hyaluronic Acid/Silver Nanoclusters on Patients After Total Laryngectomy

Postoperative bacterial infections are a major obstacle to patient recovery after total laryngectomy, and the development of antibiotics seemed to satisfactorily solve this problem. However, bacteria develop drug resistance to a large number of antibiotic drugs and form “superbugs,” which cause great harm to the public health. Based on this, the development of new antimicrobials has become the focus of research worldwide. In this study, we prepared a hyaluronic acid/silver nanocluster (HA/Ag NC) composite hydrogel based on a hyaluronic acid carrier and proved with clinical trials that it has an excellent antibacterial effect and can significantly reduce the incidence of inflammatory reactions in postoperative patients. In addition, the hydrogel effectively promotes the healing of surgical incisions and accelerates the proliferation of granulation tissue. As a result, the HA/Ag NCs compound hydrogel can offers a high-quality healing effect in patients after total laryngectomy.

Hyaluronic Acid Fibres in Solid Phase Peptide Synthesis — Their Properties, Morphology and Stability

Different methods and materials can be used for peptide synthesis. One of the most common approaches is synthesis on a solid phase. In this paper, we describe fibres based on hyaluronic acid (HA) and their properties under solid-phase peptide synthesis (SPPS) conditions. The fibres were prepared by wet spinning technology and were used to study their stability and mechanical properties under the reaction conditions for direct peptide synthesis or conjugation with a pre-synthesized peptide. Fibres in the form of a non-woven textile were then used as a proof of concept for the adhesion of cells on short cell-adhesion peptides. The methods, solvents and reaction conditions used showed no significant influence on the necessary stability of the HA fibres when the Fmoc/tBu strategy was applied. Furthermore, the stability of the HA fibres in aqueous solution was strongly improved. The stabilization and presence of cell-adhesive peptides supported the adhesion of cardiomyocyte cells, which confirmed the functionality of the modified textile. Therefore, HA carriers bearing peptides could be advantageously employed in various biomedical applications as repair patches.

Development of Novel Nano Hyaluronic Acid Carrier for Diagnosis and Therapy of Atherosclerosis

For an efficient atherosclerosis diagnosis and treatment, we have a persistent requirement of developing a carrier that can precisely carry agents into the pathological location. Herein we examined the ability of hyaluronic acid nanoparticles (HA NPs) as a carrier for the active aiming of atherosclerosis. To prepare HA NPs, 100 mg of Hyaluronic acid was added to 20 ml of formamide, and 61 mg of EDC followed by adding 36.4 mg of NHS in order to activate –COOH functionalities of HA. The resultant mixture was then added with 33.16 mg of aminated 5b-cholanic acid in 40 ml of DMF under contentious stirring at standard temperature conditions for about 12 h, followed by purification and lyophilization. The prepared NPs were examined to study their use in the treatment of atherosclerosis. The prepared HA NPs were studied by using different characterization techniques. By in vitro cellular acceptance investigation, it was exposed that the HA NPs were taken up selectively by over expressing the cells CD44 or stabilin-2. Conversely, the cellular acceptance of HA NPs was noticed to be decreased extremely by pretreating the cells with surplus quantity of free HA, indicating that the HA NPs was taken up by the receptor intervened endocytosis. In conclusion, HA NPs were prepared and confirmed by using different characterization techniques. Also, the prepared HA NPs possesses high ability to be a carrier for the atherosclerosis diagnosis and treatment.

Vascular Endothelial Growth Factor-Releasing Microspheres Based on Poly(ε-Caprolactone-PEG-ε-Caprolactone)-b-Poly(L-Lactide) Multiblock Copolymers Incorporated in a Three-Dimensional Printed Poly(Dimethylsiloxane) Cell Macroencapsulation Device.

Pancreatic islet transplantation is a promising advanced therapy that has been used to treat patients suffering from diabetes type 1. Traditionally, pancreatic islets are infused via the portal vein, which is subsequently intended to engraft in the liver. Severe immunosuppressive treatments are necessary, however, to prevent rejection of the transplanted islets. Novel approaches therefore have focused on encapsulation of the islets in biomaterial implants which can protect the islets and offer an organ-like environment. Vascularization of the device's surface is a prerequisite for the survival and proper functioning of transplanted pancreatic islets. We are pursuing a prevascularization strategy by incorporation of vascular endothelial growth factor (VEGF)-loaded microspheres in 3-dimensional printed poly(dimethylsiloxane)-based devices prior to their prospective loading with transplanted cells. Microspheres (~50 μm) were based on poly(ε-caprolactone-PEG-ε-caprolactone)-b-poly(L-lactide) multiblock copolymers and were loaded with 10 μg VEGF/mg microspheres, and subsequently dispersed in a hyaluronic acid carrier liquid. Invitro release studies at 37°C demonstrated continuous release of fully bioactive VEGF for 4weeks. In conclusion, our results demonstrate that incorporation of VEGF-releasing microspheres ensures adequate release of VEGF for a time window of 4weeks, which is attractive in view of the vascularization of artificial pancreas implants.

Targeted Reinforcement of Macrophage Reprogramming Toward M2 Polarization by IL-4-Loaded Hyaluronic Acid Particles.

Alteration of macrophage polarization from inflammatory (M1) to anti-inflammatory (M2) phenotype can have striking implications for the regeneration of injured tissues, treatment of inflammatory diseases, and relief of autoimmune disorders. Although certain cytokines like interleukin (IL)-4 and IL-13 are capable of inducing M2 macrophage polarization, their therapeutic potential in vivo is suffering from low efficacy due to their instability and poor access to target cells. Here, we report the synthesis of IL-4-loaded hyaluronic acid (HA) particle for the targeted delivery of cytokines through the high affinity of HA to CD44 receptors of macrophages. HA carriers composed of low, middle, and high molecular weight (MW) polymers were synthesized using divinyl sulfone (DVS) cross-linking. The MW of HA had a negligible effect on the physicochemical properties and biocompatibility of the macrophages, but as an indicative of M2 polarization, a significant change in the arginase-1 (Arg-1) activity, TNF-α release, and IL-10 secretion was observed for the HA particles prepared with high MW polymers. Therefore, these particles were loaded with IL-4 for simultaneous macrophage targeting and M1 to M2 reprogramming, evidenced by a remarkable increase in the Arg-1 to iNOS ratio, as well as CD163 and CD206 upregulation in the M1 macrophages, which were initially triggered by lipopolysaccharide and interferon-γ.

PH-sensitive and biocompatible quercetin-loaded GO–PEA–HA carrier improved antitumour efficiency and specificity

A novel drug carrier was designed based on a new biomaterial, that is, graphene oxide (GO), to improve the efficiency and specificity of anticancer drug. In this study, GO was successively modified with polyetheramine (PEA) and hyaluronic acid (HA). The carrier was utilized to load an antitumor component, that is, quercetin (Que), which was derived from traditional Chinese medicine, namely the pagoda tree flower bud. This drug delivery system (DDS) exhibited pH sensibility under subacid condition and good biocompatibility even when GO concentration reached 350 μg/mL. Moreover, the antitumor efficacy was doubly improved and more long-acting compared with Que alone. Results show that the GO-based material has potential clinical applications for antitumor drug delivery.

Receptor‐Targeted Drug Delivery and the (Many) Problems We Know of: The Case of CD44 and Hyaluronic Acid

AbstractCD44 is best known for being the most common receptor of hyaluronic acid (HA). It is also a heterogeneous molecule: while its standard isoform (CD44s) is ubiquitously expressed, there are also a range of variants (CD44v), and both CD44s and CD44v undergo a variety of post‐translational modifications. The signaling roles and frequent overexpression of both CD44s and CD44v in cancer (e.g., in cancer initiating cells/cancer stem cells) has raised interest in them for diagnostic applications, but also—and most importantly for this review—as possible molecular targets in tumor therapy, with their endocytic character being a clear advantage for the intracellular release of payloads. In this area, the most popular approach employs HA‐based carriers. However, their rational design and therefore the success of HA‐based therapies are hampered by the rather limited understanding of not only the identity, but also the dynamic properties of CD44. In this review, the reader is exposed to the full breadth of the challenges that HA carriers currently face, which start at the CD44 post‐transcriptional and post‐translational heterogeneity, and also include the understanding of receptor clustering phenomena (influencing also HA avidity), as well as the evaluation of off‐target effects.

Investigation of Overrun-Processed Porous Hyaluronic Acid Carriers in Corneal Endothelial Tissue Engineering.

Hyaluronic acid (HA) is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC) sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function.

Influence of Pre-Freezing Temperature on the Corneal Endothelial Cytocompatibility and Cell Delivery Performance of Porous Hyaluronic Acid Hydrogel Carriers.

The development of porous hyaluronic acid (HA) hydrogels for corneal endothelial tissue engineering is attractive because they can be used as functional cell delivery carriers to help in the reconstruction of damaged areas. The purpose of this study was to investigate the corneal endothelial cytocompatibility and cell delivery performance of porous HA hydrogel biomaterials fabricated at different pre-freezing temperatures. As compared to their counterparts prepared at −80 °C, the HA samples fabricated at higher pre-freezing temperature (i.e., 0 °C) exhibited a larger pore size and higher porosity, thereby leading to lower resistance to glucose permeation. Live/dead assays and gene expression analyses showed that the restricted porous structure of HA carriers decreases the viability and ionic pump function of cultured corneal endothelial cells (CECs). The results also indicated that the porous hydrogel biomaterials fabricated at high pre-freezing temperature seem to be more compatible with rabbit CECs. In an animal model of corneal endothelial dysfunction, the wounded rabbit corneas receiving bioengineered CEC sheets and restricted porous-structured HA carriers demonstrated poor tissue reconstruction. The therapeutic efficacy of cell sheet transplants can be improved by using carrier materials prepared at high pre-freezing temperature. Our findings suggest that the cryogenic operation temperature-mediated pore microstructure of HA carriers plays an important role in corneal endothelial cytocompatibility and cell delivery performance.

A Lanthanum-Tagged Chemotherapeutic Agent HA-Pt to Track the In Vivo Distribution of Hyaluronic Acid Complexes.

Hyaluronic acid drug conjugates can target anti-cancer drugs directly to tumor tissue for loco-regional treatment with enhanced bioavailability, local efficacy and reduced toxicity. In this study, the distribution and pharmacokinetics of hyaluronic acid carrier and a conjugated cisplatin anti-cancer drug were tracked by lanthanum (III) [La(III)] affinity tagging of the nanocarrier. The strong binding affinity of La(III) to HA enabled the simple preparation of a physiologically stable complex HA-Pt-La and straightforward simultaneous detection of HA-La and Pt in biological matrices using inductively coupled plasma-mass spectrometry (ICP-MS). Consequently, after subcutaneous injection of HA-Pt-La nanoparticles in human head and neck squamous cell carcinoma (HNSCC) tumor-bearing mice, the HA and Pt content were detected and quantified simultaneously in the plasma, primary tumor, liver and spleen.

Nanostructured hyaluronic acid-based materials for active delivery to cancer

Importance of the field: Active targeting of bioactive molecules by physicochemical association with hyaluronic acid (HA) is an attractive approach in current nanomedicine because HA is biocompatible, non-toxic and non-inflammatory.Areas covered in this review: This review focuses on synthesis, physicochemical characterization and biological properties of different nanoparticulate delivery systems that include HA in their structures. Chemically based approaches to the delivery of small molecule drugs, proteins and nucleic acids in which they become chemically or physically bound to hyaluronic acid are reviewed, including the use of molecular HA conjugates and nanocarriers. The systems are considered in terms of intracellular delivery to different cultured cells that express HA-specific receptors (hyaladherines) differently. The in vivo biodistribution and therapeutic effect of these systems are discussed.What the reader will gain: Different synthetic methodologies for preparations of HA-based nanoparticles are presented extensively. HA nanoparticulate systems of various structures can be compared with respect to their in vitro assays and in vivo biodistribution.Take home message: To make HA useful as an intravenous targeting carrier, strategies have to be devised to: reduce HA clearance from the blood; suppress the HA uptake by liver and spleen; and provide tumor-triggered mechanisms of release of an active drug from the HA carrier.

Ocular Biocompatibility of Carbodiimide Cross-Linked Hyaluronic Acid Hydrogels for Cell Sheet Delivery Carriers

Due to its innocuous nature, hyaluronic acid (HA) is one of the most commonly used biopolymers for ophthalmic applications. We recently developed a cell sheet delivery system using carbodiimide cross-linked HA carriers. Chemical cross-linking provides an improvement in stability of polymer gels, but probably causes toxic side-effects. The aim of this study was to investigate the ocular biocompatibility of HA hydrogels cross-linked by 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). HA discs without cross-linking and glutaraldehyde (GTA) cross-linked HA samples were used for comparison. The disc implants were inserted in the anterior chamber of rabbit eyes for 24 weeks and characterized by slit-lamp biomicroscopy, histology and scanning electron microscopy. The ophthalmic parameters obtained from biomicroscopic examinations were also scored to provide a quantitative grading system. Results of this study showed that the HA discs cross-linked with EDC had better ocular biocompatibility than those with GTA. The continued residence of GTA cross-linked HA implants in the intraocular cavity elicited severe tissue responses and significant foreign body reactions, whereas no adverse inflammatory reaction was observed after contact with non-cross-linked HA or EDC cross-linked HA samples. It is concluded that the cross-linking agent type gives influence on ocular biocompatibility of cell carriers and the EDC-HA hydrogel is an ideal candidate for use as an implantable material in cell sheet delivery applications.

Intervertebral Disc Repair Using Adipose Tissue-Derived Stem and Regenerative Cells

Therapeutic treatment of intervertebral disc repair using cells. The goal of the study was to test the hypothesis that repair of a damaged disc is possible using autologous adipose tissue derived stem and regenerative cells (ADRCs). Degradation resulting from either acute or chronic repetitive disc injury leads to disc degeneration. However, if a damaged disc could be repaired in the early stages, before the onslaught of degradation, then the disc degeneration process may be slowed down. Twelve dogs underwent a partial nucleotomy at 3 lumbar levels (L3-L4, L4-L5, and L5-L6); adjacent levels served as nonoperated controls. The animals (or discs) were allowed to recover from the surgery for 6 weeks. At that time subcutaneous adipose tissue was harvested and ADRCs were isolated. The 3 experimental discs that had undergone a partial nucleotomy were randomized to receive: (1) ADRCs in hyaluronic acid carrier (Cells/HA); (2) HA only; or (3) No Intervention. Assessments of the 3 experimental discs plus the 2 adjacent untouched discs were made using MRI, radiography, histology, and biochemistry. The animals were killed at 6 months and at 12 months. Repair in this study was specifically demonstrated through histology and biochemical analysis. Disc levels receiving ADRCs more closely resembled the healthy controls as evidenced in matrix translucency, compartmentalization of the anulus, and in cell density within the nucleus pulposus. Matrix analysis for Type-II collagen and aggrecan demonstrated evidence of a statistically better regenerative stimulation to the disc provided by ADRCs when compared to either the HA only or no intervention treatments. Autologous adipose tissue derived stem and regenerative cells, as used in this disc injury model, were effective in promoting disc regeneration, as evidenced by disc matrix production and overall disc morphology.

Clinical evaluation of demineralized bone allograft in a hyaluronic acid carrier for sinus lift augmentation in humans: a computed tomography and histomorphometric study

Natural and synthetic graft materials are used routinely in sinus floor augmentations to help support implants in atrophic maxillary ridges. This clinical study was based on the hypothesis that the clinical effectiveness of demineralized freeze-dried bone allograft/demineralized bone matrix (DFDBA/DBM) in sinus lifts varies when used in combination bone graft substitute materials. To test this hypothesis, DFDBA was used together with one of three materials: in saline plus anorganic bone (DFDBA: Bio-Oss; in hyaluronic acid (DFDBA: HY, 32 : 68, w/w; DBX alone; DBX plus Bio-Oss; and DBX plus tricalcium phosphate granules (beta-TCP). Thirty-two sinus lift procedures, eight per group, were performed on 26 patients. Before surgery and at 8 months post-surgery when implants were placed, ridge heights were visualized by computed tomography (CT) and measured by morphometric analysis. Cores of bone were removed by trephine at the sites of implant placement; these biopsies from the graft sites were used for histomorphometric analysis. All 32 sinus lift elevations were successful when measured by CT, increasing from an average 2.84+/-0.2 mm before treatment to 15.2+/-0.6 mm after treatment. The percent of each biopsy that was occupied by new bone and incorporated bone graft materials varied with each treatment: DFDBA+Bio-Oss, DBX+Bio-Oss, or DBX alone was higher than that for DBX+beta-TCP by approximately 10%. When comparing only newly formed bone, DBX+beta-TCP treatment resulted in 50% less bone than the other three preparations. All grafted sites received implants as per the treatment plan for each patient. This study confirmed the hypothesis that new bone formation is dependent on the DFDBA formulation used and demonstrated that DBX, alone or in combination with other materials, can be used successfully for sinus floor elevation.

Application of periodontal ligament cell sheet for periodontal regeneration: a pilot study in beagle dogs

The ultimate goal of periodontal treatment is to regenerate the damaged periodontal support. Although periodontal ligament (PDL) cells are essential for periodontal regeneration, few studies have reported the transplantation of periodontal ligament cells to periodontal defects. We developed a new method to apply periodontal ligament cells as a sheet to the defect. The aim of this study was to investigate the periodontal healing after application of the periodontal ligament cell sheet in beagle dogs. Autologous periodontal ligament cells were obtained from extracted premolars of each beagle dog. Periodontal ligament cell sheets were fabricated using a temperature-responsive cell culture dish. Dehiscence defects were surgically created on the buccal surface of the mesial roots of bilateral mandibular first molars of each dog. In the experimental group (five defects), periodontal ligament cell sheet with reinforced hyaluronic acid carrier was applied to the defect. Only the hyaluronic acid carrier was applied to the contralateral side as a control (five defects). Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Healing of the periodontal defects was evaluated histologically and histometrically. No clinical signs of inflammation or recession of gingiva were observed in both experimental and control groups. In the experimental group, periodontal tissue healing with bone, periodontal ligament and cementum formation was observed in three out of five defects. In the control group, such periodontal tissue formation was not observed except in one defect. Histometric analysis revealed that the formation of new cementum in the experimental group was significantly higher than that in the control group. The periodontal ligament cell sheet has a potential to regenerate periodontal tissue and may become a novel regenerative therapy.

Recombinant human bone morphogenetic protein 2 enhances bone healing in an experimental model of fractures at risk of non-union

Identification of patients at risk of developing non-union and institution of procedures preventing non-union could be attractive in routine fracture management. We investigated whether recombinant human bone morphogenetic protein (rhBMP-2) delivered in a hyaluronic acid carrier could prevent non-union development in an experimental non-union model, which simulates the clinical situation of open mid-tibial fractures. Sixteen rabbits underwent a standard non-union operation comprising mid-tibial osteotomy, excision of periosteum and endosteum, and plate fixation. Before closure of the wound eight rabbits received interfragmentary deposition of 200 microg rhBMP-2 delivered in a hyaluronan gel carrier, and eight rabbits received gel carrier alone. After 7 weeks, torsional failure moment of the osteotomy and energy absorbed at failure, macroscopic and radiographic appearance, callus area, and interfragmentary bone volume fraction confirmed that rhBMP-2 delivery significantly improved bone healing. Blood flow at the osteotomy site, measured using radiolabelled microspheres, was not higher in the united osteotomies than in non-united osteotomies. rhBMP-2 delivered in a hyaluronic acid carrier-induced formation of competent bone in an experimental model of compromised healing. We, therefore, propose interfragmentary deposition of rhBMP-2 delivered in a hyaluronic acid carrier to patients encountering fractures at risk of non-union or delayed union.

Treatment of avascular ulcers with cytokine-induced tissue generation and skin grafting

Recombinant platelet-derived growth factor (rPDGF-BB) stimulates migration and proliferation of fibroblasts and smooth muscle cells and induces the rapid development of granulation tissue. This study investigated the use of rPDGF-BB and skin grafting to heal avascular ulcers using a rabbit model. We further investigated the effect of a hyaluronic acid carrier and a vascular pedicle on rPDGF-induced tissue generation in this model. Large avascular ulcers were created on both ears of New Zealand white rabbits. One ulcer was treated with topical rPDGF-BB, the other with control buffer. After 5 or 7 days, the amount of granulation tissue migration from the wound margin was measured, and the wounds were skin grafted. In another group of ulcers, rPDGF-BB treatment was combined with a hyaluronic acid disk or an intact central axial ear artery and vein. Whereas control wounds generated 1.00 +/- 0.27 mm and 1.75 +/- 0.25 mm of granulated tissue migration from the wound margin by days 5 and 7, respectively, rPDGF-BB treatment increased the amount of granulation tissue migration to 1.88 +/- 0.23 mm and 3.00 +/- 0.86 mm by days 5 and 7 after treatment, respectively (P <0.05 at both time points). Hyaluronic acid disks stimulated 2.50 +/- 0.22 mm of granulation tissue migration by day 7 in controls; when rPDGF-BB was added to the carrier, the migration increased to 4.50 +/- 0.29 mm from the wound margin (P<0.05). Granulation tissue migration was further increased with an intact vascular pedicle: 5.75 +/- 0.48 mm in controls versus 7.75 +/- 0.25 mm with rPDGF-BB treatment (P<0.01). Skin grafts applied to the treated ulcers failed to survive in all groups except those with intact vascular pedicles. CONCLUSIONS. This study demonstrates that rPDGF-BB can increase the amount of granulation tissue generated over an avascular wound. This tissue generation is enhanced by both a hyaluronic acid carrier and a vascular pedicle. A vascular pedicle was required for skin graft survival. This study supports the role of hyaluronic acid in rPDGF-BB induced tissue generation and the requirement of a direct blood supply for functional cytokine-induced tissue generation.

Peritoneal Lavage Fluid Protease Levels after in Vivo Administration of Tolmetin in Hyaluronic Acid

Tolmetin sodium in a hyaluronic acid carrier (tolmetin-HA) was previously shown to reduce adhesion formation and alter the rate and extent to which wound repair cells enter the peritoneal cavity after surgery. In this study, the effect of tolmetin-HA on the levels of protease activities present in lavage fluid from the peritoneal cavity was determined at various postsurgical times. Collagenase activity in peritoneal lavage fluid was supressed at 6, 12, and 24 hr after administration of tolmetin-HA in comparison to control. Elastase activity levels were biphasic with peak levels at 6 and 72 hr in lavage fluid from controls compared to peak levels at 6 and 48 hr in lavage fluid from treated rabbits. Plasminogen activator activity present in lavage fluid was significantly decreased at 48 hr after surgery in the tolmetin-HA-treated rabbits compared to controls. However, no alteration in the level of plasminogen activator inhibitor activity was observed in either the tolmetin-HA-treated or control rabbits. These data suggest that tolmetin-HA treatment altered the levels of neutral protease activity present in the peritoneal cavity and may therefore effect the proteolytic potential in the peritoneal cavity after surgery.

In Vivo Administration of Tolmetin in Hyaluronic Acid Modulates Protease Levels in Postsurgical Macrophage-Conditioned Media

Tolmetin sodium in a hyaluronic acid carrier (tolmetin-HA) was previously shown to reduce adhesion formation and alter the kinetics and levels of cellular influx into the peritoneal cavity after surgery. In this study, the effect of tolmetin-HA on the level of protease activity in macrophage-conditioned media was determined. The level of collagenase activity in macrophage-conditioned media was suppressed at 12 and 24 h after administration of tolmetin-HA. Alternatively, the peak level of elastase activity measured in macrophage-conditioned media was unchanged after tolmetin-HA treatment, but the kinetics of expression of maximal protease activity was delayed from 12 h in the control surgical rabbits to 24 h in tolmetin-HA-treated rabbits. Elevated plasminogen activator activity was detected in acid-treated conditioned media from the tolmetin-HA-treated rabbits when compared to control levels. However, no alteration in the level of plasminogen activator inhibitor activity was present in conditioned media of macrophages harvested from tolmetin-HA-treated rabbits compared to controls. These data suggest that tolmetin-HA treatment altered the levels of neutral protease activity secreted by postsurgical macrophages and may therefore elevate the fibrinolytic potential of the peritoneal cavity after surgery.