PURPOSE: Osteoporosis is a severe health problem with social and economic impacts on society. The standard treatment consists of the systemic administration of drugs such as bisphosphonates, with alendronate (ALN) being one of the most common. Nevertheless, complications of systemic administration occur with this drug. Therefore, it is necessary to develop new strategies, such as local administration. METHODS: In this study, emulsion/dispersion scaffolds based on W/O emulsion of PCL and PF68 with ALN, containing hydroxyapatite (HA) nanoparticles as the dispersion phase were prepared using electrospinning. Scaffolds with different release kinetics were tested in vitro on the co-cultures of osteoblasts and osteoclast-like cells, isolated from adult osteoporotic and control rats. Cell viability, proliferation, ALP, TRAP and CA II activity were examined. A scaffold with a gradual release of ALN was tested in vivo in the bone defects of osteoporotic and control rats. RESULTS: The release kinetics were dependent on the scaffold composition and the used system of the poloxamers. The ALN was released from the scaffolds for more than 22 days. The behavior of cells cultured in vitro on scaffolds with different release kinetics was comparable. The difference was evident between cell co-cultures isolated from osteoporotic and control animals. The PCL/HA scaffold show slow degradation in vivo and residual scaffold limited new bone formation inside the defects. Nevertheless, the released ALN supported bone formation in the areas surrounding the residual scaffold. Interestingly, a positive effect of systemic administration of ALN was not proved. CONCLUSION: The prepared scaffolds enabled tunable control release of ALN. The effect of ALN was proved in vitro and in in vivo study supported peri-implant bone formation.

• Keywords
• alendronate, co-culture, drug delivery system, fibrous scaffold, osteoporosis,
• MeSH
• Alendronate * pharmacology   MeSH
• Emulsions pharmacology   MeSH
• Durapatite pharmacology   MeSH
• Bone Density Conservation Agents * pharmacology   MeSH
• Rats MeSH
• Osteoblasts MeSH
• Osteogenesis MeSH
• Osteoclasts MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Alendronate * MeSH
• Emulsions MeSH
• Durapatite MeSH
• Bone Density Conservation Agents * MeSH

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure-the removal of the plates and screws-can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.

• Keywords
• absorbable metals, alloy accumulation, biocompatibility, in vivo, internal organs, magnesium, strontium, systemic reactions, toxicity, zinc,
• MeSH
• Tibial Fractures * metabolism   surgery   MeSH
• Magnesium chemistry   pharmacokinetics   pharmacology   MeSH
• Rabbits MeSH
• Humans MeSH
• Alloys * chemistry   pharmacokinetics   pharmacology   MeSH
• Strontium chemistry   pharmacokinetics   pharmacology   MeSH
• Materials Testing * MeSH
• Tibia metabolism   pathology   MeSH
• Absorbable Implants * MeSH
• Zinc chemistry   pharmacokinetics   pharmacology   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Magnesium MeSH
• Alloys * MeSH
• Strontium MeSH
• Zinc MeSH

This study aims to point out the main drawback with respect to the design of simulated body environments. Three media commonly used for the simulation of the identical body environment were selected, i.e., Kokubo's simulated body fluid that simulates the inorganic component of human blood plasma, human blood plasma, and phosphate buffer saline. A comparison was performed of the effects of the media on collagen scaffolds. The mechanical and structural effects of the media were determined via the application of compression mechanical tests, the determination of mass loss, and image and micro-CT analyses. The adsorption of various components from the media was characterized employing energy-dispersive spectrometry. The phase composition of the materials before and after exposure was determined using X-ray diffraction. Infrared spectroscopy was employed for the interpretation of changes in the collagen secondary structure. Major differences in terms of the mechanical properties and mass loss were observed between the three media. Conversely, only minor structural changes were detected. Since no general recommendation exists for selecting the simulated body environment, it is necessary to avoid the simplification of the results and, ideally, to utilize alternative methods to describe the various aspects of degradation processes that occur in the media.

• Keywords
• XRD, blood plasma, collagen, mass loss, mechanical properties, micro-CT, porosity, scaffold, simulated body fluid, structural parameters,
• Publication type
• Journal Article MeSH

In this pilot study, we investigated the biocompatibility and degradation rate of an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. An alloy screw was implanted into one of the tibiae of New Zealand White rabbits. After 120 days, the animals were euthanized. Evaluation included clinical assessment, microCT, histological examination of implants, analyses of the adjacent bone, and assessment of zinc, magnesium, and strontium in vital organs (liver, kidneys, brain). The bone sections with the implanted screw were examined via scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). This method showed that the implant was covered by a thin layer of phosphate-based solid corrosion products with a thickness ranging between 4 and 5 µm. Only negligible changes of the implant volume and area were observed. The degradation was not connected with gas evolution. The screws were fibrointegrated, partially osseointegrated histologically. We observed no inflammatory reaction or bone resorption. Periosteal apposition and formation of new bone with a regular structure were frequently observed near the implant surface. The histological evaluation of the liver, kidneys, and brain showed no toxic changes. The levels of Zn, Mg, and Sr after 120 days in the liver, kidneys, and brain did not exceed the reference values for these elements. The alloy was safe, biocompatible, and well-tolerated.

• Keywords
• alloy accumulation, bioabsorbable metals, biocompatibility, in-vivo biocompatibility, internal organs, magnesium, strontium, systemic reactions, toxicity, zinc,
• Publication type
• Journal Article MeSH

The aim of the study was to develop an orthopedic implant coating in the form of vancomycin-loaded collagen/hydroxyapatite layers (COLHA+V) that combine the ability to prevent bone infection with the ability to promote enhanced osseointegration. The ability to prevent bone infection was investigated employing a rat model that simulated the clinically relevant implant-related introduction of bacterial contamination to the bone during a surgical procedure using a clinical isolate of Staphylococcus epidermidis. The ability to enhance osseointegration was investigated employing a model of a minipig with terminated growth. Six weeks following implantation, the infected rat femurs treated with the implants without vancomycin (COLHA+S. epidermidis) exhibited the obvious destruction of cortical bone as evinced via a cortical bone porosity of up to 20% greater than that of the infected rat femurs treated with the implants containing vancomycin (COLHA+V+S. epidermidis) (3%) and the non-infected rat femurs (COLHA+V) (2%). The alteration of the bone structure of the infected COLHA+S. epidermidis group was further demonstrated by a 3% decrease in the average Ca/P molar ratio of the bone mineral. Finally, the determination of the concentration of vancomycin released into the blood stream indicated a negligible systemic load. Six months following implantation in the pigs, the quantified ratio of new bone indicated an improvement in osseointegration, with a two-fold bone ingrowth on the COLHA (47%) and COLHA+V (52%) compared to the control implants without a COLHA layer (27%). Therefore, it can be concluded that COLHA+V layers are able to significantly prevent the destruction of bone structure related to bacterial infection with a minimal systemic load and, simultaneously, enhance the rate of osseointegration.

• Keywords
• Staphylococcus epidermidis, bone, collagen, hydroxyapatite, implant-related bone infection, minipig, orthopedic implant, osseointegration, rat, vancomycin,
• Publication type
• Journal Article MeSH

The study presents a novel vancomycin-releasing collagen wound dressing derived from Cyprinus carpio collagen type I cross-linked with carbodiimide which retarded the degradation rate and increased the stability of the sponge. Following lyophilization, the dressings were subjected to gamma sterilization. The structure was evaluated via scanning electron microscopy images, micro-computed tomography, and infrared spectrometry. The structural stability and vancomycin release properties were evaluated in phosphate buffered saline. Microbiological testing and a rat model of a wound infected with methicillin-resistant Staphylococcus aureus (MRSA) were then employed to test the efficacy of the treatment of the infected wound. Following an initial mass loss due to the release of vancomycin, the sponges remained stable. After 7 days of exposure in phosphate buffered saline (37°C), 60% of the material remained with a preserved collagen secondary structure together with a high degree of open porosity (over 80%). The analysis of the release of vancomycin revealed homogeneous distribution of the antibiotic both across and between the sponges. The release of vancomycin was retarded as proved by in vitro testing and further confirmed by the animal model from which measurable concentrations were observed in blood samples 24 hours after the subcutaneous implantation of the sponge, which was more than observed following intraperitoneal administration. The sponge was also highly effective in terms of reducing the number of colony-forming units in biopsies extracted from the infected wounds 4 days following the inoculation of the wounds with the MRSA solution. The presented sponges have ideal properties to serve as wound dressing for prevention of surgical site infection or treatment of already infected wounds.

• MeSH
• Anti-Bacterial Agents pharmacokinetics   MeSH
• Wound Healing drug effects   MeSH
• Carps MeSH
• Carbodiimides pharmacokinetics   MeSH
• Collagen pharmacokinetics   MeSH
• Rats MeSH
• Methicillin-Resistant Staphylococcus aureus drug effects   MeSH
• Bandages MeSH
• Vancomycin pharmacokinetics   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Carbodiimides MeSH
• Collagen MeSH
• Vancomycin MeSH

BACKGROUND: Collagen-based scaffolds provide a promising option for the treatment of bone defects. One of the key parameters of such scaffolds consists of porosity, including pore size. However, to date, no agreement has been found with respect to the methodology for pore size evaluation. Since the determination of the exact pore size value is not possible, the comparison of the various methods applied is complicated. Hence, this study focuses on the comparison of two widely-used methods for the characterization of porosity-scanning electron microscopy (SEM) and micro-computed tomography (micro-CT). METHODS: 7 types of collagen-based composite scaffold models were prepared by means of lyophilization and collagen cross-linking. Micro-CT analysis was performed in 3D and in 2D (pore size parameters were: major diameter, mean thickness, biggest inner circle diameter and area-equivalent circle diameter). Afterwards, pore sizes were analyzed in the same specimens by an image analysis of SEM microphotographs. The results were statistically evaluated. The comparison of the various approaches to the evaluation of pore size was based on coefficients of variance and the semi-quantitative assessment of selected qualities (e.g. the potential for direct 3D analysis, whole specimen analysis, non-destructivity). RESULTS: The pore size values differed significantly with respect to the parameters applied. Median values of pore size values were ranging from 20 to 490 µm. The SEM values were approximately 3 times higher than micro-CT 3D values for each specimen. The Mean thickness was the most advantageous micro-CT 2D approach. Coefficient of variance revealed no differences among pore size parameters (except major diameter). The semi-quantitative comparison approach presented pore size parameters in descending order with regard to the advantages thereof as follows: (1) micro-CT 3D, (2) mean thickness and SEM, (3) biggest inner circle diameter, major diameter and area equivalent circle diameter. CONCLUSION: The results indicated that micro-CT 3D evaluation provides the most beneficial overall approach. Micro-CT 2D analysis (mean thickness) is advantageous in terms of its time efficacy. SEM is still considered as gold standard for its widespread use and high resolution. However, exact comparison of pore size analysis in scaffold materials remains a challenge.

• Keywords
• Bone regeneration, Micro-CT, Pore size, Porosity, SEM, Scaffold,
• MeSH
• Collagen chemistry   MeSH
• Porosity MeSH
• X-Ray Microtomography MeSH
• Tissue Engineering * MeSH
• Tissue Scaffolds * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Collagen MeSH