Imaging was carried out in the Indiana Center for Biological Microscopy at Indiana University, directed by Dr. Ken Dunn. The stereotaxic device is a prototype designed and made by Mark Soonpaa, Wells Center for Pediatric Research. This work was supported by NIH/R01DK097837-09 (NC), NIH/R01HL068256-05 (NC), NIH/NIDDK1U54DK106846-01 (NC), the MPN research Foundation (NC) and the CTSI Collaborative project IUSM/Notre Dame (NC).

All procedures involving the use of animals were performed with authorization of the Animal Care and Use Committee of Indiana University School of Medicine. Ensure to adhere to the legislation on animal experimentation of the country where the work is performed.
1. Preparation of Mx1CreRBPJ-/- Recipient Mice
<ol>
	<li>Cross Mx1-Cre+ mice with RBPJlox/lox mice10 to obtain Mx1-Cre positive RBPJlox/lox mic...

<ol>
	<li>Carlesso, N., Cardoso, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stem+cell+regulatory+niches+and+their+role+in+normal+and+malignant+hematopoiesis.">Stem cell regulatory niches and their role in normal and malignant hematopoiesis.</a> Curr Opin Hematol. 17 (4), 281-286 (2010).</li><li>Lo Celso, C., Scadden, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+haematopoietic+stem+cell+niche+at+a+glance.">The haematopoietic stem cell niche at a glance.</a> J Cell Sci. 124 (PT 21), 3529-3535 (2011).</li><li>Calvi, L. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoblastic+cells+regulate+the+haematopoietic+stem+cell+niche.">Osteoblastic cells regulate the haematopoietic stem cell niche.</a> Nature. 425 (6960), 841-846 (2003).</li><li>Kiel, M. J., Yilmaz, O. H., Iwashita, T., Terhorst, C., Morrison, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SLAM+family+receptors+distinguish+hematopoietic+stem+and+progenitor+cells+and+reveal+endothelial+niches+for+stem+cells.">SLAM family receptors distinguish hematopoietic stem and progenitor cells and reveal endothelial niches for stem cells.</a> Cell. 121 (7), 1109-1121 (2005).</li><li>Zhang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+the+haematopoietic+stem+cell+niche+and+control+of+the+niche+size.">Identification of the haematopoietic stem cell niche and control of the niche size.</a> Nature. 425 (6960), 836-841 (2003).</li><li>Mendez-Ferrer, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+and+haematopoietic+stem+cells+form+a+unique+bone+marrow+niche.">Mesenchymal and haematopoietic stem cells form a unique bone marrow niche.</a> Nature. 466 (7308), 829-834 (2010).</li><li>Naveiras, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone-marrow+adipocytes+as+negative+regulators+of+the+haematopoietic+microenvironment.">Bone-marrow adipocytes as negative regulators of the haematopoietic microenvironment.</a> Nature. 460 (7252), 259-263 (2009).</li><li>Scheiermann, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adrenergic+nerves+govern+circadian+leukocyte+recruitment+to+tissues.">Adrenergic nerves govern circadian leukocyte recruitment to tissues.</a> Immunity. 37 (2), 290-301 (2012).</li><li>Faust, N., Varas, F., Kelly, L. M., Heck, S., Graf, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insertion+of+enhanced+green+fluorescent+protein+into+the+lysozyme+gene+creates+mice+with+fluorescent+granulocytes+and+macrophages.">Insertion of enhanced green fluorescent protein into the lysozyme gene creates mice with fluorescent granulocytes and macrophages.</a> Blood. 96 (2), 716-726 (2000).</li><li>Han, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducible+gene+knockout+of+transcription+factor+recombination+signal+binding+protein-J+reveals+its+essential+role+in+T+versus+B+lineage+decision.">Inducible gene knockout of transcription factor recombination signal binding protein-J reveals its essential role in T versus B lineage decision.</a> Int Immunol. 14 (6), 637-645 (2002).</li><li>Lo Celso, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live-animal+tracking+of+individual+haematopoietic+stem/progenitor+cells+in+their+niche.">Live-animal tracking of individual haematopoietic stem/progenitor cells in their niche.</a> Nature. 457 (7225), 92-96 (2009).</li><li>Wang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Notch-dependent+repression+of+miR-155+in+the+bone+marrow+niche+regulates+hematopoiesis+in+an+NF-kappaB-dependent+manner.">Notch-dependent repression of miR-155 in the bone marrow niche regulates hematopoiesis in an NF-kappaB-dependent manner.</a> Cell Stem Cell. 15 (1), 51-65 (2014).</li><li>Miyamoto, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myeloid+or+lymphoid+promiscuity+as+a+critical+step+in+hematopoietic+lineage+commitment.">Myeloid or lymphoid promiscuity as a critical step in hematopoietic lineage commitment.</a> Dev Cell. 3 (1), 137-147 (2002).</li><li>Luc, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Down+Regulation+of+Mpl+marks+the+transition+to+lymphoid-primed+multipotent+progenitors+with+gradual+loss+of+granulocyte-monocyte+potential.">Down Regulation of Mpl marks the transition to lymphoid-primed multipotent progenitors with gradual loss of granulocyte-monocyte potential.</a> Blood. 111 (7), 3424-3434 (2008).</li><li>Suzuki, M., Moriguchi, T., Ohneda, K., Yamamoto, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+contribution+of+the+Gata1+gene+hematopoietic+enhancer+to+erythroid+differentiation.">Differential contribution of the Gata1 gene hematopoietic enhancer to erythroid differentiation.</a> Mol Cell Biol. 29 (5), 1163-1175 (2009).</li><li>Essers, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IFNalpha+activates+dormant+haematopoietic+stem+cells+in+vivo.">IFNalpha activates dormant haematopoietic stem cells in vivo.</a> Nature. 458 (7240), 904-908 (2009).</li><li>Pietras, E. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Re-entry+into+quiescence+protects+hematopoietic+stem+cells+from+the+killing+effect+of+chronic+exposure+to+type+I+interferons.">Re-entry into quiescence protects hematopoietic stem cells from the killing effect of chronic exposure to type I interferons.</a> J Exp Med. 211 (2), 245-262 (2014).</li><li>Scott, M. K., Akinduro, O., Lo Celso, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+4-dimensional+tracking+of+hematopoietic+stem+and+progenitor+cells+in+adult+mouse+calvarial+bone+marrow.">In vivo 4-dimensional tracking of hematopoietic stem and progenitor cells in adult mouse calvarial bone marrow.</a> J Vis Exp. (91), e51683 (2014).</li></ol>

The authors have nothing to disclose.

This protocol describes an experimental design optimized to study the kinetics of hematopoietic cells engraftment by Intravital Florescent Microscopy. In this study, the expansion of myeloid progenitor cells in a WT BM or in a Notch signaling defective BM was tracked in the bone calvarium by following Lys-GFP positive myeloid cells after BMT into RBPJWT or RBPJKO recipients. This approach is proposed as a model that can be applied to address similar questions, for example: i) to determine the expansion and localization i...

Intravital multiphoton fluorescence microscopy (IVFM) is a powerful imaging technique that allows for the high-resolution, real-time imaging of tissues with depth up to 1mm, depending on the tissue. When applied to the mouse calvarium, it permits observing the behavior of the hematopoietic cells within the BM in a non-invasive manner up to 60-100 &#956;m11. This approach is used here to determine the kinetics of engraftment of normal myeloid progenitors in the BM of RBPJ knock-out mice lacking canonical Notch signaling.
Recent work from our group demonstrated that defective canonical Notch signaling in the BM microenvironment leads to a myeloproliferative-like disease12. Loss of Notch signaling was obtained by conditional deletion of the DNA binding domain of RBPJ, the critical transcription factor downstream of canonical Notch signaling, using Mx1-Cre induced recombination10. In this study, the Mx1-Cre/RBPJlox/lox mice model was used. Conditional deletion of the DNA-binding motif of RBPJ results in the loss of signaling from all Notch receptors. In the Mx1-Cre model, Cre expression is driven by the Mx1 promoter activated upon administration of polyI:C resulting in the induction of targeted gene deletion in blood cells as well as in stromal components of multiple organs, including BM, spleen and liver.
Mx1-Cre+/RBPJlox/lox and Mx1-Cre-/RBPJlox/lox mice induced with polyI:C (hereon indicated as RBPJKO and RBPJWT, respectively) were lethally irradiated and transplanted with normal, wild type hematopoietic cells. Starting from week 4 after transplantation, RBPJKO recipients developed significant leukocytosis followed by splenomegaly. Although RBPJKO mice presented increased percentage of myeloid progenitors in the BM at week 8 after transplant and at later time points, analysis of BM at weeks 4 and 6 did not reveal striking differences in their myeloid cell content compared to control RBPJWT recipients. This observation, together with the fact that Mx1-Cre is expressed in different hematopoietic organs, raised the question whether the BM microenvironment had direct impact on the initiation of the myeloproliferative phenotype.
To determine whether the BM was a critical initial site of disease development, IVFM of the mouse calvarium was used in combination with BM transplantation (BMT), the RBPJ knock-out model, and a lineage tracking system. Transgenic mice expressing EGFP under the control of the specific lysozyme promoter (Lys-GFP)9 were used to obtain donor cells that could be visualized during BM imaging after BMT. Lysozyme expression is specific to myeloid cells and Lys-GFP marks cells from the common myeloid progenitor (CMP) to the mature granulocyte13.
IVFM of the BM at different time points demonstrated that Lys-GFP cells homed similarly to the BM of RBPJWT and RBPJKO recipients, but expanded and engrafted faster in the BM of RBPJKO recipients. This difference was dramatic at the earlier time point (week 2) and decreased over time (weeks 4 and 6). However, at these later time points, evaluation of the hematopoietic compartment in the same recipient showed a steady increase in the number of myeloid cells circulating in the PB and localized in the spleen of RBPJKO mice, indicating an increased output of cells from the BM into the circulation. Analysis of Lys-GFP cells localization in the BM of transplanted mice at 6 weeks revealed that myeloid cells were residing further from the vasculature in the RBPJKO microenvironment than in the control.
Collectively, the combination of IVFM with these specific animal models provided insights in the engraftment dynamics of myeloid cells in the RBPJKO BM microenvironment. The experimental design and quantitative approach described here is proposed as a paradigm that can be applied to address similar questions. For example, the use of other cell specific lineage tracking models, such as RAG1-GFP14 or Gata1-GFP15 mice, may allow following the behavior of lymphoid or erythroid progenitors, respectively, in the BM.

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			<td height="21" style="height:21px;width:216px;">Ketamine cocktail</td>
			<td style="width:167px;">IU School of Medicine</td>
			<td style="width:139px;"></td>
			<td style="width:511px;">Ketamine 90-100mg/kg, Xylazine 2.5-5.0 mg/kg, Acepromazine 1.0-2.5 mg/kg</td>
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			<td height="21" style="height:21px;width:216px;">TRITC dextran</td>
			<td style="width:167px;">Tdb Consultancy</td>
			<td style="width:139px;">TD150-100mg</td>
			<td>Other color dextran may be used.</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Andis hair trimmer</td>
			<td style="width:167px;">Braintree Scientific</td>
			<td style="width:139px;">CLP-323 75</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gauze sponge</td>
			<td style="width:167px;">Med Vet International</td>
			<td style="width:139px;">PK224</td>
			<td>4-ply, 2X2</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Nair depilatory cream</td>
			<td style="width:167px;">Commercial store</td>
			<td style="width:139px;"></td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Saline</td>
			<td style="width:167px;">Med Vet International</td>
			<td style="width:139px;">RXSAL-POD1LT</td>
			<td>0.9% Sodium Chloride poly bottle</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Insulin syringe</td>
			<td style="width:167px;">Fisher Scientific</td>
			<td style="width:139px;">14-826-79</td>
			<td>28g, 1/2cc</td>
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		<tr height="26">
			<td height="26" style="height:26px;width:216px;">Fine Forceps</td>
			<td style="width:167px;">Fine Science Tools</td>
			<td style="width:139px;">00108-11, 00109-11</td>
			<td>straight forcep, angled forcep</td>
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			<td height="21" style="height:21px;width:216px;">Scissor</td>
			<td style="width:167px;">Fine Science Tools</td>
			<td style="width:139px;">15018-10</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Needle holder</td>
			<td style="width:167px;">Fine Science Tools</td>
			<td style="width:139px;">12002-14</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">5-0 silk suture</td>
			<td style="width:167px;">Fisher Scientific</td>
			<td style="width:139px;">MV-682</td>
			<td>Other non-absorbable suture may be used</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">WillCo- glass bottom dish</td>
			<td style="width:167px;">WillCo</td>
			<td style="width:139px;">GWSt-5040</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical microscope oil</td>
			<td style="width:167px;">Leica</td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Stereotaxic stage insert&#160;</td>
			<td style="width:167px;">IU School of Medicine</td>
			<td style="width:139px;">Custom design</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Olympus FV1000 confocal microscope system&#160;</td>
			<td style="width:167px;">Olympus</td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Olympus XLUMPLFL 20xW, NA 0.95 objective&#160;</td>
			<td style="width:167px;">Olympus</td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Small heating pad</td>
			<td style="width:167px;">Commercial store</td>
			<td style="width:139px;"></td>
			<td>Zoo Med reptile heating pad</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Imaris 8.1 imaging software</td>
			<td style="width:167px;">Bitplane</td>
			<td style="width:139px;"></td>
			<td>3/4 D Image Visualization and Analysis software</td>
		</tr>
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combining intravital fluorescent microscopy (ivfm) with genetic models to study engraftment dynamics of hematopoietic cells to bone marrow niches

Increasing evidence indicates that normal hematopoiesis is regulated by distinct microenvironmental cues in the BM, which include specialized cellular niches modulating critical hematopoietic stem cell (HSC) functions1,2. Indeed, a more detailed picture of the hematopoietic microenvironment is now emerging, in which the endosteal and the endothelial niches form functional units for the regulation of normal HSC and their progeny3,4,5. New studies have revealed the importance of perivascular cells, adipocytes and neuronal cells in maintaining and regulating HSC function6,7,8. Furthermore, there is evidence that cells from different lineages, i.e. myeloid and lymphoid cells, home and reside in specific niches within the BM microenvironment. However, a complete mapping of the BM microenvironment and its occupants is still in progress.
Transgenic mouse strains expressing lineage specific fluorescent markers or mice genetically engineered to lack selected molecules in specific cells of the BM niche are now available. Knock-out and lineage tracking models, in combination with transplantation approaches, provide the opportunity to refine the knowledge on the role of specific &#34;niche&#34; cells for defined hematopoietic populations, such as HSC, B-cells, T-cells, myeloid cells and erythroid cells. This strategy can be further potentiated by merging the use of two-photon microscopy of the calvarium. By providing in vivo high resolution imaging and 3-D rendering of the BM calvarium, we can now determine precisely the location where specific hematopoietic subsets home in the BM and evaluate the kinetics of their expansion over time. Here, Lys-GFP transgenic mice (marking myeloid cells)9 and RBPJ knock-out mice (lacking canonical Notch signaling)10 are used in combination with IVFM to determine the engraftment of myeloid cells to a Notch defective BM microenvironment.

Cohorts of 2 RBPJKO and 2 RBPJWT recipients were imaged in an individual imaging session at different time points: 24 h and 2, 4 and 6 weeks after transplantation of BM Lys-GFP cells (workflow is illustrated in Figure 1A).
In each mouse, images were acquired from 6 standard regions of the BM calvarium, identified by their position in relation to the bifurcation of the central vein (Figure 2A, <s...

Watch this Scientific Journal Video about Combining Intravital Fluorescent Microscopy IVFM with Genetic Models to Study Engraftment Dynamics of Hematopoietic Cells to Bone Marrow Niches at JoVE.com

Combining Intravital Fluorescent Microscopy IVFM with Genetic Models to Study Engraftment Dynamics of Hematopoietic Cells to Bone Marrow Niches

Intravital fluorescence microscopy (IVFM) of the calvarium is applied in combination with genetic animal models to study the homing and engraftment of hematopoietic cells into bone marrow (BM) niches.

Combining Intravital Fluorescent Microscopy (IVFM) with Genetic Models to Study Engraftment Dynamics of Hematopoietic Cells to Bone Marrow Niches

Increasing evidence indicates that normal hematopoiesis is regulated by distinct microenvironmental cues in the BM, which include specialized cellular ...

The overall goal of this procedure is to visualize and measure the in vivo engraftment of transplanted blood cells to recipient bone marrow niches. The main advantage of this technique is that it allows visualization of cellular processes like homing, expansion, and localization to different bone marrow niches of donor hematopoietic cells following transplantation. Used in combination with the engineered animal models, this approach can help in defining molecular pathways critical for hematopoietic cell regeneration.Unlike histology or other imaging techniques, intravital microscopy allows capturing cell-to-cell interactions in a live animal on a cellular level and in real time. We decided to use this method to determine whether the bone marrow microenvironment was the initial site of the development of the myeloproliferative disease caused by loss of Notch signaling. Challenges for individuals new to this technique include minimizing breathing artifact, optimally positioning and stabilizing the head and avoiding image saturation.One to two hours before the transplant, spray a lysed EGFP mouse with 70%ethanol. Next, use surgical scissors to make an incision in the skin of each leg around the ankle and surgical forceps to remove the skin and fur together to expose the clean muscle tissue. Remove as much muscle from the legs as possible.Then cut the bones at the knee and ankle joints and use gauze sponges to remove any remaining muscle tissue from the femurs and tibias. Rinse the cleaned bones in a six-well plate containing DMEM supplemented with 10%FBS. Then transfer all four hind leg bones into 10 milliliters of cold EDTA in PBS into a mortar and crush the bones with a pestle.Triturate the bone marrow cells to obtain a single-cell suspension and strain the slurry through a 70 micron filter into a 15 milliliter centrifuge tube. Rinse the filter with two to three milliliters of PBS. Then centrifuge the cells and resuspend the pellet in 10 milliliters of fresh DMEM plus 10%FBS.For the injection, centrifuge the cell suspension then count and adjust the concentration of cells to 1.5 times 10 to the seventh cells per milliliter in IMDM without serum. Place the cells on ice. Five to six hours after the second dose of radiation, inject three times 10 to the sixth bone marrow cells into the tail vein of each radiated recipient animal.Add the appropriate time point post-transplantation. Place the anesthetized recipient mouse onto a 37 degrees Celsius heating pad and confirm a lack of response to toe pinch. Apply ointment to the animal's eyes and administer 100 microliters of the appropriate fluorescent marker via the tail vein.Next, use small electric clippers to remove the hair from the dorsal surface of the animal's head, followed by the application of a depilatory cream. After five minutes, remove the cream with gauze sponges and rinse off any remaining solution with saline. Disinfect the scalp with a 70%ethanol soaked cotton swab.Then use fine forceps and scissors to make a 10 to 20 millimeter midline skin incision on the scalp to expose the underlying dorsal skull surface. Using 5-0 surgical silk, place two stay sutures on each side of the incision creating a flap to expose the calvarium for imaging. Apply a droplet of oil on the exposed skull.With the mouse in the supine position, submerge the exposed scalp in a glass bottom dish filled with microscope oil. Then place the animal on a multiphoton imaging stage with the calvarium above the objective and cover the animal with a 37 degrees Celsius heating pad. It is essential that the head remain stabilized in the correct position during the multiphoton image acquisition.Use a stereotactic device or secure the mouse with tape as appropriate. Using an inverted confocal system modified for multiphoton imaging, tune the two photon laser to 830 nanometers. Next, open the appropriate image acquisition software.Under the acquisition settings menu, confirm that the one directional scanning mode is selected and set the scanning speed to four microseconds per pixel, the frame rate to 512 by 512 pixels and the zoom to 1.5. Select the 20X watt in a 0.95 objective. Open the dye list window and select two photon.Then select the RDM690 mirror in the microscope controller window. In the light path and dice window, select the laser unit two box to check if the two photon laser shutter is open. Select EPI Lamp and choose the B/G EPI filter cube.Then focus the objective on the specimen to visualize the vascular flow in the calvarium bone marrow niche, using the bifurcation of the central vein and the coronary suture as reference points. Using the non-descanned mode, select three external detectors and image the specimen at a scan rate of four microseconds per pixel with no averaging and a constant laser power and detector gain to utilize the full dynamic range of the detector with a minimal saturation. After collecting a series of sections through the depth of the tissue, open the appropriate dedicated 3 to 4D image quantitation and visualization software.Interactively visualize the Z stacks using the appropriate 3D rendering algorithm according to the manufacturer's instructions. Then use the spot object segmentation module to segment the GFP cells and apply stack arithmetic processing to eliminate the false positive GFP cells in the green and red channels. Finally, use the surface segmentation module to reform the segmentation of the vasculature and bone surface, applying X tension distance of spot to surface algorithms to calculate the distances of the cells to any of the distal surfaces as necessary.Here, Z stacks collected from each of the six standard regions of the bone marrow calvarium were rendered as 3D maximal intensity projection, 3D shadow projection including the bone component, and 3D segmented images, allowing quantitation of the cells and the measurement of their distances from the bone and vessels. In this experiment, in vivo imaging of myeloid cells in the Notch-defective bone marrow microenvironment revealed that donor lysed GFP cells have a similar homing efficiency in the wild type and knockout recipients at 24 hours after transplant while they exhibit different engraftment at later time points. Analysis of the dynamics of myeloid progenitor expansion showed that adaptively bone marrow transplanted cells expanded more rapidly and in greater numbers in knockout recipients at two weeks after transplant.The donor bone marrow cells in wild type recipients expanded later but in two-fold higher numbers than the donor cells and knockout recipients at four weeks, a time where donor cells in the knockout bone marrow are decreased because it's going rapidly into circulation. And that by six weeks, the differences in the number of donor cells in the bone marrow calvarium level out. Further, 3D segmentation analysis of the lower middle region of knockout and wild type calvaria at six weeks post-bone marrow transplant indicates that the lysed GFP cells localized at the same distance from the bone in both types of recipient animals, but interestingly, they reside more distantly from the vasculature in the knockout mice.Once mastered, the intravital bone marrow imaging can be completed in one hour and 30 minutes per mouse if performed properly. While using this approach, it's important to remember to sample multiple areas of the bone marrow of the calvarium per mouse and to analyze at least three mice per experiment to address any intra and inter sample variations. After watching this video, you should have a good understanding of how to combine bone marrow transplantation and the intravital imaging to determine the kinetics of the engraftment of specific blood subpopulation to the bone marrow microenvironment.

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7.8K Görüntüleme.  Indiana University School of Medicine. The overall goal of this procedure is to visualize and measure the in vivo engraftment of transplanted blood cells to recipient bone marrow niches. The main advantage of this technique is that it allows visualization of cellular processes like homing, expansion, and localization to different bone marrow niches of donor hematopoietic cells following transplantation. Used in combination with the engineered animal models, this approach can help in defining molecular pathways critical for hematop...