Name: treatment with vancomycin loaded calcium sulphate and autogenous bone in an improved rabbit model of bone infection
Uploaded: 2019-03-14T12:30:00
Description: Watch this Scientific Journal Video about Treatment with Vancomycin Loaded Calcium Sulphate and Autogenous Bone in an Improved Rabbit Model of Bone Infection at JoVE.com

This work was supported by the National Natural Science Foundation of China (81803808, 81873062), Zhejiang Provincial Medical and Health Science and Technology Fund (2017KY271) and the Science and Technology Project of Zhejiang Province (2017C37181).

The rabbits used in the present study were treated in accordance with the Guide for the Care and Use of Laboratory Animals. All the experimental procedures were followed by the rules of the Bioethics Committee of Zhejiang Academy of Traditional Chinese Medicine.
1. Preparation of the Bacterial Suspension
<ol>
	<li>Dissolve 0.5 mg of S. aureus freeze-drying powder (ATCC 6538) with 0.3 mL of Luria-Bertani culture medium. Mix suspension completely.</li>
	<li>Streak the bacteria suspens...

<ol>
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In the previous studies, various kinds of animal models were constructed to study both acute and chronic bone infection; however, the search for the ideal model still persists17,18. In addition, the ideal bone infection model is expected to simulate the pathological characteristics of bone infection in clinical setting, while the modelling periods, remain low cost and easy to carry out. So far, the rabbit bone infection model is the most common model in inflammat...

Bone infection usually results from bacteria or other microorganism invasion after trauma, bone fracture, or other bone diseases1. Bone infection may induce a high level of inflammation and bone tissue destruction. In the clinic, Staphylococcus aureus (S. aureus) is the predominant causative agent of bone infection2,3. The bone infection is painful, debilitating, and often takes a chronic course that is extremely difficult to treat4. At present, debridement of necrotic tissue and implanting of vancomycin-loaded calcium (VCS) beads have been confirmed as an efficient strategy for controlling local infection5,6. However, 10% to 15% of patients experienced a prolonged bone repair process, delayed union, or non-union after anti-infection treatment7. The large segment of a bone defect is the most difficult issue for orthopedic surgeons. An autologous bone graft is considered the optimal bone replacement in bone non-union treatment8,9.
To date, most of the studies on bone infection and autologous bone implantation have been conducted in various kinds of animal models, such as rats, rabbits, dogs, pigs and sheep10,11. Rabbit models are most commonly used for bone infection studies, as first performed by Norden and Kennedy in 197012,13. In our previous study, we used rabbit models following Norden&#39;s method, and we found that the quantity of S. aureus injected into bone marrow could not be quantified accurately, as the blood leaking out of bone marrow led to bacteria solution overflow.
This article presents an improved surgical method for inducing bone infection on rabbits. At the end of the procedure, a blood biochemistry test, a bacteriological examination, and a histopathologic examination were performed to verify the bone infection model. Then, VCS was implanted to inhibit infection, and autogenous bone was implanted to promote bone regeneration.

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	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">absorbable surgical suture</td>
			<td style="width:264px;">Jinghuan</td>
			<td style="width:119px;">18S0604A</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">asepsis injector</td>
			<td style="width:264px;">Jinglong</td>
			<td style="width:119px;">20170501</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">bone wax</td>
			<td style="width:264px;">ETHICON</td>
			<td style="width:119px;">JH5CQLM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">CCD camera</td>
			<td style="width:264px;">Olympus</td>
			<td style="width:119px;">DP72</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">EDTA-K2 anticoagulant blood vessel</td>
			<td style="width:264px;">XINGE</td>
			<td style="width:119px;">20170802</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Electric bone drill unit</td>
			<td style="width:264px;">Bao Kang</td>
			<td style="width:119px;">BKZ-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Electric shaver</td>
			<td style="width:264px;">Codos</td>
			<td style="width:119px;">3800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">flexible silica gel mold&#160;</td>
			<td style="width:264px;">WRIGHT</td>
			<td style="width:119px;">1527745</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Hematoxylin and Eosin Staining Kit</td>
			<td style="width:264px;">Beyotime</td>
			<td style="width:119px;">20170523</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Luria-Bertani culture medium</td>
			<td style="width:264px;">Baisi Biothchnology</td>
			<td style="width:119px;">20170306</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Medical-grade calcium sulphate</td>
			<td style="width:264px;">WRIGHT</td>
			<td style="width:119px;">1527745</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">microcomputed tomography (micro-CT)</td>
			<td style="width:264px;">Bruker</td>
			<td style="width:119px;">SkyScan 1172&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Microscope</td>
			<td style="width:264px;">Olympus</td>
			<td style="width:119px;">CX41</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">New Zealand white rabbits</td>
			<td style="width:264px;">Zhejiang Experimental Animal Center&#160;</td>
			<td style="width:119px;">SCXK 2014-0047</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:275px;">No. 11 scalpel&#160;</td>
			<td style="width:264px;">Yuanlikang</td>
			<td style="width:119px;">20170604</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">normal saline</td>
			<td style="width:264px;">Mingsheng</td>
			<td style="width:119px;">20170903</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">PBS</td>
			<td style="width:264px;">TBD(Jingyi)</td>
			<td style="width:119px;">20170703-0592</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">pentobarbital sodium</td>
			<td style="width:264px;">Merk</td>
			<td style="width:119px;">2070124</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">povidone-iodinesolution</td>
			<td style="width:264px;">Lierkang</td>
			<td style="width:119px;">20170114</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">S. aureus freeze drying powder</td>
			<td style="width:264px;">China General Microbiological Culture Collection Center</td>
			<td style="width:119px;">ATCC 6538</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">sheep blood agar</td>
			<td style="width:264px;">HuanKai Microbial</td>
			<td style="width:119px;">3103210</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:275px;">tryptic soy agar plates</td>
			<td style="width:264px;">HuanKai Microbial</td>
			<td style="width:119px;">3105697</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">tryptic soy broth tubes</td>
			<td style="width:264px;">HuanKai Microbial</td>
			<td style="width:119px;">3104260</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Vancomycin</td>
			<td style="width:264px;">Lilly</td>
			<td style="width:119px;">C599180</td>
			<td></td>
		</tr>
	</tbody>
</table>

treatment with vancomycin loaded calcium sulphate and autogenous bone in an improved rabbit model of bone infection

Bone infection results from bacterial invasion, which is extremely difficult to treat in clinical, orthopedic, and traumatic surgery. The bone infection may result in sustained inflammation, osteomyelitis, and eventual bone non-union. Establishment of a feasible, reproducible animal model is important to bone infection research and antibiotic treatment. As an in vivo model, the rabbit model is widely used in bone infection research. However, previous studies on rabbit bone infection models showed that the infection status was inconsistent, as the amount of bacteria was variable. This study presents an improved surgical method for inducing bone infection on a rabbit, by blocking the bacteria in the bone marrow. Then, multi-level evaluations can be carried out to verify the modelling method.
In general, debriding necrotic tissue and implantation of vancomycin-loaded calcium sulphate (VCS) are predominant in antibiotic treatment. Although calcium sulphate in VCS benefits osteocyte crawling and new bone growth, massive bone defects occur after debriding. Autogenous bone (AB) is an appealing strategy to overcome bone defects for the treatment of massive bone defects after debriding necrotic bone.
In this study, we used the tail bone as an autogenous bone implanted in the bone defect. Bone repair was measured using micro-computed-tomography (micro-CT) and histological analysis after animal sacrifice. As a result, in the VCS group, bone non-union was consistently obtained. In contrast, the bone defect areas in the VCS-AB group were decreased significantly. The present modeling method described a reproducible, feasible, stable method to prepare a bone infection model. The VCS-AB treatment resulted in lower bone non-union rates after antibiotic treatment. The improved bone infection model and the combination treatment of VCS and autogenous bone could be helpful in studying the underlying mechanisms in bone infection and bone regeneration pertinent to traumatology orthopedic applications.

Evaluation of Bone Infection Model 
After infection with S. aureus, the pathological manifestations of rabbits were similar to the representative symptom of chronic osteomyelitis in the clinic. In our study, 30 rabbits were infected, and subjected as a model group, and 10 rabbits were subjected as control animals. All the model rabbits have infected sinuses of the tibia local site, with white and yellow pus over flow from the sinuses (Fi...

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Treatment with Vancomycin Loaded Calcium Sulphate and Autogenous Bone in an Improved Rabbit Model of Bone Infection

This study presents an improved rabbit model infected with Staphylococcus aureus by blocking the same amount of bacteria in bone marrow. Vancomycin loaded calcium sulphate and autogenous bone are used for antibiotic and bone repair treatment. The protocol could be helpful for studying bone infection and regeneration.

Bone infection results from bacterial invasion, which is extremely difficult to treat in clinical, orthopedic, and traumatic surgery. The bone infection ...

A producible animal model is very important for the bone infection research. However, currently there is no rabbit model for which the infections status and the number of bacteria is consistent. Our bone infection rabbit model uses a consistent bacteria and is treated by vancomycin-loaded calcium sulfate and autogenous fragments.The technique could be extended toward the diagnosis of bone infection and bone nonunion therapy, and in understanding the pathogenesis of bone infection. This method could provide insight into other bone infection models in rats, mice, and pigs. It's difficult to load the same volume of bacterial suspension into bone marrow.Visual demonstration can help researchers to carry out the critical steps easily and accurately. To prepare the bacterial suspension, first dissolve 0.5 milligrams of S.aureus freeze-dried powder in 0.3 milliliters of LB culture medium. Mix the suspension thoroughly, and streak the bacteria onto tryptic soy agar plates for their incubation for 16 hours at 37 degrees Celsius.The next morning, pick a single bacterial colony-forming unit for culture in tryptic soy broth tubes for 24 hours at 37 degrees Celsius. When the bacteria are in the mid-logarithmic growth phase, transfer 1 milliliter of bacteria into a 1.5 milliliter tube, and collect the bacteria by centrifugation. Then, wash the bacterial cell pellet three times in 100 microliters of PBS per wash, resuspending the bacteria in 3 milliliters of fresh PBS after the final wash.To set up the bone infection mold, confirm a lack of response to paw pinch in a three month old three kilogram male New Zealand white rabbit, and use an electric shaver to remove the hair from the proximal tibial region against the direction of the hair growth. Disinfect the exposed skin with povidone iodine solution, and use a pen and a ruler to mark the upper end of the tibia and the drilling hole position for the S.Aureus injection, taking care that the drilling hole position is in the horizontal middle of the tibial plateau. Next, use a number 11 scalpel to make an incision in the skin, followed by a one centimeter incision in the peritoneum.Using an electric bone drill unit, punch a two millimeter diameter hole in the tibia, and press the hole with a two millimeter diameter two millimeter long cylinder of bone wax. Remove any spare bone wax along the horizontal plane of the tibial plateau, and confirm that the hole is full of bone wax. Then, use absorbable surgical sutures to sew up the periosteum and skin in a vertical mattress suture to prevent the animal from chewing the stitches.And use a one milliliter asepsis injector to slowly inject one times 10 to the eight colony-forming units per milliliter of S.Aureus solution into the drill hole. At day seven, 14, 21 and 28 after injection, place the infected rabbits into a rabbit restrainer with the head and ear outside of the restrainer, and collect blood samples from the auricular veins for white blood cells and C-reactive protein analysis. After anesthesia, use a number 11 scalpel to make centimeter tibial skin and peritoneal incisions, and clean the bone wax.Next, use an electric bone drill unit to punch two adjacent 4.8 millimeter diameter holes to debride the necrotic bone, and use a bone spoon to debride the necrotic bone marrow and granulation tissue. Then, scrape and clean the bone tissue between the two holes, and spread one milliliter of the debrided bone marrow onto sheep blood agar plates for an overnight incubation at 37 degrees Celsius. The next morning, select plates with 30 to 300 colonies, and calculate the number of colony-forming units per infected animal.On the 28th day after infection, add one gram of vancomycin hydrochloride powder to 9.5 grams of medical grade calcium sulfate, and use a spatula to stir the mixture with three milliliters of normal saline for 30 to 45 seconds. Add the mixed product into a flexible silica gel mold, and allow the product to dry at room temperature for 15 minutes. Then, flex the mold to remove the vancomycin loaded calcium sulfate, or VCS bead.For antibiotic treatment and implantation of the autogenous bone, first, re-expose the injured tibia before shaving the tail region, and disinfecting the exposed tail skin with povidone iodine solution. Use surgical scissors to cut down the tail, and use absorbable surgical sutures to close the skin in a vertical mattress suture to prevent the animal from chewing the stitches. Use a number 11 scalpel to cut the tail skin to reveal the tail bone.Remove any muscle, soft tissue, and periosteum, and detach the tailbone at each joint. Transfer the bone fragments to a 100 millimeter plastic dish containing sterile saline. Next, use curved scissors to implant four pieces of the VCS bead into the tibial marrow cavity, and use curved forceps to fill the bone defect with eight pieces of autogenous tailbone fragments.Then, close the periosteum and skin incisions with absorbable surgical sutures in a mattress suture manner. C-reactive protein and white blood cell levels are higher in the bone infection model group than in the control animals. Two, four, six, and eight weeks after VCS or VCS autogenous bone treatment, C-reactive protein and white blood cell levels are significantly reduced.Two dimensional reconstruction images indicate a progressive increase in the bone volume during the 12 week period after treatment with VCS or VCS and autogenous bone, while bone loss is significant in the untreated bone infection model group. To analyze the bone regeneration quantitative indexes, 3D model images can be reconstructed using bitmap data, and an oval 4.8 millimeter diameter by 9.6 millimeter length oval region of interest can be selected in each bone. The ratio of bone volume to tissue volume in the untreated bone infection model group are significantly lower than those measured in the VCS and the VCS autogenous bone groups.The trabecular number and thickness scores in the VCS autogenous bone group are significantly higher than those in the untreated bone infection model and VCS animals. Moreover, the trabecular separation scores in the VCS autogenous bone group are markedly lower than those measured in the untreated bone infection model and VCS groups. Take care to select rabbits with appropriate body weight.Block the Staphylococcus aureus solution with bone wax. Debride the necrotic bone completely, and punch the two adjacent 4.8 millimeter diameter holes. Following the procedure, other diagnostic measure method such as ultrasound, radiology and computer tomography can be performed to monitor the pathological processes of the bone infection and repair.This improved bone infection model and the combination VCS and autogenous bone treatment could be helpful in studying the underlining mechanism of bone infection and bone regeneration. As the Staphylococcus aureus freeze-dried powder is hazardous, the bacterial suspension should always be prepared in an isolated bacterial laboratory.

treatment-with-vancomycin-loaded-calcium-sulphate-autogenous-bone-an

Research

Education

JoVE Core

JoVE Journal

Anatomy and Physiology

Medicine

Unit 1

Bone Tissue and the Skeletal System

SCIENTISTS IN ACTION

Using Quantitative Real-time PCR to Determine Donor Cell Engraftment in a Competitive Murine Bone Marrow Transplantation Model

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules that regulate HSCs. In these transplant model systems, the function of HSCs is determined by the ability of these cells to engraft and reconstitute lethally irradiated recipient mice. Commonly, the donor cell contribution/engraftment is measured by antibodies to donor- specific cell surface proteins using flow cytometry. However, this method heavily depends on the specificity and the ability of the cell surface marker to differentiate donor-derived cells from recipient-originated cells, which may not be available for all mouse strains. Considering the various backgrounds of genetically modified mouse strains in the market, this cell surface/ flow cytometry-based method has significant limitations especially in mouse strains that lack well-defined surface markers to separate donor cells from congenic recipient cells. Here, we reported a PCR-based technique to determine donor cell engraftment/contribution in transplant recipient mice. We transplanted male donor bone marrow HSCs to lethally irradiated congenic female mice. Peripheral blood samples were collected at different time points post transplantation. Bone marrow samples were obtained at the end of the experiments. Genomic DNA was isolated and the Y chromosome specific gene, Zfy1, was amplified using quantitative Real time PCR. The engraftment of male donor-derived cells in the female recipient mice was calculated against standard curve with known percentage of male vs. female DNAs. Bcl2 was used as a reference gene to normalize the total DNA amount. Our data suggested that this approach reliably determines donor cell engraftment and provides a useful, yet simple method in measuring hematopoietic cell reconstitution in murine bone marrow transplantation models. Our method can be routinely performed in most laboratories because no costly equipment such as flow cytometry is required.

Determining donor cell engraftment presents a challenge in mouse bone marrow transplant models that lack well-defined phenotypical markers. We described a methodology to quantify male donor cell engraftment in female transplant recipient mice. This method can be used in all mouse strains for the study of HSC functions.

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules ...

Pre-clinical Evaluation of Tyrosine Kinase Inhibitors for Treatment of Acute Leukemia

Receptor tyrosine kinases have been implicated in the development and progression of many cancers, including both leukemia and solid tumors, and are attractive druggable therapeutic targets. Here we describe an efficient four-step strategy for pre-clinical evaluation of tyrosine kinase inhibitors (TKIs) in the treatment of acute leukemia. Initially, western blot analysis is used to confirm target inhibition in cultured leukemia cells. Functional activity is then evaluated using clonogenic assays in methylcellulose or soft agar cultures. Experimental compounds that demonstrate activity in cell culture assays are evaluated in vivo using NOD-SCID-gamma (NSG) mice transplanted orthotopically with human leukemia cell lines. Initial in vivo pharmacodynamic studies evaluate target inhibition in leukemic blasts isolated from the bone marrow. This approach is used to determine the dose and schedule of administration required for effective target inhibition. Subsequent studies evaluate the efficacy of the TKIs in vivo using luciferase expressing leukemia cells, thereby allowing for non-invasive bioluminescent monitoring of leukemia burden and assessment of therapeutic response using an in vivo bioluminescence imaging system. This strategy has been effective for evaluation of TKIs in vitro and in vivo and can be applied for identification of molecularly-targeted agents with therapeutic potential or for direct comparison and prioritization of multiple compounds.

Receptor tyrosine kinases are ectopically expressed in many cancers and have been identified as therapeutic targets in acute leukemia. This manuscript describes an efficient strategy for pre-clinical evaluation of tyrosine kinase inhibitors for the treatment of acute leukemia.

Receptor tyrosine kinases have been implicated in the development and progression of many cancers, including both leukemia and solid tumors, and are ...

Combined In vivo Optical and &#181;CT Imaging to Monitor Infection, Inflammation, and Bone Anatomy in an Orthopaedic Implant Infection in Mice

Multimodality imaging has emerged as a common technological approach used in both preclinical and clinical research. Advanced techniques that combine in vivo optical and &#956;CT imaging allow the visualization of biological phenomena in an anatomical context. These imaging modalities may be especially useful to study conditions that impact bone. In particular, orthopaedic implant infections are an important problem in clinical orthopaedic surgery. These infections are difficult to treat because bacterial biofilms form on the foreign surgically implanted materials, leading to persistent inflammation, osteomyelitis and eventual osteolysis of the bone surrounding the implant, which ultimately results in implant loosening and failure. Here, a mouse model of an infected orthopaedic prosthetic implant was used that involved the surgical placement of a Kirschner-wire implant into an intramedullary canal in the femur in such a way that the end of the implant extended into the knee joint. In this model, LysEGFP mice, a mouse strain that has EGFP-fluorescent neutrophils, were employed in conjunction with a bioluminescent Staphylococcus aureus strain, which naturally emits light. The bacteria were inoculated into the knee joints of the mice prior to closing the surgical site. In vivo bioluminescent and fluorescent imaging was used to quantify the bacterial burden and neutrophil inflammatory response, respectively. In addition, &#956;CT imaging was performed on the same mice so that the 3D location of the bioluminescent and fluorescent optical signals could be co-registered with the anatomical &#956;CT images. To quantify the changes in the bone over time, the outer bone volume of the distal femurs were measured at specific time points using a semi-automated contour based segmentation process. Taken together, the combination of in vivo bioluminescent/fluorescent imaging with &#956;CT imaging may be especially useful for the noninvasive monitoring of the infection, inflammatory response and anatomical changes in bone over time.

Combined In vivo Optical and  &#181;CT Imaging to Monitor Infection, Inflammation, and Bone Anatomy in an Orthopaedic Implant Infection in Mice

Combined optical and &#956;CT imaging in a mouse model of orthopaedic implant infection, utilizing a bioluminescent engineered strain of Staphylococcus aureus, provided the capability to noninvasively and longitudinally monitor the dynamics of the bacterial infection, as well as the corresponding inflammatory response and anatomical changes in the bone.

Multimodality imaging has emerged as a common technological approach used in both preclinical and clinical research. Advanced techniques that combine in ...

An Improved Method for Rapid Intubation of the Trachea in Mice

Despite some anatomical and physiological differences, mouse models continue to be an essential tool for studying human lung disease. Bleomycin toxicity is a commonly used model to study both acute lung injury and fibrosis, and multiple methods have been developed for administering bleomycin (and other toxic agents) into the lungs. However, many of these approaches, such as transtracheal instillation, have inherent drawbacks, including the need for strong anesthetics and survival surgery. This paper reports a quick, reproducible method of intratracheal intubation that involves mild inhaled anesthesia, visualization of the trachea, and the use of a surrogate spirometer to confirm exposure. As a proof of concept, 8-12 week old C57BL/6 mice were administered either 2.0 U/kg of bleomycin or an equivalent volume of PBS, and both damage and fibrotic endpoints were measured post-exposure. This procedure allows researchers to treat a large cohort of mice in a relatively short period with little expense and minimal post-procedure care.

This article presents a rapid and simple method for administering bleomycin directly into the mouse trachea via intubation. Key advantages of this method are that it is highly reproducible, easy to master, and does not require specialized equipment or lengthy recovery times.

Despite some anatomical and physiological differences, mouse models continue to be an essential tool for studying human lung disease. Bleomycin toxicity ...

Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ROM is called a joint contracture and results in increased morbidity. Due to the difficulty of reversing established knee contractures, early detection is important, and hence, knowing risk factors for their development is essential. The rat represents a good model with which the effect of an intervention can be studied due to the similarity of rat knee anatomy to that of humans, the rat's ability to tolerate long durations of knee immobilization in flexion, and because mechanical data can be correlated with histologic and biochemical analysis of knee tissue.
Using an automated arthrometer, we demonstrate a validated, precise, reproducible, user-independent method of measuring the extension ROM of the rat knee joint at specific torques. This arthrometer can be used to determine the effects of interventions on knee joint ROM in the rat.

The goal of the protocol is to measure the extension range of motion of the rat knee. The effects of various diseases that increase the stiffness of the knee joint and the effectiveness of treatments can be quantified.

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ...

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.

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

Flow Cytometry Analysis of Immune Cell Subsets within the Murine Spleen, Bone Marrow, Lymph Nodes and Synovial Tissue in an Osteoarthritis Model

Osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases, affecting patients suffering from pain and physical limitations. Recent evidence indicates a potential inflammatory component of the disease, with both T-cells and monocytes/macrophages potentially associated with the pathogenesis of OA. Further studies postulated an important role for subsets of both inflammatory cell lineages, such as Th1, Th2, Th17, and T-regulatory lymphocytes, and M1, M2, and synovium-tissue-resident macrophages. However, the interaction between the local synovial and systemic inflammatory cellular response and the structural changes in the joint is unknown. To fully understand how T-cells and monocytes/macrophages contribute towards OA, it is important to be able to quantitively identify these cells and their subsets simultaneously in synovial tissue, secondary lymphatic organs and systemically (the spleen and bone marrow). Nowadays, the different inflammatory cell subsets can be identified by a combination of cell-surface markers making multi-color flow cytometry a powerful technique in investigating these cellular processes. In this protocol, we describe detailed steps regarding the harvest of synovial tissue and secondary lymphatic organs as well as generation of single cell suspensions. Furthermore, we present both an extracellular staining assay to identify monocytes/macrophages and their subsets as well as an extra- and intra-cellular staining assay to identify T-cells and their subsets within the murine spleen, bone marrow, lymph nodes and synovial tissue. Each step of this protocol was optimized and tested, resulting in a highly reproducible assay that can be utilized for other surgical and non-surgical OA mouse models.

Here, we describe a detailed and reproducible flow cytometry protocol to identify monocyte/macrophage and T-cell subsets using both extra- and intracellular staining assays within the murine spleen, bone marrow, lymph nodes and synovial tissue, utilizing an established surgical model of murine osteoarthritis.

Osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases, affecting patients suffering from pain and physical limitations. Recent ...

Evaluation of Amino Acid Consumption in Cultured Bone Cells and Isolated Bone Shafts

Bone development and homeostasis is dependent upon the differentiation and activity of bone forming osteoblasts. Osteoblast differentiation is sequentially characterized by proliferation followed by protein synthesis and ultimately bone matrix secretion. Proliferation and protein synthesis require a constant supply of amino acids. Despite this, very little is known about amino acid consumption in osteoblasts. Here we describe a very sensitive protocol that is designed to measure amino acid consumption using radiolabeled amino acids. This method is optimized to quantify changes in amino acid uptake that are associated with osteoblast proliferation or differentiation, drug or growth factor treatments, or various genetic manipulations. Importantly, this method can be used interchangeably to quantify amino acid consumption in cultured cell lines or primary cells in vitro or in isolated bone shafts ex vivo. Finally, our method can be easily adapted to measure the transport of any of the amino acids as well as glucose and other radiolabeled nutrients.

This protocol presents a radiolabeled amino acid uptake assay, which is useful for evaluating amino acid consumption either in primary cells or in isolated bones.

Bone development and homeostasis is dependent upon the differentiation and activity of bone forming osteoblasts. Osteoblast differentiation is ...

Improved Rodent Model of Myocardial Ischemia and Reperfusion Injury

Myocardial ischemia and reperfusion injury (MIRI), induced by coronary heart disease (CHD), causes damage to the cardiomyocytes. Furthermore, evidence suggests that thrombolytic therapy or primary percutaneous coronary intervention (PPCI) does not prevent reperfusion injury. There is still no ideal animal model for MIRI. This study aims to improve the MIRI model in rats to make surgery easier and more feasible. A unique method for establishing MIRI is developed by using a soft tube during a key step of the ischemic period. To explore this method, thirty rats were randomly divided into three groups: sham group (n = 10); experimental model group (n = 10); and existing model group (n = 10). Findings of triphenyltetrazolium chloride staining, electrocardiography, and percent survival are compared to determine the accuracies and survival rates of the operations. Based on the study results, it has been concluded that the improved surgery method is associated with a higher survival rate, elevated ST-T segment, and larger infarct size, which is expected to mimic the pathology of MIRI better.

Myocardial ischemia-reperfusion model of rat heart is improved by using a self-made retractor, polyvinyl chloride tube, and a unique knotting method. Electrocardiogram, triphenyltetrazolium chloride and histological staining, and percent survival analysis results showed that the improved model group has higher success and survival rates than the already existing model group.

Myocardial ischemia and reperfusion injury (MIRI), induced by coronary heart disease (CHD), causes damage to the cardiomyocytes. Furthermore, evidence ...

3D Reconstruction for the Diagnosis and Treatment of Pulmonary Nodules

A 3D Digital Model for the Diagnosis and Treatment of Pulmonary Nodules

The three-dimensional (3D) reconstruction of pulmonary nodules using medical images has introduced new technical approaches for diagnosing and treating pulmonary nodules, and these approaches are progressively being acknowledged and adopted by physicians and patients. Nonetheless, constructing a relatively universal 3D digital model of pulmonary nodules for diagnosis and treatment is challenging due to device differences, shooting times, and nodule types. The objective of this study is to propose a new 3D digital model of pulmonary nodules that serves as a bridge between physicians and patients and is also a cutting-edge tool for pre-diagnosis and prognostic evaluation. Many AI-driven pulmonary nodule detection and recognition methods employ deep learning techniques to capture the radiological features of pulmonary nodules, and these methods can achieve a good area under-the-curve (AUC) performance. However, false positives and false negatives remain a challenge for radiologists and clinicians. The interpretation and expression of features from the perspective of pulmonary nodule classification and examination are still unsatisfactory. In this study, a method of continuous 3D reconstruction of the whole lung in horizontal and coronal positions is proposed by combining existing medical image processing technologies. Compared with other applicable methods, this method allows users to rapidly locate pulmonary nodules and identify their fundamental properties while also observing pulmonary nodules from multiple perspectives, thereby providing a more effective clinical tool for diagnosing and treating pulmonary nodules.

Author Spotlight: A 3D Digital Model for the Diagnosis and Treatment of Pulmonary Nodules  

The objective of this study is to develop a novel 3D digital model of pulmonary nodules that serves as a communication bridge between physicians and patients and is also a cutting-edge tool for pre-diagnosis and prognostic evaluation.

The three-dimensional (3D) reconstruction of pulmonary nodules using medical images has introduced new technical approaches for diagnosing and treating ...