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A bioartifical nerve guide using a resorbable collagen matrix
S4 Methods: The experimental protocol was approved by the Animal Experiments Committee Thirty-two female Wistar rats underwent a standardized crush injury of the sciatic nerve. The animals were randomly allocated to RGTA treatment or sham treatment in a blinded design. To score neural adhesions, the force required to break the adhesions between the nerve and its surrounding tissue was measured 6 weeks after nerve crush injury. To assess axonal regeneration, magnetoneurographic (MNG) measurements were carried out after 5 weeks. Static footprint analysis was performed preoperatively and 1, 7, 14, 17, 21, 24, 28, 35, and 42 days postoperatively. Results: MNG data show no significant difference in conduction capacity between the RGTA and the control group. In addition, results of the static footprint analysis demonstrate no improved or accelerated recovery pattern. However, the mean pull-out force of the RGTA group (67 g; SEM 9 g) was significantly (p < 0.01) lower than that of the control group (207 g; SEM 14 g). Conclusion: RGTAs strongly reduce nerve adherence to surrounding tissue after nerve crush injury.
O8. A bioartifical nerve guide using a resorbable collagen matrix A. Bozkurt a, F. Lassner a, J. Tank a, C. Beckmann a, ¨ltje b, R. Smeets b, G.A. Brook c, S. Mo ¨llers c, M. Wo B. Sellhaus d, J. Weis d, Damink L. Olde e, I. Heschel e, N. Pallua a a Klinik fu¨r Plastische Chirurgie, Hand und Verbrennungschirurgie, Universita¨tsklinikum der RWTH Aachen, Germany b IZKF-Biomat, Universita¨tsklinikum der RWTH Aachen, Germany c Klinik fu¨r Neurologie, Universita¨tsklinikum der RWTH Aachen, Germany d Institut fu¨r Neuropathologie, Universita¨tsklinikum der RWTH Aachen, Aachen, Germany e Matricel GmbH, Herzogenrath, Germany Introduction: Reconstruction of peripheral nerve lesions remains a major challenge in plastic surgery. Clinical strategies to treat extensive peripheral nerve injuries include the use of nerve. The goal of the current study is the development of a bioartificially synthesized nerve graft. We present modifications of a specially designed collagen matrix with the attempt to achieve the standard of autologous nerve grafts. The objective is to advance previous in-vivo regeneration results by improving the schwann cell-biomaterial interaction. Method: An advanced collagen type-I matrix with longitudinal orientated fibers serves as guidance structure for axonal regeneration. On the basis of biomaterial modifications, different collagen membranes (plane; two-dimensional) were developed and seeded with rat Schwann cells (SC’s). Biocompatibility was tested by vitality staining (FDA & PI), XTT-test and SEM. Furthermore, based on the experiences and results with the plane membranes, the respective modification was used to create collagen spongelike matrices (tubular; three-dimensional). Cell vitality and biocompatibility was assessed by immunocytochemistry (S100, p75, GFAP, Vimentin), SEM, morphometry analyses as well as by in-vitro regeneration experiments with dorsal root ganglia (DRG’s). Results: Modifications of the collagen matrix revealed an appropriate Schwann cell vitality and proliferation. The respective developed tubular sponge like-matrices were stable over the whole period and SC’s displayed an advanced cell adherence, penetration depth, and vitality and cell-cell interactions. SEM demonstrated typical SC morphology with cigar-like cell bodies and bipolar dendrites with an orientation along longitudinal channels within the matrix. In-vitro regeneration experiments with DRG’s revealed axonal regeneration within londitudinal channels in the collagen matrix originating from sensible neurons.
ECSAPS 2006 Abstracts Conclusion: Modification of biomaterial resulted in an improved interaction between SC’s and the nerve guide biomaterial. The current study deals as a basis for comprehensive in vivo studies in order to test this collagen scaffold as a practible bioartificial nerve guide. O9. Porous polyethylene as an endoskeleton for the flexible tissue-engineered auricle N.A. O’Sullivan, M. Ranka, S. Kobayashi, K. Zaleski, L.J. Bonasser, M.A. Randolph, M.J. Yaremchuk Plastic Surgery Research Laboratory, Massachusetts General Hospital and Harvard Medical School, WACC 453, 15 Parkman Street, Boston, MA 02114, USA Introduction: Porous polyethylene (PPE) has been used successfully for craniofacial augmentation and auricular reconstruction. This inert material offers reliable projection and definition and reduced operative time, permitting earlier auricle reconstruction. Tissue engineered auricular cartilage would obviate the current need for costal grafting and its associated morbidity; however it currently lacks biomechanical strength. We propose a composite construct as a model for the tissue engineered auricle, combining the advantages of tissue engineering and alloplast technology. We postulate that PPE could be used as an endoscaffold to support the growth of tissue engineered cartilage and enhance the mechanical properties and morphology of the engineered auricle. Aims: 1) To assess the adhesion and integration of tissue engineered cartilage to PPE. 2) To determine whether a pseudoperichondrium could confer flexibility to the tissue engineered cartilage and PPE framework. Methods: All surgical procedures were approved by the IACUC. 1) Trilayer constructs were made by placing fresh auricular chondrocytes combined with FG between 6 mm discs of PPE. 2) Five-layer constructs composed of a PPE core, coated with auricular chondrocytes in FG, and laminated with Enduragenâ (type I collagen matrix. Porex). Control constructs consisted of acellular FG, and PPE alone. Constructs were implanted subcutaneously in athymic mice for 6 and 12 weeks. Upon harvest the samples underwent histological and biomechanical testing. Results: PPE supported the growth of engineered cartilage which adhered to and integrated with the PPE and Enduragen. The 5 layer constructs exhibited flexibility and strength (flexion and torsion testing) superior to that of controls. Conclusion: PPE supports the growth of neo-cartilage. A PPE core, coated with engineered cartilage and laminated with Enduragen, may provide a model for an alternative 3D construct for auricular reconstruction. Further studies are needed to transfer this model to a full size auricular framework and further biomechanically analyse the construct.
O10. An ex-vivo study of the potential use of bipolar diathermy for cartilage manipulation in otoplasty T. Qureshi, J. Hurren, T. Gourlay Department of Cardiothoracic Surgery, National Heart and Lung Institute, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK Aims: Scoring to weaken cartilage was first employed by Stenstrom in 1963 following observations by Gibson and Davis on the natural ability of cartilage to warp away from the scored surface. A scalpel blade is the usual and preferred method in clinical practise. However aggressive scoring can cause unattractive and painful ridging or may just not be enough resulting in suture tension, under-correction and recurrence. The novel use of bipolar diathermy to reshape cartilage has not previously been investigated. We developed an ex-vivo pig ear model to compare the effectiveness of bipolar diathermy with blade scoring for cartilage warping.
O8. A bioartifical nerve guide using a resorbable collagen matrix A. Bozkurt a, F. Lassner a, J. Tank a, C. Beckmann a, ¨ltje b, R. Smeets b, G.A. Brook c, S. Mo ¨llers c, M. Wo B. Sellhaus d, J. Weis d, Damink L. Olde e, I. Heschel e, N. Pallua a a Klinik fu¨r Plastische Chirurgie, Hand und Verbrennungschirurgie, Universita¨tsklinikum der RWTH Aachen, Germany b IZKF-Biomat, Universita¨tsklinikum der RWTH Aachen, Germany c Klinik fu¨r Neurologie, Universita¨tsklinikum der RWTH Aachen, Germany d Institut fu¨r Neuropathologie, Universita¨tsklinikum der RWTH Aachen, Aachen, Germany e Matricel GmbH, Herzogenrath, Germany Introduction: Reconstruction of peripheral nerve lesions remains a major challenge in plastic surgery. Clinical strategies to treat extensive peripheral nerve injuries include the use of nerve. The goal of the current study is the development of a bioartificially synthesized nerve graft. We present modifications of a specially designed collagen matrix with the attempt to achieve the standard of autologous nerve grafts. The objective is to advance previous in-vivo regeneration results by improving the schwann cell-biomaterial interaction. Method: An advanced collagen type-I matrix with longitudinal orientated fibers serves as guidance structure for axonal regeneration. On the basis of biomaterial modifications, different collagen membranes (plane; two-dimensional) were developed and seeded with rat Schwann cells (SC’s). Biocompatibility was tested by vitality staining (FDA & PI), XTT-test and SEM. Furthermore, based on the experiences and results with the plane membranes, the respective modification was used to create collagen spongelike matrices (tubular; three-dimensional). Cell vitality and biocompatibility was assessed by immunocytochemistry (S100, p75, GFAP, Vimentin), SEM, morphometry analyses as well as by in-vitro regeneration experiments with dorsal root ganglia (DRG’s). Results: Modifications of the collagen matrix revealed an appropriate Schwann cell vitality and proliferation. The respective developed tubular sponge like-matrices were stable over the whole period and SC’s displayed an advanced cell adherence, penetration depth, and vitality and cell-cell interactions. SEM demonstrated typical SC morphology with cigar-like cell bodies and bipolar dendrites with an orientation along longitudinal channels within the matrix. In-vitro regeneration experiments with DRG’s revealed axonal regeneration within londitudinal channels in the collagen matrix originating from sensible neurons.
ECSAPS 2006 Abstracts Conclusion: Modification of biomaterial resulted in an improved interaction between SC’s and the nerve guide biomaterial. The current study deals as a basis for comprehensive in vivo studies in order to test this collagen scaffold as a practible bioartificial nerve guide. O9. Porous polyethylene as an endoskeleton for the flexible tissue-engineered auricle N.A. O’Sullivan, M. Ranka, S. Kobayashi, K. Zaleski, L.J. Bonasser, M.A. Randolph, M.J. Yaremchuk Plastic Surgery Research Laboratory, Massachusetts General Hospital and Harvard Medical School, WACC 453, 15 Parkman Street, Boston, MA 02114, USA Introduction: Porous polyethylene (PPE) has been used successfully for craniofacial augmentation and auricular reconstruction. This inert material offers reliable projection and definition and reduced operative time, permitting earlier auricle reconstruction. Tissue engineered auricular cartilage would obviate the current need for costal grafting and its associated morbidity; however it currently lacks biomechanical strength. We propose a composite construct as a model for the tissue engineered auricle, combining the advantages of tissue engineering and alloplast technology. We postulate that PPE could be used as an endoscaffold to support the growth of tissue engineered cartilage and enhance the mechanical properties and morphology of the engineered auricle. Aims: 1) To assess the adhesion and integration of tissue engineered cartilage to PPE. 2) To determine whether a pseudoperichondrium could confer flexibility to the tissue engineered cartilage and PPE framework. Methods: All surgical procedures were approved by the IACUC. 1) Trilayer constructs were made by placing fresh auricular chondrocytes combined with FG between 6 mm discs of PPE. 2) Five-layer constructs composed of a PPE core, coated with auricular chondrocytes in FG, and laminated with Enduragenâ (type I collagen matrix. Porex). Control constructs consisted of acellular FG, and PPE alone. Constructs were implanted subcutaneously in athymic mice for 6 and 12 weeks. Upon harvest the samples underwent histological and biomechanical testing. Results: PPE supported the growth of engineered cartilage which adhered to and integrated with the PPE and Enduragen. The 5 layer constructs exhibited flexibility and strength (flexion and torsion testing) superior to that of controls. Conclusion: PPE supports the growth of neo-cartilage. A PPE core, coated with engineered cartilage and laminated with Enduragen, may provide a model for an alternative 3D construct for auricular reconstruction. Further studies are needed to transfer this model to a full size auricular framework and further biomechanically analyse the construct.
O10. An ex-vivo study of the potential use of bipolar diathermy for cartilage manipulation in otoplasty T. Qureshi, J. Hurren, T. Gourlay Department of Cardiothoracic Surgery, National Heart and Lung Institute, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK Aims: Scoring to weaken cartilage was first employed by Stenstrom in 1963 following observations by Gibson and Davis on the natural ability of cartilage to warp away from the scored surface. A scalpel blade is the usual and preferred method in clinical practise. However aggressive scoring can cause unattractive and painful ridging or may just not be enough resulting in suture tension, under-correction and recurrence. The novel use of bipolar diathermy to reshape cartilage has not previously been investigated. We developed an ex-vivo pig ear model to compare the effectiveness of bipolar diathermy with blade scoring for cartilage warping.