Chondroitin sulfate-polydopamine modified polyethylene terephthalate with extracellular matrix-mimetic immunoregulatory functions for osseointegration.

Optimal integration between the polyethylene terephthalate (PET) graft and host bone is a prerequisite to obtain a satisfactory outcome after graft implantation for ligament reconstruction. Recent studies indicate that complex biosignals including immunoregulation, cell recruitment, and osteogenic differentiation provided by the extracellular matrix (ECM) are conducive to promoting osseointegration. In the present study, a chondroitin sulfate (CS)/polydopamine-modified PET graft was developed to regulate the local immune microenvironment, guide stem cell behavior, and promote new bone formation. We found that CS-modified PET grafts significantly regulated the macrophage phenotype switching from M1 to M2 and promoted the expression of pro-repair cytokines including interleukin (IL)-4, IL-10 and transforming growth factor (TGF)-ß1. Moreover, the immunoregulatory function of CS-modified PET guided stem cell behaviors, including recruitment, adhesion, and proliferation, and enhanced the osteogenic differentiation of stem cells. In vivo experiments confirmed that CS-modified PET switched the local immune microenvironment status from pro-inflammatory to anti-inflammatory, up-regulated osteogenic marker expression, and promoted the bone regeneration process, so as to achieve graft-bone osseointegration. These results indicate that an ECM-biomimetic immunoregulatory coating is an effective approach to promote graft integration. This study proposes an effective strategy for an artificial graft to achieve graft-bone osseointegration through immunoregulatory osteogenesis.

Preparation of hemoglobin-loaded nano-sized particles with porous structure as oxygen carriers.

Hb (hemoglobin)-loaded particles (HbP) encapsulated by a biodegradable polymer used as oxygen carrier were prepared. A modified double emulsion and solvent diffusion/evaporation method was adopted. All experiments were performed based on two types of biodegradable polymers, poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone-ethylene glycol) (PCL-PEG). The biodistribution and the survival time in blood of the particles were investigated in a mouse model. Encapsulation efficiency and pore-connecting efficiency were evaluated by a novel sulfocyanate potassium method. The influence of process parameters on the particle size and pore-connecting efficiency (PCE%) of nanoparticles have been discussed. The prepared conditions: solvent, external aqueous phase, pressure were discussed. The system utilizing dichloromethane (DCM)/ethyl acetate (EA) as a solvent with an unsaturated external aqueous phase yielded the highest encapsulation efficiency (87.35%) with a small mean particle size (153 nm). The formation of porous channels was attributed to the diffusion of solvent. The PCE% was more sensitive to the rate of solvent diffusion that was obviously affected by the preparation temperature. The PCE% reached 87.47% when PCL-PEG was employed at 25 degrees C. P(50) of HbP was 27 mmHg, which does not seem to be greatly affected by the encapsulation procedure. In vivo, following intravenous injection of 6-coumarin labeled HbP, the major organ accumulating Hb-loaded particles was the liver. The half-life of nano-sized PCL HbP was 3.1 times as long as the micro-sized PCL HbP. Also, Nano-sized as well as a PEGylated surface on HbP is beneficial for prolonged blood residence (7.2 fold increase).

Enteric-coated capsules filled with mono-disperse micro-particles containing PLGA-lipid-PEG nanoparticles for oral delivery of insulin.

The success of the oral delivery of insulin (INS) as a therapeutic protein drug would significantly improve the quality of life of diabetic patients who would otherwise receive multiple daily INS injections. The oral delivery of INS, however, is still limited in its delivery efficiency, which could be due to the chemical, enzymatic, and adsorption barriers. In this work, in an attempt to improve the delivery efficiency, the INS-loaded polymer-lipid hybrid nanoparticles (INS-PLGA-lipid-PEG NPs) were designed and constructed through a double-emulsion solvent evaporation technique, followed by formulation of the spherical micro-particles using a spray freeze dryer (SFD). This kind of dryers has a uniquely designed microfluidic aerosol nozzle (MFAN), ensuring the formation of uniform particles. The resulted particles of ∼212 µm could easily be reverted to discrete INS-PLGA-lipid-PEG NPs in an aqueous solution. The INS-PLGA-lipid-PEG NPs created in this work showed a highly negative surface charge, excellent entrapment efficiency (92.3%) and a sustained drug release (∼24 h). Confocal laser scanning microscopy and flow cytometer were used to show that the cellular uptake efficiency for the INS-PLGA-lipid-PEG NPs was more effective than the INS in Caco-2 cells. More importantly, the in vivo pharmacodynamics demonstrated that the orally delivered system induced a prolonged decrease in blood glucose levels among diabetic rats. The relative bioavailability of INS compared with subcutaneous injection in diabetic rats was found to be approximately 12%. These results suggested that the encapsulated INS-PLGA-lipid-PEG NPs are promising and should be investigated further in the near future as an effective INS oral delivery system.

Subtype-specific binding peptides enhance the therapeutic efficacy of nanomedicine in the treatment of ovarian cancer.

Currently, epithelial ovarian cancer is viewed as a heterogeneous disease with five major histological subtypes. Clear cell carcinoma represents a specific histological subtype of epithelial ovarian cancer that demonstrates more aggressive clinical behavior and drug resistance compared with other subtypes. Nevertheless, clear cell carcinoma is treated in the same manner as the other subtypes without any particular consideration to its unique clinical characteristics. To improve the therapeutic efficacy of the current liposomal doxorubicin approach for the treatment of clear cell carcinoma, we aimed to develop a novel peptide-conjugated liposomal doxorubicin to actively target this subtype. Two phage clones (OC-6 and OC-26) that specifically bound to clear cell carcinoma were isolated from a phage peptide display library after biopanning procedures. The peptide sequences were translated and aligned (OCSP-6 for OC-6, and OCSP-26 for OC-26, respectively). Peptide-conjugated nanoparticles demonstrated better tumor endocytosis and time-dependent gradual increase of intracellular drug uptake than non-targeting liposomal nanoparticles. Furthermore, peptide-conjugated liposomal doxorubicin better controlled tumors than did non-targeting liposomal doxorubicin. The current work may pave a new way for the development of drugs that target each subtype of epithelial ovarian cancer in the future.

[Synthesis of nanometer hydroxyapatite by sol-gel method].

OBJECTIVE: To synthesize nanometer hydroxyapatite (HAP) by sol-gel method from Ca (NO3)2.4H2O and PO (CH3O)3 with water and ethanol as solvents and to study the factors that can affect the formation of sol-gel, including the type of solvents, amount of solvents, pH value, as well as properties under the condition of low temperature combustion of dried gel. METHODS: The viscosities of sol were determined on WU viscosimeter. TG-DTA was used to analyze the thermal procedure of dried gel by increasing temperature. Characterization of the dried gel and powder after combustion were evaluated by X-ray diffraction and infrared spectrum. The morphology of the powder was observed by transmission electron microscopy. RESULTS: Stable and homogeneous gel could be obtained at appropriate pH value when ethylene glycol was added into solvent. The dried gel had the feature of low temperature combustion. HAP powder with particle size of 50 nm was directly prepared. CONCLUSION: Nanometer HAP powder with uniform particle size can be synthesized by sol-gel method.

Controlled preparation and antitumor efficacy of vitamin E TPGS-functionalized PLGA nanoparticles for delivery of paclitaxel.

Vitamin E TPGS-functionalized polymeric nanoparticles have been developed as a promising drug delivery platform in recent years. Obtaining reproducible monodisperse TPGS/polymeric nanoparticles with high encapsulation efficiency (EE%) still remains a big challenge. In this study, an inverse-phase nanoprecipitation method was developed to synthesize TPGS-functionalized PLGA nanoparticles (TPNs) for controlled release of paclitaxel (PTX). To take advantages of lipids, a part of TPGS in the TPNs was replaced by lipids. The results showed that with weight ratio of TPGS-to-PLGA of 2-3 and a molar replacement of lecithin ratio of 30%, the PTX-loaded TPNs (PTPNs) and PTX-loaded lipid-containing TPNs (PLTPNs) exhibited controllable and nearly uniform size of 130-150nm and EE% of over 80%. Compared to Taxol(®), both the PTPNs and PLTPNs significantly increased the intracellular uptake and exerted strong inhibitory effect on human lung cancer A549 model cells. Furthermore, a selective accumulation to tumor site and significant antitumor efficacy of TPNs in the A549 lung cancer xenografted nude mice were observed by intravenous administration, especially for the PTPNs group. Our data suggested that the inverse-phase nanoprecipitation method holds great potential for the fabrication of the paclitaxel-loaded TPNs and the TPNs prepared here is a promising controllable delivery system for paclitaxel.

Study of pharmacokinetics and tissue distribution of liposomal brucine for dermal administration.

OBJECTIVE: To evaluate the pharmacokinetics and tissue distribution of liposomal brucine (LB) for dermal application. METHODS: Pharmacokinetics and tissue distribution were studied by in vivo animal testing. High performance liquid chromatography (HPLC) was used to detect the concentration of brucine in rats' skin, plasma and various tissues. RESULTS: After dermal administration, LB was absorbed rapidly in the skin and could be detected after 0.5 hours. After 36 hours, levels were too low to be detected. In plasma, levels were also too low to be detected after 36 hours. The concentration of LB reached 50% of the maximum in all tissues except the brain, peaking after 1.5 hours but still detectable after 12 hours. CONCLUSION: The concentration of LB was high in skin at the application site. LB was quickly absorbed into tissues through the blood circulation and widely distributed throughout the whole body. There was no obvious toxicity and LB did not readily accumulate in tissues and organs. It showed local potency but low overall systemic toxicity.

[The experimental study on porous calcium phosphate cement with bone marrow stromal cells for bone tissue engineering].

OBJECTIVE: To observe the biocompatibility of new biomaterials porous calcium phosphate (CPC) and ectopic bone formation of CPC with bone marrow stromal cells (BMSCs). METHODS: The BMSCs were cultured from Beagle dog and combined with the porous CPC with the best concentration after transfect green fluorescent protein (GFP). The adhesion and growth of BMSCs on CPC were observed under inversion, fluorescence and scanning electron microscopy. The ectopic bone formation were observed at the 8th week after CPC and BMSCs were implanted subcutaneously into nude mice. RESULTS: When BMSCs with CPC were cultured at the 1st day, cells were climbing out from CPC with normal morphology. At the 7th day cells can be seen protruding pseudopods, secretion of matrix. Bone formation could be seen histomorphologically at the 8th week. CONCLUSION: Porous CPC has good biocompatibility and is an ideal scaffold material for bone tissue engineering.

Preparation of liposomal brucine and its pharmaceutical/pharmacodynamic characterization.

AIM: To prepare a novel transdermal preparation of liposomal brucine (LB) and investigate its pharmaceutical/pharmacodynamic characterization. METHODS: LB was prepared by a modified ethanol-dripping method. Its drug encapsulation efficiency (EE), particle size, in vitro release, and skin permeation were studied. Furthermore, a safety evaluation and pharmacodynamic analysis of LB, including acute dermal toxicity, skin irritation, and analgesic and anti-inflammatory effects were investigated. RESULTS: the EE of LB was 72% and the mean particle size of the liposomes was 55.4 nm. The in vitro release profile indicated that less than 68% of the encapsulated brucine was released in 10 h. A skin permeation study showed that compared with the free brucine, LB exhibited higher cumulative drug permeation through the skin and lower drug accumulation in skin tissue, indicative of an obvious promotion of skin permeation with liposomal encapsulation. The acute dermal LD50 of LB was greater than 100 mg/kg (brucine content) and skin irritation tests revealed that LB had no irritation to both integrity and broken skin. A pharmacodynamic evaluation of LB was performed by xylene-induced mouse ear edema test and acetic acid-induced writhing test at the dosage of 1.5, 3, and 6 mg/kg, respectively. The results showed that anti-inflammatory activities and analgesic effects of brucine encapsulated were significantly higher than that of the free brucine (P<0.01). Moreover, LB maintained a remarkably longer antiinflammatory and analgesic duration. CONCLUSION: It can be proposed that LB prepared here could represent a safe, effective and promising transdermal formulation for analgesic and anti-inflammatory effects.