No abstract

Injectable polycaprolactone (PCL) porous beads were fabricated for use as cell carriers by a novel isolated particle-melting method (for nonporous beads) and the following melt-molding particulate-leaching method (for porous beads). The prepared beads showed highly porous and uniform pore structures with almost the same surface and interior porosities (porosity, over 90%). The PCL porous beads (bead size, 400-550 microm) with different pore sizes (25-50 and 50-100 microm) were compared for their in vitro cell (human chondrocyte) growth behavior with the nonporous beads. The porous beads showed higher cell seeding density and growth than the nonporous beads. The pore size effect between the porous beads was not significant up to 7 days, but after that time the beads with pore sizes of 50-100 microm showed significantly higher cell growth than those of 25-50 microm. To evaluate the tissue compatibility of the PCL porous beads, the beads were dispersed, uniformly, in cold Pluronic F127 solution and injected into hairless mice, subcutaneously, in the gel state of Pluronic F127 at room temperature, leading to the homogeneous bead delivery. The histological findings confirmed that the PCL porous beads in Pluronic F127 gel are biocompatible: surrounding tissues gradually infiltrated into the porous beads for up to 4 weeks with little inflammatory response. The PCL porous beads with highly porous and uniform pore structures fabricated in this study can be widely applicable as cell carriers.

In order to induce the chondrogenesis of mesenchymal stem cells (MSCs) in tissue engineering, a variety of growth factors have been adapted and encouraging results have been demonstrated. In this study, we developed a delivery system for dual growth factors using a gelation rate controllable alginate solution (containing BMP-7) and polyion complex nanoparticles (containing TGF-beta(2)) to be applied for the chondrogenesis of MSCs. The dual growth factors (BMP-7/TGF-beta(2))-loaded nanoparticle/hydrogel system showed a controlled release of both growth factors: a faster release of BMP-7 and a slower release of TGF-beta(2), ca., approximately 80 and 30% release at the end of an incubation period (21 days), respectively, which may be highly desirable for chondrogenic differentiation of MSCs. On the contrary, the release of each growth factor from the dual growth factors-loaded hydrogel (without the nanoparticles) was much slower than that of the nanoparticle/hydrogel system, approximately 36% (BMP-7) and 16% (TGF-beta(2)) for 21 days, and this is more than likely attributed to the aggregation between growth factors during the hydrogel fabrication step. The nanoparticle/hydrogel system with separate growth factor loading may provide desirable growth factor delivery kinetics for cartilage regeneration, as well as the chondrogenesis of MSCs.

Liver fibrosis is a common outcome of chronic liver disease and leads to liver cirrhosis and hepatocellular carcinoma. No FDA-approved targeted anti-fibrotic therapy exists. Activated hepatic stellate cells (aHSCs) are the major cell types responsible for liver fibrosis; therefore, eradication of aHSCs, while preserving quiescent HSCs and other normal cells, is a logical strategy to stop and/or reverse liver fibrogenesis/fibrosis. However, there are no effective approaches to specifically deplete aHSCs during fibrosis without systemic toxicity. aHSCs are associated with elevated expression of death receptors (DRs) and become sensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cell death. Treatment with recombinant TRAIL could be a potential strategy to ameliorate liver fibrosis; however, the therapeutic application of recombinant TRAIL is halted due to its very short half-life. To overcome this problem, we previously generated PEGylated TRAIL (TRAILPEG) that has a much longer half-life in rodents than native-type TRAIL. Here, we demonstrate that intravenous TRAILPEG has a markedly extended half-life over native-type TRAIL in non-human primates and has no toxicity in primary human hepatocytes. Intravenous injection of TRAILPEG directly induces apoptosis of aHSCs in vivo and ameliorates carbon tetrachloride-induced fibrosis/cirrhosis in rats by simultaneously down-regulating multiple key fibrotic markers that are associated with aHSCs. In conclusion, TRAIL-based therapies could serve as new therapeutics for liver fibrosis/cirrhosis and possibly other fibrotic diseases.

No abstract

Chitosans with different degree of acetylation (DA, 10-50%) were synthesized by the acetylation reaction of deacetylated chitosan and acetic anhydride with different ratios. The porous beads (approx. 500 mum) fabricated from the acetylated chitosans were used to investigate the degradation behaviors of chitosans with different DA in vitro and in vivo. The in vitro degradation behavior of the acetylated chitosan beads was investigated in solutions of lysozyme and/or N-acetyl-beta-D-glucosaminidase (NAGase), which are enzymes for chitosan present in the human body. It was observed that the degradation rate of acetylated chitosans can be controlled by adjusting the DA value: the degradation increased with increasing DA value of the acetylated chitosans. It seemed that NAGase plays an important role for the full degradation of chitosans in the body, even though NAGase itself can not initiate the degradation of chitosans. The in vitro degradation behavior of the chitosans in the mixture solution of lysozyme and NAGase was more similar to the in vivo degradation behavior than in the single lysozyme or NAGase solution. It may be owing to the sequential degradation reaction of chitosans in the mixture solution of lysozyme and NAGase (initial degradation by lysozyme to low-molecular-weight species or oligomers and the following degradation by NAGase to monomer forms). The in vivo degradation rate of acetylated chitosan beads was faster than the in vitro degradation rate. The acetylated chitosan porous beads with different DA value (and thus different degradation time) can be widely applicable as cell carriers for tissue-engineering applications.

Although elevated resting heart rate (RHR) has been shown to be associated with mortality in the general population and patients with certain diseases, no study has examined this association in patients with breast cancer. A total of 4786 patients with stage I-III breast cancer were retrospectively selected from the Severance hospital breast cancer registry in Seoul, Korea. RHR was measured at baseline and the mean follow-up time for all patients was 5.0 ± 2.5 years. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated using Cox regression models. After adjustment for prognostic factors, patients in the highest quintile of RHR (≥85 beat per minute (bpm)) had a significantly higher risk of all-cause mortality (HR: 1.57; 95 %CI 1.05-2.35), breast cancer-specific mortality (HR: 1.69; 95 %CI 1.07-2.68), and cancer recurrence (HR: 1.49; 95 %CI 0.99-2.25), compared to those in the lowest quintile (≤67 bpm). Moreover, every 10 bpm increase in RHR was associated with 15, 22, and 6 % increased risk of all-cause mortality, breast cancer-specific mortality, and cancer recurrence, respectively. However, the association between RHR and cancer recurrence was not statistically significant (p = 0.26). Elevated RHR was associated with an increased risk of mortality in patients with breast cancer. The findings from this study suggest that RHR may be used as a prognostic factor for patients with breast cancer in clinical settings.

Transferrin (Tf) is considered an effective tumor-targeting agent, and PEGylation effectively prolongs in vivo pharmacokinetics by delaying excretion via the renal route. The authors describe the active tumor targeting of long-acting Tf–PEG–TNF-related apoptosis-inducing ligand conjugate (Tf–PEG–TRAIL) for effective cancer therapy. Tf–PEG–TRAIL was prepared using a two-step N-terminal specific PEGylation procedure using different PEGs (Mw: 3.4, 5, 10 kDa). Eventually, only 10 kDa PEG was linked to Tf and TRAIL because TRAIL (66 kDa) and Tf (81 kDa) were too large to link to 3.4 and 5 kDa PEG. The final conjugate Tf–PEG10K–TRAIL was successfully purified and characterized by SDS-PAGE, western blotting. To determine the specific binding of Tf–PEG10K–TRAIL to Tf receptor, competitive receptor binding assays were performed on K 562 cells. The results obtained demonstrate that the affinity of Tf–PEG10K–TRAIL for Tf receptor is similar to that of native Tf. In contrast, PEG10K–TRAIL demonstrated no specificity. Biodistribution patterns and antitumor effects were investigated in C57BL6 mice bearing B16F10 murine melanomas and BALB/c athymic mice bearing HCT116. Tumor accumulation of Tf–PEG10K–TRAIL was 5.2 fold higher (at 2 h) than TRAIL, because Tf–PEG10K–TRAIL has both passive and active tumor targeting ability. Furthermore, the suppression of tumors by Tf–PEG10K–TRAIL was 3.6 and 1.5 fold those of TRAIL and PEG10K–TRAIL, respectively. These results suggest that Tf–PEG10K–TRAIL is a superior pharmacokinetic conjugate that potently targets tumors and that it should be viewed as a potential cancer therapy.