Injectable thermogelling chitosan for the local delivery of bone morphogenetic protein.

The aim of the present study was to evaluate the in vivo biocompatibility of injectable thermo gelling chitosan-ammonium hydrogen phosphate solution (chitosan-AHP) and its efficacy to deliver recombinant human bone morphogenetic protein-2 (rhBMP-2) in a bioactive form. The thermogel showed a typical foreign body response upon subcutaneous implantation surrounded by a fibrous capsule. Even at 4 and 8 weeks post implantation, significant neutrophil infiltration was observed within the gel. Chitosan-AHP gel retained most of the loaded rhBMP-2 after a small initial release. The bioactivity of the released protein was demonstrated in vitro by the increase in alkaline phosphatase activity of mouse pre osteoblast cells (MC3T3-E1). Histological and micro-computed tomography (µCT) evaluation showed evidence of ectopic bone formation upon 4 µg/mL rhBMP-2 loaded chitosan-AHP injection. The study demonstrated a neutrophil mediated local tissue response to chitosan-AHP gel and its ability to encapsulate and maintain the bioactivity of rhBMP-2.

Evaluation of the value of Preoperative Sialic Acid Levels in Diagnosis and Localization of Urothelial Tumors.

Objective: To explore SA levels in the serum of urothelial tumor patients and their correlation with clinical pathological features and localization. Materials and Methods: Our research retrospectively collected data from 591 patients with urothelial tumors between July 2014 and April 2018. The SA levels in the serum of urothelial tumor patients and their correlation with clinical pathological features and localization were investigated. Univariate and multivariate logistic regression analyses were further performed to identify independent associations. Results: The levels of SA were significantly associated with the malignant degree (tumor grade and infiltration) of bladder cancer and tumor localization (all p < 0.05). The multivariate logistic regression model showed that SA levels were independently associated with the presence of high-grade urothelial carcinoma (BUC: HR = 1.941, UTUC: HR = 3.820, all p <0.05) and upper urinary tract urothelial carcinoma (HR = 2.047, p < 0.05). Finally, we validated the diagnosis and localization value of SA in an independent cohort from another institutions. Conclusions: Elevated serum SA levels are an independent predictor of high-grade urothelial carcinoma and upper urinary tract urothelial carcinoma, indicating that SA levels may be a potential biomarker for the diagnosis, prognosis and localization of urothelial tumors.

The Value of Preoperative Alpha-L-Fucosidase Levels in Evaluation of Malignancy and Differential Diagnosis of Urothelial Neoplasms.

PURPOSE: To evaluate the role of Alpha-L-fucosidase (AFU) in diagnosis and differential diagnosis of pure urothelial carcinoma (UC), urothelial carcinoma with squamous differentiation (UCSD), and squamous cell carcinoma (SqCC). METHODS: A retrospective study was performed for 599 patients who were histologically confirmed with urothelial tumor. Preoperative AFU levels were compared across the distinct subgroups with different clinicopathological parameters. ROC curve analysis and logistic regression analysis were performed to further evaluate the clinical application value of serum AFU levels in diagnosis and differential diagnosis of urothelial tumors. RESULTS: There were no statistically significant differences in the AFU levels between different groups with different malignant degrees (UC versus papilloma and papillary urothelial neoplasm of low malignant potential [PUNLMP], high-grade UC versus low-grade UC, invasive versus noninvasive malignant uroepithelial tumor) and different pathological types (UC, UCSD, and SqCC) (all P > 0.05). ROC curve analysis and logistic regression analysis showed that there was no statistically significant association between AFU levels and the tumor characteristics (all P > 0.05). CONCLUSIONS: Preoperative AFU levels cannot serve as a reliable predictor for malignant degree and differential diagnosis, including pure UC, UCSD, and SqCC of urothelial tumors.

Enzymatically cross-linked bovine lactoferrin as injectable hydrogel for cell delivery.

Lactoferrin (LF), a 78 kDa glycoprotein, has recently been recognized as an effector molecule in the skeleton due to its ability to decrease osteoclastogenesis and increase osteoblast proliferation, survival, and differentiation. The objective of the study is to investigate the feasibility of developing an injectable hydrogel from bovine lactoferrin (bLF) as a cell delivery vehicle. The study demonstrated the feasibility of cross-linking tyramine substituted bLF in the presence of horse radish peroxidase and hydrogen peroxide (H2O2). The gel presented a mild environment to maintain mouse bone marrow-derived stromal cell (mBMSC) viability and proliferation. Stromal cells derived from multiple gene reporter transgenic mouse (Ibsp-Topaz/Dmp1-mCherry) line showed the ability of the cells to undergo osteogenic differentiation in the hydrogel when cultured in mineralization media. The cross-linked gel supported protein phosphorylation/de-phosphorylation in the encapsulated MC3T3-E1 cells. bLF and bLF gel also showed the ability to modulate growth factor production in mBMSCs.

A chitosan thermogel for delivery of ropivacaine in regional musculoskeletal anesthesia.

Postoperative pain within the first days following musculoskeletal surgeries is a significant problem for which appropriate management correlates to positive clinical outcomes. While a variety of pain management modalities are currently used for postoperative pain, an optimal strategy has yet to be identified. Utilizing local anesthetics to convey analgesia through neural blockade represents a promising approach to alleviate postoperative pain. Unfortunately, local anesthetics are often associated with short half-lives, local tissue site reactions, and systemic toxicity. Drug delivery systems such as liposomes, microparticles, and nanoparticles have been previously utilized to extend analgesia, but these systems can easily diffuse from the injection site. In order to overcome this limitation a combination of drug delivery technologies were utilized. Ropivacaine base nanoparticles were fabricated and entrapped with dexamethasone using a chitosan thermogel delivery system in order to enhance neural blockade. Using a rat sciatic neural blockade model, this system was able to limit sensory function and motor function for up to 48 h. This approach utilized a low solubility drug, a drug action enhancer, nanoparticles, and a thermogel matrix together to yield a multi-faceted delivery system capable of providing moderate-term pain management.

In vitro and in vivo demonstration of physically and chemically in situ gelling NIPAAm-based copolymer system.

Poly(NIPAAm-co-hydroxyethylmethacarylate (HEMA)) acrylate and poly(NIPAAm-co-cysteine ethyl ester (CysOEt)) were synthesized and characterized by GPC(gel permeation chromatography), rheology, NMR (nuclear magnetic resonance), and Ellman's method. Upon mixing of these materials in aqueous solution, they formed gels immediately at body temperature owing to temperature-driven physical gelling, and gradually cured by chemical cross-linking through Michael-type addition reactions between thiols and acrylates. The rate of nucleophilic attack in the Michael-type addition reaction was shown to be highly dependent on the mole ratio of thiol to acrylate at neutral pH. Physical and chemical gelation improved the mechanical properties of the materials compared to purely physical gels. In vitro and in vivo results revealed that chemical and physical gels formed stiffer less viscoelastic materials compared to purely physical gels. Physical and chemical gel systems using thermosensitive polymer with acrylates and thermosensitive polymer with thiols showed minimum toxicity.

Degradation, cytotoxicity, and biocompatibility of NIPAAm-based thermosensitive, injectable, and bioresorbable polymer hydrogels.

A thermosensitive, injectable, and bioresorbable polymer hydrogel, poly(N-isopropylacrylamide-co-dimethyl-γ-butyrolactone acrylate-co-acrylic acid) [poly(NDBA)], was synthesized by radical copolymerization with 7.00 mol % dimethyl-γ-butyrolactone acrylate in tetrahydrofuran. The chemical composition was determined by acid titration in conjunction with (1) H NMR quantification. The molecular weight and polydispersity were determined by gel permeation chromatography in conjunction with static light scattering. The degradation properties of the polymer hydrogel were characterized using differential scanning calorimetry, percentage mass loss, cloud point test, and swelling ratio over time. It was found that the initial lower critical solution temperature (LCST) of the polymer is between room temperature and body temperature and that it takes about 2 weeks for the LCST to surpass body temperature under physiological conditions. An indirect cytotoxicity test indicated that this copolymer has relatively low cytotoxicity as seen with 3T3 fibroblast cells. The in vivo-gelation and degradation study showed good agreement with in vitro-degradation findings, and no detrimental effects to adjacent tissues were observed after the complete dissolution of the polymer. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.

Manipulating degradation time in a N-isopropylacrylamide-based co-polymer with hydrolysis-dependent LCST.

A thermosensitive, bioresorbable and in situ gelling co-polymer, poly(N-isopropylacrylamide-co-dimethyl-gamma-butyrolactone acrylate-co-acrylic acid), was synthesized by radical co-polymerization with varying dimethyl-gamma-butyrolactone acrylate (DBA) content. The materials properties were characterized using differential scanning calorimetry, gel-permeation chromatography in conjunction with static light scattering, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and acid titration. The initial lower critical solution temperature (LCST) of the synthesized co-polymer is between room temperature and body temperature. With the increase of DBA content, the LCST decreases, but then increases after the ring-opening hydrolysis of the DBA side-group. The FT-IR and NMR spectra show the co-polymerization of three monomers, as well as the hydrolysis-dependent ring-opening of the DBA side-group. The addition of acrylic acid increases the initial LCST and accelerates the degradation rate of the co-polymer. An indirect cytotoxicity test indicated that this co-polymer has relatively low cytotoxicity as seen with 3T3 fibroblast cells.

In vivo evaluation of injectable thermosensitive polymer with time-dependent LCST.

The focus of this study was to examine the biocompatibility, time-dependent LCST, and bioerodable properties of a copolymer system composed of NIPAAm, dimethyl-gamma-butyrolactone (DMBL), and acrylic acid (AAc). Sprague Dawley rats were subcutaneously injected with 25 wt % solutions of poly(NIPAAm-co-DMBL-co-AAc). At predetermined times, animals were sacrificed and polymer implants were recovered for characterization via 1H-NMR. In addition, polymer-contacting tissue sections were harvested and processed for histology. The biocompatibility of the implants was assessed by counting the number of fibroblasts and leukocytes present at the tissue-implant interface. The LCST data obtained from the in vivo implants was shown to agree with that of in vitro findings. Implant mass was shown to decrease after 4 days, indicating accelerated diffusion rates with increased implant swelling, hydrolytic degradation was confirmed with 1H-NMR measurements. The cellular presence at the copolymer implant-tissue interface was shown to return to that of normal tissue 30 days postimplantation, which suggests a normal wound healing response.

New hydrolysis-dependent thermosensitive polymer for an injectable degradable system.

Novel, bioerodible, thermosensitive poly(NIPAAm-co-dimethyl-gamma-butyrolactone acrylate), with a hydrolysis-dependent thermosensitivity, was synthesized by radical polymerization with a varying dimethyl-gamma-butyrolactone acrylate (DBA) content, and the properties of the copolymers were characterized using differential scanning calorimetry, gel permeation chromatography in conjunction with static light scattering, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and acid titration. The lower critical solution temperature of the copolymers decreases with increasing DBA content, but then increases after ring-opening hydrolysis of the DBA side group. FTIR and NMR spectra showed the copolymerization of these two monomers and the hydrolysis-dependent ring-opening of the DBA side group. It was also found that there are no low-molecular-weight byproducts but rather dissolution of the polymer chains at 37 degrees C during the time frame of application. Models of the kinetics suggest that the hydrolysis reaction is self-catalytic due to an increase in hydrophilicity and charge, and thus accessible water concentration, caused by ring-opening of the DBA.