Laurent Galois

Osteogenic differentiation of human bone marrow mesenchymal stem cells in hydrogel containing nacre powder

Nacre (or mother of pearl) can facilitate bone cell differentiation and can speed up their mineralization. Here we report on the capability of nacre to induce differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) and the production of extracellular matrix. hBM-MSCs were encapsulated in an alginate hydrogel containing different concentrations of powdered nacre and cultured in the same environment until Day 28. Analysis of osteogenic gene expression, histochemistry, second harmonic generation (SHG) microscopy, and Raman scattering spectroscopy were used to characterize the synthesis of the extracellular matrix. In the presence of nacre powder, a significant increase in matrix synthesis from D21 in comparison with pure alginate was observed. Histochemistry revealed the formation of a new tissue composed of collagen fibers in the presence of nacre (immunostaining and SHG), and hydroxyapatite crystals (Raman) in the alginate beads. These results suggest that nacre is efficient in hBM-MSCs differentiation, extracellular matrix production and mineralization in alginate 3D biomaterials.

Comblement des pertes de substance osseuse par le phosphatetricalcique β en traumatologie

AIM OF STUDYnSynthetic bone substitutes like calcium phosphate ceramics have been used in orthopaedic surgery for several years. The aim of this study was to assess the results of the use of tricalcium phosphate beta for filling bone defects in trauma cases.nnnPATIENTS AND METHODnbeta tricalcium phosphate was used in 24 trauma cases. The GESTO classification (Association pour létude des Greffes et Substituts Tissulaires en Orthopédie) and a qualitative scale were used to estimate the integration.nnnRESULTSnWith a mean follow-up of 20 months, integration was excellent in 41.2%, good in 29.2% and moderate in 17.4%. No fibrous encapsulation was observed around the implants in any case. Sepsis occurred in 3 cases with open fractures.nnnCONCLUSIONnbeta-Tricalcium phosphate seems in our experience to be an excellent bone substitute for filling bone defects in trauma cases.Resume But de l’etudexa0: Les substituts osseux d’origine synthetique, en particulier les ceramiques de phosphate de calcium sont de plus en plus utilisees en chirurgie osseuse. Le but de cette etude etait d’apprecier les resultats de l’utilisation de ce substitut dans le comblement des pertes de substance osseuse en traumatologie. Patients et methodexa0: Le phosphate tricalcique β a ete utilise en traumatologie dans 24 cas. La classification du GESTO (Association pour l’etude des greffes et substituts tissulaires en orthopedie) prenant en compte le type, la nature et la taille de la perte de substance a ete couplee a une echelle qualitative de l’integration. Resultatsxa0: Avec un recul moyen de 20 mois, l’integration etait excellente dans 41,2xa0% des cas, bonne dans 29,2xa0% des cas et moyenne dans 17,4xa0% des cas. Aucune encapsulation fibreuse n’a ete notee. En revanche, trois complications septiques ont necessite l’ablation des substitutsxa0; il s’agissait dans les trois cas de fractures ouvertes. Conclusionxa0: Le phosphate tricalcique β apparait comme un substitut osseux de choix pour le comblement des pertes de substance osseuse moderees observees en traumatologie.

Analyse opto-électronique de la marche après arthrodèse métatarso-phalangienne de l'hallux : À propos de 15 cas

Resume L’objectif de ce travail etait de faire une analyse tridimensionnelle de la marche apres arthrodese metatarso-phalangienne de l’hallux. La marche de 12 patients porteurs d’une arthrodese metatarso-phalangienne de l’hallux depuis plus de 6 mois a ete analysee par un systeme Vicon 3D avec 5 cameras et 2 plates-formes de forces AMTI integrees. Nous avons analyse les courbes cinetiques et cinematiques de la marche ainsi que les forces de reaction au sol. Les objectifs de ce travail etaient de determiner dans les trois plans de l’espace les modifications observees lors d’un cycle de marche et d’apprecier les eventuelles compensations mises en œuvre au niveau des articulations talo-crurale et inter-phalangienne. Le traitement statistique sur les valeurs obtenues a consiste en un test de Wilcoxon pour series appariees. Les parametres generaux ainsi que les valeurs cinetiques et cinematiques de la marche n’etaient pas modifies (hormis une diminution non significative de la dorsiflexion maximale de la cheville). Une diminution significative de la force de propulsion dans les plans antero-posterieur et vertical, un decollement significativement plus tardif du talon et le passage systematique de la force de reaction du sol en avant de l’articulation metatarso-phalangienne ont ete mis en evidence du cote arthrodese. Grâce a la presence des mires situees a l’extremite distale de l’hallux, nous avons pu montrer que l’essentiel de la compensation de l’arthrodese se faisait au niveau de l’articulation inter-phalangienne.PURPOSE OF THE STUDYnDegeneration of the metatarsophalangeal joint of the hallux is a frequent secondary lesion of the first ray subsequent to hallux valgus. Different surgical techniques have been proposed for cure, including metatarsophalangeal arthrodesis. Joint fusion relieves pain but sacrifices joint motion. The purpose of this work was to assess changes observed in gait after metatarsophalangeal arthrodesis of the hallux using a three-dimensional optoelectronic system.nnnMATERIAL AND METHODSnGait analysis was performed with a Vicon 3D system with five cameras and two AMTI force platforms in twelve patients who had undergone metatarsophalangeal arthrodesis more than six months earlier. The kinetic and kinematic curves and ground reaction forces were analyzed. Changes in the gait cycle and any compensations observed in the talocrural and interphalangeal joints were noted in the three dimensions. Wilcoxon test for paired series was applied for the statistical analysis.nnnRESULTSnThe general gait parameters and kinetic and kinematic values were not modified (excepting a non-significant decline in maximal dorsiflexion of the ankle joint). There was a significant decrease in propulsion force in the anteroposterior and vertical planes, with significantly later heal lift-off and systematic displacement of ground reaction forces anterior to the metatarsophalangeal joint on the arthrodesis side. Reflectors positioned on the distal extremity of the hallux demonstrated that the essential part of compensation occurred at the level of the interphalangeal joint.nnnDISCUSSIONnGait analysis after tibiotalar arthrodesis has been widely reported in the literature. The consequence of joint fusion on the rear foot and/or the torsion couple have also been studied. However, to our knowledge, there has been only one report using a different methodology devoted to metatarsophalaneal arthrodesis of the hallux. In this study, only step length and interphalangeal moment as well as ankle force were found to be decreased. Function of the interphalangeal joint was not assessed. The Vicon system enabled an adapted study of gait after metatarsophalangeal arthrodesis. This method offers several perspectives: study of the effect of the position of the arthrodesis in the sagittal plane on gait, changes over time in interphalangeal joint motion, or consequences of fusion on walking up and down stairs.nnnCONCLUSIONnMetatarsophalangeal arthrodesis of the hallux does not modify general gait parameters nor the kinetic and kinematic values. Compensation is achieved via the interphalangeal joint.

Nacre extract restores the mineralization capacity of subchondral osteoarthritis osteoblasts

Osteoarthritis (OA) is the most common cause of joint chronic pain and involves the entire joints. Subchondral osteoarthritic osteoblasts present a mineralization defect and, to date, only a few molecules (Vitamin D3 and Bone Morphogenetic Protein2) could improve the mineralization potential of this cell type. In this context, we have tested for the first time the effect of nacre extract on the mineralization capacity of osteoblasts from OA patients. Nacre extract is known to contain osteogenic molecules which have demonstrated their activities notably on the MC3T3 pre-osteoblastic cell line. For this goal, molecules were extracted from nacre (ESM, Ethanol Soluble Matrix) and tested on osteoblasts of the subchondral bone from OA patients undergoing total knee replacement and on MC3T3 cells for comparison. We chose to investigate the mineralization with Alizarin Red staining and with the study of extracellular matrix (ECM) structure and composition. In a complementary way the structure of the ECM secreted during the mineralization phase was investigated using second harmonic generation (SHG). Nacre extract was able to induce the early presence (after 7 days) of precipitated calcium in cells. Raman spectroscopy and electron microscopy showed the presence of nanograins of an early crystalline form of calcium phosphate in OA osteoblasts ECM and hydroxyapatite in MC3T3 ECM. SHG collagen fibers signal was present in both cell types but lower for OA osteoblasts. In conclusion, nacre extract was able to rapidly restore the mineralization capacity of osteoarthritis osteoblasts, therefore confirming the potential of nacre as a source of osteogenic compounds.

Nacre, a natural, multi-use and timely biomaterial for bone graft substitution.

During the past two decades, with a huge and rapidly increasing clinical need for bone regeneration and repair, bone substitutes are more and more seen as a potential solution. Major innovation efforts are being made to develop such substitutes, some having advanced even to clinical practice. It is now time to turn to natural biomaterials. Nacre, or mother-of-pearl, is an organic matrix-calcium carbonate coupled shell structure produced by molluscs. In vivo and in vitro studies have revealed that nacre is osteoinductive, osteoconductive, biocompatible, and biodegradable. With many other outstanding qualities, nacre represents a natural and multi-use biomaterial as a bone graft substitute. This review aims at summarising the current needs in orthopaedic clinics and the challenges for the development of bone substitutes; most of all, we systematically review the physiological characteristics and biological evidence of nacres effects centred on osteogenesis, and finally we put forward the potential use of nacre as a bone graft substitute.

A new method for the separation and purification of the osteogenic compounds of nacre Ethanol Soluble Matrix

Nacre is able to induce bone-forming cells mineralization, and gains widely interest in bone regeneration. While, the osteoinductive compounds are not yet identified. ESM (Ethanol Soluble Matrix), a nacre extract from powder of Pinctada margaritifera pearl oyster shell, has been firstly proven having the capacity to induce mineralization and to restore mineralization defect in vitro. It is suitable to treat ESM as a source of osteoinductive compounds. Herein, we develop a new method for separating and purifying nacre extracts by an ionic approach. At first, cationic ESM (ESMc) and anionic ESM (ESMa) were achieved with ion-exchange resin. Then, ESM was separated and collected on cation exchange HPLC. Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometry (EDS) was used to reveal the concentrated elements in ESM fractions. A coupled cell models were used to test the ESM fractions. Alizarin Red staining was performed and quantified to evaluate the mineralization level. ESMc and 2 HPLC fractions stimulated the mineralization in both cells. EDS demonstrated the abundant presence of calcium and chloride in the osteogenic fractions. To validate, pure CaCl2 was tested and proven having an osteogenic effect in both cells, but less stable than ESM. The mineralization nodules induced by ESM fractions and CaCl2 differed in both cells. In conclusion, a new method was developed for separating and purifying nacre extracts by an ionic approach. By which, the osteoinductive compounds in ESM were proven cationic, and calcium in ESM was demonstrated to play a role in inducing the cell mineralization.