Proceedings of the National Academy of Sciences · 1972 · 807 citations · 7 references
MedicineOrthopaedic SurgeryBone MetabolismTissue DifferentiationTissue EngineeringBone DevelopmentBone FormationBone TissueCartilage MetabolismOsteoblast BiologyOsteogenesisParietal Bone DevelopmentParietal Bone OssificationPhosphatase Enzyme Activity
Alkaline phosphatase activity and radioactive sulfate, phosphate, and calcium incorporation were used as sensitive quantitative assays to detect cartilage and bone formation. Acid‑insoluble bone matrix powders rapidly converted fibroblasts into cartilage and bone with marrow, forming a fibroblast‑encapsulated plaque within 24 hr; the conversion to chondroblasts was unstable, whereas osteoblast formation was stable, and the process followed a rigid timetable of sequences.
Coarse powders of acid-insoluble matrix of diaphysis and calvarial parietal bone rapidly and consistently transformed fibroblasts into masses of cartilage and bone containing hemopoietic marrow. The transformant was encapsulated by fibroblasts within 24 hr to form a plaque. Transformation was restricted to the central thicknesses of the plaque. Under the stated conditions the alteration of the phenotype, fibroblast to chondroblast, was an unstable transformation, whereas the phenotype change, fibroblast to osteoblast, was stable. The transformation occurred on a rigid timetable of sequences. Measurements of alkaline phosphatase activity and incorporation of radioactive sulfate, phosphate, and calcium were sensitive and quantitative assays for the appearance of the transformed products, cartilage and bone.
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