Biomedical subjects

Brett Peterson

Publications and source records attributed to Brett Peterson.

5 recordsLinked to original sources

PubMed2006

Carpal osteoarthrosis.

Despite improved understanding of carpal mechanics, increased awareness of intercarpal ligament injuries, and improved techniques for treating carpal instability, post-traumatic intercarpal osteoarthrosis remains a common problem. Osteoarthritis of the carpal bones, including scapholunate advance collapse wrist, scaphotrapeziotrapezoid arthritis, lunotriquetral arthritis, triquetrohamate arthritis, and pisotriquetral arthritis, follows specific unique patterns, but in each, the final common pathway leads to degenerative change. Injury or deformity leads to instability and altered kinematics, producing abnormal joint contact pressures. Cartilage injury and eventual degeneration of the join follow. The etiology, prevalence, and current evaluation and treatment of these conditions are of importance to hand surgeons.

Carpal Joints↗

PubMed2005

Genetically modified human derived bone marrow cells for posterolateral lumbar spine fusion in athymic rats: beyond conventional autologous bone grafting.

STUDY DESIGN: This experimental study consisted of four groups. In Group I, 8 animals were implanted with a collagen sponge containing 5 million human-derived bone marrow cells (HBMCs) infected with the BMP-2-containing adenovirus. In Group II, 5 animals were implanted with a collagen sponge containing 5 million HBMCs, which had been infected with an adenovirus containing the cDNA for the lacZ gene. In Group III, 5 animals were implanted with a collagen sponge containing 5 million uninfected HBMCs. In Group IV, 5 animals were implanted with a collagen sponge alone. All animals were killed at 12 weeks. OBJECTIVES: The purpose of this study was to assess the ability of HBMCs infected with a BMP-2 adenovirus to induce a posterolateral spine in an athymic rat model. SUMMARY OF BACKGROUND DATA: High pseudarthrosis rates after attempted spinal arthrodesis as well as the morbidity associated with iliac crest bone graft harvest make alternative bone graft materials desirable. Alternatives include allograft bone, demineralized bone matrices, and more recently, recombinant bone morphogenetic proteins. However, high doses of the recombinant protein are required, and a single dose of recombinant protein may not induce a sufficient osteoinductive response in all patients. An alternative strategy is to genetically manipulate cells to overexpress a bone morphogenetic protein. METHODS: HBMCs grown in culture were infected with an adenovirus containing the cDNA for BMP-2 (AdBMP-2) or the gene for beta-galactosidase (AdlacZ). Cells were implanted on the decorticated transverse processes of L4-L5 as previously described. Rats were assessed by radiographs at 4-week intervals and were killed at 12 weeks. After death, spines were explanted and assessed by manual palpation and histologic analysis. RESULTS: Eight of eight rats implanted with AdBMP-2-infected HBMCs (Group I) were fused by radiographic evaluation and manual palpation at 12 weeks. Control groups consisted of: 5 rats implanted with the collagen sponge alone (Group II), 5 rats implanted with a collagen sponge and 5 million uninfected HBMCs (Group III), and 5 rats implanted with HBMCs infected with AdlacZ (Group IV). None of the rats in the control groups (0 of 15) developed a fusion at L4-L5. CONCLUSION: This study demonstrates that human-derived bone marrow cells can be infected with a BMP-2-containing adenovirus and produce sufficient bone in vivo to fuse the lumbar spine.

Adenoviridae↗

PubMed2004

Osteoinductivity of commercially available demineralized bone matrix. Preparations in a spine fusion model.

BACKGROUND: Although autogenous bone is the most widely used graft material for spinal fusion, demineralized bone matrix preparations are available as alternatives or supplements to autograft. They are prepared by acid extraction of most of the mineralized component, with retention of the collagen and noncollagenous proteins, including growth factors. Differences in allograft processing methods among suppliers might yield products with different osteoinductive activities. The purpose of this study was to compare the efficacy of three different commercially available demineralized bone matrix products for inducing spinal fusion in an athymic rat model. METHODS: Sixty male athymic rats underwent spinal fusion and were divided into three groups of eighteen animals each. Group I received Grafton Putty; Group II, DBX Putty; and Group III, AlloMatrix Injectable Putty. A control group of six animals (Group IV) underwent decortication alone. Six animals from each of the three experimental groups were killed at each of three intervals (two, four, and eight weeks), and the six animals from the control group were killed at eight weeks. At each of the time-points, radiographic and histologic analysis and manual testing of the explanted spines were performed. RESULTS: The spines in Group I demonstrated higher rates of radiographically evident fusion at eight weeks than did the spines in Group III or Group IV (p < 0.05). Manual testing of the spines at four weeks revealed variable fusion rates (five of six in Group I, two of six in Group II, and none of six in Group III). At eight weeks, all six spines in Group I, three of the six in Group II, and no spine in Group III or IV had fused. Histologic analysis of the spines in Groups I, II, and III demonstrated varying amounts of residual demineralized bone matrix and new bone formation. Group-I spines demonstrated the most new bone formation. CONCLUSIONS: This study demonstrated differences in the osteoinductive potentials of commercially available demineralized bone matrices in this animal model.

Animals↗

PubMed2003

Gene therapy in orthopaedic surgery.

Gene therapy has the potential to revolutionize the treatment of a variety of musculoskeletal disorders. In the past decade, more than 4,000 patients have been enrolled in clinical trials involving gene therapy. Gene therapy is becoming increasingly important in modern orthopaedic clinical practice. It is important to discuss the issues that physicians and scientists face when designing an experiment or clinical trial involving gene therapy, along with the potential clinical applications for gene therapy in the treatment of patients with musculoskeletal problems.

Bone Development↗

PubMedDate not supplied

Healing of critically sized femoral defects, using genetically modified mesenchymal stem cells from human adipose tissue.

The FDA has approved the clinical use of recombinant bone morphogenetic proteins (BMPs). However, the use of recombinant BMPs in humans has required large doses of the proteins to be effective, which suggests that the delivery method of bone morphogenetic proteins needs to be optimized. Gene therapy is an alternative method to deliver such recombinant proteins, and gene transfer techniques have been tested on a variety of cell types including bone marrow cells, skin fibroblasts, peripheral blood monocytes, and muscle-derived cells. In this study, we sought to determine the ability of BMP-2-producing human adipose-derived mesenchymal stem cells to heal a critically sized femoral defect in a nude rat model. After approval by the human subjects protection committee, human adipose tissue was obtained from healthy donors. The lipoaspirate was processed as previously described (De Ugarte, D.A., et al. Cells Tissues Organs 174, 101, 2003). Cells were grown in culture and infected with a BMP-2-carrying adenovirus. Five million cells were applied to a collagen- ceramic carrier and implanted into femoral defects as previously described (Zuk, P.A., et al. Mol. Biol. 13, 4279, 2002). All animals were killed at 8 weeks. Femora were dissected out and underwent radiographic, histologic, and biomechanical analysis. Eleven of the 12 femora in the group treated with human processed lipoaspirate (HPLA) cells genetically modified to overexpress BMP-2 had healed at 8 weeks. This was assessed by radiographs, by mechanical testing, and by histology. The one femur that did not heal had a subacute infection. All eight of the femora treated with the rhBMP-2-impregnated collagen-ceramic carrier healed. No statistically significant difference was detected between these two groups. Evaluation of the control groups: group II (collagen- ceramic carrier with HPLA cells) and group III (collagen-ceramic carrier alone) showed that none of the femora had healed by 8 weeks. Our results indicate that HPLA cells genetically modified by adenoviral gene transfer to overexpress BMP-2 can induce bone formation in vivo and heal a critically sized femoral defect in an athymic rat. The HPLA cells alone did not induce significant bone formation. However, when combined with an osteoinductive factor these cells may be an effective method for enhancing bone healing and the tissue engineering of bone.

Adenoviridae↗