Search

Your search keyword '"Attawia, Mohamed"' showing total 35 results
Start Over Author "Attawia, Mohamed"
35 results on '"Attawia, Mohamed"'

5. Structural Assessment of a Tissue Engineered Scaffold for Bone Repair

Author

DREXEL UNIV PHILADELPHIA PA CENTER FORADVANCED BIOMATERIALS AND TISSUE ENGINEERING, Laurencin, Cato T., Borden, Mark, Attawia, Mohamed, El-Amin, Saadig, DREXEL UNIV PHILADELPHIA PA CENTER FORADVANCED BIOMATERIALS AND TISSUE ENGINEERING, Laurencin, Cato T., Borden, Mark, Attawia, Mohamed, and El-Amin, Saadig

Abstract

The limitations of current grafting materials have driven the search for synthetic alternatives to cancellous bone. A variety of biodegradable polymer foams composed of poly(lactide-co-glycolide) PLAGA have been evaluated for such uses. However, structural limitations may restrict the clinical use of these scaffolds. We have developed a sintered microsphere scaffold composed of 85:15 poly(lactide-co-glycolide) with a biommetic pore system equivalent to the structure of cancellous bone. Analysis of the structural data, indicated that the microsphere matrix sintered at a temperature of 160 degrees C with a microsphere diameter of 355-425 micrometer resulted in a optimal, biomimetic structure with an approximate pore diameter of 75 to 275 micrometer, 35% porosity, and compressive modulus of 272 MPa. The in vitro evaluation of human osteoblasts on the sintered matrix indicated that the structure was capable of supporting the attachment and proliferation of the cells throughout its pore system. Immunofluorescent staining of actin showed that the cells were proliferating 3-dimensionally through the pore system. The stain for osteocalcin showed that the cells had maintained the phenotypic expression for this bone specific protein. Through this work, it was shown that an osteoconductive PLAGA scaffold with a pore system equivalent to the structure of cancellous bone could be fabricated through the sintered microsphere method., Papers from 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Oct 25-28, 2001, held in Istanbul, Turkey. See also ADM001351 for entire conference on cd-rom.

Published
2001

8. Intradiscal Thermal Therapy Using Interstitial Ultrasound

Author

Nau, William H., primary, Diederich, Chris J., additional, Shu, Richard, additional, Kinsey, Adam, additional, Bass, Elisa, additional, Lotz, Jeff, additional, Hu, Serena, additional, Simko, Jeff, additional, Ferrier, William, additional, Sutton, Jeff, additional, Attawia, Mohamed, additional, and Pellegrino, Richard, additional

Published
2007
Full Text
View/download PDF

31. The sintered microsphere matrix for bone tissue engineering: In vitroosteoconductivity studies

Author

Borden, Mark, Attawia, Mohamed, and Laurencin, Cato T.

Abstract

A tissue engineering approach has been used to design threedimensional synthetic matrices for bone repair. The osteoconductivity and degradation profile of a novel polymeric bonegraft substitute was evaluated in an in vitrosetting. Using the copolymer polylactidecoglycolide PLAGA, a sintering technique based on microsphere technology was used to fabricate threedimensional porous scaffolds for bone regeneration. Osteoblasts and fibroblasts were seeded onto a 50:50 PLAGA scaffold. Morphologic evaluation through scanning electron microscopy demonstrated that both cell types attached and spread over the scaffold. Cells migrated through the matrix using cytoplasmic extensions to bridge the structure. Crosssectional images indicated that cellular proliferation had penetrated into the matrix approximately 700 μm from the surface. Examination of the surfaces of cellmatrix constructs demonstrated that cellular proliferation had encompassed the pores of the matrix by 14 days of cell culture. With the aim of optimizing polymer composition and polymer molecular weight, a degradation study was conducted utilizing the matrix. The results demonstrate that degradation of the sintered matrix is dependent on molecular weight, copolymer ratio, and pore volume. From this data, it was determined that 75:25 PLAGA with an initial molecular weight of 100,000 has an optimal degradation profile. These studies show that the sintered microsphere matrix has an osteoconductive structure capable of functioning as a cellular scaffold with a degradation profile suitable for bone regeneration. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 421–429, 2002

Published
2002
Full Text
View/download PDF

32. Preliminary in vivoreport on the osteocompatibility of poly(anhydride-co-imides) evaluated in a tibial model

Author

Ibim, Sobrasua E. M., Uhrich, Kathryn E., Attawia, Mohamed, Shastri, Venkatram R., El-Amin, Saadiq F., Bronson, Roderick, Langer, Robert, and Laurencin, Cato T.

Abstract

A novel class of polymers with mechanical properties similar to cancellous bone are being investigated for their ability to be used in weight-bearing areas for orthopedic applications. The poly(anhydride-co-imide) polymers based on poly[trimellitylimidoglycine-co-1,6-bis(carboxyphenoxy)hexane] (TMA-Gly:CPH) and poly[pyromellitylimidoalanine-co-1,6-bis(carboxyphenoxy)hexane] (PMA-Ala:CPH) in molar ratios of 30:70 were investigated for osteocompatibility, with effects on the healing of unicortical 3-mm defects in rat tibias examined over a 30-day period. Defects were made with surgical drill bits (3-mm diameter) and sites were filled with poly(anhydride-co-imide) matrices and compared to the control poly(lactic acid-glycolic acid) (PLAGA) (50:50), a well-characterized matrix frequently used in bone regeneration studies, and defects without polymeric implants. At predetermined time intervals (3, 6, 9, 12, 20, and 30 days), animals were sacrificed and tissue histology was examined for bone formation, polymer-tissue interaction, and local tissue response by light microscopy. The studies revealed that matrices of TMA-Gly:CPH and PMA-Ala:CPH produced responses similar to the control PLAGA with tissue compatibility characterized by a mild response involving neutrophils, macrophages, and giant cells throughout the experiment for all matrices studied. Matrices of PLAGA were nearly completely degraded by 21 days in contrast to matrices of TMA-Gly:CPH and PMA-Ala:CPH that displayed slow erosion characteristics and maintenance of shape. Defects in control rats without polymer healed by day 12, defects containing PLAGA healed after 20 days, and defects containing poly(anhydride-co-imide) matrices produced endosteal bone growth as early as day 3 and formed bridges of cortical bone around matrices by 30 days. In addition, there was marrow reconstitution at the defect site for all matrices studied along with matured bone-forming cells. This study suggests that novel poly(anhydride-co-imides) are promising polymers that may be suitable for use as implants in bone surgery, especially in weight-bearing areas. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 374–379, 1998

Published
1998
Full Text
View/download PDF

34. Effects of growth differentiation factor-5 on the intervertebral disc--in vitro bovine study and in vivo rabbit disc degeneration model study.

Author

Chujo T, An HS, Akeda K, Miyamoto K, Muehleman C, Attawia M, Andersson G, and Masuda K

Subjects
Animals, Cattle, Cells, Cultured, Disease Models, Animal, Growth Differentiation Factor 5, Humans, Intervertebral Disc pathology, Intervertebral Disc Displacement pathology, Rabbits, Spinal Diseases pathology, Bone Morphogenetic Proteins pharmacology, Bone Morphogenetic Proteins therapeutic use, Intervertebral Disc drug effects, Intervertebral Disc Displacement drug therapy, Spinal Diseases drug therapy
Abstract

Study Design: In vitro studies on the effects of recombinant human growth and differentiation factor-5 (rhGDF-5) on matrix metabolism of bovine intervertebral disc cells and an in vivo study on the effect of rhGDF-5 in the rabbit anular puncture model., Objective: To determine the reparative capacity of rhGDF-5 on the intervertebral disc., Summary of Background Data: The in vitro and in vivo effects of rhGDF-5, a crucial protein in the developing musculoskeletal system, on repair of the degenerated intervertebral disc remain unidentified., Methods: In vitro, bovine nucleus pulposus and anulus fibrosus cells were cultured with or without rhGDF-5 (100 or 200 ng/mL). On days 7, 14, and 21, the contents of deoxyribonucleic acid and proteoglycan, and the synthesis of proteoglycan and collagen were assessed. In vivo, 16 adolescent New Zealand white rabbits received anular punctures in 2 lumbar discs. Four weeks later, phosphate buffered saline or rhGDF-5 (10 ng, 1 and 100 mug) was injected into the nucleus pulposus. The rabbits were followed up for 16 weeks for disc height, magnetic resonance imaging, and histologic grading., Results: In vitro, rhGDF-5 increased the deoxyribonucleic acid and proteoglycan contents of both cell types significantly after day 14. rhGDF-5 at 200 ng/mL significantly stimulated proteoglycan synthesis (nucleus pulposus: +138%, anulus fibrosus: +24%) and collagen synthesis (nucleus pulposus: +95%, anulus fibrosus: +23%) at day 21. In vivo, the injection of rhGDF-5 resulted in a restoration of disc height, improvement of magnetic resonance imaging scores, and histologic grading scores with statistical significance (P < 0.05-0.001)., Conclusion: A single injection of rhGDF-5 has a reparative capacity on intervertebral discs, presumably based on its effects to enhance extracellular matrix production in vitro.

Published
2006
Full Text
View/download PDF

35. The sintered microsphere matrix for bone tissue engineering: in vitro osteoconductivity studies.

Author

Borden M, Attawia M, and Laurencin CT

Subjects
Animals, Biodegradation, Environmental, Cell Adhesion, Cell Division, Fibroblasts cytology, Microspheres, Osteoblasts cytology, Polyesters, Polyglycolic Acid, Rats, Biocompatible Materials chemistry, Bone Substitutes, Osseointegration, Tissue Engineering methods
Abstract

A tissue engineering approach has been used to design three-dimensional synthetic matrices for bone repair. The osteoconductivity and degradation profile of a novel polymeric bone-graft substitute was evaluated in an in vitro setting. Using the copolymer poly(lactide-co-glycolide) [PLAGA], a sintering technique based on microsphere technology was used to fabricate three-dimensional porous scaffolds for bone regeneration. Osteoblasts and fibroblasts were seeded onto a 50:50 PLAGA scaffold. Morphologic evaluation through scanning electron microscopy demonstrated that both cell types attached and spread over the scaffold. Cells migrated through the matrix using cytoplasmic extensions to bridge the structure. Cross-sectional images indicated that cellular proliferation had penetrated into the matrix approximately 700 microm from the surface. Examination of the surfaces of cell/matrix constructs demonstrated that cellular proliferation had encompassed the pores of the matrix by 14 days of cell culture. With the aim of optimizing polymer composition and polymer molecular weight, a degradation study was conducted utilizing the matrix. The results demonstrate that degradation of the sintered matrix is dependent on molecular weight, copolymer ratio, and pore volume. From this data, it was determined that 75:25 PLAGA with an initial molecular weight of 100,000 has an optimal degradation profile. These studies show that the sintered microsphere matrix has an osteoconductive structure capable of functioning as a cellular scaffold with a degradation profile suitable for bone regeneration., (Copyright 2002 Wiley Periodicals, Inc.)

Published
2002
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results