This work was supported by the Swiss National Foundation Grant CR3I3_140717/1 and the Swiss Paraplegic Foundation.

NOTE: Human bone marrow aspirates from the iliac crest were collected from consenting donors with the approval of the ethics committee of the canton of Lucerne. Canine bone marrow aspirates from the iliac crest were collected with dog owner&#8217;s consent.Human (approx. 20 ml) and canine (approx. 10 ml) bone marrow aspirates were anti-coagulated by addition of 15 ml of 3.8% sodium citrate immediately after withdrawal in the operation theatre. The samples were transferred to the laboratory environment for processing the same day as withdrawn.
1. Preparation of Urokinase (Prior to 1st Use)
<ol>
	<li>Reconstitute urokinase using sterile phosphate buffered saline (PBS) according to the manufacturer&#8217;s instructions: Add 10 ml PBS to the septum-inlet flask using a 10 ml syringe. Dissolve the dry substance by swirling to obtain 50,000 injection units (U) per ml.</li>
	<li>Prepare 500 &#181;l aliquots (25,000 U each) into sterile tubes. Store aliquots -20 &#176;C and use it when required for at least 6 months.</li>
</ol>
2. Preparative Steps (Prior to Every Bone Marrow Treatment)
<ol>
	<li>Thaw one aliquot of urokinase (25,000 U) per clotted bone marrow aspirate (aspirate volumes up to 25 ml have been successfully treated using a single aliquot of 25,000 U).</li>
	<li>Preheat a water bath or shaking incubator to 37 &#176;C.</li>
</ol>
3. Enzymatic Digest of the Clot
<ol>
	<li>Perform all work in a laminar flow biosafety cabinet to avoid microbial contamination of the bone marrow samples during processing. When working with potentially infectious human material, the use of protective gloves as well as careful handling is advised.</li>
	<li>Place a 100 &#181;m cell strainer on top of a sterile 50 ml tube. Carefully pour the bone marrow aspirate through the cell strainer, tilting the strainer or moving around the clot material. Use a sterile pipet tip for better flow through the filter mesh. 
	NOTE: Avoid any dilution of the clot, e.g., by washing the clot with PBS. Urokinase acts indirectly and requires components of the serum (i.e., plasminogen) from the biopsy for effective digest. While continuing the procedure with the clot material, the filtrate can be kept at RT until further use in step 3.6.</li>
	<li>Transfer the bone marrow clot material into an empty cell culture dish using sterile forceps. Cut the debris into small pieces of approximately 2 mm3 using a sterile scalpel.</li>
	<li>Transfer the small pieces of the clot into a 50 ml reaction tube using the sterile forceps. Ensure that the minced clot has a wet appearance. If it appears to be dry, use some of the filtrate from step 3.1 to moisten.</li>
	<li>Triturate the clot by pipetting up and down for 5 times using a 5 ml microtiter pipet. Add 1 aliquot of urokinase to the sample. Incubate for 30 min at 37 &#176;C either in a water bath or in a shaking (gently) incubator.</li>
	<li>Triturate by pipetting up and down for 5 times using a 5 ml pipet. Perform this step in a biosafety cabinet. Incubate for another 30 min at 37 &#176;C. After the incubation, triturate again 5 times using a 5 ml pipet. Pass over a fresh 100 &#181;m cell strainer to pool with the filtrate from step 3.2.</li>
	<li>Centrifuge the cell suspension at ambient temperature for 10 min at 500 x g. Discard the supernatant. Re-suspend the cell pellet in media as described below or according to the standard procedure of your laboratory for MSC expansion culture.</li>
</ol>
4. Seeding for Expansion Cell Culture and CFU Plates
<ol>
	<li>Resuspend the cells (consisting of erythrocytes and mononuclear cells) in 50 ml of basal medium: Alpha-MEM supplemented with 10% fetal bovine serum (FBS), 100 U/ml penicillin, 100 mg/ml streptomycin and 2.5 mg/ml amphotericin B. Count the cells diluted 1:10 in Trypan Blue solution using a Neubauer chamber.</li>
	<li>Plate the cells in cell culture flasks at the density of 5 x 107 cells/cm2 and incubate in a humidified incubator at 37 &#176;C. If available, use hypoxic (5% oxygen) conditions. For the CFU assay control, plate 109 cells in a cell culture dish of 10 cm diameter.</li>
	<li>After 3 days of culture, mesenchymal stem cells are attached to the cell culture dish while other cells remain in suspension. Change the media with basal medium supplemented with 5 ng/ml basic fibroblast growth factor (bFGF). For the CFU assay control, treat the cell culture dish likewise.</li>
	<li>Continue cell culture for a total of 2 weeks, exchanging media three times a week. If cells exceed 80% confluency, split by trypsinization. For the CFU assay control, exchange the media likewise, but do not split the cells for the course of the two weeks.</li>
</ol>
5. Giemsa Stain for CFU Assay
<ol>
	<li>Prepare 10 ml of Giemsa-solution per dish: dilute the stock solution (7.6 g/l Giemsa in glycerol:methanol) 1:10 in sterile water (always prepare a fresh working dilution).</li>
	<li>Remove the media from the cell culture dish and wash the cells with PBS. Be very precautious when applying liquid to the petri dish and avoid washing off the cells.</li>
	<li>Fix cells in pure Methanol for 5 min at RT. Discard the Methanol. Add the Giemsa-solution and incubate for 60 min in a humidified incubator at 37 &#176;C.</li>
	<li>Wash two times with PBS. Air dry the plate head first on a paper towel. Count the colonies manually. This is best achieved using a marker pen on the back of the plate.</li>
</ol>
6. MSC Differentiation
<ol>
	<li>Canine MSCs differentiation 
	NOTE: Canine MSCs were differentiated into chondrogenic, osteogenic and adipogenic lineages by stimulation with the appropriate media for four weeks.</li>
	<li>For Adipogenic differentiation, culture MSCs in monolayer at 4 x 105 cells/cm2 alternating two different culture conditions as follows;
	<ol>
		<li>Culture in adipogenesis maintenance media containing DMEM + GlutaMAX, 3% FBS, 100 units/ml penicillin, 100 mg/ml streptomycin, 2.5 &#181;g/ml amphotericin B and 170 mM insulin.</li>
		<li>Culture in adipogenesis inducing media with maintenance medium supplemented with 3% FBS, 5% rabbit serum, 1 &#181;M dexamethasone, 500 &#181;M 3-Isobutyl-1-methylxanthine, 33 &#181;M biotin, 5 &#181;M rosiglitazone and 17 &#181;M pantothenate 16.</li>
		<li>Revel the lipid droplets by staining with Oil Red-O. Briefly, fix cells with 10% formaldehyde, wash with PBS and stain with 0.35% Oil red O in isopropanol.</li>
	</ol>
	</li>
	<li>For Osteogenic differentiation culture MSCs in monolayer at 7 x 103 cells/cm2 and stimulate in the following:
	<ol>
		<li>Advanced DMEM (GIBCO) + GlutaMAX, 5 % FBS, 100 units/ml penicillin, 100 mg/ml streptomycin, 2.5 &#181;g/ml amphotericin B, 50 &#181;M L-ascorbic acid 2-phosphate, 10 mM &#223;-glycerophosphate and 100 nM dexamethasone.</li>
		<li>Identify the mineralization deposits by Von Kossa stain (5 % AgNO3). Briefly, fix the cells with 10% formaldehyde, wash with PBS and stain with 5 % AgNO3in distilled water.</li>
	</ol>
	</li>
	<li>Chondrogenic differentiation
	<ol>
		<li>Cut cubes (3 mm per side) from a sponge shaped medical device, constituted from lyophilized collagen type I, and used as scaffold material to support cells 17.</li>
		<li>Seed MSCs on the top of the cubes at the concentration of 4 x 106 cells/ml (~70,000 cells/cube).</li>
		<li>Prior to the addition of media, allow the cells to adhere to the cubes for 30 min.</li>
		<li>Maintain MSC-collagen constructs in chondrogenic media consisting of DMEM/F12 + GlutaMAX, 2.5 % FBS, 100 units/ml penicillin, 100 mg/ml streptomycin, 2.5 &#181;g/ml amphotericin B, 40 ng/ml dexamethasone, 50 &#181;g/ml ascorbic acid 2-phosphate, 50 &#181;g/ml L-proline, 1x Insulin-Transferrin-Selenium X, and 10 ng/ml transforming growth factor-&#946;1.</li>
		<li>Use alcian blue staining to visualize accumulation of proteoglycans in constructs sections. Briefly, stain the sections O/N with 0.4% alcian blue dissolved in 0.01% H2SO4 and 0.5M guanidine hydrochloride. Next, wash the sections were washed for 30 min in 40% DMSO and 0.05M MgCl2. Cells were counterstained with nuclear fast red.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

Routinely we sample bone marrow while the patient is undergoing surgery (in our case mainly spine surgery), with the advantage that only little additional work has to be carried out by the personnel in the operation theatre. Even though the samples are mixed with sodium citrate immediately after withdrawal, many samples were partially clotted when they arrived in the laboratory for processing. At this stage, resampling to replace clotted specimens would be a separate additional intervention necessitating again local or g...

Mesenchymal stem cells (MSCs) play a major role in regenerative medicine and tissue engineering. They can migrate, differentiate into various cell types 1 and engraft, which renders them the ideal candidates for autologous therapies 2,3. Lately, clinical trials using MSCs for bone and cartilage repair, graft versus host disease or heart disease were launched 4. These MSCs can be harvested from the umbilical cord or adipose tissue but most promising results were obtained from bone marrow derived stem cells 5.
The iliac crest allows to collect a considerable amount of bone marrow and therefore serves as main site of aspiration 6. However, the quality of the aspirate decreases with increasing volume of bone marrow withdrawn. While the first 5 ml of bone marrow aspirate contain MSCs of high quality, withdrawal of larger volumes leads to dilution of the aspirate with peripheral blood from the highly vascularized bone 7. Because of the present megakaryocytes and platelets, bone marrow aspirates are prone to clotting, unless anticoagulants are used. But even with anticoagulants, clots may occur.
In bone marrow, MSCs represent only a small proportion of the total cell pool 8 and have to be expanded in culture for most tissue engineering or therapeutic applications 4. The quality of such a culture largely depends on the initial cell pool, i.e., diversity and a high starting number 9. Low numbers of MSCs from withdrawals may be partly explained by donor variability. On the other hand, MSCs from low quality samples require longer time in culture and extended passaging to reach the desired number of cells. In either case, extended passaging is a source of cell senescence and can lead to the loss of differentiation potential 10. Therefore, optimized protocols that can maximize cell yield and prevent from detrimental effects have to be developed 11,12.
When we began to work with canine MSCs, we were astonished to see that about three in four canine bone marrow samples contained clots, while fortunately clotted human samples (one in ten) were less frequent. On the other hand it was no surprise, that we observed much lower yields of MSCs from clotted samples. To solve the recurring issue of clotted samples, we developed the protocol using the thrombolytic drug urokinase instead of resampling.
Thrombolytic therapies can counteract life threatening situations such as occlusion of blood vessels causing heart attack, stroke or embolisms because of unwanted clotting. They work by degradation of the clots through enzymatic cleavage of fibrin by plasmin and enzymatic plasminogen activators. Despite the wide use for treatment of patients, only very few publications exist that utilized thrombolytic activities for laboratory applications to rescue clotted samples, mostly focusing on lymphocytes. In 1987, Niku et al. described the use of streptokinase for dissolving blood clots resulting in functional lymphocytes 13 and four years later, De Vis et al. extended the use of streptokinase to isolate leukemia cells from blood and bone marrow for flow cytometric applications 14. A more recent publication suggests the use of Alteplase for cancer diagnostics 15. While using the same enzymatic approach, our protocol focuses on the isolation of multipotent MSCs form bone marrow to provide a tool for researchers in the stem cell field.

<table border="0" cellpadding="0" cellspacing="0" width="674">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Basal Medium Components</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">PenStrep 100X</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:119px;">15140122</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Human FGF-basic</td>
			<td style="width:227px;">Peprotech</td>
			<td style="width:119px;">100-18B</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">MEM Alpha w/ Nucleoside, w/ stable Glutamine</td>
			<td style="width:227px;">Amimed</td>
			<td style="width:119px;">1-23S50-I</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:328px;">FBS Heat Inactivated</td>
			<td style="width:227px;">Amimed</td>
			<td style="width:119px;">2-01F36-I</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Amphotericin B</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A1907</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Adipogenic Medium Components</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">DMEM-HAM F12 + GlutaMAX</td>
			<td style="width:227px;">Amimed</td>
			<td style="width:119px;">1-26F09-I</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Insulin&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">I5500</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Rabbit serum&#160;</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:119px;">16120099</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Dexamethasone</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">D4902</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">3-Isobutyl-1-methylxanthine</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">I5879</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Biotin&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">B4639</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Rosiglitazone&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">R2408</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Pantothenate&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">P5155</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Oil Red-O&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">O0625</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Osteogenic Medium Components</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">L-ascorbic acid 2-phosphate</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">A8960</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">&#223;-glycerophosphate</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">G9422</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:328px;">Silver nitrate (AgNO3)</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">S6506</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Chondrogenic Medium Components</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Biopad - sponge shaped medical device&#160;</td>
			<td style="width:227px;">Euroresearch</td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">L-proline&#160;</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">P5607</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Insulin-Transferrin-Selenium X</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:119px;">51500056</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Human transforming growth factor-&#946;1&#160;</td>
			<td style="width:227px;">Peprotech</td>
			<td style="width:119px;">100-21</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Alcian Blue 8GX</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">A3157</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Nuclear fast red</td>
			<td style="width:227px;">Sigma</td>
			<td style="width:119px;">N8002</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Generic</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Tri-Sodium citrate dihydrate</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A3901</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">PBS</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">964.9100</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Urokinase</td>
			<td style="width:227px;">Medac</td>
			<td style="width:119px;">1976826</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">0.5% Trypsin-EDTA</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:119px;">15400054</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Giemsa stain</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A0885</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Formaldehyde</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A0877</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sulfuric acid (H2SO4)</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A0655</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dimethyl sulfoxide (DMSO)</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A1584</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Magnesium chloride (MgCl2)</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A3618</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Guanidine hydrochloride</td>
			<td style="width:227px;">Applichem</td>
			<td style="width:119px;">A1499</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Consumables</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">50 mL reaction tube</td>
			<td style="width:227px;">Axygen</td>
			<td style="width:119px;">SCT-50ML-25-S</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">10 mL syringe</td>
			<td style="width:227px;">Braun</td>
			<td style="width:119px;">4606108V</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Sterican needle (22G)</td>
			<td style="width:227px;">Braun</td>
			<td style="width:119px;">4657624</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">1.7 mL Microtubes</td>
			<td style="width:227px;">Brunschwig</td>
			<td style="width:119px;">MCT-175-C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">100 &#956;m cell strainer</td>
			<td style="width:227px;">Falcon</td>
			<td style="width:119px;">6.05935</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">sterile forceps</td>
			<td style="width:227px;">Bastos Viegas, SA</td>
			<td style="width:119px;">489-001</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">sterile scalpel</td>
			<td style="width:227px;">Braun</td>
			<td style="width:119px;">5518059</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Primaria cell cuture dish</td>
			<td style="width:227px;">Falcon</td>
			<td style="width:119px;">353803</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">C-Chip Neubauer Improved</td>
			<td style="width:227px;">Bioswisstech</td>
			<td style="width:119px;">505050</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">cell culture flask - Flask T300</td>
			<td style="width:227px;">TPP</td>
			<td style="width:119px;">90301</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;"></td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Equipment</td>
			<td style="width:227px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Microbiological biosafety cabinet class II</td>
			<td style="width:227px;">Skan</td>
			<td style="width:119px;">82011500</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">water bath</td>
			<td style="width:227px;">Memmert</td>
			<td style="width:119px;">1305.0377</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Stripettes Serological Pipette 5ml</td>
			<td style="width:227px;">Corning</td>
			<td>4487-200ea</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">microscope</td>
			<td style="width:227px;">Olympus</td>
			<td style="width:119px;">CKX41</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">humidified incubator Heracells 240</td>
			<td style="width:227px;">Thermo scientific</td>
			<td>51026331</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:328px;">Heraeus Multifuge 1S-R</td>
			<td style="width:227px;">Thermo scientific</td>
			<td style="width:119px;">75004331</td>
		</tr>
	</tbody>
</table>

an enzymatic method to rescue mesenchymal stem cells from clotted bone marrow samples

Mesenchymal stem cells (MSCs) - usually obtained from bone marrow - often require expansion culture. Our protocol uses clinical grade urokinase to degrade clots in the bone marrow and release MSCs for further use. This protocol provides a rapid and inexpensive alternative to bone marrow resampling. Bone marrow is a major source of MSCs, which are interesting for tissue engineering and autologous stem cell therapies. Upon withdrawal bone marrow may clot, as it comprises all of the hematopoietic system. The resulting clots contain also MSCs that are lost for expansion culture or direct stem cell therapy. We experienced that 74% of canine bone marrow samples contained clots and yielded less than half of the stem cell number expected from unclotted samples. Thus, we developed a protocol for enzymatic digestion of those clots to avoid labor-intense and costly bone marrow resampling. Urokinase - a clinically approved and readily available thrombolytic drug &#8211; clears away the bone marrow clots almost completely. As a consequence, treated bone marrow aspirates yield similar numbers of MSCs as unclotted samples. Also, after urokinase treatment the cells kept their metabolic activity and the ability to differentiate into chondrogenic, osteogenic and adipogenic lineages. Our protocol salvages clotted blood and bone marrow samples without affecting the quality of the cells. This obsoletes resampling, considerably reduces sampling costs and enables the use of clotted samples for research or therapy.

The facts that 74% of canine bone marrow samples (n=54) contained clots when they arrived in our laboratory (Figure 1A) along with decreased MSC yields from these samples, made us believe that a considerable number of MSCs was trapped within the clots. Indeed, a simple DAPI-stain of sectioned clot material confirms the presence of nucleated cells in high density (Figure 1B). This ultimately leads to low numbers of MSCs available for expansion culture, which triggered us to develop the pr...

Watch this Scientific Journal Video about An Enzymatic Method to Rescue Mesenchymal Stem Cells from Clotted Bone Marrow Samples at JoVE.com

An Enzymatic Method to Rescue Mesenchymal Stem Cells from Clotted Bone Marrow Samples

Mesenchymal stem cells are usually obtained from bone marrow and require expansion culture. When samples clot before processing, a protocol using the (enzymatic) thrombolytic drug urokinase can be applied to degrade the clot. Thus, cells are released and available for expansion culture. This protocol provides a rapid and inexpensive alternative to resampling.

Mesenchymal stem cells (MSCs) - usually obtained from bone marrow - often require expansion culture. Our protocol uses clinical grade urokinase to degrade ...

an-enzymatic-method-to-rescue-mesenchymal-stem-cells-from-clotted

Research

JoVE Journal

Developmental Biology

9.1K Aufrufe.  Swiss Paraplegic Research. Mesenchymal stem cells are usually obtained from bone marrow and require expansion culture. When samples clot before processing, a protocol using the (enzymatic) thrombolytic drug urokinase can be applied to degrade the clot. Thus, cells are released and available for expansion culture. This protocol provides a rapid and inexpensive alternative to resampling.

Serie: An Enzymatic Method to Rescue Mesenchymal Stem Cells from Clotted Bone Marrow Samples

Isolation of Human Mesenchymal Stem Cells and their Cultivation on the Porous Bone Matrix

Mesenchymal stem cells (MSCs) have a differentiation potential towards osteoblastic lineage when they are stimulated with soluble factors or specific biomaterials. This work presents a novel option for the delivery of MSCs from human amniotic membrane (AM-hMSCs) that employs bovine bone matrix Nukbone (NKB) as a scaffold. Thus, the application of MSCs in repair and tissue regeneration processes depends principally on the efficient implementation of the techniques for placing these cells in a host tissue. For this reason, the design of biomaterials and cellular scaffolds has gained importance in recent years because the topographical characteristics of the selected scaffold must ensure adhesion, proliferation and differentiation into the desired cell lineage in the microenvironment of the injured tissue. This option for the delivery of MSCs from human amniotic membrane (AM-hMSCs) employs bovine bone matrix as a cellular scaffold and is an efficient culture technique because the cells respond to the topographic characteristics of the bovine bone matrix Nukbone (NKB), i.e., spreading on the surface, macroporous covering and colonizing the depth of the biomaterial, after the cell isolation process. We present the procedure for isolating and culturing MSCs on a bovine matrix.

Mesenchymal stem cells (MSCs) have a differentiation potential towards osteoblastic lineage when they are stimulated with soluble factors or specific biomaterials. This work presents a novel option for the delivery of MSCs from human amniotic membrane (AM-hMSCs) that employs the bovine bone matrix Nukbone (NKB) as a scaffold.

Mesenchymal stem cells (MSCs) have a differentiation potential towards osteoblastic lineage when they are stimulated with soluble factors or specific ...

Epigenetic Conversion as a Safe and Simple Method to Obtain Insulin-secreting Cells from Adult Skin Fibroblasts

Regenerative medicine requires new, fully functional cells that are delivered to patients in order to repair degenerated or damaged tissues. When such cells are not readily available, they can be obtained using different approaches that include, among the many, reprogramming and trans-differentiation, with advantages and limitations that are specific of the different techniques. Here a new strategy for the conversion of an adult mature fibroblast into an insulin-secreting cell, arbitrarily designated as epigenetic converted cells (EpiCC), is described. The method has been developed, based on the increasing understanding of the mechanisms controlling epigenetic regulation of cell fate and differentiation. In particular, the first step uses an epigenetic modifier, namely 5-aza-cytidine, to drive adult cells into a "highly permissive" state. It then takes advantage of this brief and reversible window of epigenetic plasticity, to re-address cells toward a different lineage. The approach is designated "epigenetic cell conversion". It is a simple and robust way to obtain an efficient, controlled and stable cellular inter-lineage switch. Since the protocol does not involve the use of any gene transfection, it is free of viral vectors and does not involve a stable pluripotent state, it is highly promising for translational medicine applications.

Here, a new method that allows the conversion of adult skin fibroblasts into insulin-secreting cells is presented. This technique is based on epigenetic conversion, does not involve the use of retroviral vectors nor the acquisition of a stable pluripotent state. It is therefore highly promising for translational medicine applications.

Regenerative medicine requires new, fully functional cells that are delivered to patients in order to repair degenerated or damaged tissues. When such ...

Isolation and Expansion of Mesenchymal Stem/Stromal Cells Derived from Human Placenta Tissue

Mesenchymal stem/stromal cells (MSC) are promising candidates for use in cell-based therapies. In most cases, therapeutic response appears to be cell-dose dependent. Human term placenta is rich in MSC and is a physically large tissue that is generally discarded following birth. Placenta is an ideal starting material for the large-scale manufacture of multiple cell doses of allogeneic MSC. The placenta is a fetomaternal organ from which either fetal or maternal tissue can be isolated. This article describes the placental anatomy and procedure to dissect apart the decidua (maternal), chorionic villi (fetal), and chorionic plate (fetal) tissue. The protocol then outlines how to isolate MSC from each dissected tissue region, and provides representative analysis of expanded MSC derived from the respective tissue types. These methods are intended for pre-clinical MSC isolation, but have also been adapted for clinical manufacture of placental MSC for human therapeutic use.

Herein we describe methods for the dissection of fetal and maternal tissues from human term placenta, followed by isolation and expansion of mesenchymal stem/stromal cells (MSC) from these tissues.

Mesenchymal stem/stromal cells (MSC) are promising candidates for use in cell-based therapies. In most cases, therapeutic response appears to be cell-dose ...

Isolating Mesangiogenic Progenitor Cells (MPCs) from Human Bone Marrow

In a research study aimed to isolate human bone marrow (hBM)-derived Mesenchymal Stromal Cells (MSCs) for clinical applications, we identified a novel cell population specifically selected for growth in human serum supplemented medium. These cells are characterized by morphological, phenotypic, and molecular features distinct from MSCs and we named them Mesodermal Progenitor Cells (MPCs). MPCs are round, with a thick highly refringent core region; they show strong, trypsin resistant adherence to plastic. Failure to expand MPCs directly revealed that they are slow in cycling. This is as also suggested by Ki-67 negativity. On the other hand, culturing MPCs in standard medium designed for MSC expansion, gave rise to a population of exponentially growing MSC-like cells. Besides showing mesenchymal differentiation capacity MPCs retained angiogenic potential, confirming their multiple lineage progenitor nature. Here we describe an optimized highly reproducible protocol to isolate and characterize hBM-MPCs by flow cytometry (CD73, CD90, CD31, and CD45), nestin expression, and F-actin organization. Protocols for mesengenic and angiogenic differentiation of MPCs are also provided. Here we also suggest a more appropriate nomenclature for these cells, which has been re-named as "Mesangiogenic Progenitor Cells".

Isolating Mesangiogenic Progenitor Cells MPCs from Human Bone Marrow

Here we describe an optimized, highly reproducible protocol to isolate Mesodermal Progenitor Cells (MPCs) from human bone marrow (hBM). MPCs were characterized by flow cytometry and nestin expression. They showed the ability to give rise to exponentially growing MSC-like cell cultures while retaining their angiogenic potential.

In a research study aimed to isolate human bone marrow (hBM)-derived Mesenchymal Stromal Cells (MSCs) for clinical applications, we identified a novel ...

Temporal Ordering of Dynamic Expression Data from Detailed Spatial Expression Maps

During somitogenesis, pairs of epithelial somites form in a progressive manner, budding off from the anterior end of the pre-somitic mesoderm (PSM) with a strict species-specific periodicity. The periodicity of the process is regulated by a molecular oscillator, known as the "segmentation clock," acting in the PSM cells. This clock drives the oscillatory patterns of gene expression across the PSM in a posterior-anterior direction. These so-called clock genes are key components of three signaling pathways: Wnt, Notch, and fibroblast growth factor (FGF). In addition, Notch signaling is essential for synchronizing intracellular oscillations in neighboring cells. We recently gained insight into how this may be mechanistically regulated. Upon ligand activation, the Notch receptor is cleaved, releasing the intracellular domain (NICD), which moves to the nucleus and regulates gene expression. NICD is highly labile, and its phosphorylation-dependent turnover acts to restrict Notch signaling. The profile of NICD production (and degradation) in the PSM is known to be oscillatory and to resemble that of a clock gene. We recently reported that both the Notch receptor and the Delta ligand, which mediate intercellular coupling, themselves exhibit dynamic expression at both the mRNA and protein levels. In this article, we describe the sensitive detection methods and detailed image analysis tools that we used, in combination with the computational modeling that we designed, to extract and overlay expression data from distinct points in the expression cycle. This allowed us to construct a spatio-temporal picture of the dynamic expression profile for the receptor, the ligand, and the Notch target clock genes throughout an oscillation cycle. Here, we describe the protocols used to generate and culture the PSM explants, as well as the procedure to stain for the mRNA or protein. We also explain how the confocal images were subsequently analyzed and temporally ordered computationally to generate ordered sequences of clock expression snapshots, hereafter defined as "kymographs," for the visualization of the spatiotemporal expression of Delta-like1 (Dll1) and Notch1 throughout the PSM.

The segmentation clock drives oscillatory gene expression across the pre-somitic mesoderm (PSM). Dynamic Notch activity is key to this process. We use imaging and computational analyses to extract temporal dynamics from spatial expression data to demonstrate that Delta ligand and Notch receptor expression oscillate in the vertebrate PSM.

During somitogenesis, pairs of epithelial somites form in a progressive manner, budding off from the anterior end of the pre-somitic mesoderm (PSM) with a ...

Isolation and Characterization of Mesenchymal Stromal Cells from Human Umbilical Cord and Fetal Placenta

The human umbilical cord (UC) and placenta are non-invasive, primitive and abundant sources of mesenchymal stromal cells (MSCs) that have increasingly gained attention because they do not pose any ethical or moral concerns. Current methods to isolate MSCs from UC yield low amounts of cells with variable proliferation potentials. Since UC is an anatomically-complex organ, differences in MSC properties may be due to the differences in the anatomical regions of their isolation. In this study, we first dissected the cord/placenta samples into three discrete anatomical regions: UC, cord-placenta junction (CPJ), and fetal placenta (FP). Second, two distinct zones, cord lining (CL) and Wharton&#39;s jelly (WJ), were separated. The explant culture technique was then used to isolate cells from the four sources. The time required for the primary culture of cells from the explants varied depending on the source of the tissue. Outgrowth of the cells occurred within 3 - 4 days of the CPJ explants, whereas growth was observed after 7 - 10 days and 11 - 14 days from CL/WJ and FP explants, respectively. The isolated cells were adherent to plastic and displayed fibroblastoid morphology and surface markers, such as CD29, CD44, CD73, CD90, and CD105, similarly to bone marrow (BM)-derived MSCs. However, the colony-forming efficiency of the cells varied, with CPJ-MSCs and WJ-MSCs showing higher efficiency than BM-MSCs. MSCs from all four sources differentiated into adipogenic, chondrogenic, and osteogenic lineages, indicating that they were multipotent. CPJ-MSCs differentiated more efficiently in comparison to other MSC sources. These results suggest that the CPJ is the most potent anatomical region and yields a higher number of cells, with greater proliferation and self-renewal capacities in vitro. In conclusion, the comparative analysis of the MSCs from the four sources indicated that CPJ is a more promising source of MSCs for cell therapy, regenerative medicine, and tissue engineering.

Here, we present a protocol for the dissection of human umbilical cord (UC) and fetal placenta sample into cord lining (CL), Wharton&#39;s jelly (WJ), cord-placenta junction (CPJ), and fetal placenta (FP) for the isolation and characterization of mesenchymal stromal cells (MSCs) using the explant culture technique.

The human umbilical cord (UC) and placenta are non-invasive, primitive and abundant sources of mesenchymal stromal cells (MSCs) that have increasingly ...

Preparation of Plasma Membrane Vesicles from Bone Marrow Mesenchymal Stem Cells for Potential Cytoplasm Replacement Therapy

We have previously reported on the generation of plasma membrane vesicles (PMVs) through the mechanical extrusion of mammalian cells. The fusion of PMVs with mitochondrial deficient Rho0 cells restored mitotic activity under normal culture conditions. Atherosclerosis, type 2 diabetes, Alzheimer&#39;s disease, and cancer are age-related diseases that have been reported to be associated with multiple mechanical and functional defects in the cytosol and organelles of a variety of cell types. Bone marrow mesenchymal stem cells (BMSCs) represent a unique cell population from the bone marrow that possess self-renewal capabilities while maintaining their multipotency. The supplementation of senescence cells with young cytoplasm from autologous BMSCs via the fusion of PMVs provides a promising approach to ameliorate or even reverse age-associated phenotypes. This protocol describes how to prepare PMVs from BMSCs via extrusion through a polycarbonate membrane with 3 &#181;m pores, determine the existence of mitochondria and examine the maintenance of membrane potential within PMVs using a confocal microscope, concentrate PMVs by centrifugation, and carry out the in vivo injection of PMVs into the gastrocnemius muscle of mice.

Age-related diseases are associated with multiple defects in components of the cytoplasm. Here, we present a protocol to prepare plasma membrane vesicles from bone marrow mesenchymal stem cells. This technique could potentially be used as a means of cytoplasm replacement therapy to ameliorate or even reverse age-associated phenotypes.

We have previously reported on the generation of plasma membrane vesicles (PMVs) through the mechanical extrusion of mammalian cells. The fusion of PMVs ...

Bioengineering of Humanized Bone Marrow Microenvironments in Mouse and Their Visualization by Live Imaging

Human hematopoietic stem cells (HSCs) reside in the bone marrow (BM) niche, an intricate, multifactorial network of components producing cytokines, growth factors, and extracellular matrix. The ability of HSCs to remain quiescent, self-renew or differentiate, and acquire mutations and become malignant depends upon the complex interactions they establish with different stromal components. To observe the crosstalk between human HSCs and the human BM niche in physiological and pathological conditions, we designed a protocol to ectopically model and image a humanized BM niche in immunodeficient mice. We show that the use of different cellular components allows for the formation of humanized structures and the opportunity to sustain long-term human hematopoietic engraftment. Using two-photon microscopy, we can live-image these structures in situ at the single-cell resolution, providing a powerful new tool for the functional characterization of the human BM microenvironment and its role in regulating normal and malignant hematopoiesis.

A method to create and live-image different humanized bone-marrow niches in mice is presented. Based on the supportive niche created by human mesenchymal cells, the addition of human endothelial cells induces the formation of human vessels, while the addition of rhBMP-2 induces the formation of human-mouse chimeric mature bone tissue.

Human hematopoietic stem cells (HSCs) reside in the bone marrow (BM) niche, an intricate, multifactorial network of components producing cytokines, growth ...

Isolation, Culture, and Differentiation of Bone Marrow Stromal Cells and Osteoclast Progenitors from Mice

Bone marrow stromal cells (BMSCs) constitute a cell population routinely used as a representation of mesenchymal stem cells in vitro. They reside within the bone marrow cavity alongside hematopoietic stem cells (HSCs), which can give rise to red blood cells, immune progenitors, and osteoclasts. Thus, extractions of cell populations from the bone marrow results in a very heterogeneous mix of various cell populations, which can present challenges in experimental design and confound data interpretation. Several isolation and culture techniques have been developed in laboratories in order to obtain more or less homogeneous populations of BMSCs and HSCs invitro. Here, we present two methods for isolation of BMSCs and HSCs from mouse long bones: one method that yields a mixed population of BMSCs and HSCs and one method that attempts to separate the two cell populations based on adherence. Both methods provide cells suitable for osteogenic and adipogenic differentiation experiments as well as functional assays.

In this article, we present methods to isolate and differentiate bone marrow stromal cells and hematopoietic stem cells from mouse long bones. Two different protocols are presented yielding different cell populations suitable for expansion and differentiation into osteoblasts, adipocytes, and osteoclasts.

Bone marrow stromal cells (BMSCs) constitute a cell population routinely used as a representation of mesenchymal stem cells in vitro. They reside within ...

Isolation and Characterization of Cardiac Mesenchymal Stromal Cells from Endomyocardial Bioptic Samples of Arrhythmogenic Cardiomyopathy Patients

A normal adult heart is composed of several different cell types, among which cardiac mesenchymal stromal cells represent an abundant population. The isolation of these cells offers the possibility of studying their involvement in cardiac diseases, and, in addition, provides a useful primary cell model to investigate biological mechanisms.
Here, the method for the isolation of C-MSC from arrhythmogenic cardiomyopathy patients&#39; bioptic samples is described. The endomyocardial biopsy sampling is guided in the right ventricular areas adjacent to the scar visualized by electro-anatomical mapping. The digestion of the biopsies in collagenase and their plating on a plastic dish in culture medium to allow C-MSC growth is described. The isolated cells can be expanded in culture for several passages. To confirm their mesenchymal phenotype, the description of immuno-phenotypical characterization is provided. C-MSC are able to differentiate into several cell types like adipocytes, chondrocytes, and osteoblasts: in the context of ACM, characterized by adipocyte deposits in patients&#39; hearts, the protocols for the adipogenic differentiation of C-MSC and the characterization of lipid droplet accumulation are described.

In this article, a method to isolate cardiac mesenchymal stromal cells from endomyocardial bioptic samples of arrhythmogenic cardiomyopathy patients is provided. Their characterization and the protocol to boost their adipogenic differentiation are described.

A normal adult heart is composed of several different cell types, among which cardiac mesenchymal stromal cells represent an abundant population. The ...