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).

NOTE: All procedures are in accordance with an animal protocol approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Southern California.
1. Preparation for Surgery
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	<li>Lay out the necessary surgical tools and supplies (sterilized, items 1 - 18 in Materials list) and arrange a dissecting microscope and a fiber optics trans-illuminator in a hood or on a downdraft table.</li>
	<li>Place a sexually mature mouse (20 - 30 g, 1 - 3 months o...

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The authors have nothing to disclose

When first learning this protocol, determining where to locate the initial incision can be challenging. However, practice on euthanized mice helps the surgeon learn where to place the initial incision and expose the desired rib to be resected. Working on cadavers also improves the fine-motor skills required to remove the rib portion with or without the periosteum. In addition, someone new to this procedure might find manipulating the fine tools and thin sutures to be difficult. While tying off, excess pulling on the sutu...

Debilitating skeletal injury, chronic osteoarthritis, and the severe problems associated with reconstructive surgery impact economic productivity, family well-being, and quality of life. While small breaks and lesions can heal fairly well, humans are not capable of repairing large defects and therefore must rely on reconstructive procedures&#160;to restore structure and function. Reconstruction may involve allogeneic or heterogeneic grafts, morcellized bone, implanted scaffolds, or distraction osteogenesis. Unfortunately, not only are there persistant morbidity factors associated with these treatments but the original strength of the repaired bone is rarely attained. Thus, new clinical approaches are needed.
One-way to develop innovative methods to treat segmental defects is to study situations in which large-scale repair occurs naturally. Amphibians famously can regenerate skeletal elements, while mammals are considered limited in this ability. However, since the early part of the 20th century, a few reports of regeneration in the human rib have been published suggesting that humans may not be so limited1-4 . Currently this phenomenon is best known by plastic surgeons who use rib material for jaw, face and ear reconstruction, but it is not more broadly appreciated5. In order to study this repair in more detail, we have developed a surgical model using the mouse. Using this protocol, researchers can identify the innate factors involved and use this information to facilitate skeletal healing in other locations.
There are many advantages to using the ribs as a model for studying skeletal repair. First, the surrounding ribs provide a natural fixator (as compared to resection of the femur6,7). This decreases the morbidity risk of internal and external fixators and simplifies the surgical procedure. Secondly, the thin muscular layers of the chest wall provide for easy access and excellent visibility which make the assay comparable to the convenience of calvarial resections8. Thirdly, in contrast to the calvariae which form by intramembranous ossification, the ribs form by endochondral ossification and grow in length via extension at growth plates located at either end of a central diaphysis. Therefore, repair of the ribs may be more comparable to repair of the long bones of the appendicular skeleton. Furthermore, we have found that compared to the femur, the periosteum of the rib is thicker and can be more easily manipulated. Thus, investigators who wish to assay bone repair for the purpose of studying the periosteum or testing cell therapies, pharmacological agents, and/or tissue scaffolds may find this surgical model useful. In summary, this rib resection model provides a context within which to study natural large-scale bone repair in mammals as no such model in general use currently exists.

<table border="0" cellpadding="0" cellspacing="0" width="896">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Name of Reagent/ Equipment</td>
			<td style="width:160px;">Company</td>
			<td style="width:157px;">Catalog Number</td>
			<td style="width:304px;">Comments/Description</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:275px;">Medium sized micro-dissection scissors (Vannas-T&#252;bingen Spring Scissors 5 mm)</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td>15003-08</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Fine micro-dissection scissors (Vannas Spring Scissors - 2mm Cutting Edge)</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td style="width:157px;">15000-04</td>
			<td>curved tip is beneficial</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Micro-scalpel 5.0 mm</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td>10315-12</td>
			<td>other fine scalpels can be substituted</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Dumont 55 forceps</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td style="width:157px;">11295-51</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Retractor&#160;</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td>17004-05</td>
			<td>adjustability is convenient</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Micro-needle holders</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td style="width:157px;">12060-01</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">9.0 nylon sutures (Ethilon), taper point best</td>
			<td style="width:160px;">Ethicon</td>
			<td>2819G or similar</td>
			<td>taper point best but reverse cutting is also good</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">7.0 prolene sutures (Prolene)</td>
			<td style="width:160px;">Ethicon</td>
			<td>8700H or similar</td>
			<td>6-0 can be used too, needle point can vary</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Large forceps (Adson Forceps)</td>
			<td style="width:160px;">Fine Science Tools</td>
			<td style="width:157px;">11006-12</td>
			<td>other brands are fine</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Lubricant Eye Ointment (Akwa Tears)</td>
			<td style="width:160px;">Akorn</td>
			<td style="width:157px;">17478-062-35</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:275px;">Suture glue (GLUture Topical Tissue Adhesive)</td>
			<td style="width:160px;">Abbot</td>
			<td style="width:157px;">32046-01</td>
			<td>has excellent working time</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Shaver</td>
			<td style="width:160px;">Wahl</td>
			<td>9918-6171 or similar</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Clamp lamp</td>
			<td>Zoo Med</td>
			<td style="width:157px;">LF-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Infrared Bulb, 75W</td>
			<td style="width:160px;">Zoo Med</td>
			<td>RS-75</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:275px;">RC2 Rodent Anesthesia System</td>
			<td style="width:160px;">VetEquip&#160;</td>
			<td style="width:157px;">922100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">IsoFlo (Isoflurane)</td>
			<td style="width:160px;">Abbot</td>
			<td style="width:157px;">05260-05</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Buprenorphine (Buprenex)</td>
			<td style="width:160px;">Reckitt Benckiser</td>
			<td style="width:157px;">12496-0757-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Betadine</td>
			<td style="width:160px;">Purdue Frederick</td>
			<td>67618015017</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:275px;">Flavored Gelatin, raspberry</td>
			<td style="width:160px;">Jell-O</td>
			<td>B000E1FYL0</td>
			<td>made up firm, to the consistency of &#39;jigglers&#39;</td>
		</tr>
	</tbody>
</table>

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

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation of the animal for surgery, opening the thoracic body wall, exposing the desired rib from the surrounding intercostal muscles, excising the desired section of rib without inducing a pneumothorax, and closing the incisions. Compared to the bones of the appendicular skeleton, the ribs are highly accessible. In addition, no internal or external fixator is necessary since the adjacent ribs provide a natural fixation. The surgery uses commercially available supplies, is straightforward to learn, and well-tolerated by the animal. The procedure can be carried out with or without removing the surrounding periosteum, and therefore the contribution of the periosteum to repair can be assessed. Results indicate that if the periosteum is retained, robust repair occurs in 1 - 2 months. We expect that use of this protocol will stimulate research into rib repair and that the findings will facilitate the development of new ways to stimulate bone repair in other locations around the body.

Animals typically recover quickly from this procedure, the incision heals well, and the animals exhibit normal behavior. The procedure uses commercially available supplies and after practice, can be completed in under 1 hr. Before using this procedure to generate experimental data, it is important to analyze the resection at the day 0 time point to determine if any large bone fragments might remain within the resection zone. One way to assess proper procedure is to assess the animals by X-ray or microCT imaging postopera...

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.

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

a-surgical-procedure-for-resecting-mouse-rib-model-for-large-scale

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JoVE Journal

Medicine

13.0K Views.  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.