Authors would like to thank Catherine Solioz for her skillful assistance.

1. BCM Preparation
<ol>
	<li>Obtain pig mandibles from the local butcher as fresh as possible. Place the mandibles onto a firm surface and release a full thickness flap paying special attention not to leave any soft tissue or periosteum attached to the bone. Work in a clean environment without the need to work under the flow hood.</li>
	<li>Once a full thickness flap is released, use a bone scraper to harvest the bone chips from the buccal side. Please note that the bone scraper has to be sharp. Handle firmly the bone ...

<ol>
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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+novel+biphasic+calcium+phosphate+in+standardized+bone+defects:+a+histologic+and+histomorphometric+study+in+the+mandibles+of+minipigs.">Evaluation of a novel biphasic calcium phosphate in standardized bone defects: a histologic and histomorphometric study in the mandibles of minipigs.</a> Clinical oral implants research. 18, 752-760 (2007).</li><li>Grabowski, G., Bone Cornett, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=graft+and+bone+graft+substitutes+in+spine+surgery:+current+concepts+and+controversies.">graft and bone graft substitutes in spine surgery: current concepts and controversies.</a> The Journal of the American Academy of Orthopaedic Surgeons. 21, 51-60 (2013).</li><li>Khan, S. 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D., Buser, D., Gruber, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+analysis+of+porcine+bone+conditioned+medium.">Proteomic analysis of porcine bone conditioned medium.</a> The International journal of oral &amp; maxillofacial implants. , (2014).</li><li>Peng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone-Conditioned+Medium+Inhibits+Osteogenic+and+Adipogenic+Differentiation+of+Mesenchymal+Cells+In+Vitro.">Bone-Conditioned Medium Inhibits Osteogenic and Adipogenic Differentiation of Mesenchymal Cells In Vitro.</a> Clinical implant dentistry and related research. , (2014).</li><li>Brolese, E., Buser, D., Kuchler, U., Schaller, B., Gruber, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+bone+chips+release+of+sclerostin+and+FGF-23+into+the+culture+medium:+an+in+vitro+pilot+study.">Human bone chips release of sclerostin and FGF-23 into the culture medium: an in vitro pilot study.</a> Clinical oral implants research. , (2014).</li><li>Caball&#233;-Serrano, J., Bosshardt, D. D., Gargallo-Albiol, J., Buser, D., Bone Gruber, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=conditioned+medium+enhances+osteoclastogenesis+in+murine+bone+marrow+cultures.+Clin+Oral+Impl+Res;+in.">conditioned medium enhances osteoclastogenesis in murine bone marrow cultures. Clin Oral Impl Res; in.</a> Int J Oral Maxillofac Surg. , (2015).</li><li>Zimmermann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone-conditioned+medium+changes+gene+expression+in+bone-derived+fibroblasts).">Bone-conditioned medium changes gene expression in bone-derived fibroblasts).</a> IJOMI accepted. , (2014).</li><li>Fulzele, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelopoiesis+is+regulated+by+osteocytes+through+Gsalpha-dependent+signaling.">Myelopoiesis is regulated by osteocytes through Gsalpha-dependent signaling.</a> Blood. 121, 930-939 (2013).</li><li>Becerra, J., Andrades, J. A., Ertl, D. C., Sorgente, N., Nimni, M. 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T., Weber, H. P., Belser, U. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+implant+placement+following+single-tooth+extraction+in+the+esthetic+zone:+biologic+rationale+and+surgical+procedures).">Early implant placement following single-tooth extraction in the esthetic zone: biologic rationale and surgical procedures).</a> The International journal of periodontics &amp; restorative dentistry. 28, 441-451 (2008).</li><li>Stoecklin-Wasmer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Absorbable+collagen+membranes+for+periodontal+regeneration:+a+systematic+review.">Absorbable collagen membranes for periodontal regeneration: a systematic review.</a> Journal of dental research. 92, 773-781 (2013).</li></ol>

Bone-conditioned medium reflects the released activity of bone grafts during the early stages of bone regeneration. The protocol described here can be adapted to study the response of different types of cells involved in bone regeneration. Furthermore, the protocol can be used to prepare conditioned medium from processed bone or bone fillers. The methods are easy to perform and rely on a simple concept: the factors released from various native and processed bone. Understanding how BCM affects mesenchymal cells can help t...

Autologous bone is widely used to bridge defects that occurred as a consequence of malformation, resective surgery, reconstructive trauma surgery, and prior to implant placement 1,2. Understanding the biological principles of how bone grafts support the process of graft consolidation is not only key to understand why autografts are considered to be the gold standard in reconstructive surgery, it is also bionic to the improved design of bone substitutes 3. Still, graft consolidation is faster with autologous bone compared to bone substitutes 4,5. Thus, it is imperative to reveal the molecular and cellular mechanisms that make autologous bone so effective to support bone regeneration.
There are three textbook characteristics of autografts that are considered to support the consolidation process 6,7. First, autologous bone is osteoconductive, providing guidance for the newly formed bone to grow into the defect. Secondly, autologous bone is osteogenic, meaning that it contains mesenchymal cells that can differentiate into osteoblasts 8. Third, autologous bone is osteoinductive as growth factors like bone morphogenetic proteins entombed in the matrix can initiate the process of endochondral or even intramembranous bone formation 9. There is another aspect: freshly prepared bone chips hold a paracrine function based on the in vitro observations with &#8220;bone-conditioned medium&#8221; 10-15. Also the impact of myelopoiesis should be mentioned 16. A similar term &#8220;demineralized bone matrix-conditioned medium&#8221; was already coined in 1996 and supports the overall concept of a paracrine function of bone, even when processed by demineralization 17. For our purposes, BCM can be prepared from fresh pig mandibles 10,11. Proteomic analyses of BCM revealed the complex composition, including growth factors and constituents of the extracellular matrix 10, also extending existing knowledge on the proteasome of whole bone 18,19. Thus, BCM should reflect the released activity of various modifications of bone grafts in vitro.
What happens when mesenchymal cells, for example those isolated from bone chips or from oral soft tissue, are exposed to BCM? In vitro, BCM reduces osteogenic and adipogenic differentiation, and provokes a strong increase of IL11 expression 11. Genome wide microarray revealed more genes to be differentially expressed in mesenchymal cells in response to BCM. Among these genes are adrenomedullin (ADM), IL11, IL33, NADPH oxidase 4 (NOX4), proteoglycan 4 (PRG4, or lubricin) and pentraxin 3 (PTX3) 15. BCM obtained from autoclaved bone chips failed to change the expression of the respective genes 14. BCM from bone chips that underwent pasteurization and freezing was able to change gene expression 14. Also conditioned medium of demineralized bone matrix (DBM-CM) changes the expression of TGF-&#946;-regulated genes 20. Interestingly, collagen barrier membranes used to shield the bone chips from the surrounding soft tissue 21,22, adsorbed those parts of BCM that are responsible for the changes in gene expression 23. BCM research can be extended to other cell types involved in bone regeneration such as bone-resorbing osteoclasts and endothelial cells, to name a few. Overall, the accumulating in vitro data provide the scientific basis for the design of a preclinical study.
The present protocol is two-fold: First, it shows how to prepare BCM. Secondly, it shows how to test its biological activity based on mesenchymal cells in vitro.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Pig Mandibles</td>
			<td>Local bucher</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bone Scraper</td>
			<td>Hu-Friedy</td>
			<td>PPBUSE2/36</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotics &#38; Antimicotics</td>
			<td>All life Technologies</td>
			<td>15240-062</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen Membranes (Bio-Gide)</td>
			<td>Geistlich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Calf Serum</td>
			<td>Invitrogen Corporation</td>
			<td align="right">16030074</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Invitrogen Corporation</td>
			<td>21885-025</td>
			<td></td>
		</tr>
		<tr>
			<td> 
			High Pure RNA Isolation Kit</td>
			<td>Roche</td>
			<td align="right">11828665001</td>
			<td></td>
		</tr>
		<tr>
			<td>Transcriptor First Strand cDNA Synthesis Kit</td>
			<td>Roche</td>
			<td align="right">4379012001</td>
			<td></td>
		</tr>
		<tr>
			<td>Primers</td>
			<td>Microsynth</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SYBR Green (for Q-RT-PCR)</td>
			<td>Roche</td>
			<td align="right">4673484001</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Roche</td>
			<td align="right">11666789001</td>
			<td></td>
		</tr>
	</tbody>
</table>

bone conditioned medium: preparation and bioassay

Autologous bone grafts are widely used in oral and maxillofacial surgery, orthopedics, and traumatology. Autologous bone grafts not only replace missing bone, they also support the complex process of bone regeneration. This favorable behavior of autografts is attributed to the three characteristics: osteoconductivity, osteogenicity, and osteoinductivity. However, there is another aspect: Bone grafts release a myriad of molecules, including growth factors, which can target mesenchymal cells involved in bone regeneration. The paracrine properties of bone grafts can be studied in vitro by the use of bone-conditioned medium (BCM). Here we present a protocol on how to prepare bone-conditioned medium from native pig cortical bone, and bone that underwent thermal processing or demineralization. Cells can be directly exposed to BCM or seeded onto biomaterials, such as collagen membranes, previously soaked with BCM. We give examples for in vitro bioassays with mesenchymal cells on the expression of TGF-&#946; regulated genes. The presented protocols should encourage to further reveal the paracrine effects of bone grafts during bone regeneration and open a path for translational research in the broad field of reconstructive surgery.

Bone Conditioned Medium is prepared from fresh porcine bone chips. General overview of the process to prepare BCM and to use biomaterials in combination with BCM is shown in Figure 1 and Figure 2 respectively. During the BCM preparation, it is important to obtain large bone chips with long movements as short movements or very small bone chips can affect the quality of the final BCM. Quality of BCM can be controlled by analyzing the gene expression of BCM target genes: ADM, PTX3, IL11, IL...

Watch this Scientific Journal Video about Bone Conditioned Medium: Preparation and Bioassay at JoVE.com

Bone Conditioned Medium: Preparation and Bioassay

We describe here how to prepare bone-conditioned medium (BCM) and test its activity in vitro.

Autologous bone grafts are widely used in oral and maxillofacial surgery, orthopedics, and traumatology. Autologous bone grafts not only replace missing ...

bone-conditioned-medium-preparation-and-bioassay

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10.9K Views.  School of Dental Medicine, University of Bern. We describe here how to prepare bone-conditioned medium (BCM) and test its activity in vitro.