Composite clinoptilolite/PCL-PEG-PCL scaffolds for bone regeneration: In vitro and in vivo evaluation.

In this study, clinoptilolite (CLN) was employed as a reinforcement in a polymer-based composite scaffold in bone tissue engineering and evaluated in vivo for the first time. Highly porous, mechanically stable, and osteogenic CLN/PCL-PEG-PCL (CLN/PCEC) scaffolds were fabricated with modified particulate leaching/compression molding technique with varying CLN contents. We hypothesized that CLN reinforcement in a composite scaffold will improve bone regeneration and promote repair. Therefore, the scaffolds were analyzed for compressive strength, biodegradation, biocompatibility, and induction of osteogenic differentiation in vitro. CLN inclusion in PC-10 (10% w/w) and PC-20 (20% w/w) scaffolds revealed 54.7% and 53.4% porosity, higher dry (0.62 and 0.76 MPa), and wet (0.37 and 0.45 MPa) compressive strength, greater cellular adhesion, alkaline phosphatase activity (2.20 and 2.82 mg/gDNA /min), and intracellular calcium concentration (122.44 and 243.24 g Ca/mgDNA ). The scaffolds were evaluated in a unicortical bone defect at anterior aspect of proximal tibia of adult rabbits 4 and 8 weeks postimplantation. Similar to in vitro results, CLN-containing scaffolds led to efficient regeneration of bone in a dose-dependent manner. PC-20 demonstrated highest quality of bone union, cortex development, and bone-scaffold interaction at the defect site. Therefore, higher CLN content in PC-20 permitted robust remodeling whereas pure PCEC (PC-0) scaffolds displayed fibrous tissue formation. Consequently, CLN was proven to be a potent reinforcement in terms of promoting mechanical, physical, and biological properties of polymer-based scaffolds in a more economical, easy-to-handle, and reproducible approach.

In vitro and in vivo evaluation of doxycycline-chondroitin sulfate/PCLmicrospheres for intraarticular treatment of osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease, which has no complete treatment with medication yet. Intraarticular hyaluronan (HA) injection can decrease pain and modify the natural course of OA. This study was designed to provide long term delivery of an MMP (matrix-metalloproteinase) inhibitor agent-doxycycline, together with matrix regenerative agent-chondroitin sulfate for treating OA which progress with matrix degenerations. Doxycycline (D) and doxycycline-chondroitin sulfate (D-CS) loaded poly-ɛ-caprolactone (PCL) microspheres (MS) were prepared as intraarticular delivery systems. Bio-effectiveness of developed microspheres was first evaluated with three-dimensional in vitro model of OA where both MS showed significant reduction in MMP-13 levels compared to untreated OA-chondrocytes at 15 and 24 days. Significant decrease was observed in GAG release into the media for both D MS and D-CS MS treated groups at 15 and 24 days. Second, the microspheres were injected to rabbit knee in hyaluronan (HA) to evaluate the effectiveness of the treatment. Radiographic scores of D MS and D-CS MS groups improved after 8 weeks when compared to OA group. Mankin-Pitzker histological scores similarly showed improvement with D MS and D-CSMS groups when compared to OA group. Ex vivo hardness tests of cartilages demonstrated superior hardness values with both doses of D-CSMS compared to OA group. D MS showed promising improvement of OA in histology results. Although, both MS groups had similar effects on cells in the in vitro model, D-CSMS had a positive contribution on all in vivo treatment outcomes and showed potential as a new strategy for treatment when applied to OA knee joints.

In vitro/in vivo comparison of cefuroxime release from poly(ε-caprolactone)-calcium sulfate implants for osteomyelitis treatment.

This study aimed to investigate the release of cefuroxime axetil (CF) and calcium from poly(ε-caprolactone) (PCL)-calcium sulfate (CaS) implants (PCL:CaS 2:1-10% CF; PCL:CaS 2:1-20% CF; PCL:CaS 1:1-10% CF) for treating infectious bone diseases. Bioactivity, crystallinity and strength, and release profiles under standard and pressurized release conditions were studied. PCL:CaS 2:1-20% CF had slower release than 10% loading. These groups had no significant change in CF and Ca release in response to pressure. The PCL:CaS 1:1 group had the slowest release despite having higher CaS, probably due to more compaction of discs. In contrast, pressure caused significant differentiation of CF and Ca(2+) release. The presence of CaS enhanced mechanical properties and bioactivity of discs. SEM and XPS results showed calcium-phosphate containing accumulations on surfaces upon SBF incubation. CF-loaded implants were applied in a rabbit osteomyelitis model. In vivo CF release was enhanced with increased CaS proportions, suggesting that in vivo release conditions are closer to pressurized in vitro conditions. In the control group, there was still some inflammation in the bone and no complete coverage with bone was achieved in the defect site. Discs provided a suitable surface for regeneration of bone. However, bone formation in the PCL:CaS 1:1 disc implanted group was more complete and regular than in the 2:1 group.