Verapamil-containing silicone gel reduces scar hypertrophy.

A hypertrophic scar is a common dermal fibroproliferative lesion usually treated with topical silicone. Verapamil, a type of calcium channel blocker, is considered a candidate drug for the treatment of hypertrophic scars. Here, we report that the addition of verapamil to topical silicone gel enhances treatment outcomes of hypertrophic scars. Upon creation of hypertrophic scars with the rabbit ear model, varying concentrations of verapamil-added silicone gel (0.1, 1, and 10 mg/g) were applied daily for 28 days. After the animals were euthanised, microscopic measurement was performed for (a) scar elevation index (SEI), (b) fibroblast count, and (c) capillary count. On gross analysis, features of hypertrophic scars were significantly alleviated in the verapamil-added groups. On histologic examination, verapamil-added groups showed (a) reduced SEI (1.93 (1.79-2.67) for control vs 1.34 (1.21-1.51) for silicone only and 1.13 (1.01-1.65) for verapamil-added silicone), (b) fibroblast count 700.5 (599.5-838.5) for control, 613.25 (461-762.5) for silicone only, and 347.33 (182.5-527) for verapamil-added silicone), and (c) capillary formation (52 (35.5-96.5) for control, 46 (28-64.5) for silicone only, and 39.83(24-70) for verapamil-added silicone) (Kruskal-Wallis test, P < .05). On western blot, expression levels of collagen I protein was lower in the 1 mg/g and 10 mg/g verapamil-added silicone compared with control. Therefore, we suggest a therapeutic concentration of verapamil-added silicone gel of at least over 1 mg/g. Further study regarding maximally effective concentration and deeper insight into the mechanism of action should follow.

Preparation of polymeric micelles consisting of poly(propylene glycol) and poly(caprolactone).

The ring-opening polymerization of epsilon-caprolactone (CL) was carried out with polypropylene glycol (PPG) as an initiator in the presence of the monomer activator HCl. Et2O to synthesize poly(epsilon-caprolactone)-poly(propyleneglycol)-poly(epsilon-caprolactone) (PCL-PPG-PCL) triblock copolymers with change of length PPG and PCL. The micelle formation of PCL-PPG-PCL triblock copolymers in an aqueous phase was confirmed by NMR, dynamic light scattering and fluorescence techniques. The critical micelle concentration (CMC) of the PCL-PPG-PCL triblock copolymers, determined from fluorescence measurements, was in range of 1.4 x 10(-3)-4.6 x 10(-3) mg/ml with dependence on block lengths of PPG and PCL. The partition equilibrium constant, K(v), which is an indicator of the hydrophobicity of the micelles of the PCL-PPG-PCL triblock copolymers in aqueous media, was also changed with dependence on length PPG and PCL. We confirmed that the PCL-PPG-PCL triblock copolymers formed micelles and hence may be potential hydrophobic drug carriers.

Effects of structurally stabilized EGF and bFGF on wound healing in type I and type II diabetic mice.

Diabetes mellitus comprises a multiple metabolic disorder that affects millions of people worldwide and consequentially poses challenges for clinical treatment. Among the various complications, diabetic ulcer constitutes the most prevalent associated disorder and leads to delayed wound healing. To enhance wound healing capacity, we developed structurally stabilized epidermal growth factor (ST-EGF) and basic fibroblast growth factor (ST-bFGF) to overcome limitations of commercially available EGF (CA-EGF) and bFGF (CA-bFGF), such as short half-life and loss of activity after loading onto a matrix. Neither ST-EGF nor ST-bFGF was toxic, and both were more stable at higher temperatures than CA-EGF and CA-bFGF. We loaded ST-EGF and ST-bFGF onto a hyaluronate-collagen dressing (HCD) matrix, a biocompatible carrier, and tested the effectiveness of this system in promoting wound healing in a mouse model of diabetes. Wounds treated with HCD matrix loaded with 0.3 µg/cm2 ST-EGF or 1 µg/cm2 ST-bFGF showed a more rapid rate of tissue repair as compared to the control in type I and II diabetes models. Our results indicate that an HDC matrix loaded with 0.3 µg/cm2 ST-EGF or 1 µg/cm2 ST-bFGF can promote wound healing in diabetic ulcers and are suitable for use in wound dressings owing to their stability for long periods at room temperature. STATEMENT OF SIGNIFICANCE: Various types of dressing materials loaded with growth factors, such as VEGF, EGF, and bFGF, are widely used to effect wound repair. However, such growth factor-loaded materials have several limitations for use as therapeutic agents in healing-impaired diabetic wounds. To overcome these limitations, we have developed new materials containing structurally stabilized EGF (ST-EGF) and bFGF (ST-bFGF). To confirm the wound healing capacity of newly developed materials (ST-EGF and ST-bFGF-loaded hyaluronate-collagen dressing [HCD] matrix), we applied these matrices in type I and type II diabetic wounds. Notably, these matrices were able to accelerate wound healing including re-epithelialization, neovascularization, and collagen deposition. Consequentially, these ST-EGF and ST-bFGF-loaded HCD matrix may be used as future therapeutic agents in patients with diabetic foot ulcers.

Biodegradable poly(lactide-co-glycolide-co-ε-caprolactone) block copolymers - evaluation as drug carriers for a localized and sustained delivery system.

To develop an appropriate drug carrier for drug delivery systems, we prepared random poly(lactide-co-glycolide-co-ε-caprolactone) (PLGC) copolymers in comparison to commercial poly(lactic acid-co-glycolic acid) (PLGA) grades. The molecular weights of PLGC copolymers varied from 20k to 90k g mol-1 in the total polyester segments, when poly-l-lactic acid (PLLA), polyglycolic acid (PGA), and polycaprolactone (PCL) compositions were kept constant. The lengths of PLGC copolymers varied from 10 : 10 : 80 to 40 : 40 : 20 in the PLLA : PGA : PCL segments, when the molecular weights of the total polyester segments were kept constant. The crystalline properties of the PLGA copolymers can be changed to amorphous by the incorporation of PCL segments. In vitro and in vivo degradation behavior can be easily tuned from a few days to a few weeks by changing the chemical composition of the PLGC copolymers. The in vivo inflammation associated with the PLGC implants was less pronounced than that associated with PLGA. In this study, as drug delivery carriers for locally implantable paclitaxel (Ptx) dosages, Ptx-loaded PLGC and PLGA films showed in vitro and in vivo Ptx release for 35 days. The orders of Ptx release showed profiles similar to those of in vitro and in vivo degradation of PLGC. Using near-infrared (NIR) fluorescence imaging, we confirmed the sustained release of NIR over an extended period from IR-780-loaded PLGC and PLGA implanted in live animals. In conclusion, we confirmed that compared to PLGA, PLGC effectively acts as a drug carrier for drug delivery systems.

An injectable biodegradable temperature-responsive gel with an adjustable persistence window.

ɛ-Caprolactone (CL) and 3-benzyloxymethyl-6-methyl-1,4-dioxane-2,5-dion (fLA), with a benzyloxymethyl group at the 3-position of the lactide, were randomly copolymerized. The methoxy polyethylene glycol (MPEG)-b-[poly(ɛ-caprolactone)-ran-poly(3-benzyloxymethyl lactide) (PCL-ran-PfLA)] diblock copolymers were designed such that the PfLA content (0-15 mol%) in the PCL segment was varied. The MPEG-b-(PCL-ran-PfLA) diblock copolymers were derivatized by introducing a pendant benzyl group (MC(x)L(y)-OBn), hydroxyl group (MC(x)L(y)-OH), or carboxylic acid group (MC(x)L(y)-COOH) at the PfLA segment. The derivatized MPEG-b-(PCL-ran-PfLA) diblock copolymer solutions exhibited sol-to-gel phase transitions upon a temperature increase. The sol-to-gel phase transition depended on both the type of functional pendant group on the PfLA and the PfLA content in the PCL segment. MC(x)L(y)-COOH diblock copolymer solutions formed gels immediately after injection into Fischer rats. The gels gradually degraded over a period of 0-6 weeks after the initial injection, and the rate of degradation increased for higher concentrations of PfLA. Immunohistochemical characterization showed that the in vivo MPEG-b-(PCL-ran-PfLA) diblock copolymer gels provoked only a modest inflammatory response. These results show that the MPEG-b-(PCL-ran-PfLA) diblock copolymer gel described here may serve as a minimally invasive therapeutic, in situ-forming gel system with an adjustable temperature-responsive and in vivo biodegradable window.

In vivo biofunctionality comparison of different topographic PLLA scaffolds.

In this work, the in vivo biodegradation of, biocompatibility of, and host response to various topographic scaffolds were investigated. Randomly oriented fibrous poly(L-lactide) (PLLA) nanofibers were fabricated using the electrospinning technique. A PLLA scaffold was obtained by salt leaching. Both the electrospun PLLA nanofibers and the salt-leaching PLLA scaffolds formed three-dimensional pore structures. Cytotoxicity studies, in which rat muscle-derived stem cells (rMDSCs) were grown on electrospun PLLA nanofibers or the salt-leaching PLLA scaffolds, revealed that the rMDSCs cell count on the PLLA nanofibers was slightly higher than that on the salt-leaching PLLA scaffolds. An in vivo study was carried out by implanting the scaffolds subcutaneously into rats to test the biodegradation, biocompatibility, and host response at regular intervals over 0-4 weeks. The degradation of the PLLA nanofibers 1, 2, and 4 weeks after initial implantation was more extensive than that observed for the salt-leaching PLLA scaffolds. PLLA nanofibers seeded the growth of larger fibrous tissue masses due to in vivo cellular infiltration into the randomly oriented fibrillar structures of the PLLA nanofibers. In addition, the inflammatory cell accumulation in PLLA nanofibers was lower than that in the salt-leaching PLLA scaffolds. These results indicate that the electrospun PLLA nanofibers may serve as a good scaffold to elicit fibrous cellular infiltration, to minimize host response, and to enhance tissue-scaffold integration.