Arthritis News – 1999

Bone marrow transplantation has not been utilized previously to attempt to correct genetic disorders of mesenchymal tissues (i.e., bone, cartilage and muscle). However, it has been shown in animal studies that bone marrow derived mesenchymal cells are capable of homing to, and incorporating themselves, into bone and muscle of recipient animals. In a recent study (Nature Medicine 5:309-313, 1999), Horwitz and colleagues reported on the results of allogeneic bone marrow transplantation in three children with osteogenesis imperfecta (O.I.) O.I. is a genetic disorder of type I collagen which leads to osteopenia, fractures, bone deformities, and short stature. Bone biopsies performed 6 months after transplantation demonstrated an increase in number of osteoblasts and new dense bone formation compared to pre-transplantation biopsies. In addition, all three children had increases in total body bone mineral content, increases in growth velocity an d reduced frequencies of bone fracture following transplantation.

These studies demonstrate, for the first time, successful engraftment of functional mesenchymal progenitor cells into bone of human recipients. Long-term follow-up of these, and similarly treated patients, will be needed to evaluate the longevity of the response. This approach may be appropriate for other stem cell mesenchymal disorders.