Abstract: The use of individual or combinations of cytokines, particularly IL-3, GM-CSF, and c-kit ligand are employed for long-term hematopoiesis in serum free culture in the absence of stromal cells. The cultures can be used for evaluating compounds and their effect on hematopoiesis, particularly as to lifetime and nature of differentiation. In addition, the expanded cells may be used for engraftment in a mammalian host or enhancement of particular cell lineages in a mammalian host. The subject systems may be used with any mammalian hemopoietic cells, but finds particular application with primates, more particularly humans.

Abstract: Disclosed are human pluripotent hematopoietic stem cell (PHSC) enriched compositions and methods for obtaining and using the compositions. A substantially homogeneous population of human hematopoietic cells characterized as CD34.sup.+, HLA-DR.sup.-, and c-kit receptor positive (KR.sup.+) and capable of in vitro self-renewal and differentiation to members of at least the erythroid, myeloid, and megakaryocytic lineages, is obtained by separating the population from a cellular mixture, for example by cytometric cell sorting techniques. Also disclosed is a method of obtaining persistent maintenance of grafted human hematopoietic cells in a mammal, which includes grafting a mammal in utero with a cellular composition enriched in human hematopoietic cells characterized as CD34.sup.+, HLA-DR.sup.- and capable of in vitro self-renewal and differentiation to members of the lymphoid, myeloid, erythroid and megakaryocytic lineages.

Abstract: A process for supporting hematopoietic progenitor cells in a culture medium which contains at least one cytokine effective for supporting the cells, and preferably, is essentially free of stromal cells.

Abstract: Surgical needles are attached to sutures with controlled pull-out characteristics by a short crimp--that is a crimp whose length is markedly less than the length of the end of the suture in the needle; with an essentially undistorted portion of the needle adjacent to where the suture emerges from the needle, and an essentially undistorted portion around the front of the suture, so that only a short section of the needle is crimped around the suture. This leaves the suture uncrushed where it emerges from the needle and hence of superior strength where sharp bends occur during use. It also leaves an undistorted portion of the suture ahead of the crimp so that on pull-out, the suture is retained not only by frictional engagement of the crimp but also by the forces required for the distortion of the head of the suture so that it will pull through the reduced section of the crimp.

Abstract: Surgical needles are attached to sutures with controlled pull-out characteristics by a short crimp--that is a crimp whose length is markedly less than the length of the end of the suture in the needle; with an essentially undistorted portion of the needle adjacent to where the suture emerges from the needle, and an essentially undistorted portion around the front of the suture, so that only a short section of the needle is crimped around the suture. This leaves the suture uncrushed where it emerges from the needle and hence of superior strength where sharp bends occur during use. It also leaves an undistorted portion of the suture ahead of the crimp so that on pull-out, the suture is retained not only by frictional engagement of the crimp but also by the forces required for the distortion of the head of the suture so that it will pull through the reduced section of the crimp.