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 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Correlation between the callus formation and its microvascular regeneration during the fracture healing process in the rat femur was examined under SEM and TEM utilizing the plastic injection method. Stabilization of bony fragments was provided by a miniature external fixator. Normal periosteal microvasculature consisted of 2 layers. In the outer layer, arterioles and venules formed the course network. In the inner layer, capillaries were situated in contact with the compact bone, forming polygonal meshes. In the medulla, the central longitudinal artery gave rise to numerous arterioles, which communicated with sinusoidal capillaries. The proliferation of the internal layer of the periosteal capillary network was observed in the periosteal callus. It is revealed that the trabecular structure of the periosteal and medullary calluses depended on their microvascular architecture. The anastomoses of newly-formed capillaries at the fracture site started first from the outer layer of the periosteum extended to the medulla then finally to the inner layer of the periosteum.
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PMID:[Callus formation and microvascular regeneration during the fracture healing process in the rat femur]. 151 85

Mineralized extracellular matrix formation is representative for the osteoinductive capacity of biomaterials and is often tested in vitro. Characteristics of in vitro mineralization of primary rat osteoblastic cells (bone marrow, calvaria, periosteum, fetal and adult long bone) and UMR-106 cells were compared by von Kossa staining, FTIR, X-ray diffractometry, TEM and related to parameters of early (ALP and collagen I formation) and late (osteocalcin secretion) osteoblast expression. All cultures expressed high alkaline phosphatase activity and were able to form bone apatite. However, a nodular versus diffuse mineralization pattern was observed. Bone marrow, calvaria and periosteum (early passage) derived cells mineralized restrictively on the three-dimensional area of a nodule. The extracellular matrix consisted of collagen I fibers, among matrix vesicles loaded with needle-like crystals. Long bone, late passage periosteum derived and UMR-106 cells exhibited a diffuse mineralization pattern. Needle-like crystals were observed between the cells but collagen fibers and matrix vesicles could not be detected. Secretion of osteocalcin was detected in cultures derived from bone marrow and absent in UMR-106 and long bone derived cell cultures. The present study demonstrates that dystrophic calcification can not be distinguished from cell-mediated calcification with von Kossa, FTIR and X-ray diffractometry. Primary osteoblastic cells capable of forming nodules are recommended to evaluate the osteoinductive properties of biomaterials.
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PMID:Calcification as an indicator of osteoinductive capacity of biomaterials in osteoblastic cell cultures. 1576 32

Biomaterial, an essential component of tissue engineering, serves as a scaffold for cell attachment, proliferation, and differentiation; provides the three dimensional (3D) structure and, in some applications, the mechanical strength required for the engineered tissue. Both synthetic and naturally occurring calcium phosphate based biomaterial have been used as bone fillers or bone extenders in orthopedic and reconstructive surgeries. This study aims to evaluate two popular calcium phosphate based biomaterial i.e., hydroxyapatite (HA) and tricalcium phosphate/hydroxyapatite (TCP/HA) granules as scaffold materials in bone tissue engineering. In our strategy for constructing tissue engineered bone, human osteoprogenitor cells derived from periosteum were incorporated with human plasma-derived fibrin and seeded onto HA or TCP/HA forming 3D tissue constructs and further maintained in osteogenic medium for 4 weeks to induce osteogenic differentiation. Constructs were subsequently implanted intramuscularly in nude mice for 8 weeks after which mice were euthanized and constructs harvested for evaluation. The differential cell response to the biomaterial (HA or TCP/HA) adopted as scaffold was illustrated by the histology of undecalcified constructs and evaluation using SEM and TEM. Both HA and TCP/HA constructs showed evidence of cell proliferation, calcium deposition, and collagen bundle formation albeit lesser in the former. Our findings demonstrated that TCP/HA is superior between the two in early bone formation and hence is the scaffold material of choice in bone tissue engineering.
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PMID:Differential osteogenic activity of osteoprogenitor cells on HA and TCP/HA scaffold of tissue engineered bone. 1768 85