We thank members of the Mariani lab for critical reading of the manuscript. Our funding sources were: the Baxter Medical Scholar Research Fellowship (to M.K.S.), USC undergraduate fellowships and the Provost, Dean Joan M. Schaeffer, and Rose Hills Fellowships, (to M.K.S.). We also acknowledge a CIRM BRIDGES fellowship through Pasadena City College (to T.T.T). and the James H. Zumberge Research and Innovation Fund, the USC Regenerative Medicine Initiative, and the NIAMS NIH under Award Number R21AR064462 (to F.V.M).

NOTA: Todos los procedimientos se ajustan con un animal protocolo aprobado por el Cuidado y Uso de Animales Comité Institucional (IACUC) de la Universidad del Sur de California. 1. Preparación para la Cirugía <ol><li> Coloque los instrumentos quirúrgicos y suministros necesarios (esterilizada, artículos 1 a 18 en la lista de materiales) y organizar un microscopio de disección y una fibra óptica de trans-iluminador en una campana o en una mesa de aspiración. </li><li> Coloque un ratón sexualmente maduros (20 - 30 g, 1 - 3 meses de edad) en una cámara de inducción con 4% de isoflurano para inducir la anestesia. </li><li> Confirme la anestesia con una pata y / o prueba del pellizco cola. </li><li> Aplique una pomada para los ojos del ratón para evitar la sequedad del ojo durante la cirugía. </li><li> Mueve el ratón a la platina del microscopio. Coloque el ratón en el cono de la nariz de la manguera de mantenimiento y posicionar lateralmente. Proporcionar una bolsa de calentamiento adyacente al animal para ayudar a mantener la temperatura corporal. NOE:. Posición del ratón depende de la preferencia y / o uso de las manos del cirujano personal, lateral izquierda o derecha está muy bien. </li><li> Ajuste isoflurano al 2-3% para el mantenimiento, y ver la frecuencia respiratoria. </li><li> Inyectar buprenorfina (0,05 mg / kg) por vía subcutánea (flanco lateral de la pierna) para el dolor después de la cirugía con una aguja 25 G. La pierna puede contracción que es una respuesta normal. </li></ol> Incisión 2. Apertura <ol><li> Detectar la costilla deseada por palpación, y limpiar la zona de pelo con una maquinilla de afeitar. NOTA: Costillas 8-10 se recomiendan desde las costillas 1-7 están más cerca de los pulmones y 11-13 son considerablemente más cortos. Contando las costillas debe comenzar con la costilla más rostral como número 1. </li><li> Prepare el área con la alternancia de povidona yodada y el isopropanol (70%) hisopado (3x se recomienda a menudo por los protocolos de uso animal). </li><li> Cortar una incisión de 2 cm a través de la piel, directamente arriba y paralela a la costilla deseado con tijeras de microcirugía de tamaño medio. Inc¿Estee a través de las capas de músculo y grasa subyacentes. </li><li> Coloque todos los 3 capas (piel, músculo, grasa) en un retractor para exponer el área quirúrgica, y reducir al mínimo el tamaño de la incisión. </li></ol> 3. Ablación la costilla <ol><li> Corte a través de los músculos intercostales suprayacentes la sección deseada de la costilla con un bisturí 5,0 mm. Posición de esta incisión alrededor de 5 mm proximal a la articulación condrocostal ya que es donde la costilla no es tan altamente curvada. Separar cuidadosamente el músculo del hueso con unas pinzas de punta fina. </li><li> Para crear una resección al tiempo que conserva el periostio en el animal, cortar a través del periostio, a lo largo de la longitud de la costilla con un bisturí 5,0 mm. Separar cuidadosamente el periostio del hueso subyacente lateralmente con unas pinzas de punta fina. Proceda con precaución, ya que el periostio es muy delicada y tiene una consistencia gelatinosa. </li><li> Siguiente hacer una sección transversal a través del hueso en un extremo con finas micro-tijeras. Si es necesario, medir la resección conuna retícula en el microscopio o un medidor de tipo regla. A continuación, levante con cuidado el hueso del periostio y cortar el otro extremo. NOTA: Proceda con precaución. Este es el paso más delicado, ya que tirando hacia arriba sin extirpar el nervio continuación se rompa la membrana pleural y dar lugar a un neumotórax. Si se rompe la membrana pleural este será fácilmente evidente como el interior de la cavidad torácica se hará visible. </li><li> Si el sangrado se produce como resultado de cortar el hueso, aplicar presión en el extremo de corte con un hisopo de algodón con punta de 4 - 5 segundos para detener el sangrado. NOTA: En las raras ocasiones en que el sangrado continúa, puede que sea necesario para detener y practicar la eutanasia del animal pérdida de sangre tan significativo comprometerá recuperación (sin reposición de líquidos, el volumen máximo de sangre que puede ser con seguridad se pierde es el 10% del volumen total de sangre o 7.7 -. 8 l / g Para un 25 g de ratón, esto es equivalente a alrededor de 180 a 200 l 9). </li><li> Coloque inmediatamente la costilla eliminado en4% PFA para el análisis futuro. NOTA: Si la resección de tanto el hueso y el periostio se llevará a cabo, omita la incisión periostio y la separación (paso 3.2). Desde el periostio está muy estrechamente unida a la membrana pleural proceder con cautela, las burlas la nervadura de distancia de la membrana pleural con pinzas para evitar que se rompa. </li></ol> 4. Cierre de la incisión <ol><li> Suturar los músculos intercostales sobre la parte superior de la manga perióstica restante con 9-0 suturas (2 suturas suelen ser suficientes). Coloque las suturas directamente sobre los extremos cortados de la costilla, para actuar como indicadores para la ubicación de la cirugía. </li><li> Retire el retractor. Suturar el músculo y la grasa que recubre con 9-0 suturas (3-4 suturas suelen ser suficientes). En ratones con capas particularmente gruesas de músculo y / o grasa, suturar cada capa por separado (por ejemplo, 1 capa de suturas para la capa muscular y 1 capa de suturas para la capa de grasa). </li><li> Cierre lapiel con 7-0 suturas (4-5 suturas suelen ser suficientes). </li><li> Asegure la incisión con pegamento de sutura, pellizcar los bordes juntos con grandes pinzas. </li><li> Lentamente destetar el ratón fuera isoflurano ajustando primero al 1% durante unos minutos y luego se apagará. </li><li> Coloque el ratón bajo una lámpara de calor y dejar hasta que se recupere la conciencia, 5-10 min. Después de la conciencia se recuperó y en todo el período de cicatrización, el ratón debe moverse y deambular normalmente y no muestran signos de sufrimiento. </li></ol> 5. Recuperación y análisis <ol><li> Proporcionar el manejo del dolor postoperatorio incluyendo la administración de buprenorfina en forma de gelatina oral a 0,5 mg / kg cada 12 horas durante 48 horas. La administración oral no requiere restringir el animal que puede provocar dolor a la región torácica. </li><li> Mantener el ratón en una jaula con libre acceso al alimento y agua durante el período de cicatrización. Después de la incisión es seco, las hembras pueden co-alojados mientras que el varóns debe permanecer aislado para evitar enfrentamientos. </li><li> Tras el período de cicatrización, siga el procedimiento aprobado por la eutanasia. Retire la caja torácica para la fijación y el análisis. </li></ol>

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The authors have nothing to disclose

La primera vez que el aprendizaje de este protocolo, determinar dónde ubicar la incisión inicial puede ser un reto. Sin embargo, la práctica en los ratones sacrificados ayuda al cirujano a aprender dónde colocar la incisión inicial y exponer el nervio deseado para ser resecado. Trabajando en cadáveres también mejora las habilidades motoras finas requeridas para eliminar la porción de la costilla con o sin el periostio. Además, alguien nuevo en este procedimiento podría encontrar la manipulación de las herrami...

Debilitante lesión esquelética, la osteoartritis crónica y los problemas graves asociados con la cirugía reconstructiva impactar la productividad económica, el bienestar de la familia, y la calidad de vida. Mientras que las pequeñas roturas y lesiones pueden sanar bastante bien, los seres humanos no son capaces de reparar defectos grandes y por lo tanto deben confiar en los procedimientos de reconstrucción para restaurar la estructura y función. Reconstrucción puede implicar injertos alogénicos o heterogeneic, hueso morcelado, andamios implantados, o osteogénesis de distracción. Desafortunadamente, no sólo hay factores de morbilidad persistentes asociados con estos tratamientos, pero la resistencia original del hueso reparado raramente se alcanza. Por lo tanto, se necesitan nuevos enfoques clínicos. De una vía para desarrollar métodos innovadores para el tratamiento de defectos segmentarios es estudiar situaciones en las que la reparación a gran escala se produce de forma natural. Anfibios famoso puede regenerar elementos esqueléticos, mientras que los mamíferos se consideran limitadas en ºes la capacidad. Sin embargo, desde principios del siglo 20, algunos informes de la regeneración de la costilla humana se han publicado lo que sugiere que los seres humanos no pueden ser tan limitados 1-4. Actualmente este fenómeno es el más conocido por los cirujanos plásticos que utilizan material de la costilla de la mandíbula, la cara y la oreja de reconstrucción, pero no es más ampliamente apreciado 5. Para estudiar esta reparación con más detalle, hemos desarrollado un modelo quirúrgico con el ratón. El uso de este protocolo, los investigadores pueden identificar los factores innatos involucrados y utilizar esta información para facilitar la curación esquelético en otros lugares. Hay muchas ventajas de utilizar las nervaduras como un modelo para estudiar la reparación esquelética. En primer lugar, las costillas que rodean proporcionan un fijador natural (en comparación con la resección del fémur 6,7). Esto disminuye el riesgo de morbilidad de fijadores internos y externos y simplifica el procedimiento quirúrgico. En segundo lugar, las capas musculares delgadas de los wa pecholl proporcionar un fácil acceso y una excelente visibilidad que hacen que el ensayo comparables a la comodidad de las resecciones de calota 8. En tercer lugar, en contraste con la calotas que forman por la osificación intramembranosa, la forma de las costillas por la osificación endocondral y crecer en longitud a través de la extensión en placas de crecimiento situados en cualquier extremo de una diáfisis central. Por lo tanto, la reparación de los nervios puede ser más comparable a la reparación de los huesos largos del esqueleto apendicular. Además, hemos encontrado que en comparación con el fémur, el periostio de la costilla es más gruesa y puede ser más fácilmente manipulada. Por lo tanto, los investigadores que desean ensayar la reparación del hueso con el propósito de estudiar el periostio o probar terapias celulares, agentes farmacológicos, y / o andamios de tejido pueden encontrar este modelo quirúrgica útil. En resumen, este modelo de resección de costilla proporciona un contexto en el que para estudiar la reparación ósea a gran escala natural en mamíferos como tal modelo de uso general en la actualidad existe.

<table><tbody><tr><td>Medium sized micro-dissection scissors (Vannas-T&amp;uuml;bingen Spring Scissors 5 mm)</td><td>Fine Science Tools</td><td>15003-08</td><td></td></tr><tr><td>Fine micro-dissection scissors (Vannas Spring Scissors - 2mm Cutting Edge)</td><td>Fine Science Tools</td><td>15000-04</td><td>curved tip is beneficial</td></tr><tr><td>Micro-scalpel 5.0 mm</td><td>Fine Science Tools</td><td>10315-12</td><td>other fine scalpels can be substituted</td></tr><tr><td>Dumont 55 forceps</td><td>Fine Science Tools</td><td>11295-51</td><td></td></tr><tr><td>Retractor&amp;nbsp;</td><td>Fine Science Tools</td><td>17004-05</td><td>adjustability is convenient</td></tr><tr><td>Micro-needle holders</td><td>Fine Science Tools</td><td>12060-01</td><td></td></tr><tr><td>9.0 nylon sutures (Ethilon), taper point best</td><td>Ethicon</td><td>2819G or similar</td><td>taper point best but reverse cutting is also good</td></tr><tr><td>7.0 prolene sutures (Prolene)</td><td>Ethicon</td><td>8700H or similar</td><td>6-0 can be used too, needle point can vary</td></tr><tr><td>Large forceps (Adson Forceps)</td><td>Fine Science Tools</td><td>11006-12</td><td>other brands are fine</td></tr><tr><td>Lubricant Eye Ointment (Akwa Tears)</td><td>Akorn</td><td>17478-062-35</td><td></td></tr><tr><td>Suture glue (GLUture Topical Tissue Adhesive)</td><td>Abbot</td><td>32046-01</td><td>has excellent working time</td></tr><tr><td>Shaver</td><td>Wahl</td><td>9918-6171 or similar</td><td></td></tr><tr><td>Clamp lamp</td><td>Zoo Med</td><td>LF-5</td><td></td></tr><tr><td>Infrared Bulb, 75W</td><td>Zoo Med</td><td>RS-75</td><td></td></tr><tr><td>RC&lt;sup&gt;2&lt;/sup&gt; Rodent Anesthesia System</td><td>VetEquip&amp;nbsp;</td><td>922100</td><td></td></tr><tr><td>IsoFlo (Isoflurane)</td><td>Abbot</td><td>05260-05</td><td></td></tr><tr><td>Buprenorphine (Buprenex)</td><td>Reckitt Benckiser</td><td>12496-0757-1</td><td></td></tr><tr><td>Betadine</td><td>Purdue Frederick</td><td>67618015017</td><td></td></tr><tr><td>Flavored Gelatin, raspberry</td><td>Jell-O</td><td>B000E1FYL0</td><td>made up firm, to the consistency of &#039;jigglers&#039;</td></tr></tbody></table>

a surgical procedure for resecting the mouse rib: a model for large-scale long bone repair

Este protocolo introduce investigadores a un nuevo modelo para la reparación ósea a gran escala utilizando el nervio de ratón. El procedimiento se detalla lo siguiente: preparación del animal para la cirugía, la apertura de la pared del cuerpo torácica, exponiendo la costilla deseado de los músculos intercostales circundantes, la escisión de la sección deseada de la costilla sin inducir un neumotórax, y el cierre de las incisiones. En comparación con los huesos del esqueleto apendicular, las costillas son muy accesibles. Además, no fijador interno o externo es necesario ya que las costillas adyacentes proporcionan una fijación natural. La cirugía utiliza comercialmente la oferta disponible, es fácil de aprender, y bien tolerado por el animal. El procedimiento puede llevarse a cabo con o sin retirar el periostio, y por lo tanto la contribución del periostio a la reparación se puede evaluar. Los resultados indican que si se mantiene el periostio, la reparación robusta se produce en 1 - 2 meses. Esperamos que el uso de este protocoloestimular la investigación en la reparación de costilla y que los hallazgos facilitarán el desarrollo de nuevas formas de estimular la reparación ósea en otros lugares del cuerpo.

Animales suelen recuperarse rápidamente de este procedimiento, la incisión cicatriza bien, y los animales presentan un comportamiento normal. El procedimiento utiliza los suministros disponibles comercialmente y después de la práctica, se puede completar en menos de 1 hr. Antes de utilizar este procedimiento para generar los datos experimentales, es importante analizar la resección en el punto de tiempo del día 0 para determinar si los fragmentos óseos grandes pueden permanecer dentro de la zona de resección. Un...

Watch this Scientific Journal Video about A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair at JoVE.com

A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

Un procedimiento quirúrgico para resecar la costilla del ratón: un modelo a gran escala Reparación huesos largos

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation ...

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Research

JoVE Journal

Medicine

13.1K vistas.  Keck School of Medicine, University of Southern California. The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

Video: A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

A Standardized Method for Measuring Internal Lung Surface Area via Mouse Pneumonectomy and Prosthesis Implantation

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), representing the gas-exchange capacity of the lung, is a critical criterion to assess respiratory function. However, observer bias can significantly influence measured values for lung morphological parameters. The protocol that we describe here minimizes variations during measurements of two morphological parameters used for ISA calculation: internal lung volume (ILV) and mean linear intercept (MLI). Using ISA as a morphometric and functional parameter to determine the outcome of alveolar regeneration in both pneumonectomy (PNX) and prosthesis implantation mouse models, we found that the increased ISA following PNX treatment was significantly blocked by implantation of a prosthesis into the thoracic cavity1. The ability to accurately quantify ISA is not only expected to improve the reliability and reproducibility of lung function studies in injured-induced alveolar regeneration models, but also to promote mechanistic discoveries of multiple pulmonary diseases.

Internal lung surface area (ISA) is a critical criterion for assessing lung morphology and physiology in lung diseases and injury-induced alveolar regeneration. We describe here a standardized method that can minimize the measurement bias for ISA in both lung pneumonectomy and prosthesis implantation mouse models.

Un método estandarizado para medir el área de la superficie pulmonar interna mediante neumonectomía y prótesis de ratón

Pulmonary morphology, physiology, and respiratory functions change in both physiological and pathological conditions. Internal lung surface area (ISA), ...

Investigación

Biología del Desarrollo

A Mouse Distraction Osteogenesis Model

Distraction osteogenesis (DO) is a surgical procedure that involves skeletal tissue regeneration without cell transplantation. A DO model consists of the following three phases: the latency phase after osteotomy and placement of the external distractor; the distraction phase, wherein the separated bone ends are gradually and continuously distracted; and the consolidation phase. This custom-made distractor used for DO is comprised of two incomplete acrylic resin rings and an expansion screw. The process was initiated by making a mold with silicone impression material and then creating the custom-made distractor. Dental resin was poured into the formwork made of silicone impression material, and it was allowed to polymerize to create the incomplete resin rings required for the custom-made distractor. These rings were fixed with an expansion screw using transparent resin. The custom-made distractor created via this approach was attached to the tibia of mice. The tibia was fixed to the device using one pair of 25 G needles proximally, one pair of 27 G needles distally, and acrylic resin. After a latency period of 5 days, distraction was initiated at a rate of 0.2 mm/12 h. The lengthening was continued for 8 days, resulting in a total gap of 3.2 mm. The mice were sacrificed 4 weeks after distraction. Bone formation in the distraction gap was confirmed using both radiography and histology.

We present a mouse tibial distraction osteogenesis model developed using a custom-made distractor. The use of a mouse as an analysis target is advantageous for advancing research.

Un modelo murino de osteogénesis de la distracción

Distraction osteogenesis (DO) is a surgical procedure that involves skeletal tissue regeneration without cell transplantation. A DO model consists of the ...

Mouse Pneumonectomy Model of Compensatory Lung Growth

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to disability or death. Injury-based animal models of lung repair and regeneration are limited by injury-specific responses making it difficult to differentiate changes related to the injury response and injury resolution from changes related to lung repair and lung regeneration. However, use of animal models to identify these repair and regeneration signaling pathways is critical to the development of new therapies aimed at improving pulmonary function following lung injury. The mouse pneumonectomy model utilizes compensatory lung growth to isolate those repair and regeneration signals in order to more clearly define mechanisms of alveolar re-septation. Here, we describe our technique for performing mouse pneumonectomy and sham pneumonectomy. This technique may be utilized in conjunction with lineage tracing or other transgenic mouse models to define molecular and cellular mechanism of lung repair and regeneration.

Mouse pneumonectomy is a commonly employed model of compensatory lung growth. This procedure can be used in conjunction with lineage tracing or transgenic mouse models to elucidate underlying mechanisms.

Ratón neumonectomía Modelo de Compensatoria crecimiento pulmonar

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to ...

Medicina

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

A-crítico tamaño femoral Defecto sencillo modelo en ratones

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

Establishment of a Segmental Femoral Critical-size Defect Model in Mice Stabilized by Plate Osteosynthesis

The use of tissue-engineered bone constructs is an appealing strategy to overcome drawbacks of autografts for the treatment of massive bone defects. As a model organism, the mouse has already been widely used in bone-related research. Large diaphyseal bone defect models in mice, however, are sparse and often use bone fixation which fills the bone marrow cavity and does not provide optimal mechanical stability. The objectives of the current study were to develop a critical-size, segmental, femoral defect in nude mice. A 3.5-mm mid-diaphyseal femoral ostectomy (approximately 25% of the femur length) was performed using a dedicated jig, and was stabilized with an anterior located locking plate and 4 locking screws. The bone defect was subsequently either left empty or filled with a bone substitute (syngenic bone graft or coralline scaffold). Bone healing was monitored noninvasively using radiography and in vivo micro-computed-tomography and was subsequently assessed by ex vivo micro-computed-tomography and undecalcified histology after animal sacrifice, 10 weeks postoperatively. The recovery of all mice was excellent, a full-weight-bearing was observed within one day following the surgical procedure. Furthermore, stable bone fixation and consistent fixation of the implanted materials were achieved in all animals tested throughout the study. When the bone defects were left empty, non-union was consistently obtained. In contrast, when the bone defects were filled with syngenic bone grafts, bone union was always observed. When the bone defects were filled with coralline scaffolds, newly-formed bone was observed in the interface between bone resection edges and the scaffold, as well as within a short distance within the scaffold. 
The present model describes a reproducible critical-size femoral defect stabilized by plate osteosynthesis with low morbidity in mice. The new load-bearing segmental bone defect model could be useful for studying the underlying mechanisms in bone regeneration pertinent to orthopaedic applications.

Although mouse models are invaluable tools for bone tissue engineering, models of long bone defects are sparse. This need motivated development of the present protocol which uses a locking plate with four screws and a dedicated jig to perform and stabilize a reproducible, femoral, critical-size defect with low morbidity.

Establecimiento de un defecto segmentario Modelo femoral de tamaño crítico en ratones estabilizado por osteosíntesis Plate

The use of tissue-engineered bone constructs is an appealing strategy to overcome drawbacks of autografts for the treatment of massive bone defects. As a ...

A Mouse Model of Orthopedic Surgery to Study Postoperative Cognitive Dysfunction and Tissue Regeneration

Surgery is commonly used to improve and maintain quality of life. Unfortunately, in vulnerable patients such as the elderly, complications may occur and significantly diminish the outcome. Indeed, after routine orthopedic surgery to repair a fracture, as many as 50% of elderly patients suffer from neurologic complications like delirium. Also, the capacity to heal and regenerate tissue after surgery decreases with age, and can impact the quality of fracture repair and even osseous integration of implants. Thus, a better understanding of mechanisms that drive these age-dependent changes could provide strategic targets to minimize risk for such complications and optimize outcomes. Here, we introduce a clinically relevant mouse model of tibial fracture. The postoperative changes in these mice mimic some of the cognitive impairments commonly observed after routine orthopedic surgery in humans. Briefly, an incision is performed in the right hind limb under strictly aseptic conditions. Muscles are disassociated, and a 0.38-mm stainless steel pin is inserted into the upper crest of the tibia, inside the intramedullary canal. Osteotomy is then performed, and the wound is stapled. We have used this model to investigate the effects of surgical trauma on postoperative neuroinflammation and behavioral changes. By applying this fracture model in combination with parabiosis, a surgical model in which 2 mice are anastomosed, we have studied cells and secreted factors that systemically rejuvenate organ function and tissue regeneration after injury. By following our step-by-step protocol, these models can be reproduced with high fidelity, and can be adapted to interrogate many biologic pathways that are altered by surgical trauma.

This protocol describes a mouse model of orthopedic surgery that has been used to study mechanisms of postoperative neuroinflammation and behavioral changes, and when combined with parabiosis, to study tissue regeneration during aging.

Un modelo de ratón de cirugía ortopédica para el estudio de la disfunción cognitiva postoperatoria y regeneración de los tejidos

Surgery is commonly used to improve and maintain quality of life. Unfortunately, in vulnerable patients such as the elderly, complications may occur and ...

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

This protocol describes a minimally invasive osteosynthesis technique using an intramedullary screw for standardized stabilization of femur fractures, which can be used to analyze endochondral bone healing in mice.

Un modelo mínimamente invasivo para analizar la fractura endocondral en ratones en condiciones biomecánicas estandarizadas

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an ...

The Generation of Closed Femoral Fractures in Mice: A Model to Study Bone Healing

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies that promote efficient bone healing are non-existent and in high demand. Effective and reproducible animal models of fractures healing are needed to understand the complex biological processes associated with bone regeneration. Many animal models of fracture healing have been generated over the years; however, murine fracture models have recently emerged as powerful tools to study bone healing. A variety of open and closed models have been developed, but the closed femoral fracture model stands out as a simple method for generating rapid and reproducible results in a physiologically relevant manner. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice and facilitate a post-fracture stabilization of the femur by inserting an intramedullary steel rod. Although devices such as a nail or a screw offer greater axial and rotational stability, the use of an intramedullary rod provides a sufficient stabilization for consistent healing outcomes without producing new defects in the bone tissue or damaging nearby soft tissue. Radiographic imaging is used to monitor the progression of callus formation, bony union, and subsequent remodeling of the bony callus. Bone healing outcomes are typically associated with the strength of the healed bone and measured with torsional testing. Still, understanding the early cellular and molecular events associated with fracture repair is critical in the study of bone tissue regeneration. The closed femoral fracture model in mice with intramedullary fixation serves as an attractive platform to study bone fracture healing and evaluate therapeutic strategies to accelerate healing.

The murine closed femoral fracture model is a powerful platform to study fracture healing and novel therapeutic strategies to accelerate bone regeneration. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice using an intramedullary steel rod to stabilize the femur.

La generación de fracturas femorales cerradas en ratones: un modelo para el estudio del hueso curativo

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies ...

Transverse Fracture of the Mouse Femur with Stabilizing Pin

Fracture repair is an essential function of the skeleton that cannot be reliably modeled in vitro. A mouse injury model is an efficient approach to test whether a gene, gene product or drug influences bone repair because murine bones recapitulate the stages observed during human fracture healing. When a mouse or human breaks a bone, an inflammatory response is initiated, and the periosteum, a stem cell niche surrounding the bone itself, is activated and expands. Cells residing in the periosteum then differentiate to form a vascularized soft callus. The transition from the soft callus to a hard callus occurs as the recruited skeletal progenitor cells differentiate into mineralizing cells, and the bridging of the fractured ends results in the bone union. The mineralized callus then undergoes remodeling to restore the original shape and structure of the healed bone. Fracture healing has been studied in mice using various injury models. Still, the best way to recapitulate this entire biological process is to break through the cross-section of a long bone that encompasses both cortices. This protocol describes how a stabilized, transverse femur fracture can be safely performed to assess healing in adult mice. A surgical protocol including detailed harvesting and imaging techniques to characterize the different stages of fracture healing is also provided.

This protocol describes a method to perform fractures on adult mice and monitor the healing process.

Fractura transversal del fémur del ratón con pasador estabilizador

Fracture repair is an essential function of the skeleton that cannot be reliably modeled in vitro. A mouse injury model is an efficient approach to test ...

Biología

Establishing a Diaphyseal Femur Fracture Model in Mice

Bones have a significant regenerative capacity. However, fracture healing is a complex process, and depending on the severity of the lesions and the age and overall health status of the patient, failures can occur, leading to delayed union or nonunion. Due to the increasing number of fractures resulting from high-energy trauma and aging, the development of innovative therapeutic strategies to improve bone repair based on the combination of skeletal/mesenchymal stem/stromal cells and biomimetic biomaterials is urgently needed. To this end, the use of reliable animal models is fundamental to better understanding the key cellular and molecular mechanisms that determine the healing outcomes. Of all the models, the mouse is the preferred research model because it offers a wide variety of transgenic strains and reagents for experimental analysis. However, the establishment of fractures in mice may be technically challenging due to their small size. Therefore, this article aims to demonstrate the procedures for the surgical establishment of a diaphyseal femur fracture in mice, which is stabilized with an intramedullary wire and resembles the most common bone repair process, through cartilaginous callus formation.

This protocol describes a surgical procedure for the establishment of a diaphyseal fracture in the femur of mice, which is stabilized with an intramedullary wire, for fracture healing studies.

Establecimiento de un modelo de fractura de fémur diafisario en ratones

Bones have a significant regenerative capacity. However, fracture healing is a complex process, and depending on the severity of the lesions and the age ...