Ruolo dei glicosaminoglicani su struttura e funzione dei crimps nei tendini e nei legamenti

Dionisi, Alessio (2011) Ruolo dei glicosaminoglicani su struttura e funzione dei crimps nei tendini e nei legamenti, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Scienze dello sviluppo e del movimento umano: progetto n. 1 "Discipline delle attività motorie e sportive", 23 Ciclo.
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The biomechanical roles of both tendons and ligaments are fulfilled by extracellular matrix of these tissues. In particular, tension is mainly transmitted and resisted by fibrous proteins (collagen, elastin), whereas compressive load is absorbed by water-soluble glycosaminoglycans (GAGs). GAGs spanning the interfibrillar spaces and interacting with fibrils also seem to play a part in transmitting and resisting tensile stresses. Apart from different functional roles and collagen array, tendons and ligaments share the same basic structure showing periodic undulations of collagen fibers or crimps. Each crimp is composed of many knots of each single fibril or fibrillar crimps. Fibrillar and fiber crimps act as shock absorbers during the initial elongation of both tendons and ligaments and assist the elastic recoil of fibrils and fibers when the tensile stress is removed. The aim of this thesis was to evaluate whether GAGs directly affect the 3D microstructural integrity of fibrillar crimp and fiber crimps in both tendons and ligaments. Achilles tendons and medial collateral ligaments of the knee from eight female Sprague-Dawley rats (90 days old) were digested with chondroitinase ABC to remove GAGs and observed under a scanning electron microscope (SEM). In addition, isolated fibrils from these tissues obtained by mechanical homogenization were analyzed by a transmission electron microscope (TEM). Both samples digested with chondroitinase ABC or mechanically disrupted still showed crimps and fibrillar crimps comparable to tissues with a normal GAGs content. All fibrils in the fibrillar crimp region always twisted leftwards, thus changing their running plane, and then sharply bent, changing their course on a new plane. These data suggest that GAGs do not affect structural integrity or fibrillar crimps functions that seem mainly related to the local fibril leftward twisting and the alternating handedness of collagen from a molecular to a supramolecular level.

Tipologia del documento
Tesi di dottorato
Dionisi, Alessio
Dottorato di ricerca
Scuola di dottorato
Scienze biologiche, biomediche e biotecnologiche
Settore disciplinare
Settore concorsuale
Parole chiave
Tendine Legamento Crimps fibrillari Glicosaminoglicani Condroitinasi Microscopia elettronica a scansione Microscopia elettronica a trasmissione
Data di discussione
20 Maggio 2011

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