Can Carbodiimide (EDC) and Chitosan Cross-linking Agents Effect the Longevity of Fiberglass Posts Luted with Different Types of Composite Cements to Root Dentin?

PURPOSE: To evaluate the effect of carbodiimide (EDC) and chitosan (CHI) on the enzymatic activity (EA) and bond strength (BS) of different composite cements to root dentin. MATERIALS AND METHODS: Ninety (90) maxillary canines were sectioned, standardizing the length of the roots. The roots were endodontically treated, prepared, divided into 3 groups according to dentin treatment (distilled water [DW], CHI 0.2 wt%, or EDC 0.5M), and further subdivided into 3 subgroups according to composite cement (RelyX ARC [3M Oral Care], Panavia F 2.0 [Kuraray Noritaki], or RelyX U200 [3M Oral Care]). Of the slices obtained by sectioning, the most cervical of each third were subjected to a push-out test and the most apical were subjected to in-situ zymography. Half of the slices were analyzed immediately, and the other half after 6 months. The results were analyzed with ANOVA or the chi-squared test. RESULTS: RelyX ARC showed higher BS associated with CHI, while RelyX U200 showed higher BS associated with EDC (p = 0.044). For Panavia F 2.0, the treatment did not influence BS (p > 0.05). For the cervical and middle thirds, no differences were observed between the cements, while the apical third revealed higher BS for RelyX U200 (p < 0.001). The highest percentage of adhesive-to-dentin failures was observed for Panavia F 2.0. EDC showed the lowest percentage of adhesive-to-dentin failures. According to zymographic analysis, DW and CHI showed greater fluorescence for RelyX ARC, while EDC exhibited the lowest fluorescence of all cements (p > 0.05). CONCLUSION: The different mechanisms of action of solutions for pre-treatment of intraradicular dentin yielded different results depending on the adhesive used. EDC resulted in higher bond strength and higher enzyme inhibition for RelyX U200, while the treatment with chitosan resulted in higher bond strength and lower enzymatic activity for RelyX ARC. Although EDC and chitosan treatments did not influence the bond strength for Panavia F 2.0, both resulted in higher enzyme inhibition for this composite cement.

A novel targeted iron oxide nanocarrier for inhibiting M2-type macrophages in the tumor microenvironment.

Background: Tumor-associated macrophages (TAMs) are vital to the tumor microenvironment. They are classified as antitumor M1-type or protumor M2-type macrophages. M2-type macrophages accumulate in the tumor stroma and are related to poor prognosis. Iron oxide nanoparticles are used as drug delivery vehicles because of the structure of carboxyl groups on their surface and their ability to be easily phagocytosed by macrophages. Aim: The signal transducer and activator of transcription 6 (STAT6) signaling pathway controls M2 macrophage polarization, but the STAT6 signaling pathway inhibitor AS1517499 lacks efficient targeting in vivo. Thus, our study aimed to block the polarization of TAMs to M2-type macrophages. Methods and Material: We used ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) as drug carriers coated with the STAT6 signaling pathway inhibitors AS1517499 and CD163 monoclonal antibodies to synthesize the targeted nanocomplex AS1517499-USPION-CD163 utilizing the carbodiimide method. Then, we determined its physicochemical properties, including hydrodynamic size distribution, ultrastructure, iron concentration, protein content and activity of the CD163 monoclonal antibody, AS1517499 content, and selectivity for M2-type macrophages, and its biological applications. Results: The hydrodynamic size distribution was stable (average size = 95.37 nm). Regarding biological applications, the targeted nanocomplex selectively inhibited M2-type macrophages. Conclusions: The targeted nanocomplex AS1517499-USPION-CD163 showed high selectivity for M2-type macrophages. Therefore, iron oxide nanoparticles targeting TAMs may be an effective approach to TAM therapy.

Melimine-Modified 3D-Printed Polycaprolactone Scaffolds for the Prevention of Biofilm-Related Biomaterial Infections.

Biomaterial-associated infections are one of the major causes of implant failure. These infections result from persistent bacteria that have adhered to the biomaterial surface before, during, or after surgery and have formed a biofilm on the implant's surface. It is estimated that 4 to 10% of implant surfaces are contaminated with bacteria; however, the infection rate can be as high as 30% in intensive care units in developed countries and as high as 45% in developing countries. To date, there is no clinical solution to prevent implant infection without relying on the use of high doses of antibiotics supplied systemically and/or removal of the infected device. In this study, melimine, a chimeric cationic peptide that has been tested in Phase I and II human clinical trials, was immobilized onto the surface of 3D-printed medical-grade polycaprolactone (mPCL) scaffolds via covalent binding and adsorption. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra of melimine-treated surfaces confirmed immobilization of the peptide, as well as its homogeneous distribution throughout the scaffold surface. Amino acid analysis showed that melimine covalent and noncovalent immobilization resulted in a peptide density of ∼156 and ∼533 ng/cm2, respectively. Furthermore, we demonstrated that the immobilization of melimine on mPCL scaffolds by 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride (EDC) coupling and noncovalent interactions resulted in a reduction of Staphylococcus aureus colonization by 78.7% and 76.0%, respectively, in comparison with the nonmodified control specimens. Particularly, the modified surfaces maintained their antibacterial properties for 3 days, which resulted in the inhibition of biofilm formation in vitro. This system offers a biomaterial strategy to effectively prevent biofilm-related infections on implant surfaces without relying on the use of prophylactic antibiotic treatment.

Effect of Collagen Crosslinkers on Dentin Bond Strength of Adhesive Systems: A Systematic Review and Meta-Analysis.

This study aimed to identify the role of crosslinking agents in the resin-dentin bond strength (BS) when used as modifiers in adhesives or pretreatments to the dentin surface through a systematic review and meta-analysis. This paper was conducted according to the directions of the PRISMA 2020 statement. The research question of this review was: "Would the use of crosslinkers agents improve the BS of resin-based materials to dentin?" The literature search was conducted in the following databases: Embase, PubMed, Scielo, Scopus, and Web of Science. Manuscripts that reported the effect on the BS after the use of crosslinking agents were included. The meta-analyses were performed using Review Manager v5.4.1. The comparisons were performed by comparing the standardized mean difference between the BS values obtained using the crosslinker agent or the control group. The subgroup comparisons were performed based on the adhesive strategy used (total-etch or self-etch). The immediate and long-term data were analyzed separately. A total of 50 articles were included in the qualitative analysis, while 45 articles were considered for the quantitative analysis. The meta-analysis suggested that pretreatment with epigallocatechin-3-gallate (EGCG), carbodiimide, ethylenediaminetetraacetic acid (EDTA), glutaraldehyde, and riboflavin crosslinking agents improved the long-term BS of resin composites to dentin (p ≤ 0.02). On the other hand, the use of proanthocyanidins as a pretreatment improved both the immediate and long-term BS values (p ≤ 0.02). When incorporated within the adhesive formulation, only glutaraldehyde, riboflavin, and EGCG improved the long-term BS to dentin. It could be concluded that the application of different crosslinking agents such as carbodiimide, EDTA, glutaraldehyde, riboflavin, and EGCG improved the long-term BS of adhesive systems to dentin. This effect was observed when these crosslinkers were used as a separate step and when incorporated within the formulation of the adhesive system.

Effect of Saccharides Coating on Antibacterial Potential and Drug Loading and Releasing Capability of Plasma Treated Polylactic Acid Films.

More than half of the hospital-associated infections worldwide are related to the adhesion of bacteria cells to biomedical devices and implants. To prevent these infections, it is crucial to modify biomaterial surfaces to develop the antibacterial property. In this study, chitosan (CS) and chondroitin sulfate (ChS) were chosen as antibacterial coating materials on polylactic acid (PLA) surfaces. Plasma-treated PLA surfaces were coated with CS either direct coating method or the carbodiimide coupling method. As a next step for the combined saccharide coating, CS grafted samples were immersed in ChS solution, which resulted in the polyelectrolyte complex (PEC) formation. Also in this experiment, to test the drug loading and releasing efficiency of the thin film coatings, CS grafted samples were immersed into lomefloxacin-containing ChS solution. The successful modifications were confirmed by elemental composition analysis (XPS), surface topography images (SEM), and hydrophilicity change (contact angle measurements). The carbodiimide coupling resulted in higher CS grafting on the PLA surface. The coatings with the PEC formation between CS-ChS showed improved activity against the bacteria strains than the separate coatings. Moreover, these interactions increased the lomefloxacin amount adhered to the film coatings and extended the drug release profile. Finally, the zone of inhibition test confirmed that the CS-ChS coating showed a contact killing mechanism while drug-loaded films have a dual killing mechanism, which includes contact, and release killing.

A novel detergent-based decellularization combined with carbodiimide crosslinking for improving anti-calcification of bioprosthetic heart valve.

Currently, valve replacement surgery is the only therapy for the end-stage valvular diseases because of the inability of regeneration for diseased heart valves. Bioprosthetic heart valves (BHVs), which are mainly derived from glutaraldehyde (GA) crosslinked porcine aortic heart valves or bovine pericardium, have been widely used in the last decades. However, it is inevitable that calcification and deterioration may occur within 10-15 years, which are still the main challenges for the BHVs in clinic. In this study, N-Lauroylsarcosine sodium salt (SLS) combined with N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were utilized to decellularize and crosslink the heart valves instead of GA treatment. The obtained BHVs exhibited excellent extracellular matrix stability and mechanical properties, which were similar with GA treatment. Moreover, the obtained BHVs exhibited betterin vitrobiocompatibilities than GA treatment. After subcutaneous implantation for 30 d, the obtained BHVs showed mitigated immune response and reduced calcification compare with GA treatment. Therefore, all the above results indicated that the treatment of SLS-based decellularization combined with EDC/NHS crosslink should be a promising method to fabricate BHVs which can be used in clinic in future.

Gellan gum hydrogels cross-linked with carbodiimide stimulates vacuolation of human tooth-derived stem cells in vitro.

The natural polysaccharides are promising compounds for applications in regenerative medicine. Gellan gum (GG) is the bacteria-derived polysaccharide widely used in food industry. Simple modifications of its chemical properties make GG superior for the development of biocompatible hydrogels. Beside reversible cationic integration of GG chains, more efficient binding is accomplished with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). However, the side-products of polymer cross-linking might affect viability and differentiation of stem cells introduced into the hydrogels. We found that O-acylisourea (EDU) stimulates autophagy-based vacuolation in both periodontal ligament and dental pulp stem cells. 24-h treatment of cells with GG extracts cross-linked with 15 mM EDC developed large cytoplasmic vacuoles. Freshly prepared EDU (2-6 mM) but not 15 mM EDC solutions initiated vacuole development with concomitant reduction of cell viability/metabolism. Most of the vacuoles stained with acridine orange displayed highly acidic environment further confirmed by flow cytometric analysis. Western blot of the LC3 autophagy marker followed by a transmission electron microscopy indicated the process is autophagy-dependent. We propose that the high reactivity of EDU with intracellular components initiates autophagy, although the targets of EDU remain unknown. Nevertheless, a burst release of EDU from GG hydrogels might modulate negatively cellular processes and final effectiveness of tissue regeneration.

Dopamine-Functionalized Gellan Gum Hydrogel as a Candidate Biomaterial for a Retinal Pigment Epithelium Cell Delivery System.

In this study, dopamine-functionalized gellan gum (DFG) hydrogel was prepared as a carrier for retinal pigment epithelium (RPE) cell delivery via a carbodiimide reaction. The carboxylic acid of gellan gum (GG) was replaced with catechol in a 21.3% yield, which was confirmed by NMR. Sol fraction and weight loss measurements revealed that dopamine improved degradability in the GG hydrogel. Measurements of the viscosity, injection force, and compressibility also showed that dopamine-functionalized GG hydrogels had more desirable rheological/mechanical properties for improving injectability. These characteristics were confirmed to arise from the GG's helix structure loosened by the dopamine's bulky nature. Moreover, dopamine's hydrophilic characteristics were confirmed to create a more favorable microenvironment for cell growth by promoting swelling capability and cell attachment. This improved biocompatibility became more pronounced when the hydrophilicity of dopamine was combined with a larger specific surface area stemming from the less porous structure of the dopamine-grafted hydrogels. This effect was apparent from the live/dead staining images of the as-prepared hydrogels. Meanwhile, the nonionic cross-linked DFG (DG) hydrogel showed the lowest protein expression in the immunofluorescence staining images obtained after 28 days of culture, supporting that it had the highest degradability and associated cell-releasing ability. That tendency was also observed in the gene expression data acquired by real-time polymerase chain reaction (RT-PCR) analysis. RT-PCR analysis also revealed that the DG hydrogel carrier could upregulate the visual function-related gene of RPE. Overall, the DG hydrogel system demonstrated its feasibility as a carrier of RPE cells and its potential as a means of improving visual function.

Cross-linking effects of carbodiimide, oxidized chitosan oligosaccharide and glutaraldehyde on acellular dermal matrix of basa fish (Pangasius bocourti).

Basa acellular dermal matrix (BADM) has advantages in the preparation of oral prosthetic membranes. In order to prepare high-quality BADM, a suitable cross-linking agent is necessary. In this study, acellular dermal matrix was prepared from basa fish skin and then cross-linked with carbodiimide (EDC), oxidized chitosan oligosaccharide (OCOS) and glutaraldehyde (GA), respectively. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis (XRD), histological staining, DNA electrophoresis and the limulus amoebocyte lysate chromogenic assay were used to detect the structure and properties of BADM. The compatibility of BADM was detected by implantation in vivo and cell experiments. The results showed that the majority of the cellular and DNA in BADM were removed. The endotoxin was not be detected. Furthermore, the structure of BADM was not destroyed. The mechanical and anti-degraded properties of BADM were promoted obviously after cross-linking. The thermal shrinkage temperatures of wet and dry EDC-BADM (BADM cross-linked by carbodiimide) were increased by 39.22 °C and 18.27 °C, respectively, compared with that of the uncross-linked BADM. In addition, the EDC-BADM had good biocompatibility and cytocompatibility. In conclusion, carbodiimide can improve the properties of BADM, which has potential application in the field of biomaterials.

Caries removal with Er:YAG laser followed by dentin biomodification with carbodiimide and chitosan: Wettability and surface morphology analysis.

This study aimed to investigate dentin wettability and surface morphology after selective removal of carious lesion by erbium-doped yttrium aluminum garnet (Er:YAG) laser, followed by dentin biomodification with carbodiimide (EDC) and chitosan (CHI). Seventy-eight bovine dentin specimens were submitted to caries induction. Specimens were distributed according to methods of carious removal (n = 39): bur at low-speed (40,000 rpm) or Er:YAG laser (noncontact mode, 250 mJ/pulse and 4Hz). All specimens were etched with 35% phosphoric acid, and subdivided according to dentin biomodification (n = 13): Control (no biomodification), EDC or CHI. The contact angle (n = 10) between adhesive system (3M ESPE) and dentin surface was measured by a goniometer. Eighteen specimens (n = 3) were analyzed by scanning electron microscopy. Data were analyzed by two-way ANOVA and Tukey's test (α = .05). The method used to remove carious lesion did not influence the wettability of dentinal surface (p = .748). The angles produced on the remaining dentin after biomodification were influenced (p = .007). CHI promoted higher contact angles (p = .007) and EDC did not differ from the control group (p = .586). In the bur-treated group, most tubules were open, regardless of which biomodifier was used. Laser modified the organic matrix layer. CHI promoted partially closed tubules in some areas while EDC exposed dentinal tubules. Regardless of which method was used for selective removal of carious lesion, biomodification with EDC did not affect the dentin wettability, whereas CHI changed the wettability of remaining dentin. Both biomodifiers promoted a slight change on dentin morphology.

Injectable human recombinant collagen matrices limit adverse remodeling and improve cardiac function after myocardial infarction.

Despite the success of current therapies for acute myocardial infarction (MI), many patients still develop adverse cardiac remodeling and heart failure. With the growing prevalence of heart failure, a new therapy is needed that can prevent remodeling and support tissue repair. Herein, we report on injectable recombinant human collagen type I (rHCI) and type III (rHCIII) matrices for treating MI. Injecting rHCI or rHCIII matrices in mice during the late proliferative phase post-MI restores the myocardium's mechanical properties and reduces scar size, but only the rHCI matrix maintains remote wall thickness and prevents heart enlargement. rHCI treatment increases cardiomyocyte and capillary numbers in the border zone and the presence of pro-wound healing macrophages in the ischemic area, while reducing the overall recruitment of bone marrow monocytes. Our findings show functional recovery post-MI using rHCI by promoting a healing environment, cardiomyocyte survival, and less pathological remodeling of the myocardium.

Carbodiimide inactivation of matrix metalloproteinases in radicular dentine.

OBJECTIVES: The present in vitro study evaluated the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), a cross-linking agent used as an additional therapeutic primer for luting fiber posts to radicular dentine to prevent hybrid layer degradation. METHODS: Root canal treatment was performed on 80 extracted single-rooted human teeth. A 10-mm post space was prepared and pecimens were randomly assigned to four groups (n=20) according to the bonding system: 1) All Bond 3 (Bisco); 2) All Bond 3 + 0.3M EDC; 3) Prime&Bond XP (Dentsply Sirona); 4) Prime&Bond XP + 0.3M EDC. In groups 2 and 4, EDC was applied on phosphoric acid-etched dentine for 1 min. Fiber posts (RelyX Fiber Post, 3M ESPE) were luted with a dual-cured resin cement (Core-X flow, Dentsply Sirona). Slices were prepared for micro push-out test and interfacial nanoleakage evaluation of the coronal and apical region of the canal space after 24 h and 1 year storage in artificial saliva. In-situ zymography was performed to investigate endogenous matrix metalloproteinase activities within the hybrid layer. Results were statistically analysed with three-way ANOVA test or Chi Square test. Statistical significance was set at α=0.05. RESULTS: No significant influence was identified between the two adhesives. The use of EDC significantly improved fiber post bond strength at 1 year but not at 24 h. Application of 0.3 M EDC prior to bonding significantly reduced gelatinolytic activities within the radicular hybrid layers. CONCLUSIONS: Carbodiimide was effective in preserving fibre post bond strength over time, through reducing the activities of intra-radicular endogenous proteases. CLINICAL SIGNIFICANCE: Inhibition of matrix metalloproteinases using EDC over radicular dentin could play an important role in bond strength preservation. However, the clinical relevance of these findings needs to be proven.

Effect of Cross-Linking Density on the Structures and Properties of Carbodiimide-Treated Gelatin Matrices as Limbal Stem Cell Niches.

Given that human amniotic membrane is a valuable biological material not readily available for corneal epithelial tissue engineering, gelatin is considered as a potential alternative to construct a cellular microenvironment. This study investigates, for the first time, the influence of cross-linking density of carbodiimide-treated gelatin matrices on the structures and properties of artificial limbal stem cell niches. Our results showed that an increase in the carbodiimide concentration from 1.5 to 15 mM leads to an upward trend in the structural and suture strength of biopolymers. Furthermore, increasing number of cross-linking bridges capable of linking protein molecules together may reduce their crystallinity. For the samples treated with 50 mM of cross-linker (i.e., the presence of excess N-substituted carbodiimide), abundant N-acylurea was detected, which was detrimental to the in vitro and in vivo ocular biocompatibility of gelatin matrices. Surface roughness and stiffness of biopolymer substrates were found to be positively correlated with carbodiimide-induced cross-link formation. Significant increases of integrin ß1 expression, metabolic activity, and ABCG2 expression were noted as the cross-linker concentration increased, suggesting that the bulk crystalline structure and surface roughness/stiffness of niche attributed to the number of cross-linking bridges may have profound effects on a variety of limbal epithelial cell behaviors, including adhesion, proliferation, and stemness maintenance. In summary, taking the advantages of carbodiimide cross-linking-mediated development of gelatin matrices, new niches with tunable cross-linking densities can provide a significant boost to maintain the limbal stem cells during ex vivo expansion.

Fixation of Bovine Pericardium-Based Tissue Biomaterial with Irreversible Chemistry Improves Biochemical and Biomechanical Properties.

Bioprosthetic heart valves (BHVs), derived from glutaraldehyde crosslinked (GLUT) porcine aortic valve leaflets or bovine pericardium (BP), are used to replace defective heart valves. However, valve failure can occur within 12-15 years due to calcification and/or progressive structural degeneration. We present a novel fabrication method that utilizes carbodiimide, neomycin trisulfate, and pentagalloyl glucose crosslinking chemistry (TRI) to better stabilize the extracellular matrix of BP. We demonstrate that TRI-treated BP is more compliant than GLUT-treated BP. GLUT-treated BP exhibited permanent geometric deformation and complete alteration of apparent mechanical properties when subjected to induced static strain. TRI BP, on the other hand, did not exhibit such permanent geometric deformations or significant alterations of apparent mechanical properties. TRI BP also exhibited better resistance to enzymatic degradation in vitro and calcification in vivo when implanted subcutaneously in juvenile rats for up to 30 days.

Effect of Bioactive Primers on Bacterial-Induced Secondary Caries at the Tooth-Resin Interface.

Secondary caries at the tooth-resin interface is the primary reason for replacement of resin composite restorations. The tooth-resin interface is formed by the interlocking of resin material with hydroxyapatite crystals in enamel and collagen mesh structure in dentin. Efforts to strengthen the tooth-resin interface have identified chemical agents with dentin collagen cross-linking potential and antimicrobial activities. The purpose of the present study was to assess protective effects of bioactive primer against secondary caries development around enamel and dentin margins of class V restorations, using an in vitro bacterial caries model. Class V composite restorations were prepared on 60 bovine teeth (n=15) with pretreatment of the cavity walls with control buffer solution, an enriched fraction of grape seed extract (e-GSE), 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide/N-hydroxysuccinimide, or chlorhexidine digluconate. After incubating specimens in a bacterial model with Streptococcus mutans for four days, dentin and enamel were assessed by fluorescence microscopy. Results revealed that only the naturally occurring product, e-GSE, significantly inhibited the development of secondary caries immediately adjacent to the dentin-resin interface, as indicated by the caries inhibition zone. No inhibitory effects were observed in enamel margins. The results suggest that the incorporation of e-GSE into components of the adhesive system may inhibit secondary caries and potentially contribute to the protection of highly vulnerable dentin-resin margins.

Protocatechuic acid grafted onto chitosan: Characterization and antioxidant activity.

In this study, protocatechuic acid (PA) was grafted onto chitosan (CS) by a carbodiimide mediated cross-linking reaction. The structural characterization, physical property and antioxidant activity of PA grafted CS (PA-g-CS) was investigated. As results, three copolymers with different grafting ratios (61.64, 190.11 and 279.69mg PAE/g) were obtained by varying the molar ratios of reaction substrates. PA-g-CS showed the same UV absorption peaks as PA at 258 and 292nm. As compared to CS, PA-g-CS exhibited a decreased band at 1596cm(-1) and a new band at 1716cm(-1), suggesting the formation of amide and ester linkages between PA and CS. New proton signals at δ6.77-7⋅33ppm were observed on (1)H NMR spectrum of PA-g-CS, assigning to the methine protons of PA. Signals at δ 150.8-116.6 ppm on (13)C NMR spectrum of PA-g-CS was assigned to the aromatic ring carbon of PA moieties. All the structural information confirmed the successful grafting of PA onto CS. SEM observation showed CS had a smooth surface, while PA-g-CS had a rough surface. TGA revealed the thermal stability of PA-g-CS was lower than CS. Antioxidant activity assays further verified the reducing power and DDPH radical scavenging activity of PA-g-CS was much higher than CS.

Surface Modification with Chemically Modified Synovial Fluid for Flexor Tendon Reconstruction in a Canine Model in Vivo.

BACKGROUND: Functional restoration is the major concern after flexor tendon reconstruction in the hand. The purpose of the present study was to investigate the effects of modifying the surface of extrasynovial tendon autografts with carbodiimide-derivatized synovial fluid with gelatin (cd-SF-G) on functional outcomes of flexor tendon reconstruction using a canine model. METHODS: The second and fifth flexor digitorum profundus tendons from eleven dogs were transected and repaired in zone II. The dogs then had six weeks of free activity leading to tendon rupture and scar formation (the repair-failure phase). In the reconstruction phase, two autologous peroneus longus tendons from each dog were harvested; one tendon was coated with cd-SF-G and the other, with saline solution, as a control. A non-weight-bearing rehabilitation protocol was followed for six weeks after reconstruction. The digits were then harvested and evaluations of function, adhesion status, gliding resistance, attachment strength, cell viability, and histology were performed. RESULTS: The tendons coated with cd-SF-G demonstrated significantly lower values (mean and standard deviation) compared with the saline-solution group for work of flexion (0.63 ± 0.24 versus 1.34 ± 0.42 N-mm/deg), adhesion score (3.5 ± 1.6 versus 6.1 ± 1.3), proximal adhesion breaking force (8.6 ± 3.2 versus 20.2 ± 10.2 N), and gliding resistance (0.26 ± 0.08 versus 0.46 ± 0.22 N) (p < 0.05). There was no significant difference between the cd-SF-G and saline-solution groups (p > 0.05) in distal attachment-site strength (56.9 ± 28.4 versus 77.2 ± 36.2 N), stiffness (19 ± 7.5 versus 24.5 ± 14.5 N/mm), and compressive modulus from indentation testing (4.37 ± 1.26 versus 3.98 ± 1.24 N/mm). Histological analysis showed that tendons coated with cd-SF-G had smoother surfaces and demonstrated tendon-to-bone and tendon-to-tendon incorporation. No significant difference in viable cell count between the two groups was observed on tendon culture. CONCLUSIONS: Modification of the flexor tendon surface with cd-SF-G significantly improved digital function and reduced adhesion formation without affecting graft healing and stiffness. CLINICAL RELEVANCE: This study used native synovial fluid as a basic lubricating reagent to treat a tendon graft in vivo, a novel avenue for improving clinical outcomes of flexor tendon reconstruction. This methodology may also apply to other surgical procedures where postoperative adhesions impair function.

A novel one-dimensional manganese(II) coordination polymer containing both dicyanamide and pyrazinamide ligands: synthesis, spectroscopic investigations, X-ray studies and evaluation of biological activities.

A novel 1D coordination polymer {[Mn(µ1,5-dca)2(PZA)2](PZA)2}n, 1, has been synthesized and characterized by single crystal X-ray crystallography. The coordination mode of dicyanamide (dca) and pyrazinamide (PZA) ligands was inferred by IR spectroscopy. The compound 1 was evaluated for in vitro antimycobacterial and antitumor activities. It demonstrated better in vitro activity against Mycobacterium tuberculosis than pyrazinamide and its MIC value was determined. Complex 1 was also screened for its in vitro antitumor activity towards LM3 and LP07 murine cancer cell lines. In addition, the antibacterial activity of complex 1 has been tested against Gram(+) and Gram(-) bacteria and it has shown promising broad range anti-bacterial activity.

Preemptive Tolerogenic Delivery of Donor Antigens for Permanent Allogeneic Islet Graft Protection.

We have previously developed a robust regimen for tolerance induction in murine models of islet cell transplantation using pre- and posttransplant infusions of donor splenocytes (SPs) treated with a chemical cross-linker ethylcarbodiimide (ECDI). However, the requirement for large numbers of fresh donor SPs for ECDI coupling impairs its clinical feasibility, and additionally, the compatibility of this tolerance regimen with commonly used immunosuppressive drugs is largely unknown. In the current study, we demonstrate that equivalent tolerance efficacy for islet cell transplantation can be successfully achieved not only with a significantly lower dose of ECDI-SPs than originally established but also with culture-expanded donor B-cells or with soluble donor antigens in the form of donor cell lysate, which is ECDI coupled to recipient SPs. We further demonstrate that tolerance induced by donor ECDI-SPs is dependent on a favorable apoptotic-to-necrotic cell ratio post-ECDI coupling and is not affected by a transient course of conventional immunosuppressive drugs including tacrolimus and mycophenolate mofetil. While splenic antigen-presenting cells of the recipient play an important role in mediating the tolerogenic effects of donor ECDI-SPs, splenectomized recipients can be readily tolerized and appear to employ liver Kupffer cells for uptaking and processing of the ECDI-SPs. We conclude that infusion of donor ECDI-SPs is a versatile tolerance strategy that has a high potential for adaptation to clinically feasible regimens for tolerance trials for human islet cell transplantation.

The effects of biological lubricating molecules on flexor tendon reconstruction in a canine allograft model in vivo.

BACKGROUND: Using allograft is an attractive alternative for flexor tendon reconstruction because of the lack of donor-site morbidity, and better matching to the intrasynovial environment. The purpose of this study was to use biological lubricant molecules to modify the graft surface to decrease adhesions and improve digit function. METHODS: Twenty-eight flexor digitorum profundus tendons from the second and fifth digits of 14 dogs were lacerated and repaired to create a model with repair failure and scar digit for tendon reconstruction. Six weeks after the initial operation, the tendons were reconstructed with flexor digitorum profundus allograft tendons obtained from canine cadavers. One graft tendon in each dog was treated with saline as a control and the other was treated with carbodiimide-derivatized hyaluronic acid and gelatin plus lubricin. Six weeks postoperatively, digit function, graft mechanics, and biology were analyzed. RESULTS: Allograft tendons treated with carbodiimide-derivatized hyaluronic acid-lubricin had decreased adhesions at the proximal tendon/graft repair and within the flexor sheath, improved digit function, and increased graft gliding ability. The treatment also reduced the strength at the distal tendon-to-bone repair, but the distal attachment rupture rate was similar for both graft types. Histologic evaluation showed that viable cells migrated to the allograft, but these were limited to the tendon surface. CONCLUSIONS: Carbodiimide-derivatized hyaluronic acid-lubricin treatment of tendon allograft improves digit functional outcomes after flexor tendon reconstruction. However, delayed bone-to-tendon healing should be a caution. Furthermore, the cell infiltration into the allograft tendon substance should be a target for future studies, to shorten the allograft self-regeneration period.