Clin Res Cardiol 101, Suppl 1, April 2012

V1084 - The role of the integrin activator kindlin3 in the homing process of haematopoetic stem- and progenitor cells (HSPC) into the murine bone marrow
M. Orban1, R. Ruppert2, S. Longhi1, J. Schneider1, A. Suhr1, A. Tirniceriu1, M. Moser2, R. Fässler3, S. Massberg1
1Klinik für Herz- und Kreislauferkrankungen im Erwachsenenalter, Deutsches Herzzentrum München, München; 2Abteilung für Molekulare Medizin, MPI für Biochemie, München; 3Abteilung für Molekulare Medizin, Max-Plank-Institut für Biochemie, München;
Background: Bone marrow (BM)-derived hematopoietic stem and progenitor cells (HSPCs) are mobilized to the blood in response to tissue damage such as myocardial infarction. Blood-borne HSPCs can either migrate into peripheral tissues or return to the BM compartment. However, the mechanisms that control this remigration of blood-borne HSPCs to the BM are incompletely understood. The integrin adapter protein kindlin3 (kind3) acts as an activator of the HSPC integrin ß1, which is essential in the trafficking of mature immune cells. Here, we used a novel model of intravital two photon microscopy to analyze the role of kind3 for all sequential steps involved in the dynamic process of HSPC BM homing.  
Methods: Murine lin- c-kit+ sca-1+ (KSL) HSPC were isolated from kind3+/+ and kind3-/- BM chimaeras via FACS Sorting. Subsequently, HSPCs were fluorescently labeled with the long-term cell tracker CMTMR (red fluorescence) and infused into the BM microcirculation. Transgenic mice in which green fluorescent protein (GFP) is expressed by osteoblasts, the putative niche cells, were used as recipients. The different steps of HSPC homing, including initial contact with the bone marrow endothelium as well as the subsequent steps of interstitial migration, enlodgement in the niche and the behavior within the niche were analyzed by 2-photon in vivo imaging.
Results: After injection into the BM microcirculation, kind3+/+ and kind3-/- KSL cells are capable of rolling on BM endothelium in the initial phase of homing. The rate of firm arrest and intravascular crawling/migration of kind3-/- KSL cells is significantly lower compared to kind3+/+ KSL cells (reduced by 91%)‏. Eighteen hours after cell transfer, the number of KSL cells that migrated into the BM interstitium was reduced by 80% with kind3-/- as compared to kind3+/+‏. Interstitial velocity of kind3-/- KSL cells was increased by approximately 60% compared to kind3+/+ KSL cells. Kind3-/- KSL cells migrated closer to the endosteum during their migratory route within the BM interstitium compared to kind3+/+ KSL cells, whereas the localization with regards to the vessels did not differ between kind3-/- KSL cells and kind3+/+ KSL cells.
Conclusions: We established a novel in vivo model allowing for real-time analysis of the role of the integrin adapter protein kind3 for HSPC homing to the BM. Lack of kind3 in HSPC was associated with a severe impairment of KSL adhesion and transendothalial migration. Hence, our results identify a novel role of the integrin adapter kind3 in the homing of HSPCs to the BM compartment.
Clin Res Cardiol 101, Suppl 1, April 2012
Zitierung mit Vortrags- oder Posternummer s.o.
DOI 10.1007/s00392-012-1100-6