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Two patients with prostate carcinoma and bone metastases were treated with hormonal therapy. Radioimmune imaging of bone marrow performed with 99mTc-labeled antigranulocyte antibody BW 250/183 before treatment demonstrated absence of granulopoietic bone marrow in extensive regions of the central and proximal peripheral skeleton, indicating diffuse bone marrow invasion. Bone marrow scans performed after treatment demonstrated presence of granulopoietic bone marrow in these regions, indicating bone marrow regeneration. This finding was consistent with favorable response to treatment.
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An established experimental model of tibial bone regeneration in rats was used in order to try to provide further information on the binding site of 99mTc-MDP, which is still not clearly defined. Four groups of rats on which surgical tibial bone marrow evacuation was performed and two control groups (nonoperated animals and sham-operated animals) underwent bone scan during the different stages of marrow regeneration; they were killed immediately after, and histological examination carried out. The correlation between the scintigraphic and the histological findings suggests that 99mTc-MDP binds primarily to calcification sites in young bone trabecules.
This study demonstrates, that regeneration of bone in cortical layer defect is about as intensive after application of collagen grafts as after transplantation of autologous of homologous cancellous bone.
In previous studies, DP-bioglass showed good biocompatibility and can form a chemical bond with natural bone. After implementation in the rabbit femur condyle for 32 weeks, DP-bioglass gradually biodegraded and osteocytes grew into the material. In this study, an attempt has been made to utilize low intensity pulsed ultrasound to speed up the bone regeneration rate and DP-bioglass absorption rate when the DP-bioglass is implanted into the rabbit femur condyle as a bone substitute. The fundamental parameters of the ultrasound used were 1.5 MHz frequency, 0.5 W cm-2 intensity, on-off ratio 1:1 and 2 ms for the on-off time interval. The stimulation, in all cases, was started 24 h after the operations by applying the transducer to the skin using DIR ultrasound jelly as a coupling medium. The evaluation of the progress of bone regeneration and the material's biodegradable rate were conducted by histological examination and by measurements of the areas of regenerated bone, pores and DP-bioglass made with a planimeter. It was found that low intensity pulsed ultrasound had a profound effect on the rate both of bone regeneration and DP-bioglass bioabsorption in this rabbit model and that its mechanism of the action may be via an electromechanical kinetic effect on the cell membrane interfaces.
The possibility of periodontal bone tissue regeneration induction with methyluracil, a nucleic acid precursor, was studied in guinea pig experiments. The author presents the morphologic characterization of periodontitis course under the effect of methyluracil phonophoresis and demonstrates the inductor effect of this agent.
In an animal experiment we could prove, that a spontaneous regeneration of periosteum on thermally injured bone is not to be seen within three month, when the bone is covered by soft tissue only. Using a periosteal flap to cover a burned bone, regeneration could be observed from the endosteum and the periosteum alike. After making the bone with a fluorescent labels, paths and velocity of bony regeneration could be defined.
The effect of salmon calcitonin on the maturation of the regenerate bone was assessed in an experimental model in rabbits. Twenty-six New Zealand White male rabbits, approximately 5 months old and weighing 3 to 3.5 kg, were subjected to a mid-diaphyseal tibial osteotomy. After 5 days, the right tibia was lengthened gradually at a rate of 0.375 mm every 12 hours, for 10 days. Ten international units of salmon calcitonin were administered daily subcutaneously to the study group (14 animals), whereas the animals of the control group (12 animals) were injected with a placebo, for the duration of the experiment. The bone mineral density of the regenerate bone was assessed on Days 20, 35, 45, and 55 of the experiment, in both groups, using dual energy xray absorptiometry. No statistical significant difference was found in the dual energy xray absorptiometry measurements between the study and control groups regarding the change of the bone mineral density of the new bone relative to a preoperative baseline measurement. Characteristic time-related changes were observed in the bone mineral density of the regenerate bone during its maturation, which proved to be identical in both groups. It seems that the administration of calcitonin does not enhance regenerate bone mineralization rate and tendency during bone lengthening.
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The evaluation of bone regeneration and peri-implantary bone apposition requires laboratory techniques that allow the evaluation of hard tissues without needing to decalcify them. In this study, we describe the cutting-grinding procedure (EXAKT system) for obtaining samples of undecalcified bone and aim to establish the procedures for their histological and histomorphometric evaluation. A review is made of the literature on histological and histomorphometric evaluation using undecalcified samples in surgical and oral implantology procedures in which bone regeneration or bone apposition is produced on the dental implants. The technique is a lengthy process, and is principally indicated in the investigation of bone biology. The use of undecalcified samples allows the differentiation of immature from mature bone, and the quantification of variables such as the bone-implant interface, the density of the bone area and the speed of bone apposition.
The influence of the periosteum on the regeneration of palatal bone was investigated in this study. Eighty, 8-week-old, purebred beagle dogs were assigned randomly to four groups: (1) unoperated dogs as a group control; dogs in which the mid-third of the palate was surgically removed and (2) left unrepaired (unrepaired controls); (3) repaired with mucosal flaps; (4) repaired with mucoperiosteal flaps. Five animals from each group were killed at 4, 6, 8, and 12 weeks after surgery and coronal sections examined under light microscopy. Among the animals with complete soft tissue healing, 8 of 12 dogs from Group 2, 11 of 20 from Group 3, and 10 of 19 from Group 4 showed complete bone regeneration. No significant differences were found overall in bone thickness and bone density measurements between Group 3 and Group 4. Histologically, a well-differentiated periosteum was present on the maxilla at 4 weeks, even in animals in which the periosteum had not been preserved in the original flap. These results suggest that maintaining the periosteum at surgical closure does not influence bone regeneration in beagles up to 12 weeks of age. We suggest that osteoprogenitor cells, migrating from the undisturbed local periosteum adjacent to the defect, were responsible for the new bone growth in our study.
Bone marrow mesenchymal stem cells can trans-differentiate into neuronal phenotypes. We examined the differentiation of marrow stromal cells (MSCs) in culture and during nerve regeneration. MSCs from adult rats were exposed to glial growth factor (GGF) to stimulate glial differentiation. Subsequently differentiated MSCs were retrovirally labelled with green fluorescent protein and transplanted into 1 cm nerve conduits in the rat sciatic nerve. Fifteen days post-operatively the conduits were examined for axonal and Schwann cell regeneration and MSC integration. In vitro, MSCs exposed to GGF expressed S100 and glial fibrillary acidic protein. Following transplantation, MSCs maintained S100 expression and enhanced nerve regeneration, with significant Schwann cell regeneration compared to control (2.7 +/- 0.21 vs. 2.05 +/- .21 mm; P < 0.05). MSCs not exposed to GGF prior to transplantation expressed S100 in vivo indicating glial differentiation in response to local cytokines and growth factors.
In patients with delayed bone tissue regeneration, changes in the indices of cellular immunity were revealed, consisting in a decreased number, both absolute and relative, of T lymphocytes, and in their reduced ability to respond to PHA stimulation by the reaction of blastic transformation. Autoimmunization to bone tissue antigen was observed in the same patients. This was confirmed by the reactions of blastic transformation and cytotoxicity of lymphocytes as well as by the reaction of leukocyte migration inhibition in the presence of bone antigen. It is recommended to take into account the indices of cellular immunity in treating patients with poorly healing bone fractures.