Biopolymer composites allow the creation of an optimal environment for the regeneration of chondral and osteochondral defects of articular cartilage, where natural regeneration potential is limited. In this experimental study, we used the sheep animal model for the creation of knee cartilage defects. In the medial part of the trochlea and on the medial condyle of the femur, we created artificial defects (6 × 3 mm2) with microfractures. In four experimental sheep, both defects were subsequently filled with the porous acellular polyhydroxybutyrate/chitosan (PHB/CHIT)-based implant. Two sheep had untreated defects. We evaluated the quality of the newly formed tissue in the femoral trochlea defect site using imaging (X-ray, Computer Tomography (CT), Magnetic Resonance Imaging (MRI)), macroscopic, and histological methods. Macroscopically, the surface of the treated regenerate corresponded to the niveau of the surrounding cartilage. X-ray examination 6 months after the implantation confirmed the restoration of the contour in the subchondral calcified layer and the advanced rate of bone tissue integration. The CT scan revealed a low regenerative potential in the bone zone of the defect compared to the cartilage zone. The percentage change in cartilage density at the defect site was not significantly different to the reference area (0.06–6.4%). MRI examination revealed that the healing osteochondral defect was comparable to the intact cartilage signal on the surface of the defect. Hyaline-like cartilage was observed in most of the treated animals, except for one, where the defect was repaired with fibrocartilage. Thus, the acellular, chitosan-based biomaterial is a promising biopolymer composite for the treatment of chondral and osteochondral defects of traumatic character. It has potential for further clinical testing in the orthopedic field, primarily with the combination of supporting factors.
The study focused on the effect of microwave radiation at a dose which commonly does not lead to tissue heating, however, in the rat testes it resulted in accumulation of heat. Adult rats were exposed to whole body pulse radiation at a frequency of 2.45 GHz and mean power density of 28 W/m 2 , for 3 h a day for the duration of 3 weeks. Immediately after each irradiation, the body temperature and the testicular temperature were measured in the control and experimental animals. Samples for histological and immunohistochemical analysis were taken after the last irradiation and processed for light and transmission electron microscopy. An evaluation of spermatozoa motility was performed using computer-assisted sperm analysis. Although the body temperature of the rats was not elevated after the irradiations, the testicular temperature was significantly increased (P < 0.004). Testes of the experimental animals had considerably dilated and congested blood vessels and the seminiferous epithelium showed degenerative changes. The Leydig cells showed no obvious structural abnormalities. Transmission electron microscopy revealed ultrastructural changes in developing sex cells, Sertoli cells, and endothelial cells. An intensified immunoreactivity to superoxide dismutase 1 was found in spermatogonia and Leydig cells in the experimental animals. Results of the present study revealed a distinctly adverse effect of microwave radiation on the thermoregulatory capability and histological structure of rat testes as well as an oxidative damage of the tissue. The scientific knowledge confirming or denying the thermal effect of microwave radiation on living tissue is scarce and thus the present study may be regarded as unique and helpful to clarify the issue. Non-ionizing radiation, male gonads, structure, ultrastructure, immunohistochemical analysisFertility problems affect the human population worldwide. A number of reports have found an association between exposure to radiofrequency electromagnetic radiation generated by wireless devices such mobile phones, cordless phones, microwave ovens, radars, Wi-Fi and base stations and the negative effect on different reproductive indices (Panagopoulos 2013). These studies have attributed most of the male reproductive system injury to the non-thermal radiation effect but have not excluded its potential thermal effect. Thus, the occurrence of a thermal effect of microwave electromagnetic radiation (MW EMR) within tissues still remains to be further clarified. Tissues are rich in water molecules which are polar and susceptible to the effect of MW EMR. Their vibrations result in a gain of energy in the form of heat which causes an elevation in the temperature of the tissue. The body is made up of a mixture of types of tissues which may result in a non-uniform distribution
The symptomatic full-thickness cartilage lesions or cartilage degeneration leads to the destruction of the normal chondral architecture and bone structure in affected area, causes the osteoarthritis, and general damage to the health. Knee joints are most frequently affected by this condition. The permanent damage of the articular cartilage and subchondral bone has motivated many scientists and clinicians to explore new methods of regeneration of osteochondral defects, such as novel materials. We studied the potential of the biocement based on calcium phosphate consisting of a mixture of four amino acids (glycine, proline, hydroxyproline and lysine) in the regenerating process of the artificially created osteochondral defect on the porcine medial femoral condyle in the stifle joint. The mass ratio of the amino acids in biocement CAL was 4:2:2:1. The Ca/P ratio in cement was 1.67 which correspond with ratio in hydroxyapatite. We compared the results with spontaneous healing of an artificially created cyst with that of the healthy tissue. The animal group treated with biocement paste CAL presented completely filled osteochondral defects. The results were confirmed by histological and radiological assessments, which have shown regenerated chondral and bone tissue in the examined knee joints. Macroscopic evaluation showed that neocartilage was well integrated with the adjacent native cartilage in animal group with biocement CAL, compared with healing of the artificial cyst, where treated cartilage surfaces were visibly lower than the surrounding native cartilage surface and a border between native and restored tissue was apparent. The qualitative assessment of the implant histology specimens showed full regeneration of the hyaline cartilage and subchondral bone in animals with biocement CAL. The artificial cyst group showed remarkable fibrillation. The detailed MRI analysis of cross-section of osteochondral defect confirmed the complete cartilage and subchondral bone healing where the thickness of the regenerated cartilage was 1.5 mm. The MRI imaging of defects in the artificial cyst group showed incomplete healing, neo cartilage tissue reduced up to 50%.
This study aimed to clarify the therapeutic effect and regenerative potential of the novel, amino acids-enriched acellular biocement (CAL) based on calcium phosphate on osteochondral defects in sheep. Eighteen sheep were divided into three groups, the treated group (osteochondral defects filled with a CAL biomaterial), the treated group with a biocement without amino acids (C cement), and the untreated group (spontaneous healing). Cartilages of all three groups were compared with natural cartilage (negative control). After six months, sheep were evaluated by gross appearance, histological staining, immunohistochemical staining, histological scores, X-ray, micro-CT, and MRI. Treatment of osteochondral defects by CAL resulted in efficient articular cartilage regeneration, with a predominant structural and histological characteristic of hyaline cartilage, contrary to fibrocartilage, fibrous tissue or disordered mixed tissue on untreated defect (p < 0.001, modified O’Driscoll score). MRI results of treated defects showed well-integrated and regenerated cartilage with similar signal intensity, regularity of the articular surface, and cartilage thickness with respect to adjacent native cartilage. We have demonstrated that the use of new biocement represents an effective solution for the successful treatment of osteochondral defects in a sheep animal model, can induce an endogenous regeneration of cartilage in situ, and provides several benefits for the design of future therapies supporting osteochondral defect healing.
Reconstruction of bone defects and maintaining the continuity of the mandible is still a challenge in the maxillofacial surgery. Nowadays, the biomedical research within bone defect treatment is focussed on the therapy of using innovative biomaterials with specific characteristics consisting of the body’s own substances. Hydroxyapatite ceramic scaffolds have fully acceptable phase compositions, microstructures and compressive strengths for their use in regenerative medicine. The innovative hydroxyapatite ceramics used by us were prepared using the tape-casting method, which allows variation in the shape of samples after packing hydroxyapatite paste to 3D-printed plastic form. The purpose of our qualitative study was to evaluate the regenerative potential of the innovative ceramic biomaterial prepared using this method in the therapy of the cortical bone of the lower jaw in four mature pigs. The mandible bone defects were evaluated after different periods of time (after 3, 4, 5 and 6 months) and compared with the control sample (healthy cortical bone from the opposite side of the mandible). The results of the morphological, clinical and radiological investigation and hardness examination confirmed the positive regenerative potential of ceramic implants after treatment of the mandible bone defects in the porcine mandible model.
This study was designed to investigate the effects of hydroxyapatite (HA) ceramic implants (HA cylinders, perforated HA plates, and nonperforated HA plates) on the healing of bone defects, addressing biocompatibility, biodegradability, osteoconductivity, osteoinductivity, and osteointegration with the surrounding bone tissue. The HA ceramic implants were prepared using the tape-casting method, which allows for shape variation in samples after packing HA paste into 3D-printed plastic forms. In vitro, the distribution and morphology of the MC3T3E1 cells grown on the test discs for 2 and 9 days were visualised with a fluorescent live/dead staining assay. The growth of the cell population was clearly visible on the entire ceramic surfaces and very good osteoblastic cell adhesion and proliferation was observed, with no dead cells detected. A sheep animal model was used to perform in vivo experiments with bone defects created on the metatarsal bones, where histological and immunohistochemical tissue analysis as well as X-ray and CT images were applied. After 6 months, all implants showed excellent biocompatibility with the surrounding bone tissue with no observed signs of inflammatory reaction. The histomorphological findings revealed bone growth immediately over and around the implants, indicating the excellent osteoconductivity of the HA ceramic implants. A number of islands of bone tissue were observed towards the centres of the HA cylinders. The highest degree of biodegradation, bioresorption, and new bone formation was observed in the group in which perforated HA plates were applied. The results of this study suggest that HA cylinders and HA plates may provide a promising material for the functional long-bone-defect reconstruction and further research.
Researchers around the world use histological analysis to provide the most detailed morphological information of articular cartilage repair and it predominantly relies on the use of histological scoring systems which are important tools for valid evaluations. Due to hyaline cartilage complex structure and avascular nature, damaged cartilage does not heal spontaneously and it is still a challenge to regenerate and restore its tissue function. The aim of this study was to investigate the quality of regenerated cartilage by using three different histological scoring systems; O’Driscoll, Pineda and Wakitani which are all classic scores described for such animal studies. We used an in vivo ovine model in which a full thickness chondral defect was created and then implanted with the biomaterial (polyhydroxybutyrate/chitosan; PHB/ CHIT). The results of this histological analysis demonstrated that the cartilage repaired tissues received scores indicating that the majority of the regenerated tissue resembled hyaline-like cartilage. After six months of repair the regenerated cartilage showed characteristics like good surface continuity, uniformed stained extracellular matrix, clearly visible zones and cellular proliferation. In conclusion, this study may be used to investigate and improve the regenerative capacity of hyaline cartilage in preclinical models and it also sheds further light on both the evaluation and methods used for the regeneration of damaged cartilage.
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