Treatment of large bone defects in the craniomaxillofacial or axial skeleton is a challenging process. The gold standard treatment involving harvesting of bone from another anatomical location in the patient, can lead to donor site morbidity, increased pain cost and recovery time. The ideal therapy would use cell free materials to fill the defect combined with chemical agents that induce and instruct bone defect repair by cells of the patient. This would avoid the costly stages of cell harvesting and preparation under Good Manufacturing Practice conditions associated with cell therapy based approaches. Here we describe the assessment of the ability of 3 proteins, Follistatin, Nell1 and Connective Tissue Growth Factor (CTGF/CCN2) to induce osteogenic differentiation and migration of osteoprogenitors and mesenchymal stem cells (MSCs) as a model for the recruitment of resident cells in the in vivo situation. Cells were cultured with addition of each factor at a range of doses (Follistatin: 0.8 nM, 2 nM and 5 nM, Nell1: 10 ng/ml, 100 ng/ml and 500 ng/ml and CCN2: 10 ng/ml, 50 ng/ml and 100 ng/ml). svHFO (simian virus Human Foetal Osteoblasts) preosteoblasts and MSCs were cultured in osteogenic differentiation medium (dex glycerophosphate etc) for up to 21 days. Alkaline phosphatase activity (ALP), calcium deposition, total protein and DNA were measured. Chemotaxis towards each factor was also measured. Follistatin induced a dose dependent increase in ALP activity and mineralisation (calcium accumulation). In contrast, there was no significant difference in any osteogenic parameter measured with the addition of Nell 1 or CCN2. This work indicates the potential of follistatin to be used as a pro-osteogenic factor for the induction of bone formation for the repair of large bone defects.
Disclosure: The authors declared no competing interests. This work was supported by the seventh framework programme under grant agreement number 607051.