Electroactive calcium-alginate/polycaprolactone/reduced graphene oxide nanohybrid hydrogels for skeletal muscle tissue engineering.

Graphene derivatives such as reduced graphene oxide (rGO) are used as components of novel biomaterials for their unique electrical properties. Electrical conductivity is a crucial factor for muscle cells, which are electrically active. This study reports the development of a new type of semi-interpenetrated polymer network based on two biodegradable FDA-approved biomaterials, sodium alginate (SA) and polycaprolactone (PCL), with Ca2+ ions as SA crosslinker. Several drawbacks such as the low cell adhesion of SA and weak structural stability can be improved with the incorporation of PCL. Furthermore, this study demonstrates how this semi-IPN can be engineered with rGO nanosheets (0.5% and 2% wt/wt rGO nanosheets) to produce electroactive nanohybrid composite biomaterials. The study focuses on the microstructure and the enhancement of physical and biological properties of these advanced materials, including water sorption, surface wettability, thermal behavior and thermal degradation, mechanical properties, electrical conductivity, cell adhesion and myogenic differentiation. The results suggest the formation of a complex nano-network with different interactions between the components: bonds between SA chains induced by Ca2+ ions (egg-box model), links between rGO nanosheets and SA chains as well as between rGO nanosheets themselves through Ca2+ ions, and strong hydrogen bonding between rGO nanosheets and SA chains. The incorporation of rGO significantly increases the electrical conductivity of the nanohybrid hydrogels, with values in the range of muscle tissue. In vitro cultures with C2C12 murine myoblasts revealed that the conductive nanohybrid hydrogels are not cytotoxic and can greatly enhance myoblast adhesion and myogenic differentiation. These results indicate that these novel electroactive nanohybrid hydrogels have great potential for biomedical applications related to the regeneration of electroactive tissues, particularly in skeletal muscle tissue engineering.

Biometría del músculo grácil: pedículos vasculares e inervación en un grupo de individuos brasileños / Biometric characteristics of the gracilis muscle: vascular pedicles and innervation in a group of Brazilian individuals

El músculo grácil (MG) está ubicado en la cara medial del muslo, medial y posterior al aductor largo en su parte proximal. Se origina a nivel del pubis y se inserta en la cara medial de la tibia, en su parte superior. Como colgajo libre funcional ha sido uno de los injertos más utilizados en reconstrucciones diversas, tales como pene, perineo, vagina, pierna, plexo braquial, parálisis facial, lesiones rectales, entre otras. Basado en lo anterior, el objetivo de este estudio fue complementar la anatomía del MG tanto en sus dimensiones como en sus pedículos vasculares e inervación, estableciendo las relaciones biométricas existentes, contribuyendo a la anatomía quirúrgica, en su uso como injerto. Para ello, se utilizaron 30 miembros inferiores de 20 cadáveres de individuos adultos, brasileños, de sexo masculino, 14 derechos y 16 izquierdos; 17 fijados en formol y 13 en glicerina. Se dividió al muslo en 4 cuartiles enumerados de proximal a distal como C1,C2,C3 y C4. Se contabilizó el número de pedículos y se nombraron como pedículo principal (PP), pedículo menor 1 (Pm1), pedículo menor 2 (Pm2) y pedículo menor 3 (Pm3). La longitud media del GM fue de 42,25 cm ± 2,35 cm y su ancho promedio de 32,90 ± 4,86 mm. Con respecto a los pedículos vasculares se encontró un pedículo en 10/30 casos (33,3 %); un pedículo principal y uno menor en 10/30 (33,3 %); un pedículo principal y dos menores en 8/30 (26,7 %) y un pedículo principal y tres menores en 2/30 (6,7 %). Su inervación siempre procedió del ramo anterior del nervio obturador (RaNO). El punto motor se encontró a una distancia promedio de 7,94 mm proximal al ingreso del pedículo principal en el MG. Los registros biométricos están expresados en tablas. Los resultados obtenidos aportarán al conocimiento anatómico, pudiendo ser utilizados como soporte morfológico a los procedimientos quirúrgicos que involucren al músculo grácil.

The gracilis muscle (GM) is located in the medial aspect of the thigh, medial and posterior to the long adductor in its proximal part. It originates at the pubic level and is inserted in the medial face of the tibia, in its upper part. As a functional free flap, it has been one of the most co mmonly used grafts in various reconstructions, such as penis, perineum, vagina, leg, brachial plexus, facial paralysis, rectal lesions, among others. Based on the above, the objective of this study was to complement the anatomy of the GM both in its dimensions and in its vascular pedicles and innervation, establishing the existing biometric relationships, contributing to the surgical anatomy, in its use as a graft. For this, 30 lower limbs of 20 bodies of adult, Brazilian, male, 14 right and 16 left individuals were used; 17 fixed in formaldehyde and 13 in glycerin. The thigh was divided into 4 quartiles listed from proximal to distal such as C1, C2, C3 and C4. The number of pedicles was counted and they were named as principal pedicle (PP), minor pedicle 1 (mP1), minor pedicle 2 (mP2) and minor pedicle 3 (mP3). The average length of the GM was 42.25 cm ± 2.35 cm and its average width was 32.90 ± 4.86 mm. With respect to vascular pedicles, a pedicle was found in 10/30 cases (33.3 %); one PP and one mP in 10/30 (33.3 %); one PP and two mP in 8/30 (26.7 %) and one PP and three mP in 2/30 (6.7 %). Its innervation always came from the anterior branch of the obturator nerve (aBON). The motor point was found at an average distance of 7.94 mm proximal to the entry of the PP in the GM. Biometric records are expressed in tables. The results obtained will contribute to anatomical knowledge, and can be used as morphological support for surgical procedures that involve the GM.

L-selectin and SDF-1 enhance the migration of mouse and human cardiac mesoangioblasts.

Efficient delivery of stem cells to heart regions is still a major problem for cell therapy. Here, we report experiments aimed to improve migration of mouse and human cardiac mesoangioblasts to the damaged heart. Cardiac mesoangioblasts were induced to transmigrate through the endothelium by factors released by cardiomyocytes or cytokines, among which stromal-derived factor 1 (SDF-1) was the most potent. Cardiac mesoangioblasts were also delivered into the left ventricular (LV) chamber of mice after coronary artery ligation (CAL), and their in vivo homing to the damaged heart was found to be quite modest. Pretreatment of cardiac mesoangioblasts with SDF-1 or transient expression of L-selectin induced a two- to three-fold increase in their transmigration and homing to the damaged heart. Therefore, combined pretreatment with SDF-1 and L-selectin generated modified cardiac mesoangioblasts, 50% of which, after injection into the LV chamber of mice early after CAL, home directly to the damaged free wall of the heart. Finally, modified mouse cardiac mesoangioblasts, injected into the LV chamber regenerate a larger surface of the ventricle in long-term experiments in comparison with their control counterparts. This study defines the requirements for efficient homing of cardiac mesoangioblasts to the damaged heart and offers a new potent tool to optimize efficiency of future cell therapy protocols for cardiovascular diseases.