ULTRASTRUCTURAL-STUDY ON THE IN-VITRO INTERACTION BETWEEN HEMATOPOIETIC-CELLS AND STROMAL CELLS - A NEW METHOD USING GEL TECHNIQUE

The ultrastructural study of the interaction between stroma and haemop oiesis is not an easy task because the loose attachment may be damaged during manipulation. This paper describes a technique by which the lo ose connection between preestablished stromal layer and attached haemo poietic cells (derived from blast colony forming cells) can be preserv ed and studied ultrastructurally. Stromal cultures were obtained from human bone marrow cells. Blast colony forming cells were studied by co -incubating the stroma with fetal calf serum supplemented McCoy's medi um containing bovine plasma, thrombin and calcium to form a gel ('plas ma clot'). Colony formers attached to the stroma formed myeloid coloni es within 6 days. The semisolid plasma clot which solidifiers rapidly on the addition of glutaraldehyde or formaldehyde entraps the blastic colonies and haemopoietic cells in their position; Even the non-attach ed or mobile cells can be entrapped by this technique. The immature ce lls were found to be attached to the stromal surface and/or to the ext racellular matrix, while the more mature cells migrated either to the surface of the colony or attached to the non-covered areas of the plas tic surface. This method may offer a special technique to study dynami c interactions in other situations (e.g. chemotaxis etc.), too.