Osteogenic potential of cells in vitro derived from haemarthrosis of the knee induced by injury to the anterior cruciate ligament.

We have investigated whether cells derived from haemarthrosis caused by injury to the anterior cruciate ligament could differentiate into the osteoblast lineage in vitro. Haemarthroses associated with anterior cruciate ligament injuries were aspirated and cultured. After treatment with beta-glycerophosphate, ascorbic acid and dexamethasone or 1,25 (OH)(2)D(3), a significant increase in the activity of alkaline phosphatase was observed. Matrix mineralisation was demonstrated after 28 days and mRNA levels in osteoblast-related genes were enhanced. Our results suggest that the haemarthrosis induced by injury to the anterior cruciate ligament contains osteoprogenitor cells and is a potential alternative source for cell-based treatment in such injury.