Mechanism of the stimulating effect of an electric current on reparative regeneration of bone tissue]

Experiments were conducted on rabbits. Changes in ATP in the regenerating bone tissue after incomplete osteotomy and removal of a bone section, and also in cases of reparative osteogenesis stimulation in the region of the bone defect by means of pulse electric current were studied. ATP content in the bone callus after incomplete osteotomy and electrostimulation proved to exceed such in the regenerating bone tissue following removal of the bone fragment when no stimulation was applied. On the basis of the data obtained it is suggested that improvement of energy provision of the fracture consolidation process was one of the important links in the mechanism of stimulating influence of the electric current on the reparative regeneration of the bone tissue.     

Destructive and reparative processes after UHF and cryo-effect on bone regeneration in dogs

The experiment was carried out on the lower jaw of mongrel dogs. It included 36 observations on the basis of the morphological method. The aim is to study the effectiveness of the effect of cold and the combination of the UHF radiation on the proliferative reaction of cells of the lower jaw. It was proved that under the influence of cold the skeletogenic tissue undergoes changes. The combination of cold with UHF radiation cause less destructive cold effects on the bone tissue away from the injury of resorption. Hence the effect of cold on the proliferating tissue causing its necrosis proves the possibility of its use in removal of tumours, substituting wide caving around them by more protective intervention: the combination of carving of tumour with the cryodestruction of tissue around it. In such a combination the reparative processes become more effective, which enables us to recommend them for clinical use for curing benign tumour.     

Physiological and reparative regeneration of the mitochondria]

The ultrastructure of mitochondria of hepatocytes in normal and pathological conditions was studied. It was shown that the process of regeneration of the ultrastructure of swollen mitochondria with a lucent matrix up to the normal state was completed in hepatocytes of the rat and chick embryos within one day. It was established that one of the ways of intraorganoid regeneration of mitochondria in hepatocytes of chick embryos and of mice after injections of CCl4 twice a week for 5 months was clasmatosis of the destroyed mitochondria fragments and their removal through the partially disintegrated exterior membrane of mitochondria followed by the membrane restoration. The process of mitochondrial regeneration after clasmatosis of its fragments was shown to require two days in the chick embryo hepatocytes.     

Histogenesis of skeletogenic tissue in bone regeneration during distraction

Light and electron microscopy were employed to study the histogenesis of the skeletogenous tissue during stable distraction osteosynthesis according to G. A. Ilizarov. Osteosynthesis proceeded on the basis of the invariably existing fibrillar connective tissue growth plate situated in the medium part of the distraction regenerate. Osteogenesis was continuously accompanied by angiogenesis. Preservation of the connective tissue plate is accounted for by the stimulating influence of distraction on fibrillogenesis. The authors suggest the common character of the histogenesis of the vascular and bone tissues in the connective tissue blastema of the interfragmental distraction regenerate.     

Healing of bone defects by guided tissue regeneration

In this study we describe a principle for the accomplishment of bone regeneration based on the hypothesis that different cellular components in the tissue have varying rates of migration into a wound area during healing. By a mechanical hindrance, using a membrane technique, fibroblasts and other soft connective-tissue cells are prevented from entering the bone defect so that the presumably slower-migrating cells with osteogenic potential are allowed to repopulate the defect. Defects of standard size were created bilaterally through the mandibular angles of rats. On one side of the jaw the defect was covered with Teflon membranes, whereas the defect on the other side served as control. Histologic analysis after healing demonstrated that on the test (membrane) side, half the number of animals showed complete bone healing after 3 weeks and all animals showed complete healing after 6 weeks. Little or no sign of healing was evident on the control side even after an observation period of 22 weeks.     

Biodegradable bone regeneration synthetic scaffolds: in tissue engineering

A growing array of synthetic bone regeneration scaffolds has been used or investigated over the last century. These scaffolds aim to provide a three dimensional substrate for bone cells to populate on and function appropriately. To serve this function, these scaffolds should be biocompatible and biodegradable at a rate commensurate with bone remodelling. Their mechanical properties should also be similar to those of the bone regeneration site. In this review, the main families of synthetic bone scaffolds were taxonomised and expounded. The main focus of this paper will be on the basic sciences principles and properties of clinical available as well as experimental synthetic bone scaffolds. Special emphasis was put on scaffolds developed over the last ten years.     

Polycaprolactone scaffolds fabricated with an advanced electrohydrodynamic direct-printing method for bone tissue regeneration

Electrohydrodynamic (EHD) direct writing has been used in diverse microelectromechanical systems and various supplemental methods for biotechnology and electronics. In this work, we expanded the use of EHD-induced direct writing to fabricate 3D biomedical scaffolds designed as porous structures for bone tissue engineering. To prepare the scaffolds, we modified a grounded target used in conventional EHD direct printing using a poly(ethylene oxide) solution bath, elastically cushioning the plotted struts to prevent crumbling. The fabricated scaffolds were assessed for not only physical properties including surface roughness and water uptake ability but also biological capabilities by culturing osteoblast-like cells (MG63) for the EHD-plotted polycaprolactone (PCL) scaffold. The EHD-scaffolds showed significantly roughened surface and enhanced water-absorption ability (400% increase) compared with the pure rapid-prototyped PCL. The results of cell viability, alkaline phosphatase activity, and mineralization analyses showed significantly enhanced biological properties of the scaffold (20 times the cell viability and 6 times the mineralization) compared with the scaffolds fabricated using RP technology. Because of the results, the modified EHD direct-writing process can be a promising method for fabricating 3D biomedical scaffolds in tissue engineering.     

An x-ray study of the subcutaneous tissue using an artificial method of providing contrast]

The paper is concerned with the main methodological principles and potentialities of a radiocontrast study of subcutaneous fat to detect pathological changes in it. The proposed method consists in slow administration in the middle fat layers of 20-25% solution of verografin from not less than two points, and subsequent roentgenography in a necessary projection. The method was used in 15 patients with various orthopedic diseases for diagnosis of inflammatory, tumorous and degenerative-dystrophic diseases.     

Magnetic hydroxyapatite bone substitutes to enhance tissue regeneration: evaluation in vitro using osteoblast-like cells and in vivo in a bone defect

In case of degenerative disease or lesion, bone tissue replacement and regeneration is an important clinical goal. In particular, nowadays, critical size defects rely on the engineering of scaffolds that are 3D structural supports, allowing cellular infiltration and subsequent integration with the native tissue. Several ceramic hydroxyapatite (HA) scaffolds with high porosity and good osteointegration have been developed in the past few decades but they have not solved completely the problems related to bone defects. In the present study we have developed a novel porous ceramic composite made of HA that incorporates magnetite at three different ratios: HA/Mgn 95/5, HA/Mgn 90/10 and HA/Mgn 50/50. The scaffolds, consolidated by sintering at high temperature in a controlled atmosphere, have been analysed in vitro using human osteoblast-like cells. Results indicate high biocompatibility, similar to a commercially available HA bone graft, with no negative effects arising from the presence of magnetite or by the use of a static magnetic field. HA/Mgn 90/10 was shown to enhance cell proliferation at the early stage. Moreover, it has been implanted in vivo in a critical size lesion of the rabbit condyle and a good level of histocompatibility was observed. Such results identify this scaffold as particularly relevant for bone tissue regeneration and open new perspectives for the application of a magnetic field in a clinical setting of bone replacement, either for magnetic scaffold fixation or magnetic drug delivery.