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Myron Spector

Bio: Myron Spector is an academic researcher from Brigham and Women's Hospital. The author has contributed to research in topics: Tissue engineering & Cartilage. The author has an hindex of 74, co-authored 322 publications receiving 16724 citations. Previous affiliations of Myron Spector include Emory University & Harvard University.


Papers
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Journal ArticleDOI
TL;DR: The marked influence of collagen type and pore characteristics on the phenotypic expression of seeded chondrocytes in porous matrices comprising different collagen types and different pore diameters is demonstrated.

426 citations

Journal ArticleDOI
TL;DR: The effects of four cross-linking methods on the compressive stiffness of collagen-glycosaminoglycan (CG) matrices and the interaction between adult canine articular chondrocytes and the matrix are investigated to serve as a foundation for future studies of tissue engineering of articular cartilage and the association of chondrosclerosis contraction and the processes of mitosis and biosynthesis.

393 citations

Journal ArticleDOI
TL;DR: Evaluated composition of reparative tissue retrieved during revision surgery from full thickness chondral defects in 18 patients in whom abrasion arthroplasty, grafting of perichondrial flaps, and periosteal patching augmented by autologous chondrocyte implantation in cell suspension failed to provide lasting relief of symptoms.
Abstract: This study evaluated the composition of reparative tissue retrieved during revision surgery from full thickness chondral defects in 18 patients in whom abrasion arthroplasty (n = 12), grafting of perichondrial flaps (n = 4), and periosteal patching augmented by autologous chondrocyte implantation in cell suspension (n = 6) failed to provide lasting relief of symptoms. The defects were graded by gross appearance, and all of the tissue filling the defect was retrieved. Histologic evaluation included histomorphometric analysis of the percentage of selected tissue types in cross sections. Immunohistochemistry was performed using antibodies to Types I, II, and X collagen. The histologic appearance of material retrieved after abrasion arthroplasty was that of fibrous, spongiform tissue comprising Type I collagen in 22% ± 9% (mean ± standard error of the mean) of the cross sectional area, and degenerating hyaline tissue (30% ± 10%) and fibrocartilage (28% ± 7%) with positive Type II collagen staining. Three of four specimens obtained after implantation of perichondrium failed as a result of bone formation that was found in 19% ± 6% of the cross sectional area, including areas staining positive for Type X collagen, as an indicator for hypertrophic chondrocytes. Revision after autologous chondrocyte implantation was associated with partial displacement of the periosteal graft from the defect site because of insufficient ongrowth or early suture failure. When the graft edge displaced, repair tissue was fibrous (55% ± 11%), whereas graft tissue attached to subchondral bone displayed hyaline tissue (to 6%) and fibrocartilage (to 12%) comprising Type II collagen at 3 months after surgery. Evaluation of retrieved repair tissue after selected cartilage repair procedures revealed distinctive histologic features reflecting the mechanisms of failure.

382 citations

Journal ArticleDOI
TL;DR: The objective of the present study was to determine the effect of cultured autologous chondrocytes on healing in an adult canine model with use of histomorphometric methods to assess the degree of repair.
Abstract: Articular cartilage has a limited capacity for repair. In recent clinical and animal experiments, investigators have attempted to elicit the repair of defects of articular cartilage by injecting cultured autologous chondrocytes under a periosteal flap (a layer of periosteum). The objective of the present study was to determine the effect of cultured autologous chondrocytes on healing in an adult canine model with use of histomorphometric methods to assess the degree of repair. A total of forty-four four-millimeter-diameter circular defects were created down to the zone of calcified cartilage in the articular cartilage of the trochlear groove of the distal part of the femur in fourteen dogs. The morphology and characteristics of the original defects were defined in an additional six freshly created defects in three other dogs. Some residual non-calcified articular cartilage, occupying approximately 2 per cent of the total cross-sectional area of the defect, was sometimes left in the defect. The procedure sometimes damaged the calcified cartilage, resulting in occasional microfractures or larger fractures, thinning of the zone of calcified cartilage, or, rarely, small localized penetrations into subchondral bone. The forty-four defects were divided into three treatment groups. In one group, cultured autologous chondrocytes were implanted under a periosteal flap. In the second group, the defect was covered with a periosteal flap but no autologous chondrocytes were implanted. In the third group (the control group), the defects were left empty. The defects were analyzed after twelve or eighteen months of healing. Histomorphometric measurements were made of the percentage of the total area of the defect that became filled with repair tissue, the types of tissue that filled the defect, and the integration of the repair tissue with the adjacent cartilage at the sides of the defects and with the calcified cartilage at the base of the defect. In histological sections made through the center of the defects in the three groups, the area of the defect that filled with new repair tissue ranged from a mean total value of 36 to 76 per cent, with 10 to 23 per cent of the total area consisting of hyaline cartilage. Integration of the repair tissue with the adjacent cartilage at the edges of the defect ranged from 16 to 32 per cent in the three groups. Bonding between the repair tissue and the calcified cartilage at the base of the defect ranged from 41 to 89 per cent. With the numbers available, we could detect no significant difference among the three groups with regard to any of the parameters used to assess the quality of the repair. In the two groups in which a periosteal flap was sutured to the articular cartilage surrounding the defect, the articular cartilage showed degenerative changes that appeared to be related to that suturing. CLINICAL RELEVANCE: The technique of injecting cultured autologous chondrocytes under a periosteal flap recently was introduced to treat defects in the articular cartilage of humans. The long-term efficacy of this treatment is unknown. An animal model was developed to evaluate the procedure and its effectiveness.

358 citations

Journal ArticleDOI
TL;DR: After rupture, the human anterior cruciate ligament undergoes four histological phases, consisting of inflammation, epiligamentous regeneration, proliferation, and remodeling, which is similar to that reported in other dense connective tissues.
Abstract: Background:Four phases in the response to injury of the ruptured human anterior cruciate ligament are observed histologically; these include an inflammatory phase, an epiligamentous repair phase, a proliferative phase, and a remodeling phase. One objective of this study was to describe the h

338 citations


Cited by
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Journal ArticleDOI
TL;DR: Hydrogels are an appealing scaffold material because they are structurally similar to the extracellular matrix of many tissues, can often be processed under relatively mild conditions, and may be delivered in a minimally invasive manner.

4,573 citations

Journal ArticleDOI
TL;DR: This work highlights recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for biomedical and biological applications and shows how such systems' intelligent behavior can be used in sensors, microarrays, and imaging.
Abstract: Hydrophilic polymers are the center of research emphasis in nanotechnology because of their perceived “intelligence”. They can be used as thin films, scaffolds, or nanoparticles in a wide range of biomedical and biological applications. Here we highlight recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for these applications. Natural, biohybrid, and synthetic hydrophilic polymers and hydrogels are analyzed and their thermodynamic responses are discussed. In addition, examples of the use of hydrogels for various therapeutic applications are given. We show how such systems’ intelligent behavior can be used in sensors, microarrays, and imaging. Finally, we outline challenges for the future in integrating hydrogels into biomedical applications.

3,524 citations

PatentDOI
14 Nov 2002-Science
TL;DR: In this paper, pH-induced self-assembly of a peptide-amphiphile was used to make a nanostructured fibrous scaffold reminiscent of extracellular matrix.
Abstract: We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.

3,125 citations

Journal ArticleDOI
TL;DR: A comprehensive review of existing piezoelectric generators is presented in this paper, including impact coupled, resonant and human-based devices, including large scale discrete devices and wafer-scale integrated versions.
Abstract: This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric, electromagnetic and electrostatic. Piezoelectric generators employ active materials that generate a charge when mechanically stressed. A comprehensive review of existing piezoelectric generators is presented, including impact coupled, resonant and human-based devices. Electromagnetic generators employ electromagnetic induction arising from the relative motion between a magnetic flux gradient and a conductor. Electromagnetic generators presented in the literature are reviewed including large scale discrete devices and wafer-scale integrated versions. Electrostatic generators utilize the relative movement between electrically isolated charged capacitor plates to generate energy. The work done against the electrostatic force between the plates provides the harvested energy. Electrostatic-based generators are reviewed under the classifications of in-plane overlap varying, in-plane gap closing and out-of-plane gap closing; the Coulomb force parametric generator and electret-based generators are also covered. The coupling factor of each transduction mechanism is discussed and all the devices presented in the literature are summarized in tables classified by transduction type; conclusions are drawn as to the suitability of the various techniques.

2,834 citations

Journal ArticleDOI
TL;DR: The functional requirements, and types, of materials used in developing state of the art of scaffolds for tissue engineering applications are described and where future research and direction is required are described.

2,648 citations