2 NEW PSEUDOPOD MORPHOLOGIES DISPLAYED BY THE HUMAN HEMATOPOIETIC KG1A PROGENITOR-CELL LINE AND BY PRIMARY HUMAN CD34(+) CELLS

A primitive human hematopoietic myeloid progenitor cell line, KG1a, ch aracterized by high expression of the CD34 surface antigen has been ob served to extend long, thin pseudopodia. Once extended, these pseudopo ds may take on one of two newly described morphologies. tenupodia or m agnupodia. Tenupodia are very thin and form in linear segments. They a dhere to the substrate, can bifurcate multiple times, and often appear to connect the membranes of cells more than 300 mu m apart. Magnupodi a are much thicker and have been observed to extend more than 330 mu m away from the cell. Magnupods are flexible and can exhibit rapid dyna mic motion, extending or retracting in a few seconds. During retractio n, the extended material often pools into a bulb located on the pod. B oth morphologies can adhere to substrates coated with fibronectin. col lagen IV, and laminin as well as plastic. The CD34 and CD44 antigens a re also present on the surface of these podia. Primary human CD34(+) c ells from fetal liver, umbilical cord blood, adult bone marrow, and mo bilized peripheral blood extend these podia as well. The morphology th at these pseudopods exhibit suggest that they may play both sensory an d mechanical roles during cell migration and homing after bone marrow transplantation. (C) 1998 by The American Society of Hematology..