8 research outputs found
The effects of biophysical stimuli on select bone cell functions pertinent to osteogenesis
No full textMay 2002School of EngineeringAlthough electric, pulsed electromagnetic, and magnetic fields have been used in attempts to accelerate bone repair in animal models and in clinical studies, the underlying cellular/molecular mechanisms responsible for new bone formation under these conditions are still not fully understood. Motivated by this need, the present in vitro study designed, assembled, and used novel laboratory systems to examine, and finally compare, the effects of alternating current, pulsed electromagnetic fields, and magnetic fields on select functions of osteoblasts (the bone-forming cells) pertinent to bone formation. The cell functions investigated were cell adhesion, proliferation, and gene expression of select bone-matrix proteins. In addition, calcium mineral accumulation, and index of formation of the inorganic phase of bone, in the extra cellular matrix of osteoblasts was also quantified.The three biophysical stimuli tested affected various functions of osteoblasts differently. For example, osteoblast (as well as fibroblast and endothelial cell) adhesion was dependent on serum proteins. Both cell proliferation and calcium content in the extracellular matrix increased under alternating current (10 μA at 10 Hz), decreased under pulsed electromagnetic (270 μT at 15 Hz), and remained unchanged under static magnetic (700 G) stimulation for 6 hours daily for 21 consecutive days. In addition, the present study provided the first molecular-level evidence that gene expression for collagen type I (the major structural protein of the organic phase of bone) was upregulated under alternating current (10 μA at 10 Hz), downregulated under pulsed electromagnetic (270 μT at 15 Hz), and remained unchanged under static magnetic (700 G) stimulation for 6 hours daily for 21 consecutive days. Furthermore, gene expression for osteocalcin was upregulated under static magnetic (700 G) stimulation for 6 hours daily for 1 and 7 days, but was not affected by exposure to either the alternating current (10 μA at 10 Hz) or the pulsed electromagnetic (270 μT at 15 Hz) field for 6 hours daily for 21 consecutive days. Of the three biophysical stimuli tested, alternating current stimulation consistently enhanced osteoblast functions relevant to new bone formation.In addition to contributions to cellular physiology, the present study provided the first evidence that the electric, magnetic, and pulsed electromagnetic stimuli tested affected osteoblast functions pertinent to the composition of both the organic and inorganic phases of bone. These results provide cellular/molecular-level explanation(s) of the events that take place during bone repair under biophysical stimulation in animal models and clinical studies. Furthermore, application(s) of the knowledge of the mechanisms underlying the effects of biophysical stimuli on the cellular/molecular responses of osteoblasts could be valuable in optimizing bone-related tissue engineering strategies as well as developing alternative therapeutic techniques for accelerating bone repair, healing, and regeneration.Ph
Human Adipose-Derived Side Population Stem Cells Cultured on Demineralized Bone Matrix for Bone Tissue Engineering
No full textLocal Antibiotic Delivery with Bovine Cancellous Chips
No full text Infected bone defects and osteomyelitis are encountered frequently in trauma cases. Currently, the standard of care for osteomyelitis cases is prolonged systemic antibiotic therapy and implantation of antibiotic carrier beads. However, this method requires a secondary surgery to remove the beads after the infection has cleared. In the present study a common bone void filler was investigated for its ability to be infused with an antibiotic. This study demonstrates that the xenograft material tested can be loaded with gentamicin and release clinically relevant levels of the drug for at least 14 days in vitro allowing for the inhibition of bacterial growth on the graft. This study also demonstrates that the levels of gentamicin released did not have an adverse effect on primary osteoblast cell proliferation or ability to generate alkaline phosphatase. This bone void filler may represent a viable alternative to current methods of local antibiotic delivery in orthopedic applications. </jats:p
Osteoconductivity and Osteoinductivity of Puros® DBM Putty
No full textBone graft substitutes have been developed due to the limited supply and morbidity associated with using autogenous graft material. Allogeneic demineralized bone matrix (DBM) has been used extensively as a clinical graft material because of its inherent osteoinductive and osteoconductive properties. Differential enhancement of these properties may optimize the performance of these products for various orthopedic and craniofacial applications. Commercially available bone paste products consist of formulations that combine DBM with a carrier to facilitate handling and containment. In the present study, we present results of a comprehensive in vitro and in vivo characterization of a 100% human DBM putty product, Puros DBM Putty. Results indicate the DBM particles are completely dispersed in the putty. Data are presented showing the porosity of and cell attachment to Puros DBM Putty, thereby demonstrating the osteoconductive properties of this DBM. Puros DBM Putty was also shown to be osteoinductive in the rat ectopic pouch model. We demonstrate here for the first time that Puros DBM Putty maintains its activity to markedly stimulate or induce bone formation over the entire period of its shelf life. Taken together, these data demonstrate that the 100% human allograft derived Puros DBM Putty could be an effective bone graft substitute.</jats:p
