Age-related changes of cell outgrowth from rat calvarial and mandibular bone in vitro.
OBJECTIVE
To establish whether within an autograft ageing has an impact on the number of cells capable of responding to growth and differentiation factors released at defect sites.


METHODS
The number of cells that grow out from calvarial and mandibular explants of rats 6 weeks and 9 months of age was evaluated and their response to mitogenic, chemotactic, and differentiation factors was characterized in vitro. The cell number was determined by automated counting, proliferation was evaluated by measuring the amount of (tritiated) (3)[H]thymidine incorporated into the DNA, and migration was assessed with the modified Boyden chamber assay. Alkaline phosphatase activity served as a marker of osteogenic differentiation.


RESULTS
A confluent layer of cells was observed in mandibular and calvarial explant cultures derived from young rats within 10 days, while only sporadic cells were counted in cultures from adult animals. The number of cells derived from calvarial and mandibular bone of young rats was nine and five times higher, respectively, than that in explants from adult rats. Cells isolated from calvarial and mandibular explants responded to platelet-released supernatant by increased proliferation and migration in both age groups. Upon incubation with bone morphogenetic protein (BMP-6), the alkaline phosphatase activity of calvaria-derived cells from both age groups was higher than in unstimulated controls. Only one sample of cells derived from mandibular explants showed responsiveness to BMP-6 in the young age group, whereas none of the cell samples responded to BMP-6 in the adult age group.


CONCLUSIONS
The number of cells capable of growing out from mandibular and calvarial grafts in vitro is lower in adult animals than in young animals. However, bone-derived cells from both young and adult rats respond to growth and differentiation factors present at defect sites, while there are topographic differences in the responsiveness to BMP-6.
Cei
Silvia
S
Cattedra di Chirurgia Speciale Odontostomatologica, University of Pisa, Pisa, Italy.
Mair
Birgit
B
Kandler
Barbara
B
Gabriele
Mario
M
Watzek
Georg
G
Gruber
Reinhard
R
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D055418:Bone Morphogenetic Protein 6; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002630:Chemotactic Factors / Q000494:pharmacology; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D005260:Female; D008334:Mandible / Q000166:cytology* / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar; D012886:Skull / Q000166:cytology* / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014316:Tritium
C525818:Bmp6 protein, rat; D055418:Bone Morphogenetic Protein 6; D019485:Bone Morphogenetic Proteins; D002630:Chemotactic Factors; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D019275:Radiopharmaceuticals; D016212:Transforming Growth Factor beta; D014316:Tritium; D000469:Alkaline Phosphatase