CD82/KAI1 Maintains the Dormancy of Long-Term Hematopoietic Stem Cells through Interaction with DARC- Expressing Macrophages

Hematopoiesis is regulated by crosstalk between long-term repopulating hematopoietic stem cells (LT-HSCs) and supporting niche cells in the bone marrow (BM). Here, we examine the role of CD82/ KAI1 in niche-mediated LT-HSC maintenance. We found that CD82/ KAI1 is expressed predominantly on LT-HSCs and rarely on other hematopoietic stem-progenitor cells (HSPCs). In Cd82 +/-/+/- mice, LTHSCs were selectively lost as they exited from quiescence and differentiated. Mechanistically, CD82based TGF-b1/ Smad3 signaling leads to induction of CDK inhibitors and cell-cycle inhibition. The CD82 binding partner DARC/ CD234 is expressed on macrophages and stabilizes CD82 on LT-HSCs, promoting their quiescence. When DARC + BMmacrophages were ablated, the level of surface CD82 on LT-HSCs decreased, leading to cell-cycle entry, proliferation, and differentiation. A similar interaction appears to be relevant for human HSPCs. Thus, CD82 is a functional surface marker of LT-HSCs that maintains quiescence through interaction with DARC-expressing macrophages in the BM stem cell niche.113525Ysciescopu

Laparoendoscopic Single-Site Nephrectomy Using a Modified

∙ The authors have no financial conflicts of interest. Purpose: To assess the clinical utility of laparoendoscopic single-site surgery (LESS) nephrectomy using a modified umbilical incision and home-made transumbilical port in cases requiring extirpative surgery. Materials and Methods: Initial consecutive 18 patients underwent LESS nephrectomies that were performed by a single surgeon. A home-made port was placed through a modified umbilical incision, the length of which had preoperatively been determined. The laparoscopic transperitoneal nephrectomy procedures were performed with various combinations of standard and articulating laparoscopic instruments. Patient characteristics and perioperative outcomes, including pathologic results, were recorded prospectively. Results: All 18 extirpative surgeries, including simple nephrectomy (eight cases), radical nephrectomy (nine cases), and nephroureterectomy (one case), were completed successfully. The median operation time was 167 min (range 82-220), and the median blood loss was 250 mL (range 0-1050). All specimens were extracte