Marco Franchi

Publications of Marco Franchi

• Tendon and ligament fibrillar crimps give rise to left-handed helices of collagen fibrils in both planar and helical crimps.

  Authors: Marco Franchi, Vittoria Ottani, Rita Stagni, Alessandro Ruggeri

  Journal of anatomy. 03/2010; 216(3):301-9.

  Collagen fibres in tendons and ligaments run straight but in some regions they show crimps which disappear or appear more flattened during the initial elongation of tissues. Each crimp is formed ofCollagen fibres in tendons and ligaments run straight but in some regions they show crimps which disappear or appear more flattened during the initial elongation of tissues. Each crimp is formed of collagen fibrils showing knots or fibrillar crimps at the crimp top angle. The present study analyzes by polarized light microscopy, scanning electron microscopy, transmission electron microscopy the 3D morphology of fibrillar crimp in tendons and ligaments of rat demonstrating that each fibril in the fibrillar region always twists leftwards changing the plane of running and sharply bends modifying the course on a new plane. The morphology of fibrillar crimp in stretched tendons fulfills the mechanical role of the fibrillar crimp acting as a particular knot/biological hinge in absorbing tension forces during fibril strengthening and recoiling collagen fibres when stretching is removed. The left-handed path of fibrils in the fibrillar crimp region gives rise to left-handed fibril helices observed both in isolated fibrils and sections of different tendons and ligaments (flexor digitorum profundus muscle tendon, Achilles tendon, tail tendon, patellar ligament and medial collateral ligament of the knee). The left-handed path of fibrils represents a new final suprafibrillar level of the alternating handedness which was previously described only from the molecular to the microfibrillar level. When the width of the twisting angle in the fibrillar crimp is nearly 180 degrees the fibrils appear as left-handed flattened helices forming crimped collagen fibres previously described as planar crimps. When fibrils twist with different subsequent rotational angles (< 180 degrees ) they always assume a left-helical course but, running in many different nonplanar planes, they form wider helical crimped fibres.

• Collagen fibre arrangement and functional crimping pattern of the medial collateral ligament in the rat knee.

  Authors: Marco Franchi, Marilisa Quaranta, Maria Macciocca, Luisa Leonardi, Vittoria Ottani, Paolo Bianchini, Alberto Diaspro, Alessandro Ruggeri

  Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 02/2010; 18(12):1671-8.

  Ligaments have been described as multifascicular structures with collagen fibres cross-connecting to each other or running straight and parallel also showing a waviness or crimping pattern playing asLigaments have been described as multifascicular structures with collagen fibres cross-connecting to each other or running straight and parallel also showing a waviness or crimping pattern playing as a shock absorber/recoiling system during joint motions. A particular collagen array and crimping pattern in different ligaments may reflect different biomechanical roles and properties. The aim of the study was to relate the 3D collagen arrangement in the crimping pattern of the medial collateral ligament (MCL) to its functional role. The MCL is one of the most injured ligaments during sports activities and an experimental model to understand the rate, quality and composition of ligaments healing. A deep knowledge of structure-function relationship of collagen fibres array will improve the development of rehabilitation protocols and more appropriate exercises for recovery of functional activity. The rat MCL was analysed by polarized light microscopy, confocal laser microscopy and scanning electron microscopy (SEM). Histomorphometric analysis demonstrated that MCL crimps have a smaller base length versus other tendons. SEM observations demonstrated that collagen fibres showing few crimps were composed of fibrils intertwining and crossing one another in the outer region. Confocal laser analyses excluded a helical array of collagen fibres. By contrast, in the core portion, densely packed straight collagen fibres ran parallel to the main axis of the ligament being interrupted both by planar crimps, similar to tendon crimps, and by newly described right-handed twisted crimps. It is concluded that planar crimps could oppose or respond exclusively to tensional forces parallel to the main ligament axis, whereas the right-handed twisted crimps could better resist/respond to a complex of tensional/rotational forces within the ligament thus opposing to an external rotation of tibia.

• Contribution of glycosaminoglycans to the microstructural integrity of fibrillar and fiber crimps in tendons and ligaments.

  Authors: Marco Franchi, Viviana De Pasquale, Désirée Martini, Marilisa Quaranta, Maria Macciocca, Alessio Dionisi, Vittoria Ottani

  TheScientificWorldJournal. 01/2010; 10:1932-40.

  The biomechanical roles of both tendons and ligaments are fulfilled by the extracellular matrix of these tissues. In particular, tension is mainly transmitted and resisted by protein (collagen,The biomechanical roles of both tendons and ligaments are fulfilled by the extracellular matrix of these tissues. In particular, tension is mainly transmitted and resisted by protein (collagen, elastin) fibers, whereas compression is opposed by water-soluble glycosaminoglycans (GAGs). GAGs spanning the interfibrillar spaces and interacting with fibrils through the interfibrillar proteoglycans also seem to play a part in transmitting and resisting tensile stresses. Both tendons and ligaments showing similar composition, but different functional roles and collagen array, exhibit 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 play a mechanical role in absorbing the initial loading during elongation of both tendons and ligaments, and in recoiling fibrils and fibers when tissues have to return to their original length. This study investigated whether GAGs covalently attached to proteoglycan core proteins directly affect the 3D microstructural integrity of fibrillar crimp regions 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) incubated in a chondroitinase ABC solution to remove GAGs were observed under a scanning electron microscope (SEM). In addition, isolated fibrils of these tissues obtained by mechanical disruption were analyzed by a transmission electron microscope (TEM). Both Achilles tendons and medial collateral ligaments of the rats after chemical or mechanical removal of GAGs still showed crimps and fibrillar crimps comparable to tissues with a normal GAG 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 crimp functions that seem mainly related to the local fibril leftward twisting and the alternating handedness of collagen from a molecular to a supramolecular level.

• Correlative microscopy of bone in implant osteointegration studies.

  Authors: Alessandra Trirè, Désirée Martini, Ester Orsini, Marco Franchi, Viviana De Pasquale, Beatrice Bacchelli, Mario Raspanti, Alessandro Ruggeri, Vittoria Ottani

  TheScientificWorldJournal. 01/2010; 10:2238-47.

  Routine morphological analyses usually include investigations by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Each of these techniquesRoutine morphological analyses usually include investigations by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Each of these techniques provides specific information on tissue morphology and all the obtained results are then combined to give an in-depth morphological overview of the examined sample. The limitations of this traditional comparative microscopy lie in the fact that each technique requires a different experimental sample, so that many specimens are necessary and the combined results come from different samples. The present study describes a technical procedure of correlative microscopy, which allows us to examine the same bone section first by LM and then, after appropriate processing, by SEM or TEM. Thanks to the possibility of analyzing the same undecalcified bone sections both by LM and SEM, the approach described in the present study allows us to make very accurate evaluations of old/new bone morphology at the bone-implant interface.

• Influence of a zirconia sandblasting treated surface on peri-implant bone healing: An experimental study in sheep.

  Authors: Beatrice Bacchelli, Gianluca Giavaresi, Marco Franchi, Désirée Martini, Viviana De Pasquale, Alessandra Trirè, Milena Fini, Roberto Giardino, Alessandro Ruggeri

  Acta biomaterialia. 02/2009;

  A sandblasting process with round zirconia (ZrO(2)) particles might be an alternative surface treatment to enhance the osseointegration of titanium dental implants. Our previous study on sheepA sandblasting process with round zirconia (ZrO(2)) particles might be an alternative surface treatment to enhance the osseointegration of titanium dental implants. Our previous study on sheep compared smooth surface titanium implants (control) with implant surfaces sandblasted with two different granulations of ZrO(2). As the sandblasted surfaces proved superior, the present study further compared the ZrO(2) surface implant with other surface treatments currently employed: machined titanium (control), titanium oxide plasma sprayed (TPS) and alumina sandblasted (Al-SL) at different times after insertion (2, 4 and 12weeks). Twelve sheep were divided into three groups of four animals each and underwent implant insertion in tibia cortical bone under general anaesthesia. The implants with surrounding tissues were subjected to histology, histomorphometry, scanning electron microscopy and microhardness tests. The experimentation indicated that at 2weeks Zr-SL implants had the highest significant bone ingrowth (p<0.05) compared to the other implant surfaces, and a microhardness of newly formed bone inside the threads significantly higher than that of Ti. The present work shows that the ZrO(2) treatment produces better results in peri-implant newly formed bone than Ti and TPS processing, whereas its performance is similar to the Al-SL surface treatment.

• Different crimp patterns in collagen fibrils relate to the subfibrillar arrangement.

  Authors: Marco Franchi, Mario Raspanti, Carlo Dell'Orbo, Marilisa Quaranta, Viviana De Pasquale, Vittoria Ottani, Alessandro Ruggeri

  Connective tissue research. 02/2008; 49(2):85-91.

  Collagen fibril ultrastructure and course were examined in different connective tissues by PLM, SEM, TEM, and AFM. In tendons, collagen fibrils were large and heterogeneous with a straightCollagen fibril ultrastructure and course were examined in different connective tissues by PLM, SEM, TEM, and AFM. In tendons, collagen fibrils were large and heterogeneous with a straight subfibrillar arrangement. They ran densely packed, parallel, and straight changing their direction only in periodic crimps where fibrils showed a local deformation (fibrillar crimps). Other tissues such as aponeurosis, fascia communis, skin, aortic wall, and tendon and nerve sheaths showed thinner uniform fibrils with a helical subfibrillar arrangement. These fibrils appeared in parallel or helical arrangement following a wavy, undulating course. Ligaments showed large fibrils as in tendon, with fibrillar crimps but less packed. Thinner uniform-sized fibrils also were observed. Fibrillar crimps seem to be related to the subfibrillar arrangement being present only in large fibrils with a straight subfibrillar arrangement. These stiffer fibrils respond mainly to unidirectional tensional forces, whereas the flexible thinner fibrils with helical subfibrils can accommodate extreme curvatures without harm, thus responding to multidirectional loadings.

• Influence of different implant surfaces on peri-implant osteogenesis: histomorphometric analysis in sheep.

  Authors: Marco Franchi, Beatrice Bacchelli, Gianluca Giavaresi, Viviana De Pasquale, Désirée Martini, Milena Fini, Roberto Giardino, Alessandro Ruggeri

  Journal of periodontology. 06/2007; 78(5):879-88.

  BACKGROUND: The present study investigated peri-implant osteogenesis and implant biologic fixation in different zirconia sandblasted endosseous titanium surfaces (SLA-60 and SLA-120) and a turnedBACKGROUND: The present study investigated peri-implant osteogenesis and implant biologic fixation in different zirconia sandblasted endosseous titanium surfaces (SLA-60 and SLA-120) and a turned titanium surface (T) 2 and 4 weeks after surgery. METHODS: Seventy-two implant screws were implanted in tibia of six sheep. Histologic sections of implants (2 and 4 weeks after surgery) were analyzed with light microscopy for histomorphometric analysis of bone-to-implant contact (BIC), bone ingrowth (BI), and bone surface (BS/BV). Histologic blocks were used to perform bone microhardness studies next to the implants. Some implants were also observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: In general, the highest values of BIC, BI, BS/BV, and Vickers hardness number (HV) were measured in SLA-60 samples, followed by SLA-120 and T implants. Two weeks after surgery, all the implants appeared biologically fixed by a newly formed woven bone arranged in thin bone trabeculae and filling the gap between implant and host bone. Four weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the SLA-60 and SLA-120 implants by a gradual deposition of parallel-fiber bone. CONCLUSIONS: Our results suggest that, in the early period of peri-implant healing, the implant surface morphology that seemed to influence the increase of peri-implant osteogenesis, bone turnover, and peri-implant bone maturation was SLA-60. We suggest that this surface, characterized by moderately deep titanium cavities very similar to the osteocyte lacunae, could act as a microscopic scaffold for mesenchymal and/or osteoblast-like cells adhesion.

• Crimp morphology in relaxed and stretched rat Achilles tendon.

  Authors: Marco Franchi, Milena Fini, Marilisa Quaranta, Viviana De Pasquale, Mario Raspanti, Gianluca Giavaresi, Vittoria Ottani, Alessandro Ruggeri

  Journal of anatomy. 02/2007; 210(1):1-7.

  Fibrous extracellular matrix of tendon is considered to be an inextensible anatomical structure consisting of type I collagen fibrils arranged in parallel bundles. Under polarized light microscopyFibrous extracellular matrix of tendon is considered to be an inextensible anatomical structure consisting of type I collagen fibrils arranged in parallel bundles. Under polarized light microscopy the collagen fibre bundles appear crimped with alternating dark and light transverse bands. This study describes the ultrastructure of the collagen fibrils in crimps of both relaxed and in vivo stretched rat Achilles tendon. Under polarized light microscopy crimps of relaxed Achilles tendons appear as isosceles or scalene triangles of different size. Tendon crimps observed via SEM and TEM show the single collagen fibrils that suddenly change their direction containing knots. The fibrils appear partially squeezed in the knots, bent on the same plane like bayonets, or twisted and bent. Moreover some of them lose their D-period, revealing their microfibrillar component. These particular aspects of collagen fibrils inside each tendon crimp have been termed 'fibrillar crimps' and may fulfil the same functional role. When tendon is physiologically stretched in vivo the tendon crimps decrease in number (46.7%) (P<0.01) and appear more flattened with an increase in the crimp top angle (165 degrees in stretched tendons vs. 148 degrees in relaxed tendons, P<0.005). Under SEM and TEM, the 'fibrillar crimps' are still present, never losing their structural identity in straightened collagen fibril bundles of stretched tendons even where tendon crimps are not detectable. These data suggest that the 'fibrillar crimp' may be the true structural component of the tendon crimp acting as a shock absorber during physiological stretching of Achilles tendon.

• Collagen structure of tendon relates to function.

  Authors: Marco Franchi, Alessandra Trirè, Marilisa Quaranta, Ester Orsini, Victoria Ottani

  TheScientificWorldJournal. 01/2007; 7:404-20.

  A tendon is a tough band of fibrous connective tissue that connects muscle to bone, designed to transmit forces and withstand tension during muscle contraction. Tendon may be surrounded by differentA tendon is a tough band of fibrous connective tissue that connects muscle to bone, designed to transmit forces and withstand tension during muscle contraction. Tendon may be surrounded by different structures: 1) fibrous sheaths or retinaculae; 2) reflection pulleys; 3) synovial sheaths; 4) peritendon sheaths; 5) tendon bursae. Tendons contain a) few cells, mostly represented by tenoblasts along with endothelial cells and some chondrocytes; b) proteoglycans (PGs), mainly decorin and hyaluronan, and c) collagen, mostly type I. Tendon is a good example of a high ordered extracellular matrix in which collagen molecules assemble into filamentous collagen fibrils (formed by microfibrils) which aggregate to form collagen fibers, the main structural components. It represents a multihierarchical structure as it contains collagen molecules arranged in fibrils then grouped in fibril bundles, fascicles and fiber bundles that are almost parallel to the long axis of the tendon, named as primary, secondary and tertiary bundles. Collagen fibrils in tendons show prevalently large diameter, a D-period of about 67 nm and appear built of collagen molecules lying at a slight angle (< 5 degrees). Under polarized light microscopy the collagen fiber bundles appear crimped with alternative dark and light transverse bands. In recent studies tendon crimps observed via SEM and TEM show that the single collagen fibrils suddenly changing their direction contain knots. These knots of collagen fibrils inside each tendon crimp have been termed "fibrillar crimps", and even if they show different aspects they all may fulfil the same functional role. As integral component of musculoskeletal system, the tendon acts to transmit muscle forces to the skeletal system. There is no complete understanding of the mechanisms in transmitting/absorbing tensional forces within the tendon; however it seems likely that a flattening of tendon crimps may occur at a first stage of tendon stretching. Increasing stretching, other transmission mechanisms such as an interfibrillar coupling via PGs linkages and a molecular gliding within the fibrils structure may be involved.

• The 3D structure of crimps in the rat Achilles tendon.

  Authors: Mario Raspanti, Alessandro Manelli, Marco Franchi, Alessandro Ruggeri

  Matrix biology : journal of the International Society for Matrix Biology. 11/2005; 24(7):503-7.

  The ultrastructure of crimps of the Achilles tendon of rat, excised and processed in a slack condition, was investigated by atomic force microscopy in air, in fluid and by scanning electronThe ultrastructure of crimps of the Achilles tendon of rat, excised and processed in a slack condition, was investigated by atomic force microscopy in air, in fluid and by scanning electron microscopy and stereo reconstruction. The tendon was made of distinct fascicles, each comprising a succession of straight segments connected by sharp angles. The length of the segments and the interposed angles varied widely. In particular, the angles ranged from almost zero to over 135 degrees . We did not observe a unique structure for the hinge regions, but rather a variety of gradations of buckling and/or torsion with no evident correlation with other features of tendon. A constant hallmark was the local loss of regular molecular packing, as revealed by the disappearance of the D-banding. Our results do not support recent reports of a helical structure or smooth sinusoidal waves in tendons. Such structures may nonetheless exist in other non-tensile structures whose collagen fibrils exhibit a helical inner architecture and are able to follow a highly convoluted course without buckling or crimping.

• Osteogenesis and morphology of the peri-implant bone facing dental implants.

  Authors: Marco Franchi, Ester Orsini, Alessandra Trire, Marilisa Quaranta, Desiree Martini, Gabriella G Piccari, Alessandro Ruggeri, Vittoria Ottani

  TheScientificWorldJournal. 02/2004; 4:1083-95.

  This study investigated the influence of different implant surfaces on peri-implant osteogenesis and implant face morphology of peri-implant tissues during the early (2 weeks) and complete healingThis study investigated the influence of different implant surfaces on peri-implant osteogenesis and implant face morphology of peri-implant tissues during the early (2 weeks) and complete healing period (3 months). Thirty endosseous titanium implants (conic screws) with differently treated surfaces (smooth titanium = SS, titanium plasma sprayed = TPS, sand-blasted zirconium oxide = Zr-SLA) were implanted in femur and tibiae diaphyses of two mongrel sheep. Histological sections of the implants and surrounding tissues obtained by sawing and grinding techniques were observed under light microscopy (LM). The peri-implant tissues of other samples were mechanically detached from the corresponding implants to be processed for SEM observation. Two weeks after implantation, we observed osteogenesis (new bone trabeculae) around all implant surfaces only where a gap was present at the host bone-metal interface. No evident bone deposition was detectable where threads of the screws were in direct contact with the compact host bone. Distance osteogenesis predominated in SS implants, while around rough surfaces (TPS and Zr-SLA), both distance and contact osteogenesis were present. At SEM analysis 2 weeks after implantation, the implant face of SS peri-implant tissue showed few, thin, newly formed, bone trabeculae immersed in large, loose, marrow tissue with blood vessels. Around the TPS screws, the implant face of the peri-implant tissue was rather irregular because of the rougher metal surface. Zr-SLA screws showed more numerous, newly formed bone trabeculae crossing marrow spaces and also needle-like crystals in bone nodules indicating an active mineralising process. After 3 months, all the screws appeared osseointegrated, being almost completely covered by a compact, mature, newly formed bone. However, some marrow spaces rich in blood vessels and undifferentiated cells were in contact with the metal surface. By SEM analysis, the implant face of the peri-implant tissue showed different results. Around the SS screws, the compact bone with areas of different mineralisation rate appeared very smooth, while around the rougher TPS screws, the bone still showed an irregular surface corresponding to the implant macro/microroughness. Around the Zr-SLA screws, a more regular implant-bone surface and sparse, calcified marrow spaces were detectable. Results from this research suggest that 2 weeks after implantation, trabecular bone represents the calcified healing tissue, which supports the early biological fixation of the implants. The peri-implant marrow spaces, rich in undifferentiated cells and blood vasculature, observed both 2 weeks and 3 months after surgery, favour the biological turnover of both early and mature peri-implant bone. The implant surface morphology strongly influences the rate and the modality of peri-implant osteogenesis, as do the morphology and arrangement of the implant face in peri-implant bone both during early healing (after 2 weeks) and when the implant is just osseointegrated; rough surfaces, and in particular Zr-SLA, seem to better favour bone deposition on the metal surface.

• Structure relates to elastic recoil and functional role in quadriceps tendon and patellar ligament

  Authors: Marco Franchi, Marilisa Quaranta, Maria Macciocca, Viviana De Pasquale, Vittoria Ottani, Alessandro Ruggeri

  Micron.

  Tendons and ligaments have similar but slightly different structure and composition. Crimps of tendons and ligaments are morphological structures related to the elastic functional properties of theseTendons and ligaments have similar but slightly different structure and composition. Crimps of tendons and ligaments are morphological structures related to the elastic functional properties of these connective tissues. Aim of this study was to investigate the morphological arrangement of collagen fibres, fibrils and crimping pattern of suprapatellar (rectus femoris tendon-RFT and vastus intermedius tendon-VIT) and infrapatellar connective tissues (patellar ligament-PL) to relate their structural aspects to their common function role of leg extension. RFT, VIT and PL were removed from knees of Sprague–Dawley rats and light and electron microscopy (TEM and SEM) performed. Sagittal sections showed that collagen array and crimping pattern were similar in RFT and PL but differed from VIT. Morphometric analysis confirmed that crimp number was about the same in RFT and PL (5.4 ± 1.4 and 6.1 ± 2.8 respectively), but it was almost three times higher in VIT (14.5 ± 4.7). Similarly crimp top angle in RFT and PL (141.5 ± 15.0° and 146.2 ± 12.2° respectively) was significantly higher than in VIT (122.3 ± 14.8°) and the crimp base length was more than twice as wide in RFT (75.5 ± 22.6 μm) and PL (72.3 ± 28.9 μm) than in VIT (36 ± 14.1 μm). The smaller, fewer and most crimped crimps in VIT show that this tendon has a greater elastic recoil and responds to higher forces as among quadriceps muscles the vastus intermedius belly contributes the most during knee extension. By contrast, RFT acting as a “stopper” tendon also plays a ligament role by limiting an excessive flexion of the joint during postural rest position of the knee.