Bone marrow contains many cellular elements that may contribute to fracture repair. We used a pluripotential stromal cell in a mouse model to demonstrate the presence of transplanted cells in fracture hematoma and subsequently in maturing fracture callus. Cells were transduced with traceable genes (lac Z and neomycin resistance) and traced in vivo after intravenous injection into syiigeneic mice. These transduced cells home to bone marrow, suggesting that they might be detected in fracture callus.Cells were injected intravenously into mice and stabilized femoral shaft fractures were induced. Control mice received intravenous lactated-Ringer's solution prior to fracture. Callus tissue and marrow were examined histologically from 1 to 10 weeks after fracture to detect transplanted cells. Transplanted cells were detected in fracture callus in areas, and at times, of most active bone formation. Control specimens showed minimal staining of the callus tissue. Levels of the traceable gene in fracture callus increased, reached a peak between 3 and 4 weeks after fracture, then diminished and disappeared by 10 weeks post-fracture as woven bone at the fracture site was replaced by lamellar bone with cells from the host mouse. The results show that pluripotent bone marrow cells home to the marrow after systemic injection and localize in fracture callus.
CD52 is composed of a 12 amino acid peptide with N-linked glycans bound to the single potential glycosylation site at position 3, and a glycosylphosphatidylinositol-anchor attached at the C-terminus. Some glycoforms of this molecule expressed in the male reproductive tract are recognized by complement-dependent sperm-immobilizing antibodies in infertile patients making this antigen an important target for immunocontraception and fertility studies. Although the amount of posttranslational modification is already remarkable for such a small polypeptide, O-glycosylation of CD52 has additionally been implicated by several studies, but never rigorously characterized. In this report, we show clear evidence for the presence of O-glycans in CD52 preparations immunopurified using the murine S19 monoclonal antibody generated against sperm agglutination antigen-1 (SAGA-1), a male reproductive tract specific form of CD52. The O-glycans have been characterized by MALDI-TOF and tandem mass spectrometry after reductive elimination and permethylation. The data indicate that the major SAGA-1 O-glycans are core 1 and 2 mucin-type structures, with and without sialic acid (NeuAc(0-2)Hex(1-3)HexNAc(1-2)HexNAcitol). Minor fucosy- lated O-glycans are also present including some struc- tures with putative Le(y) epitopes (NeuAc(0-1)Fuc(1-3)Hex(1-2) HexNAc(0-1)HexNAcitol). Analysis of O-glycopeptides by tandem mass spectrometry provided an additional level of support for the O-glycosylation of SAGA-1. Elucidation of the O-glycosylation of SAGA-1 adds to the complexity of this molecule and may help to explain its biological activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.