FRACTURE HEALING IN A RABBIT MODEL: A STUDY OF OSTEOCALCIN LOCALISATION

Immunocytochemistry was used to localise osteocalcin during fracture healing in tissue sections of adult rabbit tibiae. A peroxidase anti-peroxidase technique and an indirect peroxidase technique were assessed on newly developing bone in human fracture callus. Three antibodies which cross-reacted with human osteocalcin in serum were evaluated for use as the primary antibody in the staining procedures. The majority of morphologically typical osteoblasts lining newly formed bone stained strongly for osteocalcin; bone matrix stained lightly for the protein. The optimum method for osteocalcin localisation in human bone was adapted using a newly developed rat anti-rabbit osteocalcin antibody, for use on immature 5-day old rabbit bone, used as a source of active bone formation. Decalcification methods were evaluated on 4-week old rabbit bone to enable fracture healing in heavily mineralised adult rabbit bone to be investigated immunocytochemically. In developing rabbit bone osteocalcin was present in osteoblasts and mineralised bone ’tutrix, but not in growth plate chondrocytes or cartilage matrix. Fracture healing studies showed morphologically typical, osteocalcin-producing osteoblasts lining newly forming trabeculae. Cells in the endosteum and in the cambium layer of the periosteum stained strongly for osteocalcin. Following periostel excision, bony callus originated only from the tissue s and blood vessels external to the perisostem indicated that these tissues failed to Contribute significantly to early fracture healing. Individual chondrocytes and groups of chondrocytes within the cartilaginous callus, usually in close apposition to blood vessels, consistently stained for osteocalcin. Chondrocytic staining for osteocalcin was confirmed using electron immunocytochemistry. These results indicate that chondrocytes, under certain conditions during fracture healing, are capable of producing osteocalcin, a protein considered to be specific for bone forming cells. Chondrocytes may be capable of differentiation into certain sub-sets of the osteoblastic phenotype which are able to produce osteocalcin.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1993

Author dc:creator

• STAFFORD, HILARY JANE

Licence

• https://dora.dmu.ac.uk/bitstreams/88086d90-2fbe-4ea7-af39-ce8ce93e97ad/download