Brief Review of Models of Ectopic Bone Formation

Ectopic bone formation is a unique biologic entity?distinct from other areas of skeletal biology. Animal research models of ectopic bone formation most often employ rodent models and have unique advantages over orthotopic (bone) environments, including a relative lack of bone cytokine stimulation and cell-to-cell interaction with endogenous (host) bone-forming cells. This allows for relatively controlled in vivo experimental bone formation. A wide variety of ectopic locations have been used for experimentation, including subcutaneous, intramuscular, and kidney capsule transplantation. The method, benefits and detractions of each method are summarized in the following review. Briefly, subcutaneous implantation is the simplest method. However, the most pertinent concern is the relative paucity of bone formation in comparison to other models. Intramuscular implantation is also widely used and relatively simple, however intramuscular implants are exposed to skeletal muscle satellite progenitor cells. Thus, distinguishing host from donor osteogenesis becomes challenging without cell-tracking studies. The kidney capsule (perirenal or renal capsule) method is less widely used and more technically challenging. It allows for supraphysiologic blood and nutrient resource, promoting robust bone growth. In summary, ectopic bone models are extremely useful in the evaluation of bone-forming stem cells, new osteoinductive biomaterials, and growth factors; an appropriate choice of model, however, will greatly increase experimental success.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98476/1/scd%2E2011%2E0517.pd

Tumor induced by Moloney sarcoma virus causes periosteal osteogenesis engaging osteopontin, fibronectin, stromelysin-1 and tenascin.

Excessive bone formation occurring in such conditions as paravertebral ligamentous ossification, hallux osteophytes or some neoplastic tumors, presents a significant problem, both epidemiological and clinical. Since pathogenesis of this disorder is still unclear, we studied its mechanism in experimental model utilizing inducible orthotopic osteogenesis. Periosteal bone apposition stimulated by Moloney sarcoma is characterized by unusually high volume of new bone tissue appearing subperiosteally in the bone adjacent to the tumor. Genes engaged in this growth have not been characterized so far. Here we show the results of mRNA Representation Difference Analysis in Moloney sarcoma, which reveal high expression of four genes coding extracellular matrix proteins: osteopontin, fibronectin, stromelysin-1 and tenascin. These findings suggest that the uncommon dynamics of the Moloney sarcoma-induced osteogenesis depends on high expression of these extracellular matrix proteins