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Results for “BONE REGENERATION”

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PubMed1984

[Ultrastructural characteristics of stromal mechanocytes and their interaction with hematopoietic cells in regenerating bone marrow transplants].

Extramedullar grafts of the bone marrow have been studied electron microscopically 2-8 days after transplantation. The data on ultrastructural peculiarities of the stromal mechanocytes have been obtained at various stages of their differentiation, as well as topographic interrelationships between the mechanocytes and the hemopoietic cells. Digital junctions are described between the stromal mechanocytes (primitive) and the hemopoietic cells (in 3-day-old grafts) which are, probably, the first morphological signs demonstrating restoration of the hemopoietic microenvironment in the bone marrow grafts.

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PubMedDate not supplied

[The effect of selenium on free-radical oxidation processes in the bone regenerate after a fracture].

The paper presents the results of examining the central part of the rat mandible for a month after its fracture. The rate of free radical oxidation was estimated by the levels of diene conjugates (DC), malonic dialdehyde (MDA) and by the activity of selenium-containing glutathione peroxidase (GPO). The findings suggest that there are profound injury-induced changes in free radical oxidation and antioxidative defense. The levels of DC and MDA showed the maximum upward change as a double-peaked curve and longer restoration to the level seen in control animals. These rats had the minimum enhanced GPO activity. In the animals receiving intragastric selenium methionine or selenium electrophoresis applied to the site of mandible fracture, alterations in DC and MDA were less pronounced and GPO showed a higher activity.

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PubMedDate not supplied

Autogenous injectable bone for regeneration with mesenchymal stem cells and platelet-rich plasma: tissue-engineered bone regeneration.

We have attempted to regenerate bone in a significant osseous defect with minimal invasiveness and good plasticity, and to provide a clinical alternative to autogenous bone grafts. Platelet-rich plasma (PRP) may enhance the formation of new bone and is nontoxic, nonimmunoreactive, and accelerates existing wound-healing pathways. We have used a combination of PRP as an autologous scaffold with in vitro-expanded mesenchymal stem cells (MSCs) to increase osteogenesis, compared with using the scaffold alone or autogenous particulate cancellous bone and marrow (PCBM). The newly formed bones were evaluated by radiography, histology, and histomorphometric analysis in the defects at 2, 4, and 8 weeks. According to the histological observations, the dog MSCs (dMSCs)/PRP group had well-formed mature bone and neovascularization compared with the control (defect only), PRP, and PCBM groups at 2 and 4 weeks. Histometrically, at 8 weeks newly formed bone areas were 18.3 +/- 4.84% (control), 29.2 +/- 5.47% (PRP), 61.4 +/- 3.38% (PCBM), and 67.3 +/- 2.06% (dMSCs/PRP). There were significant differences between the PCBM, dMSCs/PRP, and control groups. These results demonstrate that the dMSCs/PRP mixture is useful as a osteogenic bone substitute.

Animals↗
PubMed1994

Effect of a bioresorbable film on regeneration of cranial bone.

Regeneration of cranial bone is usually accomplished with autografts, banked bone, or both. The effect also may be obtained by using a properly engineered alloplastic barrier. Our group assessed histomorphometrically the capacity of a bioresorbable film to promote repair of cranial bone in critical-sized defects in 50 rabbits divided over four time periods (4, 8, 16, and 24 weeks). A single circular defect 15 mm in diameter was prepared in each rabbit and either covered with films of polylactic acid (21 mm in diameter, 150 microns thick) durally and pericranially or left untreated. Only after 24 weeks was there a significant difference (p < or = 0.05) between defects covered with polylactic acid films and those untreated. We conclude that after shorter periods, regardless of covering, prolapse of soft tissue into defects prevented osseous regeneration. We speculate that at 24 weeks, defects treated with films generated new bone as a result of changes in the local milieu conducive to osteoblastic expression.

Animals↗
PubMedDate not supplied

Ectopic bone formation facilitated by human mesenchymal stem cells and osteogenic cytokines via nutrient vessel injection in a nude rat model.

In vivo studies using bone marrow-derived mesenchymal stem cells are still uncommon. Applications for bone defect replacement in undesirable clinical circumstances such as large defects, bacterial or other pathogen-contaminated fields, and irradiated surgical wound bed necessitate vascularized bone regeneration. Use of a fascial flap including regenerated bone would be a very powerful tool for treatment. It would be especially beneficial in cases where normal bone regeneration is not expected due to a lack of sufficient blood supply, extensive surgical scarring, or bacterial contamination. In this study, we used nude rats in which the superficial epigastric flap of the experimental group was used to wrap around a mixture of human mesenchymal stem cells, bone morphogenetic protein-2, and basic fibroblast growth factor cytokines in a gelatin carrier. These rats showed significantly higher bone mineral density at 4 weeks compared to the other experimental groups containing phosphate buffered saline, human mesenchymal stem cells alone, or the two cytokines alone (p < 0.01). There were no remarkable histologic differences up to 7 days. At 2 weeks, more progressive vascularity and perivascular tissue deposits were seen in the experimental group. Basophilic mineral structure surrounded the fibroblast-like mesenchymal stem cells at 4 weeks, presumably osteoblastic or osteoclastic cell lining. Bone marker immunohistochemistry against alkaline phosphatase and osteocalcin revealed diffuse and distinct immunoreactivity in osteoblastic cells in the experimental group at 4 weeks. Further transcriptional expression of polyomavirus enhancer binding protein 2alphaA suggested that the human transplanted cells proceeded to osteogenic lineage in 4 weeks. These results may be useful as a new approach for bone regeneration.

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