The origin of bone that forms in association with cancellous chips transplanted into muscle

Abstract

Summary New bone forms in association with autogenous cancellous bone chips transplanted into muscle. It could be argued that this new bone develops from local connective tissue cells as a result of metaplasia induced by chemical substances inherent in the chips and hence that the formation of new bone around chips does not prove that the covering osteogenic cells and osteoblasts of the chips survive the transplantation. In an attempt to ascertain whether the new bone that commonly forms around cancellous chips transplanted into muscle arises from local connective tissue cells as a result of metaplasia or from the covering cells of the chips, both untreated autogenous cancellous chips and thrice-frozen-and-thawed cancellous chips were transplanted into the muscles of five dogs. It was believed that although the thrice-freezing-and-thawing procedure would kill all the cells in and associated with the chips, it would not materially alter the chemical composition of possible bone-inducing substances contained in the chips. In none of five dogs did new bone form in association with the thrice-frozen-and-thawed chips. In all of five dogs new bone formed in association with the untreated chips. It is concluded that such bone as commonly forms around untreated autogenous cancellous chips that are transplanted into muscle arises from such covering cells of the chips, or undifferentiated marrow cells associated with them, as survive transplantation. The implications of the foregoing conclusions with regard to the use of bone chips of various kinds in attempts to set up new centres of osteogenesis in bone defects are discussed.