A biphasic calcium phosphate ceramic scaffold loaded with oxidized cellulose nanofiber-gelatin hydrogel with immobilized simvastatin drug for osteogenic differentiation.

A novel bone scaffold containing bioceramic and biopolymer materials with an osteoinductive simvastatin molecule was developed to enhance bone regeneration. An oxidized cellulose nanofiber (OCNF)-Gelatin (Gel) hydrogel was loaded into a biphasic calcium phosphate (BCP) ceramic in which simvastatin was entrapped, resulting in a scaffold with both osteoconductive and osteoinductive properties. The fabricated scaffold showed interconnected porosity with micro- and macroporous orientation. After loading the OCNF-Gel (HG), the mechanical stability of the ceramic BCP scaffold was increased suitable for the application of hard tissue regeneration. Fourier-transform infrared spectroscopy showed that simvastatin was successfully coated on the BCPHG scaffolds. OCNF, with its slower degradation, may contribute to the sustained release of drug from the scaffold. Initially simvastatin was released from the scaffold at high levels, then was constantly and gradually released for up to 4 weeks. Pre-osteoblast MC3T3E1 cells were seeded on the scaffolds to investigate cell viability, morphology, and differentiation. The simvastatin-loaded BCPHG-S scaffolds showed better cell proliferation and spreading compared to other scaffolds. Immunostaining assays showed the expression of proteins responsible for osteogenic differentiation. Alkaline phosphatase and osteopontin were more highly expressed in the BCPHG-S scaffold than in other scaffolds. These results suggest that simvastatin-loaded BCPHG scaffolds provided physiological environments suitable for better osteogenic differentiation.

Delayed Absorption of Oxidized Cellulose (Surgicel) in Post-Thyroidectomy Patients.

Delayed absorption of oxidized cellulose (Surgicel; Johnson & Johnson, New Brunswick, NJ) may mimic a pseudoabscess or a recurrent mass on sonography after tumor surgery. Here we present 3 cases of thyroidectomy in which Surgicel was still apparent on sonography after 26 to 47 months of follow-up. We show sonographic findings and discuss the utility of sonography for diagnosis of delayed absorption of Surgicel in post-thyroidectomy patients.

Viability of crushed and diced cartilage grafts wrapped in oxidized regenerated cellulose and esterified hyaluronic acid: an experimental study.

OBJECTIVES: The objective of this study was to investigate the viability of diced/crushed cartilage grafts wrapped in esterified hyaluronic acid (HYAFF) and oxidized regenerated cellulose (Surgicel) with respect to macroscopic and microscopic parameters. STUDY DESIGN: Experimental study. METHODS: A total of 10 New Zealand rabbits were acquired for the study. Cartilage grafts were harvested from both ears, with the ventral and dorsal perichondrial layers dissected off. There were six comparison groups in this experimental study: 1) bare, diced cartilage, 2) diced cartilage wrapped in Surgicel, 3) diced cartilage wrapped in HYAFF, 4) bare, crushed cartilage, 5) crushed cartilage wrapped in Surgicel, 6) crushed cartilage wrapped in HYAFF. Six cartilage grafts were inserted into the six subcutaneous pockets of the same animal. All the rabbits were sacrificed at the end of 2 months, the samples were collected, and the total specimen was examined histopathologically. The sections were stained with hematoxylin-eosin and Masson trichrome stain and examined under light microscopy. RESULTS: There was a significant difference among the bare, diced cartilage, the Surgicel, and the HYAFF groups with respect to fibrosis, chronic inflammation, cartilage mass, and vascularization. A significant difference was observed among the bare, crushed cartilage, Surgicel, and HYAFF groups with respect to fibrosis, chronic inflammation, and cartilage mass. There was no significant difference among the three groups regarding vascularization. CONCLUSIONS: This study suggests that wrapping cartilage grafts with Surgicel grossly reduces cartilage viability and the regeneration potential of the chondrocytes, leading to fibrosis formation. On the other hand, hyaluronic acid promotes cartilage integrity and survival, thus increasing clinical predictability and avoiding the need for overcorrection.

Examination of aqueous oxidized cellulose dispersions as a potential drug carrier. I. Preparation and characterization of oxidized cellulose-phenylpropanolamine complexes.

Partially neutralized aqueous dispersions of oxidized cellulose (OC) (COOH content 24.2%; degree of neutralization [DN] 0.22-0.44; solid content 14.4% wt/wt), a biocompatible biodegradable polymer, were prepared and their use to entrap an amine drug was demonstrated. Phenylpropanolamine hydrochloride (PPA.HCl) was used as a model drug. OCA-PPA complexes were prepared by adding the drug solution to the OC dispersion. Light microscopy, powder x-ray diffractometry (PXRD), and Fourier-transform infrared (FT-IR) spectroscopy were used to characterize hydrated and dried OC and the OC-PPA complexes. Drug loading and drug-loading efficiency were calculated from high-performance liquid chromatography. Light microscopy revealed the partially neutralized OC to exist as swollen fibers in the dispersion. The degree of swelling increased with increasing DN of the OC. All dispersions, irrespective of DN, showed a pseudo-plastic flow. The drug loading (12.6%-26.7%) and drug-loading efficiency (30%-48%) increased linearly with increasing DN and drug concentration. The PXRD of the OC-PPA complexes showed no diffraction peaks due to PPA, suggesting that the drug exists in the amorphous state. The FT-IR spectra of the complexes revealed the presence of an ionic linkage between OC and PPA. In conclusion, the results show that the aqueous OC dispersions can be used to molecularly entrap amine drugs to produce an OC-drug complex linked via an ionic linkage.

Examination of aqueous oxidized cellulose dispersions as a potential drug carrier. II. In vitro and in vivo evaluation of phenylpropanolamine release from microparticles and pellets.

The purpose of this research is to investigate the release of phenylpropanolamine from oxidized cellulose-phenylpropanolamine (OC-PPA) complexes prepared using aqueous OC dispersions (degree of neutralization, DN, 0-0.44) and phenylpropanolamine-hydrochloride (PPA.HCl) (concentration, 0.5 M or 1.4 M) in vitro and in vivo. The results showed a faster drug release from the OC-PPA complex made using the OC dispersion with a DN value of 0.22 than from those prepared using dispersions with DN values of 0.29 to 0.44. No significant difference existed between the release profiles of OC-PPA microparticles made using OC dispersions with DN values of 0.29 to 0.44. OC-PPA complexes that contained smaller size particles or higher drug levels, or that were processed by freeze drying released PPA faster. Compared with microparticles, the pellets of OC-PPA complexes released PPA more slowly initially. An increase in pH or ionic strength of the dissolution medium increased the release of PPA, which is attributable to increased polymer hydration and solubilization at higher pH and ionic strength conditions. The OC-PPA pellets implanted subcutaneously in rats released 100% of their PPA in 9 to 12 hours. A good correlation was found between the in vivo and in vitro release data. Tissue pathology results showed no significant inflammatory tissue reactions. In conclusion, the partially ionized aqueous OC dispersions have the potential to be used as an implantable biodegradable carrier for amine drugs.

[The degradation performance of bioabsorbable acylchitin fiber reinforced PLA composite materials in vitro and in vivo].

The present authors have investigated the degradation performance of acylchitin fiber reinforced polylactide composite materials plates both in vitro and in vivo. The initial flexural strength and the initial flexural modulus of this plate are 114.72 MPa and 3980.05 MPa, respectively. The flexural strength of this plate decreases to 31.42 MPa after the plate has been submerged in injectio natrii lactatic ringeri tissue fluid for a period of 16 weeks at 37 degrees C. Both the in vitro degradation performance and the strength retention of this plate are better than those of the self-reinforced PGA/PLA and PGA, though the initial strength of the latter two being much higher than that of the former. The degradation products of the chitin/PLA composite materials can be absorbed by metabolic pathway.