Drug-Eluting Stents ; Humans ; Polymers ; chemistry ; therapeutic use ; Sirolimus ; therapeutic use

BACKGROUNDDrug-eluting stents represent a major advance in interventional cardiology. However, the current drug-eluting stents have significant limitations. One of the major problems is very late stent thrombosis, which is likely caused by inflammation and a hypersensitivity reaction related to a polymer on the stent. A polymer-free sirolimus-eluting stent with a unique nano-porous surface has been developed. This study aimed to evaluate this novel polymer-free sirolimus-eluting stent for its efficacy and safety in a pig model.

METHODSStents were directly coated with sirolimus (a drug concentration of 2.2 µg/mm(2) on the stent surface). The polymer-free sirolimus-eluting stents (PFSES) were compared to standard polymer-coated sirolimus-eluting stents (PCSES) and bare-metal stents (BMS) in 18 pigs.

RESULTSAt one month the degree of neointimal hyperplasia was similar between the two sirolimus-eluting stent groups and was significantly less compared to BMS ((1.93 ± 0.51) mm(2), (1.57 ± 0.69) mm(2) vs. (4.45 ± 1.05) mm(2), P < 0.05) At three months, PFSES maintained the low level of neointima ((2.41 ± 0.99) mm(2) vs. (4.32 ± 1.16) mm(2), P < 0.05), whereas PCSES had developed significant neointimal proliferation similar to BMS. The inflammation level was significantly higher in PCSES when compared with BMS three months post-implantation (2.50 ± 0.55 vs. 0.83 ± 0.75, P < 0.05) whereas PFSES showed a low level of inflammation comparable to PCSES (1.33 ± 0.52 vs. 2.50 ± 0.55, P < 0.05).

CONCLUSIONThe PFSES is effective and safe, and appears to be superior to standard PCSEs.

Animals ; Drug-Eluting Stents ; adverse effects ; Neointima ; prevention & control ; Polymers ; chemistry ; Sirolimus ; therapeutic use ; Swine

Polyethersulfone (PES) hollow fibers were fabricated by dry-wet spinning method for hemodialysis application. The effects of additives polyethylene glycols (PEG) in the dope solution and of fiber thickness and inner diameter fiber on the membrane mechanical characters were investigated. The dialysis tests were conducted by using a simulated solution prepared by dissolving bovine serum albumin (BSA), lysozyme and urea in de-ionized water to test the effects of membrane characters and operating conditions on dialysis efficiency. The results indicated that the reduction of PEG concentration from 27.6 wt% to 24.1 wt% in the dope solution improved the clearance of toxins, but slightly decreased the mechanical characters. The reduction of fiber thickness or fiber inner diameter was found to improve the clearance of toxins by removing 64.2% of lysozyme and 89.4% of urea (membrane area 0.2 m2), whilst BSA retention was found being maintained above 98%. The dialysis efficiency was also noted to increase with the increase in the flow rate of either the simulated or the dialysate solution, or increasing the membrane area. Moreover, The result of a comparison on the clearance of toxins between commercial F60S and PES dialyzers indicated higher dialysis efficiency per area of the fabricated PES membrane.
Biocompatible Materials ; therapeutic use ; Evaluation Studies as Topic ; Membranes, Artificial ; Polyethylene Glycols ; chemistry ; Polymers ; chemistry ; Renal Dialysis ; instrumentation ; methods ; Sulfones ; chemistry

Animals ; Coronary Vessels ; surgery ; Drug-Eluting Stents ; adverse effects ; Lactic Acid ; chemistry ; Polyesters ; Polymers ; chemistry ; Sirolimus ; chemistry ; therapeutic use ; Swine

BACKGROUNDSirolimus-eluting stents (SES) are reported to be associated with reduced late lumen loss (LLL), resulting in less frequent restenosis when compared to bare-metal stent. The current study aimed to assess the difference in LLL between SES with biodegradable and with permanent polymer.

METHODSFrom March 2010 to June 2011, 300 consecutive patients having only biodegradable polymers or permanent polymer SES for all diseased vessels were included. Serial quantitative coronary analysis was performed on both the "in-stent" and "segment" area, including the stented segment, as well as both five mm margins proximal and distal to the stent. The primary endpoint was the LLL defined as the minimal lumen diameter (MLD) post-stenting minus the MLD at nine-month after the indexed procedure.

RESULTSLLL was comparable between the two stents. Importantly, LLL for the distal segment (median 0.05 mm, interquartile 0 to 0.09 mm) was less severe compared with in-stent (median 0.13 mm, interquartile 0.08 to 0.18 mm) and proximal segment LLL (median 0.12 mm, interquartile 0.06 to 0.14 mm, all P < 0.001). In general, the LLL was associated with the post-procedure MLD (b = 0.28, P = 0.002), hyperlipidemia (b = 0.14, P = 0.021), and calcified lesions (b = 0.58, P = 0.001). The R(2) and Radj of the multiple regression model were 0.651 and 0.625, respectively.

CONCLUSIONSSES with either biodegradable or permanent polymer had lower value of LLL. The small amount of LLL at the distal segment possibly contributed to the less distal edge stenosis.

Aged ; Aspirin ; therapeutic use ; Coronary Restenosis ; prevention & control ; Drug-Eluting Stents ; Female ; Humans ; Male ; Middle Aged ; Polymers ; chemistry ; Regression Analysis ; Sirolimus ; therapeutic use ; Ticlopidine ; analogs & derivatives ; therapeutic use

Photodynamic therapy (PDT) has been used to treat several types of cancer, and comprises intravascular administration of photosensitizer, uptake by cancer cells, and followed by irradiation of light of appropriate wavelength. Although PDT takes advantage of relative retention of photosensitizer by cancer cells, effective delivery of photosensitizing drugs is of great concern. Several delivery strategies have been employed in PDT. Photosensitizers can be delivered either by passive carriers such as liposomes, micelles, and polymeric particles, or by active targeting using cancer cell-directed ligands or antibodies. Although well-studied colloidal carriers effectively deliver photosensitizer to tumor cells, they are taken up by mononuclear phagocytic system. Delivery system using polymers is an attractive alternative to colloidal carriers, in which hydrophobic drugs are chemically or physically loaded to polymers. Though there are several steps to be solved, targeted delivery system utilizing receptors or antigens abundantly expressed on cancer cell theoretically provides a great deal of advantages over passive system. Selective uptake of photosensitizers by cancer cells may greatly enhance therapeutic efficacy as well as minimizing adverse effects resulting from accumulation in normal tissue. This review discusses various strategies for photosensitizer delivery that have been investigated to date.
Drug Delivery Systems ; Humans ; Liposomes/chemistry ; Micelles ; Neoplasms/*drug therapy ; *Photochemotherapy ; Photosensitizing Agents/*administration & dosage ; Polymers/chemistry/therapeutic use

Aspirin ; therapeutic use ; Coronary Disease ; therapy ; Coronary Thrombosis ; chemically induced ; epidemiology ; mortality ; Drug-Eluting Stents ; adverse effects ; Humans ; Paclitaxel ; therapeutic use ; Platelet Aggregation Inhibitors ; therapeutic use ; Polymers ; chemistry ; Sirolimus ; therapeutic use ; Ticlopidine ; analogs & derivatives ; therapeutic use

BACKGROUNDStent-based delivery of sirolimus has been shown to reduce neointimal hyperplasia significantly. However, the long-term effect of the polymer is thought to initiate and sustain an inflammatory response and contribute to the occurrence of late complications. Our study aimed to evaluate the efficacy and safety of the BuMA biodegradable drug-coated sirolimus-eluting stent (BSES) for inhibiting neointimal hyperplasia in a porcine coronary model.

METHODSFour types of stents were implanted at random in different coronary arteries of the same pig: BSES (n = 24), bare metal stent (BMS) (n = 24), biodegradable polymer coated stent without drug (PCS) (n = 24) and only poly (n-butyl methacrylate) base layer coated stent (EGS) (n = 23). In total, 26 animals underwent successful random placement of 95 oversized stents in the coronary arteries. Coronary angiography was performed after 28 days, 90 days and 240 days of stent implantation. After 14 days, 28 days, 90 days and 240 days, 6 animals at each timepoint were sacrificed for histomorphologic analysis.

RESULTSThe 28-day, 90-day and 240-day results of quantitative coronary angiography (QCA) showed reduction in luminal loss (LL) in the BSES group when compared with the BMS group; (0.20 ± 0.35) mm vs. (0.82 ± 0.51) mm (P = 0.035), (0.20 ± 0.30) mm vs. (0.93 ± 0.51) mm (P = 0.013), and (0.18 ± 0.16) mm vs. (0.19 ± 0.24) mm (P = 0.889), respectively. By 28-day, 90-day and 240-day histomorphomeric analysis results, there was also a corresponding significant reduction in neointimal tissue proliferation with similar injury scores of BSES compared with the BMS control; average neointimal area (0.90 ± 0.49) mm(2) vs. (2.16 ± 1.29) mm(2) (P = 0.049), (1.53 ± 0.84) mm(2) vs. (3.41 ± 1.55) mm(2) (P = 0.026), and (2.43 ± 0.95) mm(2) vs. (3.12 ± 1.16) mm(2) (P = 0.228), respectively. High magnification histomorphologic examination revealed similar inflammation scores and endothelialization scores in both the BSES and BMS groups.

CONCLUSIONSThe BuMA biodegradable drug-coated sirolimus-eluting stents can significantly reduce neointimal hyperplasia and in-stent restenosis. Re-endothelialization of the BuMA stent is as good as that of the BMS in the porcine coronary model due to the reduced inflammation response to the BuMA stent.

Absorbable Implants ; Animals ; Coronary Angiography ; Drug-Eluting Stents ; Female ; Hyperplasia ; pathology ; Neointima ; prevention & control ; Polymers ; chemistry ; Sirolimus ; therapeutic use ; Swine

This review presents the state of the art of pH-responsive polymeric micelles for cancer drug delivery. Solid tumors have a weakly acidic extracellular pH (pH < 7), and cancer cells have even more acidic pH in endosomes and lysosomes (pH 4-6). The pH-gradients in tumor can be explored for tumor targeting and drug release in cancer drug delivery by applying pH-responsive polymeric micelles. The pH-responsive polymeric micelles consist of a corona and a core, and are made of amphiphilic copolymers, in which there are pH-responsive polymeric blocks. Two types of pH-responsive polymers-protonizable polymers and acid-labile polymers have been mainly used to make pH-responsive micelles for drug delivery. The protonizable polymers are polybases or polyacids, and their water-soluble/insoluble or charge states undergo changes with the protonation or deprotonation stimulated by external acidity, while the acid-labile polymers change their physical properties by chemical reaction stimulated by the acidity. Polymeric micelles whose core or coronas respond to the tumor extracellular acidity can be explored for triggering the fast release of the carried drug, activating the targeting group and accelerating the endocytosis of drug-loaded polymeric micelles, and those whose core or coronas respond to the tumor lysosomal acidity can be used for facilitating their escape from the lysosomes and targeting the nucleus. Various in vivo and in vitro experiments demonstrated that pH-responsive polymeric micelles are effective for cellular targeting, internalization, fast drug release and nuclear localization, and hence enhancing the therapeutic efficacy and reducing the side effect of cancer chemical therapy.
Antineoplastic Agents ; administration & dosage ; therapeutic use ; Drug Delivery Systems ; Humans ; Hydrogen-Ion Concentration ; Micelles ; Nanoparticles ; Neoplasms ; drug therapy ; Polymers ; chemistry

Clinical and research reports concerning orthopedic biodegradable implants were reviewed. The clinical results were analyzed in terms of complications and compatibility. The possible applications of the implants and further research fields were summarized.
Absorbable Implants ; Biocompatible Materials ; chemistry ; Biodegradation, Environmental ; Bone Screws ; Fracture Fixation, Internal ; instrumentation ; Fracture Healing ; Fractures, Bone ; surgery ; Humans ; Polymers ; chemistry ; therapeutic use ; Prostheses and Implants