Zhiwen Jiang

Carboxymethyl chitosan represses tumor angiogenesis in vitro and in vivo.

Carboxymethyl chitosan (CMCS), with potent water solubility, biocompatibility, and non-toxicity, has emerged as a promising candidate for biomedical applications. In this study, the anti-tumor angiogenesis effects of CMCS were evaluated in vitro and in vivo. Our results showed that CMCS could inhibit the 2-dimensional and 3-dimensional migration of human umbilical vein endothelial cells (HUVECs) in vitro. CMCS significantly inhibited the growth of mouse hepatocarcinoma 22 tissues and could promote tumor cell necrosis as suggested by pathological observations. The CD34 expression in H22 tumor tissue, the levels of vascular endothelial growth factor and tissue inhibitor of metalloproteinase 1 in serum was regulated by CMCS treatment. CMCS could significantly improve thymus index, spleen index, tumor necrosis factor α and interferon γ level. In a conclusion, CMCS possessed potent anti-tumor effects by inhibiting tumor angiogenesis, stimulating immune functions. Our date provide more foundation for application of CMCS in biomedicine or biomaterials for targeted anticancer drugs delivery.

Synthesis of a chitosan-based photo-sensitive hydrogel and its biocompatibility and biodegradability

Hydroxyethyl chitosan (HECTS) is one of the most important water soluble derivatives of chitosan. In this study, photo-sensitive azidehydroxyethyl chitosan (AZ-HECTS) was synthesized with grafting degree 3.4%, and its water solution resulted in an insoluble hydrogel by 254nm UV irradiation for 90s. AZ-HECTS hydrogels, with water absorption 86.21%, had little impact on growth of mouse fibroblast (L929) and presented good cell biocompatibility. Obvious sudden degradation stage, slow degradation stage and no apparent toxicity was observed after AZ-HECTS hydrogels implanted into rats, and tissue inflammation was slighter, which indicated favorable biological safety. Furthermore, AZ-HECTS hydrogels was loaded with heparin, and released 50% of heparin accumulated 14d. AZ-HECTS-heparin hydrogels showed inhibitory effects on L929, and pro-growth functions within vascular endothelial cells seeded on the hydrogels, meanwhile a positive influence on vascular endothelial growth factor expression. In conclusion, AZ-HECTS hydrogels possessed favorable biocompatibility and biodegradability and had good potential as drug carrier.

Fabrication and feasibility study of an absorbable diacetyl chitin surgical suture for wound healing

Diacetyl chitin (DAC) is an acidylated chitin obtained using acetic anhydride mixed perchloric acid system. By wet spinning and weaving technique, DAC has been successfully developed into a novel absorbable surgical suture. Thanks to the unique properties of chitins, the potential application of this novel monocomponent multifilament DAC suture may break the monopoly of synthetic polymer sutures in wound closure area. In this study, DAC was synthesized and characterized by multiple approaches including elemental analysis, Fourier transform infrared spectrometry (FTIR), and X-ray diffraction (XRD). In addition, we performed the feasibility assessment of DAC suture (USP 2-0) as absorbable suture for wound healing. Several lines of evidences suggested that DAC suture had comparable mechanical properties as synthetic polymer sutures. Moreover, DAC suture retained approximately 63% of the original strength at 14 days and completely absorbed in 42 days with no remarkable tissue reaction in vivo. Most important of all, DAC suture significantly promoted skin regeneration with faster tissue reconstruction and higher wound breaking strength on a linear incisional wound model. All these results demonstrated the potential use of DAC suture in short- or middle-term wound healing, such as epithelial and connective tissue.

Preparation and anti-tumor metastasis of carboxymethyl chitosan

Carboxymethyl chitosan (CMCS), one of the most important water soluble chitosan derivatives, has great potentials in biomedical applications due to its excellent water solubility, biodegradability, biocompatibility, and non-toxicity. In the present study, the anti-tumor metastasis effect of CMCS on hepatic tumors was evaluated using human hepatic cancer cell BEL-7402 and mouse hepatoma 22 cells. The results suggested that CMCS could significantly inhibit tumor cell migration in vitro, and reduce the expression of matrix metalloproteinase-9 in BEL-7402 cells in a dose-dependent manner (P<0.05). Furthermore, CMCS significantly inhibited the lung metastasis of hepatoma-22 in Kunming mice (P<0.05). Significant improvement of the lung injury caused by the metastasis of H22 was also observed. The results suggested that the inhibitory effect of CMCS could be attributed in part to the decreased levels of vascular endothelial growth factor and E-selectin in CMCS treated mice.

Pharmacokinetics and biodegradation of chitosan in rats

Chitosan, an excellent biomedical material, has received a widespread in vivo application. In contrast, its metabolism and distribution once being implanted were less documented. In this study, the pharmacokinetics and biodegradation of fluorescein isothiocyanate (FITC) labeled and muscle implantation administrated chitosan in rats were investigated with fluorescence spectrophotometry, histological assay and gel chromatography. After implantation, chitosan was degraded gradually during its distribution to diverse organs. Among the tested organs, liver and kidney were found to be the first two highest in chitosan content, which was followed by heart, brain and spleen. Urinary excretion was believed to be the major pathway of chitosan elimination, yet 80% of chitosan administered to rats was not trackable in their urine. This indicated that the majority of chitosan was degraded in tissues. In average, the molecular weight of the degradation products of chitosan in diverse organs and urine was found to be <65 kDa. This further confirmed the in vivo degradation of chitosan. Our findings provided new evidences for the intensive and safe application of chitosan as a biomedical material.

Preparation and pharmacological evaluation of norcantharidin-conjugated carboxymethyl chitosan in mice bearing hepatocellular carcinoma

In this study, norcantharidin (NCTD), a small-molecule anticancer drug derived from Chinese traditional medicine blister beetle (Mylabris), was conjugated covalently onto carboxymethyl chitosan (CMCS). Then the hepatocellular carcinoma therapeutic properties and liver-protective effects were investigated through orthotopic transplantation tumor model. Results showed that the obtained CMCS-NCTD demonstrated remarkable anti-growth efficacy against hepatocellular 22 in mice. Significant improvement of the liver injury caused by cancer cells was observed in tumor-bearing mice administrated with CMCS-NCTD. Moreover, CMCS-NCTD remarkably increased the serum levels of TNF-α, IFN-γ, TIMP-1 and E-cadherin in mice treated for 12days. Administration of CMCS-NCTD significantly reduced the elevated serum ALT, AST, VEGF and MMP-9 levels of tumor-bearing mice. In addition, activities of SOD and GSH-Px in serum or homogenate of the CMCS-NCTD treated mice were significantly high when compared with model control group. Our data suggested that CMCS-NCTD was a promising candidate as an anti-hepatoma and liver-protection compound.

Carboxymethyl chitosan/gelatin/hyaluronic acid blended-membranes as epithelia transplanting scaffold for corneal wound healing

There is an unmet need for an optimal scaffold as cell transplantation carrier to induce corneal reconstruction. In this study, a blend membrane was prepared with carboxymethyl chitosan (CMCTS), gelatin, and hyaluronic acid. To investigate its cytocompatibility, primary rabbit corneal epithelial cells (CEpCs) were seeded on it and growth and proliferation were evaluated. The blend membrane was found to be transparent, biodegradable, and suitable for CEpCs attachment and proliferation, which could maintain the epithelial cell-like protein expression of CEpCs. The combination of CEpCs and CMCTS-blended membrane (CEpCs/CMCTS membrane) was used to treat alkali-induced corneal damage in rabbits and healing effects were evaluated by visual observation, slit lamp, hematoxylin-eosin and immunofluorescence staining. CEpCs/CMCTS membrane could improve corneal epithelial reconstruction significantly and restore cornea transparency and thickness. Hence, this combination treatment may serve as a rapid and effective way for corneal wound healing.

Biomechanical properties and healing effects of chitin patch in a rat full‐thickness abdominal wall defect model

Hernia repair is usually accompanied with the implantation of a synthetic mesh, which frequently results in a foreign body response and serious complications. In the present study, a novel biodegradable chitin-based hernia patch was prepared and characterized. Biomechanical properties and biodegradability of the chitin patch were quantified in vitro and in vivo. In repair of the rat abdominal wall full-thickness defect model, the chitin patch induced more abundant new blood vessels with milder tissue inflammation and fibrosis compared with polypropylene mesh. Chitin patch effectively inhibited excessive secretion of inflammation-associated cytokines (IL-6 and TNF-α) (p < 0.01) and significantly increased the secretion of healing-related cytokines (FGF1 and TGF-β1) (p < 0.01). Accompanied by biodegradation of the chitin patch, intra-abdominal adhesions caused by the chitin patch decreased significantly, and the tensile strength of the repaired site could meet the biomechanical requirements of human abdominal wall. After the one-year observation period, the defected abdominal wall returned to the appropriate thickness with no obvious complication or hernia occurrence. In a conclusion, the newly designed chitin patch showed good biomechanical properties and satisfactory healing effects on the full-thickness defect of abdominal wall, which makes it promising candidate for clinical hernia treatment.

Evaluation of a photocrosslinkable hydroxyethyl chitosan hydrogel as a potential drug release system for glaucoma surgery

Hydroxyethyl chitosan (HECTS) is a critical derivative of chitosan that has been widely used as biomedical materials due to great water-solubility and excellent biocompatibility. Here, photosensitive hydroxyethyl chitosan was synthesized by introducing azide group on NH2 of HECTS (HECTS-AZ), afterwards FTIR and 1H NMR spectra were detected to confirm the formation of HECTS-AZ. The solution of HECTS-AZ can achieve a sol–gel transition through UV irradiation for 30 s. The evaluation of biocompability and biodegradability in vivo was conducted in rats, visual and pathological examinations exhibited the HECTS-AZ has excellent biocompability and degradation time of the hydrogel is more than 14 weeks. Furthermore, HECTS-AZ hydrogel as an ocular drug delivery system loading heparin was prepared to implant under sclera of rabbit after glaucoma filtration surgery (GFS). The experimental results demonstrated the heparin loaded hydrogel can effectively maintain filtration bleb and lowing intraocular pressure (IOP) after GFS for prolonged time. Besides, obvious inflammatory reactions and side effects have not been observed in ocular during the experimental period. In conclusion, the HECTS-AZ hydrogel is a potential drug delivery device for the treatment of glaucoma and other ocular diseases.Graphical abstract

Study of a new biodegradable hernia patch to repair abdominal wall defect in rats

A novel biodegradable chitin hernia patch was prepared by acetylation of chitosan fabric in our study. Physicochemical properties, cell compatibility and biodegradability of the chitin patch were quantified. Histopathological study of the functional experiment showed that this newly designed hernia patch promoted collagen deposition and neovascularization by significantly promoting the secretion of FGF1 and TGF-β1 in the early postoperative (P<0.01). Chitin patch caused less inflammation by inhibiting excessive expression of IL-6 and TNF-α when compared to the polypropylene mesh (P<0.01). Acceptable fibrosis was consistent with the results of immunohistochemistry studies. The density of FGF1 and TGF-β1 positive cells in the chitin patch group at 7 d was reduced to a lower level at 15 d (P<0.01). With regeneration of the defect abdominal wall, chitin patch degraded gradually, avoiding foreign body response and chronic complications. Our studies demonstrated that the newly designed chitin patch showed good promise for the hernia treatment.