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Recent studies suggest that dihydroartemisinin (DHA), a derivative of artemisinin isolated from the traditional Chinese herb Artemisia annua L., has anticancer properties. Due to poor water solubility, poor oral activity, and a short plasma half-life, large doses of DHA have to be injected to achieve the necessary bioavailability. This study examined increasing DHA bioavailability by encapsulating DHA within gelatin (GEL) or hyaluronan (HA) nanoparticles via an electrostatic field system. Observations from transmission electron microscopy show that DHA in GEL and HA nanoparticles formed GEL/DHA and HA/DHA aggregates that were approximately 30-40 nm in diameter. The entrapment efficiencies for DHA were approximately 13 and 35% for the GEL/DHA and HA/DHA aggregates, respectively. The proliferation of A549 cells was inhibited by the GEL/DHA and HA/DHA aggregates. Fluorescent annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) staining displayed low background staining with annexin V-FITC or PI on DHA-untreated cells. In contrast, annexin V-FITC and PI stains dramatically increased when the cells were incubated with GEL/DHA and HA/DHA aggregates. These results suggest that DHA-aggregated GEL and HA nanoparticles exhibit higher anticancer proliferation activities than DHA alone in A549 cells most likely due to the greater aqueous dispersion after hydrophilic GEL or HA nanoparticles aggregation. These results demonstrate that DHA can aggregate with nanoparticles in an electrostatic field environment to form DHA nanosized aggregates., (Copyright © 2013 Wiley Periodicals, Inc.)

Using a recently established method to prepare hyaluronan/collagen II (HA/Col II) microspheres for a novel biomaterial to couple with living cells/tissues, this animal model study evaluated the effects on a 4-week healing process of chondral defects by the implantation of allogenous chondrocyte-seeded HA/Col II microspheres that had been cultured in vitro for 7 days prior to implantation compared with unseeded HA/Col II microspheres or an untreated wound. Four weeks postsurgery, the untreated group's defect was filled with translucent soft tissue. At the same time, the edges and demarcation lines of the healing defects that were implanted with either HA/Col II microspheres or chondrocyte-seeded HA/Col II microspheres were infused yet recognizable. Furthermore, the new tissues were well integrated into the surrounding articular cartilage. Less glycosaminoglycan (GAG) staining was observed in the defects implanted with HA/Col II microspheres, which indicated that most of the repair tissues were derived from fibrocartilage formation. Conversely, more GAG staining appeared in the defect implanted with chondrocyte-seeded HA/Col II microspheres, which demonstrated a higher level of hyaline cartilage regeneration. Due to the short healing period assigned to this study, the repaired cartilage showed limited incorporation into the surrounding host cartilage and some loose connection to the subchondral bone., (© 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Collagen II and hyaluronan are the two major components of the native extracellular matrix (ECM). Both biopolymers are responsible for providing the associated tissues with tensile strength, and also serve as a structural scaffold for cell adhesion and growth. Over the years, many researchers have focused on the preparation and evaluation of man-made ECM comprising the two polymers in the form of a membrane for chondrocyte culture applications. Here, a simple and in situ method, involving the injection of the hyaluronan/collagen II (HA/Col II) mixture solution through a pair of hollow-centered parallel disc electrodes (HCPDEs) of a high-voltage electrostatic field system, was developed and employed to prepare HA/Col II microspheres in watery phase. The HA/Col II microspheres were firmed up by a two-step cross-linking treatment (first by FeCl(3) and then by 1-ethyl-3-(3-dimethyl aminopropyl) carbodimide, EDC) to secure the spherical structure shape. Then, at 37 degrees C, reconstitution treatment of the Col II molecules was conducted to further strengthen the microspheres. Depending on treatment conditions, the resulting series of HA/Col II microspheres all exhibited good sphericity in the range of 486+/-43 to 679+/-24microm in diameter. Furthermore, the ratio and amount of HA/Col II in the mixture solutions would affect the morphological structure and basic characteristics, including mechanical strength, thermal properties and water content. In the preliminary study, the HA/Col II microspheres have shown to provide favorable ECM characteristics, with appropriate mechanical strength, and exhibited a 3D inclination.

The effect to the kinetics of type II collagen fibrillogenesis with the addition of hyaluronan (HA), (Mw of 1.8x10(6) Da), at various concentrations of HA (0.01, 0.05 and 0.1 wt.%) for a series of fibril formation systems was examined in this study. Evidences deduced from the turbidity-time curves revealed that the inclusion of HA had minor or no impact to the fibrillogenesis of type II collagen (collagen conc. at 0.2 mg/mL). The apparent rate constants, klag (lag phase) increased slightly but kg (growth phase) decreased not very significantly with addition of HA, as compared to the case of pure collagen. This leads us to believe tentatively that, with the addition of HA to collagen solutions, the nucleation process of the fibril formation might have been sped up slightly whereas the growth process slowed up slightly. However, data from TEM observations on the resulting fibrils indicated that the presence of HA did not significantly affect the diameters and the characteristic D-banding periods of the collagen fiber formed. And, from the statistical analyses, we found only insignificant difference (P>0.05) between the specimens from the various experimental groups. It seems to indicate that the ultimate packing of collagen monomers was probably not interfered or affected significantly by the presence of HA in vitro.

Extracellular matrix has an important part of the role in tissue engineering and regenerative medicine, so it is necessary to understand the various interactions between cells and extracellular matrix. Type II collagen and hyaluronic acid are the major structural components of the extracellular matrix of articular cartilage, and they are involved in fibril formation, entanglement and binding. The aim of this study was to prepare type II collagen fibrils with surface grafted with hyaluronic acid modified at the reducing end. The topographic pattern of type II collagen fibrils showed a significant change after the surface coupling of hyaluronic acid according to atomic force microscopy scanning. The presence of hyaluronic acid on the type II collagen fibrillar surface was confirmed by the specific binding of nanogold labelled with lectin. No significant increase in cell proliferation was detected by a WST-1 assay. According to histochemical examination, the maintenance of the round shape of chondrocytes and increased glycosaminoglycan secretion revealed that these cell pellets with Col II- g -hyaluronic acid molecules contained un-dedifferentiated chondrocytes in vitro. In the mixture with the 220-kDa Col II- g -hyaluronic acid copolymer, the expression of type II collagen and aggrecan genes in chondrocytes increased as demonstrated by real-time polymerase chain reaction analysis. Experimental results show that the amount of hyaluronic acid added during culturing of chondrocytes can maintain the functionality of chondrocytes and thus allow for increased cell proliferation that is suitable for tissue repair of human cartilage. [ABSTRACT FROM AUTHOR]

Due to limited self-healing capacity in cartilages, there is a rising demand for an innovative therapy that promotes chondrocyte proliferation while maintaining its biofunctionality for transplantation. Chondrocyte transplantation has received notable attention; however, the tendencies of cell de-differentiation and de-activation of biofunctionality have been major hurdles in its development, delaying this therapy from reaching the clinic. We believe it is due to the non-stimulative environment in the injured cartilage, which is unable to provide sustainable physical and biological supports to the newly grafted chondrocytes. Therefore, we evaluated whether providing an appropriate matrix to the transplanted chondrocytes could manipulate cell fate and recovery outcomes. Here, we proposed the development of electrosprayed nanoparticles composed of cartilage specific proteins, namely collagen type II and hyaluronic acid, for implantation with pre-seeded chondrocytes into articular cartilage defects. The fabricated nanoparticles were pre-cultured with chondrocytes before implantation into injured articular cartilage. The study revealed a significant potential for nanoparticles to support pre-seeded chondrocytes in cartilage repair, serving as a protein delivery system while improving the survival and biofunctionality of transplanted chondrocytes for prolonged period of time. [ABSTRACT FROM AUTHOR]

After tendon-repair surgery, adhesion between the surgical tendon and the synovial sheath is often presented resulting in poor functional repair of the tendon. This may be prevented using a commercially available mechanical barrier implant, Seprafilm, which is composed of hyaluronan (HA) and carboxymethyl cellulose hydrogels. In a rat model, prepared membranes of various compositions of gellan gum (GG), xanthan gum (XG) and HA as well as Seprafilm were wrapped around repaired tendons and the adhesion of the tendons was examined grossly and histologically after 3 weeks of healing. Certain formulations of the XG/GG/HA hydrogel membranes reduced tendon adhesion with equal efficacy but without reducing the tendon strength compared to Seprafilm. The designed membranes swelled rapidly and blanketed onto the tendon tissue more readily and closely than Seprafilm. Also they degraded slowly, which allowed the membranes to function as barriers for extended periods. [ABSTRACT FROM AUTHOR]

Two simple in situ methods, involving the injection of a hyaluronan (HA) solution through a pair of hollow-centred parallel disc electrodes of an electrostatic field system and a micronozzle transducer of an ultrasound atomisation system, were developed and used to prepare HA microspheres in watery phase. The HA microspheres were treated by FeCl3 and 1-ethyl-3-(3-dimethyl aminopropyl) carbodimide (EDC) to secure the spherical structure shape. Depending on certain treatment conditions, the resulting series of HA microspheres exhibited good sphericity in the range of 317±22 to 579±49 µm in diameter by the electrostatic field system. Stricter conditions were needed to produce HA microspheres by the ultrasound atomisation system because of a viscosity restriction of micronozzle transducer. However, the HA microspheres could be produced and exhibited good sphericity in a smaller size under certain HA concentrations conditions. These prepared HA microspheres had various mechanical durability and could maintain their particulate shape after intra-articular administration of HA microspheres into a rabbit articular cavity for an 11-day period. [ABSTRACT FROM AUTHOR]